**We went through a meteorological time machine this year. You experienced the meteorology of 25-50 years into the future.** For example, we have lived through a summer with the snowpack expected in 2050. The second-lowest snowpack over the past decades. **Let me prove this to you.** Below is a plot of Pacific Northwest snowpack on April 1 (after the winter accumulation season) since 1984. Wow, we had the second-lowest snowpack in over 40 years. Roughly 50% of normal. **When would we expect such a reduction in snow based on global warming?** Let us assume the RCP 4.5 global warming scenario, which is typically used by the research community these days. Under this scenario, here are the April 1 snowpack predictions for the Puget Sound region. Snowpack doesn't decline to as much as this year until the end of the century! Same thing for the entire Pacific Northwest: So this year provides a taste of the snowpack in roughly 75 years into the future, assuming nothing major is done about greenhouse gas emissions. **What about temperatures?** As shown below, it was much warmer than normal tduring the past year, roughly 2-4 F above normal in much of the area! Again, comparing to a regional climate simulation, this is like being transported in time to around 2050. ** This meteorological time travel is exhausting!** The last year has experienced conditions that will be typical during the middle to latter parts of this century if global warming increases without change. _ _ _Now the controversial part of this blog. _ **Those suggesting that such warming represents the end of the world and an acute threat to our survival are simply wrong.** There was sufficient water for human consumption (see Lake Roosevelt Level behind Grand Coulee Dam below) Blue is this year, red is average Regional agriculture has done well, with most crops near normal. Forest fire areas were modest, with most of the fires being in grass/range vegetation (which is little influenced by climate change). Those claiming the climatological sky was falling were simply wrong. **We need to do what we can to mitigate global warming, but it is not an emergency or an acute threat to humanity.** **Announcement** I will hold a special online Zoom session at 10 AM on Sunday for Patreon supporters. I plan to talk about the extended range forecasts and the strange conditions often apparent on super el nino years.

When air approaches a mountain barrier, it is forced to rise and, in doing so, cools. As the air cools, it has less ability to "hold" water vapor, and eventually the air becomes saturated, producing clouds and precipitation. On the lee side of the barrier, the air sinks and warms by compression, causing the relative humidity to drop, causing clouds to evaporate and ending any chance of precipitation This dry area on the downstream side of terrain is called a**rain shadow.** Washington State is "blessed" with world-class rain shadows...one on the downslope (eastern) side of the Olympics and the other to the west of the Cascades. According to all the AI queries I made, Washington has the most profound rain shadows around (see sample below). **This week was a great example.** On Monday, there was a potent atmospheric river of massive amounts of water vapor approaching Washington from the west. As a result, the western side of local terrain experienced heavy precipitation, but the mountains produced a profound rain shadow downstream (see the precipitation totals over the past 72 h below). 3.5 inches on the windward (western) slopes of the Olympics and 0.04 inches on the lee (northeast) side of the barrier. Wow. That's roughly 85 times more on one side than the other. Mama Mia! That is a spicy rain shadow. Here is a close-in look at the rain shadow action. No wonder some folks like living in Port Townsend and Sequim! On Tuesday morning, the rain shadow was very apparent in the visible satellite image: And the weather radars showed the profound impacts on rainfall. Very nice rain shadow. Some precipitation is coming in on Friday, but most of the precipitation and rain shadow action during the next few days will be over British Columbia: Be proud.... one online source event even provided us with a medal! ** ** **__________________________________________** ** ** **You are invited to attend a very interesting weather lecture for the general public on the UW campus. Open to the general public!** **Title:** What I Have Learned from Flying Through the Clouds **Speaker:** Armin Sorooshian, The University of Arizona **Date:** Thursday, October 8, 2026 **Time:** 7:00pm - 8:30pm **Location:** Kane Hall 220 To register, use this link: https://forms.gle/S5xWHUWhrqzexKtH9 _Abstract_ What is it like to fly through clouds in the name of science? And why should we even fly expensive aircraft filled with scientific instruments in and out of clouds? Aside from their natural beauty and ability to invoke our imagination, clouds play a critical role in regulating Earth's climate, influencing precipitation, and affecting air quality. A necessary ingredient to make clouds is particles (e.g., dust, smoke). This talk will describe (with a lot of visuals) what it is like to spend hundreds of hours in the back of various types of airplanes flying in and out of clouds. Stories and examples will highlight the importance of this type of work for reasons ranging from public health to visibility and climate change.

**The first significant atmospheric river of autumn has arrived.** The satellite imagery tonight is impressive. For example, consider the water vapor image from the NOAA GOES-West satellite. A magnificent moisture plume from the Central Pacific into our region. Here is another. The forecast of the **transport of water vapor** by the European Center model for tonight at 10 PM is shown below. The atmospheric river is moving huge amounts of water vapor into the Pacific Northwest, with the center of the plume directed to the northern Olympics and southern Vancouver Island. The plume of moisture will be forced to rise by our regional terrain, producing substantial windward precipitation. Below is the prediction of the total precipitation through 5 AM Wednesday (from the European Center forecast). Southern BC and northern WA get hit hard. **The UW, ultra-high-resolution forecast for the same period shows the details (below).** As much as 3-5 inches on the western slopes of the Olympics and central/northern Cascades. Substantial amounts reach the eastern slopes of the Cascades. Nice rain shadow over central Puget Sound. I bet I can get away with biking to the UW tomorrow! If you had refrained from watering your garden... go ahead. Probably time to find your umbrella as well. September will end up with normal precipitation for most of the region.

**Now that we have entered fall, it is time to evaluate whether our summer weather was unusual.** Are summers getting warmer or drier in Washington State? Starting with the overall view for the entire state, below is the July 1-Sept 26 precipitation difference from normal. A complex pattern. The western slope of the Cascades (where there was little fire) was drier than normal, while the eastern slopes (with more fire than normal) were WETTER than normal. The majority of the state was near normal for temperature (light green or yellow below), with a few areas a bit above normal In short, not an exceptional summer period for temperature and precipitation. **What about the long-term trends in summer temperatures?** Average daily temperatures have risen over the past 70 years at Hoquiam, Olympia, Yakima, and Spokane by about 2-3.5 F over the period. In contrast, the trend in daily high (max) temperatures has been very small west of the Cascades, and about 4F at Yakima and 1°F at Spokane. Finally, for precipitation, there is modest summer drying in the west and a small downward trend east of the Cascades. But there is very little precipitation during the summer in any case. Fortunately, there is no overall downward trend in annual precipitation, so the region should be ok with its water supply. **The bottom line of this blog.** This summer was not that unusual for temperature and precipitation in Washington State (but there was an unusual lightning event in July). The region is slowly warming, although high temperature extremes are hardly changing. Annual precipitation is steady, but our dry summers are getting slightly drier.

**As the models predicted, a strong storm with powerful winds is moving across our region, and nearly 100,000 customers are without power as I write this blog.** The radar imagery has been stunning. At 7:30 AM, a well-defined low center (red arrow) was on the coast near the Columbia River. And by 10 AM, the low was moving inland Maximum winds so far today (through 10 AM) have been substantial over northern Oregon and southern Washington, with many locations getting to 50 mph. Up to 54 mph in Olympia and several reaching 70 mph. Early-season strong winds inevitably mean lots of power outages, with trees being untested and still with lots of leaves. Right now, at 11:30 AM, about 71,000 customers have lost power in Washington, with more in Oregon, and the event is not over. The latest European Center forecast suggests the strong winds, and thus power outages, will remain south of downtown Seattle. Finally, the winds last night at Mt. Rainier's slope around 10,000 ft (Camp Muir), with gusts up to 101 mph: This is the result of the strong upper-level low associated with this storm (see map at 700 hPa pressure, about 10,000 ft, for this morning). Not a good time for an ascent. 😁 _______________________________________ Link

**Autumn began yesterday at 5 PM and the atmosphere has taken notice.** A significant midlatitude cyclone will cross the northern Oregon coast late Thursday and Friday morning, **bringing strong winds and localized power outages.** Consider the UW WRF model forecast for Friday morning at 5 AM (sea level pressure and maximum wind gusts are shown below). **Wow**. A very intense, but small, low-pressure center will make landfall on the northern Oregon Coast, with gusts up to 70 knots. Plotting the maximum wind gusts over time for this event (below) indicates the northern Oregon Coast will get a direct hit with winds reaching 50 knots. This early in the season, **this means power outages.** Other weather prediction systems are doing the same thing. The excellent European Center model has a similar maximum wind swath. (The graphic below is in mph). Seattle only gets some modest gusts. The simulated satellite imagery for Thursday evening indicates an impressive system (the arrow points to the low center). Looks like midwinter! Precipitation totals from this system will be substantial, with the mountains and the coast getting several inches (see below). Even eastern Washington gets substantial rain. All good for terminating the wildfire season and providing agriculture with a nice wetting rain. Reservoirs will gain valuable water. **I am concerned about the lack of coastal wind warnings by the National Weather Service offices in Seattle and Portland (see their latest forecast graphics below).** They really need to have some kind of warning out for the northern Oregon coast. I could comment on issues with National Weather Service forecasts, but I will leave that to another time. ____________________________________________ Finally, someone emailed me about a good book on Northwest Weather. Well, I do know one 😉 Link

**We are now at the peak of the bird migration season, and weather radar does a good job of tracking our feathered friends.** The massive bird swarms over us now are a powerful tool for determining gaps in weather radar coverage. Let's examine the regional radar imagery in more detail. As some background, here are some weather radar-based bird migration statistics (from the Cornell BirdCast website). Birds like to fly from sunset to sunrise, with a peak around midnight/ And we are nearly at the peak time of the year for the southward migration. At 5 PM yesterday, the combined radar image showed was just some local ground clutter. The situation was very different at 9 PM, with the birds in flight (below). The birds don't like to fly offshore. **But over land, there are clearly major radar gaps, such as the southern Oregon Coast, larger areas of north-central Washington, and much of eastern Washington**. Similar story around 3 AM today. And this morning at 8 AM, the bird signal is gone, with just some ground returns. The current weather radar locations are shown below with blue dots. Suggested locations for new radars are shown by the red circles. Additional radars would be very helpful for weather prediction and other uses (e.g., wildfire management, flood warnings, and more).

We are now in the time of year with the lowest electricity demand in the Pacific Northwest, driven by our meteorology (see below). The major peak occurs in winter, when electricity is needed to heat homes and buildings. There is a minor peak in mid-summer, driven by air conditioner use. With mild temperatures over the region, the demand for electricity is at a minimum during early to mid-September. **Everyone wants to maximize the use of renewable energy, such as wind and solar, so how well do they match the demand noted above?** To help answer this question, below is a plot of wind power generation for the Northwest (solar is at the noise level). A maximum in spring and a minimum in August. This makes sense meteorologically since most of our wind turbines are east of the Cascades, mainly on the lower slopes (e.g., Ellensburg area) or downwind of the Columbia Gorge. **Why this annual variation?** The difference in pressure across the Cascades, which drives the westerly winds, is largest in spring because the temperature difference across the Cascades is largest then, with eastern WA/Oregin heating up more rapidly than coastal areas. Differences in temperature drive differences in pressure, which drive the winds that produce power. **So what about the situation this year?** To find out, I downloaded the Bonaville Power Administration (BPA) numbers for total electrical demand (load, blue) and the total from wind and solar generation (red). The graphics are below. Renewable energy (mainly wind) generally has a huge amount of day-to-day variability, often declining to near zero and rarely getting to 50% of the load. Sometimes, it remains nearly zero for weeks, as in last January. **How do we make up the difference between renewables and the demand? Mainly hydropower, which our region is blessed with.** The detailed plot for the last week illustrated the collapse of renewables (again mainly wind)---even below our very limited nuclear power (purple line). Demand (red line) varies substantially over the day, but hydro is sufficiently flexible to provide the necessary power throughout the day. One thing is very, very clear. If we want to have the energy needed for growth, electric cars. and server farms, wind energy and solar are inadequate to be the solution for the Northwest. We need nuclear power.

For much of this year, some in the media and online have warned about drought and heat, **predicting serious negative consequences for Washington State agriculture.** The Drought Monitor website, often quoted in the press, has drought, some extreme, over eastern Washington. The site warns of substantial negative impacts! The headlines in many outlets have been apocalyptic; here are just a few: **The truth is very different from these scary predictions.** _There was sufficient water for agriculture this year._ _Harvests are near normal and in some cases above normal._ Let me prove this to you. Washington wheat yields in 2026 will be 20% ABOVE normal. The barley harvest? 97% of normal this year! The very important apple crop? Very good news! It is estimated to be down only 2% from last year's **record-breaking harvest** (see below), and forecasts call for exceptional quality. I look forward to the crunch of a good apple! ** Cherries?** They suffered a bit from a spring **cold wave****,** resulting in a decline of around 15% in volume. However, the industry reports that fruit quality, size, and flavor have remained exceptional throughout the season, and prices have remained favorable for the growers. I would go on, but you get the message: **this year has been a very decent year for Washington State agriculture.** The scary claims of major drought, wildfire, lack of snowpack, and global warming impacts were clearly not true. One reason eastern Washington agriculture did so well was that there was sufficient water. The water levels behind the Columbia's Grand Coulee Dam this year (blue line) were close to normal (red line). Elevation Level Behind the Grand Coulee Dam The Yakima Reservoir started well above normal in spring and ended ABOVE last year and modestly below normal. Sufficient water for normal agricultural operations in the Yakima Valley. Heavy rains and relatively cool temperatures of the past two weeks have caused surface soils and fuel moisture levels to increase greatly over the lowlands of eastern Washington. (See example below; the thick red line is observed, the gray area is the normal range.) The bottom line is that Washington State agriculture is in very good shape this year, with the Chicken Little predictions proving to be false. _ _

**With the recent rain and cooling, the wildfire season is essentially over for the Pacific Northwest.** In terms of acreage, 2026 has been one of the most prolific wildfire years of the past decades. Considering the past 50 years,**** it was the leading wildfire year in Oregon and number two or three in Washington State. Most of the major fires were started by a limited number of lightning "storms". **But now, the key point.** _The great majority of the wildfire acreage occurred in grass and range vegetation, not forests._ I**mportantly, grass and range fires have little to do with global warming and climate change.** To demonstrate all of this, let's begin by examining the areas burned this year, using graphics from the U.S. Forest Service (below, pink shading shows the fire area this year ) Massive fire area in Oregon. Nearly all in the grassy/range areas of the eastern side of the state. In contrast, essentially no fires over western Oregon, west of the Cascade crest. One of the lowest wildfire years on record for the western side of the state. Like Oregon, western Washington has also escaped wildfires this year (see below), and for the same reason: a lack of strong easterly wind events. Most of the wildfire area in Washington State has been in grass and range vegetation, but some of the fires have extended into trees on the slopes of local terrain (e.g., the Little Giant Fire) ** What about the origins of the fires in the two states?** According to the U.S. Forest Service, the vast majority of fires were ignited by humans (e.g., arson, power lines, debris burning). The major acreage fires were nearly all started by lightning. By simple inspection of the graphics, it is clear that grass/range vegetation, not trees, has dominated the 2026 fires in the Pacific Northwest. Asking various AI systems to compare the satellite-based fire areas to satellite-based land use provides similar answers. In Oregon, the dominance of light vegetation is overwhelming (see below), with three-quarters of the fires in grass and brush. For Washington State, they estimate about 60% coverage by light vegetation. Examining the fires manually, looking at BOTH satellite assets and surface imagery, it is apparent that the satellite approach underplays the availability and importance of light vegetation. To illustrate, below is an image from a "forest" area within the very large Sinlahekin fire of north-central Washington. There may be some trees, but grasses and low shrubs dominate. I have looked at dozens of other areas in both states, with similar results. Based on my review, I would suggest that at least 80% of the Oregon wildfire area this summer was in light vegetation and at least 70% of the fire area in Washington. Thus, this year was mainly a problem of flammable light fuels that dry quickly (hours to days) and are always dry enough to burn by July in our region. **Modest global warming over time was not a factor in the flammable conditions at the start of summer.** Furthermore, our region has been invaded by non-native, highly flammable grasses and light shrubs. These are human-forced vegetation changes that greatly enhance fire potential. And with decades of fire suppression, our forests have become unusually dense and full of debris, and thus highly vulnerable to wildfires In addition, the region has extperience downward trend in lightning. So global warming is not forcing more lightning ignitions. **The bottom line is that human-forced global warming had very, very little to do with the major Northwest fires this summer, and those claiming a connection are providing problematic information to the public.**

If you were to order a "storm" for the Northwest, you would request one that drops lots of rain over the crest and eastern side of the Cascades, decisively ending the wildfire season and providing needed moisture to late-season crops. To do so would require an upper-level low centered along the northern Oregon or southern Washington coast, which would swing moisture in from south into eastern Oregon and Washington. Exactly what is happening this weekend (see upper-level map for 2 PM Saturday). Upper-level chart (500 hPa pressure level) for 2 PM Saturday. The resulting clouds swirling around the low are impressive: As was the radar image last night. ** ** **Consider the "storm" precipitation totals as of this morning around 6 AM (below).** Nearly an inch at some locations east of the Cascade crest as moist air swung around the low and rose on the eastern slope. Looking forward, the total precipitation predicted through 5 AM Monday (by the UW WRF model) is quite impressive, with several inches forecast east of the Cascades, exactly where we need it to end the fire season And believe it or not, it is cold enough aloft to result in some snow at higher elevations (see below) We will have a warm/dry period this week, followed by the return to much heavier precipitation in ten days. Welcome to autumn.

**It is now clear that a very strong or "super" El Niño will be in place this year.** **Some are even calling it a GODZILLA El Niño.** **** **** ** **Several media outlets and amateur YouTube channels/social media sites suggest the impacts will be like a regular El Niño on steroids: very warm, wet, with a low snowpack. For example, Oregon Public Radio: The Bellington Herald throws caution to the wind, predicting drought and floods! Plus fires. Devastating impacts for Whatcom County. Meteorological "end times". **But there _is_ pushback on these apocalyptic predictions. ** For example, the Summit at Snoqualmie folks looked at the snow statistics associated with very strong El Niño years and found snow totals near normal (link here) And in my previous blog on very strong El Niños, I found the same thing: Northwest snowpack can be quite decent during "super" El Niño years. **So how can this be?** **Why do moderate El Niños cause one impact and "super" El Niños result in something different?** Let's figure this out using real data. The figure below shows precipitation associated with moderate, strong, and very strong ("super" or Godzilla) El Niño years for October through March. The difference from normal is shown, with blue and purple indicating above-normal, and yellow and red indicating below-normal precipitation. **Moderate and strong El Niño years are drier than normal over the Northwest, but "super" years, like this year, are WETTER than normal.** **No drought expected. Plenty of water for our region.** **Surface air temperature?** Moderate and strong years are close to normal over the Northwest (below). For "super" years like this one, temperatures are very modestly warmer (about 0.5 C or about 1F; see the blowup below). No wonder snowpacks remain decent for Super El Niño years: only slightly warmer but with much more precipitation. The Snoqualmie Pass folks were on to something! **Finally, can we explain these differences in a more fundamental way?** To do so, below are upper-level weather charts (500 hPa heights; think of these as pressure around 18,000 ft) All El Niño events are associated with an enhanced low-pressure system over the northeast Pacific (the purple colors). Air circulates counterclockwise around lows. For the moderate El Niños, the low is centered well offshore. Strong events have the low much closer to the coast, which is not favorable for precipitation over our region. But for the "super" events, the low is more offshore, producing more moist southerly flow over our region. Just right. I**n summary, past events suggest that the Northwest impacts of a very strong El Niño are quite different from its moderate relatives.** Importantly, Northwest drought conditions are not expected with a very strong El Niño, and there is good reason to hope for a near-normal snowpack. Media and social media predictions of some kind of meteorological "end of times" are without support.

**The wildfire season in the Pacific Northwest is rapidly approaching the endgame, with huge _declines_ during the past month.** To illustrate the profound change, consider the satellite-based wildfire observations for today versus one month ago (below). Today, there are only a handful of hot spots on the northeast side of the Cascades. No apparent fires in Oregon. A month ago, it was a different story with numerous and massive fires (mainly the result of lightning) in both states. Air quality is good through most of the region today, with some very localized degradation near some of the smoldering fires. A sharp drought of low pressure will move through over the weekend, mainly to the south of Washington. As a result, southern Washington State and Oregon will see substantial precipitation (see totals through Monday morning below). **Bad for fires.** And temperatures should be cooler than normal from Friday to next Wednesday (see below), which should help suppress fires as well. Pretty confident that this is the endgame for Washington/Oregon fires this year. In a future blog, I will make the case that 2026 was predominantly a grass/range wildfire year in the Northwest. The quote on AI source: _In Oregon—which surpassed historical records with over 2.3 million acres burned—short grass and dry brush served as the primary fuel source for roughly 1.8 million of those acres_ **And something else.** This is turning into a very attenuated wildfire year for California, with this year possessing less than half of the average over the past five years (see below). That could change, of course.

**Weather prediction has become****far more skillful****in recent decades, with nearly all major regional weather/climate threats accurately predicted days in advance****.** Unfortunately, several major cities have not taken advantage of the profoundly more skillful forecasts, **resulting in unnecessarily severe loss of life and property.** For example, Los Angeles experienced immense damage and many deaths from the 2025 wildfires, the result of a well-forecast Santa Ana wind event. Los Angeles, January 2025 Thousands died in New Orleans from Hurricane Katrina, whose track was skillfully forecast several days before. Seattle was caught unprepared for a well-predicted snowstorm in 2008, leading to a crippled city and the mayor being kicked out of office. In 2022, the region was not prepared for a well-forecast freezing rainstorm. I just published a paper on the topic: Excellent Forecasts but Poor Outcomes: Why Can’t We Do Better? **Seattle and the vicinity are vulnerable to well-forecast environmental threats, such as:** * Windstorms associated with Pacific cyclones * Downslope windstorms descending the Cascades * Snowstorms * Ice storms * Wildfire smoke * Coldwaves * Heatwaves * Heavy rain and flooding **To deal with all these threats, Seattle should create an ENVIRONMENTAL WARNING SYSTEM.** A system that would monitor the potential for such threats, provide online forecasts of their impacts, and push critical, site-specific information out to smartphones and other devices. Here is a sample of what I am thinking of: **** **** You could monitor on your mobile device or computer, or request a notification when a meteorological threat looms. You could receive warnings and recommendations for personal actions to save lives or property. Since your device knows your location, information and warnings could be specific to your position. Some of you may know that the UW has already built components of such a system. For example, there is Seattle SnowWatch: And Seattle WindWatch: **To build a comprehensive environmental monitoring and forecasting system for Seattle, King County, or other locations is quite possible and could save many lives and prevent property damage.** If heavy rains were expected at your location, you could attend to drains and gutters, avoid sleeping in the basement, and evacuate potentially flooded areas. Cities could bring in staff to clear drains. For cold waves, homeless folks could be required to move inside (there have been too many deaths in Seattle from exposure in the past several years). For strong wind events, folks could avoid sleeping when trees could fall and prepare for outages. City Light could pre-position crews and resources. **You get the idea.** With highly skillful and site-specific warnings, society could make better decisions and greatly reduce the impacts of strong local weather events. The number of people injured or killed by severe weather could be greatly reduced with the proper application of the amazing forecast skill available today.

Climatologically, the most costly meteorological disaster west of the Cascade crest occurs at this time of the year: massive wildfires associated with strong easterly winds. Here is a map of the big ones through 2020 And here are their dates, areas, and direct fatalities. Late August and early September are the favored times. **Why late summer?** One reason is that surface fuels are relatively dry after our warm, near-rainless summer. But even more important, early September is a period when western Washington and Oregon can experience **very strong, very dry easterly winds.** It is really hard to get big fires in the west when cool, moist air floods western Oregon and Washington. Strong easterly winds (from the east) are very dry, starting in eastern Oregon and Washington. They dry even more as they descend the eastern slopes of the Cascades. During the late summer and early fall, high pressure can build inland (associated with cold, dense air moving southward out of Canada). See example below. With high pressure inland and lower pressure along the coast, offshore-directed easterly winds develop, as illustrated by the winds at 850 hPa (about 5000 ft) at the same time. These easterly winds, and the accompanying dry air, can start and maintain fires, such as the huge Labor Day fires of 2020. **I know your next question: will this happen this year?** I have very good news. It has not happened yet, and model forecasts do not suggest that this pattern will set up during the next two weeks. After that, the threat declines rapidly. To show this, here is the forecast for meteorological conditions at Stampede Pass in the central Cascades. **No strong easterly wind periods**. Other mountain sites are similar. Major fires on the western side of the Northwest can easily run into the billions of dollars and result in many injuries and deaths. **What about climate change?** Will that make such fires more frequent? Published research (some done by my group) has found that global warming will cause a DECLINE in widespread wildfires. That is not a typo. **A DECLINE.** Why? Because global warming preferentially warms the interior of the continent, with the less dense, warmer air weakening the interior high pressure that drives easterly flow **Announcement** I will be teaching Atmospheric Sciences 101 this autumn if anyone is interested. It provides a good general intro to meteorology and weather prediction. It will be hybrid, both in person (MUCH, MUCH BETTER) and online. Information is found here: https://a.atmos.washington.edu/~cliff/ATMS101Y2026.html

**Normally, tropical storms and hurricanes avoid the area of the Hawaiian Islands.** Why? Because the nearby Pacific is usually too cool! In general, surface temperatures must reach at least 80°F (26.5°C) to sustain tropical storm development. This year, due to a very strong El Nino, temperatures south and east of Hawaii are 1-2 C above normal (see map of differences from normal for sea surface temperature) As shown by a more detailed, close-in map, the 27C line just reaches Hawaii. A "warm enough" bath is open. No wonder tropical storms can approach Hawaii this year! ** ** **The effects of the warm water have been dramatic.** ** **Consider satellite imagery from yesterday afternoon...and be prepared to be impressed! A high-resolution satellite image shows **three** hurricanes/tropical storms over the eastern Pacific, with a red arrow pointing to the Big Island. Wow. Here is an infrared image of the storms. Amazing. Even more amazing is a series of forecast maps of evolution of the tropical storms. I will show you maps of atmospheric moisture through depth. Today at 11 AM, the swirls of moisture around three tropical storms are evident. Stunning. On Saturday morning, they are still there, with one storm passing south of the Hawaiian island On Sunday morning, the western storm starts moving **northeastward** towards Hawaii! Some moisture from the eastern storm extends into southern California, which is going to get some rain as a result Now the most amazing thing. The two eastward storms start to interact on Monday. Then the combined system starts to move northwest on Tuesday. The storm's crazy movement near Hawaii is reflected in the total precipitation over the next 10 days. You can see the northward jog, followed by a turn to the east. Quite unusual! **A great time to visit Kauai if you are meteorologically inclined. 😊**

One of the most remarkable aspects of Northwest climate is the rapid fall transition from summerlike conditions to cold and wet between September 1 and November 1. This is illustrated by the average temperatures at Seattle (below). The current temperature forecasts are close to climatology, with no more 90s or 80s. Climatological precipitation is on a very steep incline up (probability of measurable precipitation is shown below). By November 1, we are about as wet as we get. A wet weather system is now right off our coast and will move in tonight and tomorrow (see infrared satellite image for this evening). Does not look like a summer pattern! Rain totals through Thursday morning (shown below) will be significant. Importantly, precipitation will extend over eastern Washington, where some fires are still smoldering. The official NOAA 6-10 day forecasts are for cooler-than-normal and wetter-than-normal conditions over the West Coast: The timing of this cool/wet weather is perfect to facilitate an early end to the serious wildfire season.

For those concerned about the wildfire threat over the Pacific Northwest, there is good news. With the turn to cooler/wetter weather and a forecast for much more, **the wildfire threat should rapidly decline over the Pacific Northwest.** Below is the latest wildfire satellite image, with active fires shown by red dots. Only two fire areas are evident. Currently, there is not much active fire activity over the entire West Coast. **California is having a very benign fire year, with roughly half the acreage of the five-year average.** Recent rainfall has greatly damped down the fires over the Pacific Northwest, and the US Forest Service is predicting that fuel moistures will decline to near climatological levels this week (see below). Looking to the future, let's check out the latest forecasts (below). For the next five days, the region is predicted to be substantially cooler than normal, indicated by green and blue colors. The next five days? **Even cooler than normal (** below**).** Eastern WA and Oregon, where most of the fire activity has occurred, will be particularly cold. And there will be plenty of precipitation during that period as well. Here is the European Center AI forecast for total precipitation through September 9. Lots of precipitation. The UW WRF model forecast, run by my group, is more detailed but similar (below). Lots of rain will be falling. Some higher elevations will get snow. Furthermore, there are no forecasts for a major wind event on either side of the Cascades. There are some folks claiming that we are now at the "peak" of the wildfire season, but that is not correct. This is the endgame for the wildfire season for our region. Yes, there will will be some smoldering for a few of the fires, but the big action will be over.

The media and social media are abuzz with talk about the upcoming "Super" El Nino, with forecasts of low snowpack, drought conditions, and massive wildfires (see sample below). My local newspaper and some amateur social media are making similar claims. **Few of these scary claims are supported by the facts: in reality, the outlook is quite favorable for our region if a "Super El Nino" continues to develop.** Let me prove this to you. Surprisingly, there is nothing called a "Super El Nino" in the scientific world. If the temperature anomaly (difference from normal) of the ocean surface in the tropical Pacific is 1.5 to 2 C above normal, it is called a **strong El Nino.** More than 2C, a **very strong El Nino**. The media calls this a "super"; the scientific community does not. Below is the latest forecast by NOAA. They are predicting a very strong El Nino this autumn (peaking around 2.2 C above normal). There is little doubt we will get a very strong El Nino, but this is not unprecedented, with others occurring in 1982-1983, 1997-1998, 2015-2016, and 2023-2024 (others have occurred before as well). **A KEY point is that very strong El Niños are very different animals than their more moderate cousins. With different impacts.** Moderate to strong El Niños are typically associated with less snowpack and drier-than-normal conditions. **Very strong El Niños bring near-normal snowpack and plenty of moisture.** Thus, our water resources are generally fine with very strong El Niños like the upcoming winter. **Want the proof?** Below is a plot of precipitation from October to April (our wet season) since 1980. The red arrows indicate very strong ("super") El Nino years, and the yellow line is the average of the period (1980 to today). **Very strong El Nino years are NOT particularly dry... their average is a bit ABOVE NORMAL.** **What about snowpack?** Let's check out a few sites, looking at April 1 snowpack (which is generally the date used for evaluations). Crystal Mountain Ski area (around 6000 ft)? Snowpack during very strong El Niños is **nearly normal** (horizontal line) during such years. The much lower Stampede Pass (4000 ft)? Same story. Very strong El Nino years have near-normal snowpack in our mountains. I could show you a dozen other locations: same story. **What about temperature?** Over Washington State at the surface, very strong El Nino years are about 1°F above normal, although one was below normal (2024). **With normal rain and mountain snow during a very strong El Nino year, the expectation is that there will be plenty of water next year for our region's needs.** So those predicting drought, drastically reduced snowpack, and enhanced wildfires over the region will have a lot of the proverbial egg on their face next summer. **So what exactly does a very strong El Nino do to the larger-scale atmospheric circulation around here? I am a weather scientist and am curious!** Below is the average of the upper-level heights at 500 hPa (think pressure at 18,000 ft), showing the difference from normal for October through March of a very strong El Nino year. Purple is much lower than normal heights/pressure (a strong trough). Mama mia! A HUGE intense low-pressure area over the north Pacific! Let's look at the local implications of this intense pattern by examining the difference from normal in the winds around 5000 ft for such a very strong El Nino year (below). There are greatly enhanced winds from the southwest offshore, bringing in lots of moisture into the West Coast. That means more precipitation. NO DROUGHT. To demonstrate this, below is the difference in precipitation from normal for such very strong El Niño years. **A lot more precipitation over the West Coast, with the greatest increase over northern CA and southern Oregon.** Our region will be a bit warmer than normal, but the additional moisture should result in near-normal snowpack in the mountains above 3500 ft. Lots of water to fill reservoirs and moisten the soils. **No problem.** **Announcement** I will hold a special online Zoom session at 10 AM on Saturday for Patreon supporters. I plan to talk about the winter forecast and answer your questions! ** **

The Pacific Northwest has begun the late summer cooling period, with a substantial cooling occurring over the entire region. A cooling that probably represents the end of hot weather for the remainder of the season. Solar radiation is now rapidly declining as daytime shortens and the sun starts to sink towards the horizon, something illustrated by the plot below: The latest forecasts for Seattle show temperatures only reaching the low 70s for the next ten days! And the Tri-Cities only rise into the 80s In fact, the whole region will be cooler than normal, something shown by the latest European Center AI forecast of the differences in surface temperatures from normal For the next five days: cooler than normal (blue colors) For the next five days, EVEN COOLER than normal For the subsequent five days, near normal in the west and colder east of the Cascade: BURR.... I am going to unpack some light sweaters! With the pattern change, substantial precipitation is predicted over the next ten days (see below, through late Thursday of next week) This change in weather should help damp down current wildfires. In fact, the fires have already gone into substantial decline, with only a few fires apparent on satellite imagery (red dots). Very, very low fire activity in California. Enjoy the transition.

Again and again I am asked: **Do I _Believe_ in Human-Caused Climate Change/GlobalWarning?** A very strange question. Scientists rarely, if ever, use the term **_believe_**. We never use the term " believe " when we apply Newton's laws of dynamics, the first law of thermodynamics, or any of the basic principles of atmospheric physics. I have attended hundreds of scientific meetings and not once did a scientist use the term **belief** in describing human-caused global warming. Science is not religion...at least it shouldn't be. Conclusions should be based on accepted scientific principles and data, not beliefs. **Religon** It appears that global warming has become like a religion to some people, replacing more traditional beliefs. Apparently, a way to fill their lives with meaning and purpose. As in many religions, there is the prediction of a catastrophic "end time", with total destruction, if people don't follow the approved "way". Self-appointed prophets describe the proper path that will lead to _life_(some shown below), I made a decision 15 years ago to stand up against those who distort the science. Those who mislead the population. Those who spread unnecessary fear. Those who benefit financially from the exaggeration and lies. And woe to a person who stands against the apocalyptic climate vision. They are cast out and rejected. Worse than wrong. Evil I should know.....and have felt the wrath of name-calling and being cast out (by the Seattle Times and KNKX) for remaining with the science. **So what are my views on climate/change and global warming?** Quite honestly, I am pretty much in the mainstream. I should note that I have published several dozen papers on climate issues, from modeling to data-driven studies. I studied climate science under leaders of the field at the University of Washington, and worked on climate research at the National Center for Atmospheric Research (NCAR) under one of the leading climate scientists in the world (Stephen Schneider, see below), with whom I published several climate papers. I have had many NSF research grants on climate subjects. **** Climatologist Stephen Schneider and I at NCAR So what is my view, based on decades of research and study of the climate? **The planet is slowly warming, and increasing greenhouse gases due to humans are a major contributor** A planetary warming of about 1 C over the past 50 years due to such gases (see plot below) Most of that warming (about 2F) is due to humanity's greenhouse gas emissions. A modest, steady warming of the planet. **What about extremes?** The warming is causing fewer cold waves, which is saving lives. But there are worsening heat waves. Since far more people die from cold than heat, fewer people are dying from extreme temperatures as the planet warms. That will be true for a while. The science and data indicate that hurricanes have not become more frequent as the planet has warmed (see below), but the strongest hurricanes may get more powerful by the end of the century. Interestingly, even with global warming, deaths from extreme weather have declined substantially (by 90% or more), even with increasingly populated areas (see below). This is due to greatly improved ability to adapt to climate extremes (e.g., air conditioning) and profoundly improved weather forecasting. **The scientific evidence and demonstrated societal impacts are clear: human-caused global warming is a modest problem. It is not an existential threat to humanity. ** As a weather/climate scientist, my views are well within the mainstream. But unlike some, I am willing to take on the exaggerations of the "believers" and media that are happy to misinform folks to get more clicks or to secure funding from climate activists (like a certain local newspaper in Seattle). This blog gives me a tool to give my readers the truth. I have paid a substantial personal price by taking on the "believers" (e.g., KNKX, Seattle Times, name-calling by commenters on this blog, name-callers on some amateur YouTube sites), but the price paid by society, panicked by exaggeration and falsehood, is worse. Religion, not Science

**Autumn doesn't wait until September 22 in the Pacific Northwest.** During most years, there is a transition to cooler temperatures and the return of rain during late August, and this year will not be different. A plot of average temperatures at SeaTac Airport (below) illustrates my point. Today (indicated by the blue line) is near the transition point. This change is not only forced by changes in solar radiation intensity, but also by changes in the large-scale pressure systems that control our weather. Let me illustrate these large-scale changes by showing you a series of average upper-air (500 hPa pressure, about 18,000 ft) monthly weather charts. During mid-summer (July) there is a big ridge (dark red) over the Southwest and a weak trough centered to the north of us. The jet stream (located where the colors change rapidly) is north of Washington State. By September, the situation is very different, with the southwest high pressure weakening and moving inland, and a trough (lower pressure) moving towards the west coast. The weather implications of these changes are profound. Consider what is going to happen during the next 15 days using the best forecast available (the European Center AI forecast), looking at the same type of upper level chart. During the next 5 days, the upper-level ridge over the Southwest is apparent. During the next 5 days, the SW ridge weakens and starts to shift eastward, and a strong trough moves into our region And the map for the subsequent five days is downright scary with a very deep trough of low pressure (purple color) offshore: cool and wet for us! The implications for our weather are profound. The European Center temperature forecast for Seattle shows highs falling into the lower 70s and 60s: Rain will return as shown by the forecast below for two 7-day blocks of time into the future. No major heatwaves are predicted in these model runs, and it is rapidly getting too late in the season to get one. **Enjoy the "fall transition" in August. One of the treats of living in the Pacific Northwest.** PS: The latest radar shows showers moving in!

Perhaps the most impactful Washington State wildfire of this summer is the **Little Giant Fire** near Lake Chelan, ignited on July 15 by a lightning storm and now extending over 135,985 acres (see map below) The fire is still active today, with plenty of smoke and flames (see satellite image yesterday afternoon) There are many claims that this fire resulted from climate change, drought, and extreme heat (see below). **As I will demonstrate in this blog, such claims are demonstrably false.** One local newspaper has been particularly over the top with such claims (see below). Those blaming the Little Giant Fire on global warming make several unfounded claims: (1) That the fire was unusual, representing something new and unprecedented (2) That lightning, which initiated the fire, is increasing due to global warming (3) That the low snowpack this year (driven by global warming) was of central importance, resulting in far earlier drying of the surface. That in a "normal" year before global warming, the fire origin location would have been snow-covered. (4) That drought contributed to the surface fuels being unusually dry at the time of the lightning strikes. _All these claims can be easily shown to be false_. **Location of the Fire Initiation** There are several claims that the fire started at 5000 ft or above. Satellite-based fire detection shows the fire initiation was down on the slopes at around 3900 ft (the red dot shows the start location). It was claimed that the fire started in the forest; in reality, it began in a debris field of previous burns with downed logs, grass, and bushes (red dot shows the initiation location). Below is a view of the fire-start area from below before it started. A picture from below looking at the same location during the early days is shown below. The fire was burning down the hill towards lower elevations. This is a sample of what burned. **The Truth About the Snowpack** As noted above, lightning initiated the fire around 3900 ft, after which it then burned towards lower elevation. There is a nearby USDA Snotel site (Pope Ridge) at 3540 ft. Just perfect for this fire. The snowpack (snow water equivalent) at this site is shown below (black line is observed this year, green line is the long-term average). Certainly, the snowpack was below normal this year. It melted out on April 7 when the normal meltout is May 7. A month early! But since the fire did not start for more than two months into the future (July 15),**the early melt-off was not relevant to the fire.** Even in a "normal" year, the snowpack would have been long gone and the moistening of the surface gone. So low snowpack was not an element in this fire. **Lightning and Global Warming** Then there are the claims that the massive lightning "storm" that initiated this and many other local fires that day was the result of global warming/climate change. And these claims cite some academic papers: The problem is that lightning observations do not agree with or confirm these predicted trends. In fact, lightning strike numbers appear to be steady or declining over the U.S., including the Pacific Northwest (see below, trend from the NLDN network). Other networks (e.g., the UW WWLLN network) show the same thing. I am working on a paper on this topic, by the way. Bottom line: Can't blame the lightning that started these fires on climate change! **Previous Fires** The region of the Little Giant Fire has burned many times before, including the historical period before the current global warming. To demonstrate this, below are the regional fire areas from 1973 until 2025. Much of the Little Giant Fire's footprint burned during that period. For example, in 1994, the Tyee Creek fire also started in mid-July and burned a similar area. It was also started by lightning. The 1970 Entiat Fire burned more than 175,000 acres and consumed over 80% of the entire Entiat Valley. Lightning initiated. **The region around Lake Chelan is very vulnerable to wildfire for many reasons.** It is on the dry side of the Cascades, but gets frequent lightning. It is vulnerable to strong westerly winds descending the eastern side of the barrier. Fire suppression allowed unnatural tree densities that support massive wildfires. Highly flammable invasive grasses have moved in (eg., cheatgrass). And each fire leaves more debris to burn in the next configuration. **Fuel Moisture** Many of the online and media claims of global warming and drought contributions to the Chelan wildfire claim that the fuel moistures were low. **The data shows otherwise**. Below are the estimated fuel moisture levels over the eastern slopes of the Cascade for bush (100-hr) and log-size (1000 hr) fuels. They were within normal levels (gray shading). Fuels are normally dry after mid-July on the Cascade slopes. Dry enough to burn without global warming. Regarding claims of drought, here is the water-year precipitation (October 1 through July 15) for Chelan. This year was a bit ABOVE NORMAL. So much for drought. What about the summer temperatures at Chelan (see plot for the past 50 years for June 1 to July 15)? Nothing unusual or particularly warm. ** ** ** Summary** When you examine the actual data, it is apparent that the Little Giant Fire has little to do with global warming and climate change. Science and facts matter. Or at least it should.

**Although in the tropics, Hawaii rarely gets hit by hurricanes.** But yesterday, the unusual happened: hurricane Lala approached, producing stunning precipitation and winds. The visible satellite imagery yesterday afternoon and evening shows a well-defined eye (indicated by red arrows), with the storm passing westward just south of the Big Island This morning, we only have an infrared image (since there is no solar radiation!) This image (indicating cloud temperature) shows the low center to the south of Oahu (red arrow) and a blow-up of convection (thunderstorms) to the northeast of the low center (blue arrow). **Precipitation totals so far have been stunning.** During this event, some parts of the northeast slopes of Hawaii received over 32 inches. In contrast, the "Kona" side only got an inch or two. All the result of strong, moist northeast winds forced by the storm. Moist air that was forced to rise by huge volcanoes on the island. Impressive precipitation contrast on Maui as well, with some locations receiving over 30 inches. **Then there were winds, driven by the huge pressure gradients (change of pressure over distance) associated with the hurricane.** Consider the maximum gusts yesterday over Hawai. Some locations on the NW side of the island gusted to over 80 mph! Strong winds near the ridge crest as well Similar gusts were found over the NE side of Maui downstream of the West Maui Mountains. I should note that the strong downslope winds on the West Maui Mountains resulted in the destruction of Lahaina from wildfire a few years ago. **Hurricanes are relatively rare in Hawaii, because the water temperatures are generally too cool (you read that right).** During the past 50 years, only one hurricane (Iniki, 1992) has made landfall on a Hawaiian island. Hurricanes need warm water, generally at least 26.5 C (around 80F), and generally Hawaiian waters are cooler than that. However, this year there is a strong El Nino, with much warmer water than normal in the tropical Pacific (see sea surface anomaly map (differences from normal) below) A close-in view of the sea surface temperatures shows the details. Need to be in the greeds, yellows, or orange colors. Just made it! Finally, I should note that hundreds of thousands are without power on the islands right now, with the Big Island substantially in the dark. Not a good time for a Hawaii vacation!

**This summer, wildfire activity east of the Cascades has been above normal.** Several media outlets and activist websites are claiming that this year's low snowpack is a major cause of the wildfires (see example below). _Poor mountain snowpack and early melt-offs have translated to low reserves,_ _drying out grasses, trees, and shrubs that easily ignite and spread wildfires._ **The facts are clear: such claims are wrong.****The below-normal snowpack has had little impact in promoting recent wildfire activity.** To demonstrate this, let's consider the most impactful fire this summer, the Little Giant Fire near Lake Chelan, which was initiated by lightning on July 16 (see map below). The location of ignition (shown with a fire symbol) was at approximately 5000 ft. We can get a good idea of snow evolution at the fire from the nearby Trinity Snotel site (see below). The snowpack (snow water equivalent) at this location this year (black line) was generally below-normal (green line), but NOT a record low (lower red line). If you look closely, the snowpack at this location melted out on May 2, when on average it melts out on May 11th. **So, the snow was lost about 9 days early.** But that does not matter for this fire, since the fire occurred OVER TWO MONTHS (July 16). There is a large body of literature showing that only days to weeks are needed for surface fuels to become dry enough to burn after the snow has melted. Furthermore, most of the water from snowmelt goes into streams and rivers and is lost to the region. T _hus, by mid-July there was plenty of time for the ground and vegetation to dry out, even in a normal year with full snowpack._ **Want more proof for different fires?** ** ** Two other big fires were found to the east near the Columbia River: the Kailser Canyon and Molrite fires (see below), which started in mid-July ** ** There is a nearby Snotel site at Gold Mountain (4500 ft, see map) Below are the snowpack observations at this location (again, the black line is this year, green line indicates normal). ** ** **Way below normal snowpack!** The snow melted out around April 8 rather than the normal of April 18. Not important for a fire that would start THREE MONTHS LATER. **Still not convinced?** Let's consider the largest fire, the Sinlahekin blaze near the Colville reservation in north-central Washington (see map). There are two Snotel sites near the fire, and I will pick one of them (Salmon Meadow, 4460 ft, with the horizontal line in the map below). This site had an abysmal snowpack, melting out on April 5, when normal is May 2. But normal melt-out was well over two months before the fire and thus the early melt-out was not relevant. In summary, the regional snowpack melted out a week to a month early this year near the big regional fires. **But that is immaterial for wildfire because the mid-July fire initiation was over two months in the future.** Even with normal...or ABOVE NORMAL... snowpack, the melt out would have occurred two months before the fire, allowing more than enough time for the soils and fuels to dry out. **In short, the low snowpack made little positive contribution to the large fires that were initiated by lightning in July.** Finally, to provide independent evidence of this lack of connection between Washington State snowpack and fires, the plot below presents the regional snowpack on April 1 (blue line) and the subsequent fires over the region (red line). **There is little correlation between them.** **Why are some folks exaggerating the role of low snowpack on regional wildfires?** Perhaps because they are trying to find a way to blame the burns on climate change, rather than invasive grasses, poor forest management, human land disturbance, and human ignitions.

**Good news for those of you who dislike heatwaves:** **There are none forecast over the Pacific Northwest for the next 10 days.** Importantly, we are running out of time to experience a serious heatwave in our region. First, let's define what is meant by a heatwave. **According to the WMO (World Meteorological Organization), a heatwave occurs when there are more than five consecutive days during which the maximum temperature exceeds normal by 9F or more.** We are now past the peak period for major Northwest heatwaves, as shown by the plot of record high temperatures (red shading) from June 1 through October 1 below. Today is down by the red arrow. The really high temperatures really decline after mid-August. Why? Because daily solar radiation is declining relatively rapidly now, and the days are getting shorter (see plot below) **The current forecasts indicate no heatwaves for much of the rest of the month.** Consider the National Weather Service forecast temperatures for Seattle Tacoma Airport (below). During the next ten days, temperatures are expected to climb to around 80F before declining in the mid-70s. Yakima warms up into the low 90s before dropping into the mid-80s. Close to average. The NOAA 6-10 day temperature outlook is for generally normal conditions over the western US. And their precipitation outlook is for wetter than normal conditions. _ _ In short, at this point it appears that our summer is heading for an unremarkable end, with near-normal conditions. You want weather excitement? Head to Hawaii, where a potent tropical storm will approach this weekend (see below) As the storm moves through, heavy rain will hit many of the islands (see below).

This year, wildfire acreage in California has been **well below average** and is being eclipsed by the lightning-initiated wildfires in the Pacific Northwest. The nearly fire-free California situation is evident satelite/ fire image from yesterday (active fires shown by the orange dots). Lots in Washington and Oregon, very little in California. In fact, according to official CALFIRE statistics (shown below), the total acreage this year is LESS THAN HALF of the five-year average! T**he media and climate activists have been quite silent about this.** Can you imagine if the wildfire acreage was twice the average? The supposed connection with climate change would be **on the front page.** In fact, some media and others are actively pushing the unsupported narrative: ** ** **Ready for the Truth?** Let's look at the actual wildfire data for California! Consider the actual burned area data for the past 30 years (below). A period in which global warming has been occurring. You see a large trend? I don't. There was a short period in the early 2020s when unusual meteorology drove some big fires, but the wildfire numbers have declined since then. This lack of a long-term trend in California wildfire activity actually occurred during a period of increasing human ignitions of wildfires (e.g., from powerlines, arson, etc.). In fact, the best estimates are that humans have initiated roughly two-thirds of wildfires in California since 1992 (see below). I suspect these ignitions have had little to do with global warming. At the same time there there has been an invasion of non-native flammable grasses. **The bottom line is that there is no rapidly increasing globe-warming-induced wildfire trend in California. Such claims are demonstrably false.** Finally, let me note that you can not believe AI inquiries on this topic. Want proof? I asked Google Gemini whether California was having a low wildfire year (see below). **Its answer was the OPPOSITE of the truth.** I then told it was wrong, **and it admitted it was fibbing** I wish the Seattle Times, YouTube Channel climate activists, and others would be willing to look at the data and acknowledge they have been providing inaccurate information regarding the climate/wildfire connection.

On July 15/16, a massive lightning storm initiated several major wildfires east of the Cascade crest. **As shown below, this was one of the most extreme lightning events in Northwest history.** This story has escaped the notice of the media. Furthermore, several media outlets (including KING-5 news and the NY Times) and podcasters/Youtube channels have claimed that Northwest lightning has increased over time due to climate change. (see example below) **Actual lightning data show that such claims are demonstrably false. ** The data is clear: the major wildfires that occurred during the past month have little to do with climate change, but were associated with a very unusual "lightning storm" of extraordinary intensity. **As I will demonstrate below, there is no upward trend in Northwest lightning, which indicates that global warming is not a major driver of regional lightning frequency.** ** ** **The Data** There are two major lightning networks that cover our region and beyond: the UW World Wide Lightning Location Network (WWLLN) and the Vaisala National Lightning Detection Network (NLDN). I first asked UW Professor Robert Holzworth and Scientist Katrina Virts, who run the WWLLN network. I**was amazed to learn that WWLLN detected 5,440 strokes over the PNW on July 16, 2026--the most of any July day in the period of record (since 2013, after which the observing network was stable).** ** ** Lightning Strikes on July 15-17. No wonder there were a lot of fire starts! Many are concerned about global warming, so I asked the WWLLN folks to see a plot of lightning over time. Katrina made a plot of the number of lightning days per month over the Pacific Northwest (below): The lightning numbers are DECLINING. And this is a period of substantial global warming. Global warming is NOT contributing to more lightning over our region!. To get an independent check on these lightning numbers, UW Research Meteorologist Jeff Baars used a completely different lightning network (NLDN), which goes back until the late 1980s. For this network, July 16 was the third greatest July lightning day since 2013. And examining a far longer period, **we see that there is no increasing trend in regional lightning...in fact, a modest decline.** **So what should you take away from all this?** (1) The July 2026 lightning event was unusually extreme in terms of the number of lightning strikes, greatly increasing the number of fires. (2) There is no observational evidence that global warming/climate change is contributing to more lightning strikes (and thus wildfires) over the region. The latter observational result suggests that some modeling studies, which suggested the opposite, are in error. Clearly, they possess some flaws in their methodology or approach.

**As expected, air quality is rapidly improving west of the Cascades, with the transition complete by tomorrow morning.** You can see the changes in the west in the visible satellite imagery at 11 AM yesterday (top) and today (bottom) The smoke plumes are now directed to the east, as the winds have reversed to westerly (from the west). Low marine clouds have pushed up the coast and invaded coastal locations. Air quality in the Portland area is hugely improved. The air quality map at 11 AM (below) shows good conditions on the coast and NW Washington (green). Moderate air quality over Puget Sound country, with some smoke trapped at low levels. Such low-level smoke will mix out today There is s good air quality at high elevations in the Cascades, which are above the shallow smoke layer. To illustrate the good conditions in the Cascades, below is the view at Paradise, on Mt. Rainier (about 5500 ft). Nice blue sky! The latest NOAA HRRR smoke forecasts predict a profound improvement in low-level smoke between today at 11 AM and tomorrow at 3 AM And REALLY better by Saturday at 5 AM: **But there is a potential problem** : much stronger winds on the eastern side of the Cascades: winds that could rev up some of the fires burning now (such as Little Giant). The forecast winds for Friday evening could gust to over 39 knots over some areas of the eastern slopes of the Cascades. And the predicted westerly winds in Ellensburg will increase substantially later tomorrow, according to the UW high-resolution modeling system: Such winds will make fire management more difficult and promote fire motion to the east. Need to watch this situation carefully.

As predicted, the winds aloft have turned easterly (from the east), resulting in smoke from eastern Washington moving aloft over western Washington. This is actually good news for eastern Washington, as it leads to reduced wildfire activity and eastward fire movement. **This situation is only temporary, and later this week the situation will reverse, again pushing strong westerly winds into eastern Washington....ith the potential for renewed rapid fire growth.** The Seattle PanoCam shot at 7 AM was not subtle. Lots of smoke. And the visible satellite image clearly showed the smoke moving westward aloft: Air quality is still relatively decent in most of western Washington (green and yellow dots below), except for the western slopes of the Cascade Mountains The fact that most of the smoke is aloft is shown by the laser ceilometers run by the Puget Sound Clean Air Agency (see the vertical plot over time at Seattle's Beacon Hill below). Surface heating during the day shows mixing down some of he smoke later today, so surface air quality may decline. The current pattern, with high pressure aloft over the eastern Pacific, is good for reducing winds in eastern Washington--which means less rapid fire growth (see max winds so far today below). Less wind means less fire spread, which gives fire crews a chance to deal with the fires. ** ** **But there is a problem.** As the upper-level ridge of high pressure moves inland (see forecast for Friday afternoon below), strong winds will push eastward down the eastern slopes of the Cascades To illustrate, here is the surface wind gust prediction for Friday afternoon. Not good. Such winds will rev up the Little Giant Fire, which is the most serious fire of concern at this point **Finally, there is a lot of talk about this fire event having to do with climate change. The Seattle Times and some current/past politicians have been particularly egregious about such claims.** Such claims are demonstrably false, and I will examine this issue in detail in a future blog. The fires were initiated by lightning and arson, neither of which is connected to climate change Winds were critical, and they have no connection with climate change. Fuel moistures were near normal before the fires, so all the drought and low snowpack claims are irrelevant.

**One of the most interesting aspects of the current smoke/fire event is that it is occurring during a cold wave.** Over the past few days, temperatures in eastern Washington have been **well below normal.** Not a heat wave associated with global warming. A cold wave with strong winds. Don't believe me? Below are the daily low surface temperatures yesterday and today (only showing values of 40F and below). My God! Several locations dropped into the mid-30s! Since such temperatures are measured around 6 feet, the surface temperatures could have dropped to freezing! Smoke and ice...what a combination. The surface temperature analysis for Sunday at 4 PM shows the very cold temperatures over the northwest. Burr..... **Temperatures aloft were also very cold.** Here are plots of Sunday and Monday morning temperatures around 5000 ft (850 hPa pressure). Blue is colder than normal. _ _ The cold and winds (which produced the rapid fire growth) are connected, both associated with a strong upper-level trough of low pressure moving through this weekend (see map at 500 hPa, about 18,000 ft below). Blue shows heights below normal (a trough). _ _ _ _ Currently, air quality is good in western Washington, with any smoke staying aloft, moderate in the Willamette Valley, and poor in eastern Washington (see below). The forecast surface smoke (NOAA HRRR Smoke model) for 11 PM tonight is good for western Washington, unchanged for the rest of the region. Really bad near the Little Giant Fire near Lake Chelan. _ _ _ _

**As feared, the great enhancement of cool, westerly winds caused a large increase in eastern Washington wildfires, with the Little Giant Fire expanding to Lake Chelan.** The change in visible satellite imagery yesterday shows the major changes Early in the day Saturday, you can see the smoke from a few fires in eastern Washington, with the Little Giant Fire possessing only a modest amount of smoke. Lots of low clouds in western Washington. But later in the afternoon, as strong winds surged into eastern Washington, the fires exploded, with massive smoke plumes. Here is a close-up at the same time. The satellite image this morning shows a massive smoke cloud from the Little Giant fire extending into Montana and beyond. Satellite sensors can pick up the emission from fires, and this morning's image of the Little Giant fire indicates a rapid spread of flames to the east, with some fire reaching Lake Chelan. As noted earlier, this major fire blowup was associated with strong winds resulting from the movement of cooler, onshore flow into the region. Cooler air associated with a Pacific weather system. Below are the maximum winds over the region on Saturday. At several locations, wind reached 40-50 mph. Zooming in to the area of the Little Giant fire, multiple locations surged to around 50 mph. _ _ The strong winds were accompanied by profound cooling, something shown by the 24-hour temperature change (ending 6 AM this morning). Many locations were 20F cooler! The strong winds also resulted in some fire expansion near Spokane, which was picked up by weather radar yesterday: The winds will calm down today, and the fire growth should greatly decline. In any case, this event illustrated the profound danger of lightning, dry fuels, and wind. Often our big fires are associated with cooling weather, not heat waves. **But one thing has profoundly changed.** Our ability to PREDICT the winds is immensely better than 20 years ago, allowing far more effective preparation and protection for such events.

**Rain is coming to western Washington and the Cascades during the climatologically driest time of the year.** _But there is an accompanying risk that needs to be mentioned_. A severe enough risk that at least one local power company (Chelan PUD) may de-energize its lines: A winter-looking system is off our coast, including an impressive cold front (indicated by a red arrow) and a low center at the center of swirling clouds. This impressive summer system is associated with a relatively strong upper-level trough, as shown by the 500 hPa heights (think pressure at 18,000 ft) tomorrow at 11 AM. Not your typical mid-summer pattern 😊 Precipitation will move in on Saturday morning. The predicted totals through 5 PM Saturday (shown below) will be most substantial on the windward sides of regional terrain (up to about .5 inches). Accompanied by cool air, this event should greatly reduce the potential for wildfires west of the Cascade crests for a week or so. Some light showers will continue into Sunday, but the totals through Monday morning will be only a bit more: **So far, good news. Reduce westside fire potential and lessen water needs for days.** However, there _is_ a risk factor that needs to be mentioned: increased surface westerly winds east of the Cascade crests, which are driven by the accumulated cool air over western Washington, as well as increased winds at crest level. Consider the forecast wind gusts on Saturday afternoon. Strong westerly winds from Yakima to Omak, with substantial gusts extending into the Columbia Basin. Maybe even some dust storms. Winds that could damage powerlines and contribute to new wildfires. Here are the forecast winds from the UW's highest resolution model. The biggest threat east of Lake Chelan and Wenachee. Consider Camp 4 on Lake Chelan ( red dot below) The predicted sustained winds by the UW modeling system at this location are substantial, with **sustained winds reaching 20 kt or more**. The threat is that some of the fires in eastern WA could be enhanced and rapidly spread by these strong westerly winds on Saturday. **If you are located east of a current fire, great caution is advisable.** ** **

**With the recent grass/range fires in Eastern Washington, there is some interest in whether conditions there have gotten drier or warmer.** **How unusual have precipitation and temperature been this year?** Let's find out! I will start with the NOAA Climate Division dataset, which is derived from multiple climate observation locations in each division (the climate division map for Washington State is shown below). For Division 8, on the eastern slopes of the Cascades, the history of summer precipitation and temperature since 1960 is shown below. For precipitation, there is little long-term trend. For temperature, there is a warming trend of about 0.2F per decade. Some of that represents the global warming signal. Moving to the lower-elevation Columbia Basin, there is again little overall trend in precipitation over the period, but there have been a few dry years in the past decade. The temperature plot for that area shows warming, particularly during the past decade. Some of that warming undoubtedly reflects the global warming signal (although land use changes, urbanization, and other factors are certainly significant as well). Same upward rate of 0.2 F per decade. **What about this year?** Here are the plots of precipitation and temperature at Ellensburg in eastern Washington for June 1 to July 28. A small warming trend in temperatures, with this year not being extreme at all-- near the long-term mean. For precipitation, there is a LOT of historical variability, with this year being relatively low (fifteenth lowest out of 67) In short, conditions in eastern Washington have hardly been exceptional for the first half of summer 2026, with a very modest warming signal evident. ** ** **This is why the fuel moistures were near normal.** The only reason we had significant grass fires was due to a huge amount of lightning, which has little to do with global warming.

During the last few weeks, a series of wildfires have occurred over the region. Today's satellite imagery shows where the fires were burning (orange dots), with smoke plumes quite evident. Most of these fires began in grass/range vegetation. In mid-June, there were a few grass/range fires in the Columbia Basin (see image below). **There has been drumbeat in the media that the wildfires were the result of, or significantly enhanced by, global warming/climate change due to increasing greenhouse gases such as CO2.** For example, a story from the Seattle Times Climate Lab was full of demonstrably false claims (such as claims that wildfires are occurring ahead of schedule due to global warming). In this blog, I will provide the facts and demonstrate that the global warming connection with the current fires contradicts current scientific understanding. ** ** **Fire Ignition** The fires during the first half of summer were either human-initiated or caused by lightning. Human ignition obviously is not related to increasing greenhouse gases, and neither is lightning. In fact, I examined this issue with colleagues at the Washington State Climatologist Office, examining the potential for lightning using state-of-the-science regional climate models. The results were clear: under global warming, there are no increases in lightning activity for Washington State (see sample graphic below for Ross Lake in the WA Cascades) Mid-summer is the lightning season in the Cascades and eastern Washington, as noted by the lightning climatology below. Nothing unusual. In short, we can say definitively that **fire initiation** in our region has nothing to do with global warming. **The Fuels** Then there are the claims that a lack of snowpack or prematurely dried fuels were important in the fires this summer, with both due to global warming. This is demonstrably false. A map of the fires this year (below) shows that nearly all occurred over grass/rangeland or started in grass/rangeland and then spread into terrain. Because the fires started at lower elevations, the below-normal snowpack of the last year had no impact on these fires. Even at one higher-elevation fire (Little Giant), the fire started in an open area of a previous burn with lots of grass and downed trees. **A key point is that the range/grass areas were already dry, as would be expected this time of the year, even without any global warming.** Their moisture content was NEAR NORMAL before the fires. Want proof? The US Forest Service summarizes the fuel moisture for various regions of the Northwest (see below) Consider region 10, which includes many of the fires. The 100-hour fuel moisture (small vegetation) has been near normal (the gray shaded area), so was the ERC (energy release component) of the fuels. **In summary, any claims that human-caused global warming contributed to the recent Northwest wildfires are demonstrably false.** Lightning ignited fuels of normal dryness. **But there is something that has radically increased the chances of wildfires east of the Cascade crest:** the invasion of highly flammable invasive grasses, such as cheatgrass. A map of the "exotic" grasses is shown below. You won't hear about this in certain media and by some advocacy groups. But the increase of these grasses during the past half-century has greatly enhanced the flammability of the landscape.

On Thursday around 5:15 PM, a Kenmore Air float plane crashed on the south side of Sucia Island in the San Juans. An image from the final seconds (shown below) does not suggest particularly strong winds at the surface, nor any precipitation. The weather radar at the time of the incident shows a convective/thunderstorm line just to the south, but with the crash location (indicated by the red arrow) being in the clear. The thunderstorms in the band were associated with lightning (see map below) for the period immediately before the crash. There was good reason that the Kenmore Air pilot, headed towards Roche Harbor, went north and east to avoid the incoming thunderstorm cells. He appeared to be circling about, waiting for a weakness in the convective line--but I am not sure of that. **So how severe were the meteorological conditions?** Examining the wind gusts at 5 PM, there was nothing exceptional, with 23 mph near the accident site (Eastsound). Precipitation with the thunderstorm line was variable, ranging from 0.44 to 0.04 inches on Orcas Island. The bottom line is that meteorology (a line of thunderstorms) obviously caused a change in the route of the Kenmore aircraft, but there is no direct and obvious causal relationship to the accident. The only possibility one could speculate on was the potential for a lightning strike at a distance.

**Sometimes the weather gets stuck in a totally benign pattern, with little threat of heatwaves, wildfire explosions, heavy rain, or anything else of note.** During the next week or so, we will be stuck in such a boring pattern, with great benefits for our region. To demonstrate this benign situation, consider the forecast upper-level (500 hPa pressure, about 18,000 t) for Sunday morning. A ridge of high pressure is inland, and a trough of low pressure is off the northwest coast. Fast forward to next Friday evening (below). Very similar! **This pattern produces moderate, unremarkable weather over our region, with no heat waves**. To illustrate this, below are the temperature forecasts for Seattle and the Tri-Cities for the next ten days. BORING. Seattle rises into the mid to upper 70s. The Tri-Cities into the 90s. Very typical. The forecast upper-level pattern is associated with modest **atmospheric rivers** , moving moisture from the southwest to the northeast. To prove this to you, below are the forecast **water vapor transport** from Sunday and next Friday. The moisture plumes are evident. When the moisture reaches our shores, expect rain. There will be regional precipitation, particularly over southwestern British Columbia. The total precipitation through Sunday evening is shown below. The Olympics and North Cascades will get a piece of it. Total through next Saturday morning is impressive. Will damp down any wildfires across southwest British Columbia. Getting moisture this time of the year....typically the warmest and driest period for our region.. is very good news and will help this summer end with normal or below normal wildfire acreage numbers. Also favorable for Northwest agriculture.

**9:30 Update** **The showers and thunderstorms are here**(see radar image). And cooler air is moving in from off the ocean. Lightning at 8:10 PM: ________________________________________________________________________________ A line of thunderstorms is now moving up western Oregon at this time and is heading into western Washington. A little after 2 PM, the thunderstorms were evident in the infrared satellite image, with the lightning indicated by red crosses. A visible satellite image around 3 PM showed the area of boomers clearly The weather radar at 3:45 PM clearly indicates some impressive thunderstorm cells: For short-term forecasts, the chosen tool is the NOAA HRRR model. Here is the predicted radar image for 8 PM today. Storms into southwest Washington and around Portland. At 11 PM, they had moved northward towards Puget Sound. Thanks to Dr. Peter Bender for suggesting a look at this.

**We are now approaching the driest time of the year, and ironically, it is going to rain that day. Temperatures will cool.** An important contributor will be a weakening tropical cyclone (Elida). Below is the path of that storm from the National Hurricane Center: And a recent infrared satellite image shows the moist storm off the northern California coast. But where will the tropical moisture go? You guessed it..... we will get a piece of it Consider the forecast of atmospheric moisture from the European model over the next few days (below). Moisture surges into our region starting late on Wednesday and hangs around through Sunday. And this moisture will be associated with precipitation! Here is the total through Thursday morning. You can see the remnant of tropical cyclone offshore. And the precipitation won't stop..... take a look at the total rainfall through Wednesday morning, July 29th...t**he driest day of the year.** ** ** **Wow. Lots in British Columbia.** Consider the forecast 24-h precipitation total ending 11 AM July 29th for our regoin. Pretty wet for this time of the year. Rain on this day will be personally embarrassing for me.... I had recommended that a couple get married that day if they wanted an outdoor wedding. ##

**During the next few days, temperatures will surge upwards west of the Cascades into the low 90s, but a significant smoke intrusion is NOT expected in the west.** This is in contrast to highly deceptive (and incorrect) media reports, such as in the Seattle Times (see below). **** In fact, a lot of media outlets are providing such inaccurate information (such as Public Radio Station KUOW: Currently, surface air quality in the west is excellent (see the proof below). Green dots indicate very clean air. The most powerful tool for looking at future smoke impacts is the NOAA HRRR smoke model. Consider the latest forecast run. Below is the predicted low-level smoke concentration for 4 AM tomorrow morning. **Minimal smoke over the lowlands.** Ditto for 5 PM tomorrow. And even less smoke west of the Cascades on Wednesday morning. If you are living west of the Cascades, you will breathe easily. There will be a short warm period (two days) with temperatures reaching as high as the low 90s, followed by a cooling to near normal levels **for the rest of the month.** This is illustrated by the latest Weather.com forecast for Seattle (below). The Weather.com forecast is generally far more accurate than the National Weather Service. With all the wildfire hype going on in social media and elsewhere, it is important to note that there are **no major wildfires over western Washington, in the Cascades, or on the eastern slopes of that barrier.** You want proof? Here is the last large fire map by the USDA Forest Service: The Cascades act as a barrier for the smoke from the easstern Washington fires or the smoke coming in from Canada. Not easy to move the smoke down to the surface from the east. Finally, for those worried about wildfire, it appears that there will be significant precipitation over the next week, **which is close to the climatologically driest time of the year.** To show this, below is the latest European Center total precipitation forecast over the next 8 days. **Impressive for this time of the year.**

**As expected, the massive lightning event this week led to the ignition of several wildfires.** But our region lucked out: few fires were started on the eastern slopes of the Cascades within forested areas. This is because we are in the early season, which means less time for drying in the slow-to-dry forested areas, and because of the distribution of lightning (relatively little lightning on the eastern slopes). Below is a map of the largest fires. Most were in grass and range vegetation, with the greatest fire activity in southeast Washington and northeast Oregon, where the most lightning occurred. You can see the smoke in the midday high-resolution visible satellite image (as well as low marine clouds over western Washington). Some satellites can observe the heat from the fires....and here is the same image with fire locations (orange dots). The grass/rangeland of northeast Oregon is clearly the "hot spot" for the fires. It is important to note that such fires have little to do with global warming or heat waves. Light fuels, such as grass and range vegetation, are typically dried by now, and lightning events like this week have no correlation with a warming planet. Want proof that the moisture level of the fuels (grass/range vegetation) was not unusual? Below is the data from the US Forest Service showing you the 100-hour fuel moisture levels. (100-hour fuels include dead organic materials, such as branches and dead roundwood, that measure between 1 and 3 inches in diameter.) The observed moisture levels (red line) are in the middle of the average range (gray shading). **But something _has_ changed over the past decades the was made our grass/rangelends far more flammable.**..the invasion of explosive-burning cheatgrass and other fire-friendly species. This map shows you the extent of the problem and why eastern Washington and Oregon are so vulnerable Flammable grasses have taken over the region (see below), and ignition by lightning or human activities can start a firestorm. And there is one more thing. To get large fire growth requires strong winds, and the weather systems that produced the thunderstorms also provided large wind gusts, both during the storms and after. Want proof? Check out the maximum winds on Thursday (below). Winds are declining now, and you can expect that the grass/range fires will quickly decline.

One of the greatest Northwest lightning outbreaks in recent memory occurred today, **with well over 5000 lightning strokes over the region.** Below are the strokes over the past 24 h: very impressive. There were three major thunderstorm paths...one down the lowlands of western Washington, one along the coast, and a broad band in eastern Oregon and Washington. Importantly, there were very few lightning strikes on the eastern side of the Cascades, which greatly reduced the chances of forecast fires there. The massive lightning activity over northeast Oregon did start fires. Normally, the Pacific Northwest is the poor stepchild of lightning activity in the U.S. But look at the national lightning activity for the past 48 hr below. For once, we were in the league of Florida or Texas! The radar image this morning was enough to promote goosebumps for the meteorologically inclined: And today's precipitation totals were quite significant, with several locations receiving over a half-inch (see today's totals below). The visible satellite image around 10 AM looked like something out of Oklahoma: During the morning, several folks told me they saw funnel clouds, based on pictures like this: I saw such clouds myself... which result from aircraft passing through a low cloud deck. NOT a tornado. **Let me end with a truly remarkable image.** Low clouds were left in the wake of the thunderstorms over western Washington, but Mount Rainier extended above the clouds. Eastern Washington is now experiencing plumes of smoke from fires ignited by the lightning over northeast Oregon. The green areas show lightning strikes.

**For most summers, during July or August there is an intrusion of "monsoon" moisture from the southwest into our region, resulting in showers and thunderstorms...and this year will be no different.** Such thunderstorms can be both good and bad. Good at providing needed rain and lessening fire risk, but bad if lightning starts fires. The predicted totals through Friday morning (seen below) range from a few tenths to a half inch, with higher values along the coast. The wet fun will begin later this afternoon and evening as convection and thunderstorms build near the crest of the Cascades (see forecast for 5 PM below). _ _ Overnight, more serious thunderstorms/convective showers will move into the region, as suggested by the forecast weather radar image at 2 AM from the University of Washington forecast system: _ _ _ _ The latest forecast of the NOAA HRRR model is quite similar (simulated radar at 1 AM shown below). ** Why this wet bounty?** Two things are occurring together. The upper-level pattern includes an approaching upper-level trough (500 hPa, about 18,000 ft shown for tomorrow morning). Such troughs produce upward motion (which helps initiate cumulus clouds) and bring in moisture from the south. Such "monsoon" moisture and unstable air from the southwest are evident in the forecast below. Total water vapor content of the atmosphere this evening. Blue and red are higher values Enjoy the show overnight!

If you viewed the skies around sunrise and sunset during the last day, it was evident that a massive cloud of smoke had moved in overhead. For example, here is a northwest view from the Seattle PanoCam just before sunrise this morning. Stunning. Lots of smoke in the sky. And if you needed more evidence that our sky was full of smoke, below is the visible satellite image at 6:52 AM this morning (Monday, July 13). Wow. Lots of smoke over our region. Yet, with all this smoke, surface air quality is excellent, as shown by the latest observations from the Puget Sound Clean Air Agency (green means good air quality). How could this be? The answer to this conundrum is that the smoke is located many thousands of feet aloft, so high that it can not mix down to the surface. To prove this, here are observations from a laser-based ceilometer in Marysville, Washington. This device shoots a laser vertically, allowing it to sense smoke and clouds above the surface. This morning, the smoke was around 3000 meters (about 10,000 ft) above the surface. **Where did this smoke come from?** Not from local fires, but from major fires in the Canadian arctic and sub-arctic regions, something shown by the visible satellite image two days ago (see visible satellite image from two days ago): This smoke then swung around an upper-level low off our coast and into our region. I can demonstrate this with the upper-level weather map (about 18,000 ft, 500 hPa pressure) for early Sunday morning (below). The wind barbs show the wind speed and direction. Air from northwest Canada moved offshore over British Columbia and then swung around the low and into the Pacific Northwest! The pattern is now shifting, and the smoke aloft will move out of our region today. _ _ _ _

If you asked Google AI where the best weather in the U.S. will be, the answer will warm your heart: Seattle gets called out with "perfect weather conditions". As a trained meteorologist, I concur. The forecast high-temperature map for Sunday across the U.S. shows only one urban area in the upper 60s to low 70s: western Washington. Even eastern Washington is reasonable. You dislike humid conditions with high dewpoints (above 60F) and want to avoid very dry, parching air (dewpoints below 40F)? Western Washington and Oregon are for you! (see plot of forecast dewpoint temperatures for 5 PM Sunday below) Want sunny skies on Sunday? Western Washington and Oregon residents will see blue skies. And you like some light winds, but not too strong? The wind gust forecast for tomorrow shows perfect conditions over western Washington. Air quality? Clean air (green dots) over the Northwest (see below). You can take a deep breath! There is so much negative information today about the environment, so it is good to acknowledge when things are spectacularly nice. I won't get many online hits in saying this... but it is true.😋

Late June or early July is the traditional start time for the**North American (or Southwest) Monsoon,** during which moisture streams northward from Mexico into the southwestern U.S., bringing substantial showers to Arizona, New Mexico, Nevada, and sometimes Oregon, Idaho, and eastern Washington. See the schematic below. Such monsoons are often associated with an area of high pressure over Colorado and northern New Mexico, which draws moist air from the Gulf of Mexico into the American Southwest. In a few days, the monsoon will get revved up, and some of the wet action will reach portions of the Northwest. **Let me show you!** Here is the predicted precipitation total over the next 10 days. Some of the Mexican moisture pushes into Arizona and Nevada, and a small amount will extend into eastern Oregon. The official NOAA Climate Prediction Center 6-10 day forecast is for wetter-than-normal conditions over the southwest U.S. The far southeastern portion of Oregon gets a wet taste of it. As expected, this monsoon moisture will be driven by an upper-level high over the 4-corners area that will move moisture into the southwest from the southeast (500 hPa --about 18,000 ft map for each Sunday morning is shown below) Here is the predicted precipitation for Tucson, Arizona. Very wet! There will be some good thunderstorms in Arizona, if you enjoy big boomers. This is not a particularly hot pattern for the Northwest, and Seattle will stay moderate in temperature (see below). _________________ **Announcement** ** ** I will hold a special online Zoom session at 10 AM on Saturday for Patreon supporters. Will talk about the latest forecasts for the remainder of the summer and answer your questions!

**One of the reasons Northwest weather is so temperate in summer is the cool coastal waters off our coast.** And this year, we start the summer with surface waters **cooler than normal.** This is illustrated by the sea surface temperature anomalies (differences) from normal (below), with blue indicating cooler than normal water. Below is a map of sea surface temperatures off the U.S. West Coast (°C). The purple and blue colors indicate the coldest temperatures. You will need a sweater to enjoy a coastal stroll! **Why such cold water along the coast?** One reason is the upwelling of cold water from below, as illustrated by the figure below. Such upwelling is forced by northerly (from the north) winds along the West Coast. Importantly, these northerly winds have been stronger than normal for the past month. Why? ** ** **Because of stronger-than-normal surface high pressure offshore of the northwest.** This is demonstrated by the figure below, which shows the sea-level pressure anomaly (difference) from normal over the past month. The red area indicates a much higher-than-normal high-pressure area offshore. Since winds move clockwise around high-pressure areas in the Northern Hemisphere, this implies enhanced northerly flow along the coast, something shown explicitly in the figure below (which shows the wind differences from normal of the past month). With this persistent pressure/wind pattern in place, the current 5-day forecasts are for colder than normal conditions over western Washington, Oregon, and British Columbia (blue and green indicate colder than normal conditions) Keep your sweaters handy!

The Chelan Hills fire, reported to have been started by some irresponsible fireworks Saturday morning, has now spread to over 10,000 acres (see map below). A high-resolution visible satellite image this morning shows the burnt area (dark color), and the satellite imagery shows some still-active fires (red dots). Smoke from another (smaller) fire is apparent to the southwest. The fire started in grass and range vegetation, not forest. Importantly, this vegetation was NOT unusually dry, as shown in the figure below, which provides 100-h fuel moisture levels on the eastern slopes of the Cascades. Red is observed moisture level, and the shading shows the normal range. Current moisture levels were **above normal.** So "climate change" can not be blamed. What can be blamed was strong winds. Winds that were skillfully forecast by the UW WRF modeling system and the NOAA models. To illustrate, below is the wind forecast for Saturday afteroon be the UW WRF weather model....**strong winds were predicted around Chelan!** Below are the strongest observed winds yesterday around the fire area. A 36 mph gust was observed near the fire start. Winds at this location really revved up during the afternoon and early evening (see below). At the same time, relative humidity plummeted to less than 20%--the result of drying of air moving downslope on the eastern side of the Cascades. There is reason that wildfire starts are maximized on July 4th. The ignitions are there, the grasses/range vegetation are dry enough to burn, and it is early enough in the summer so that strong onshore flow produces powerful winds.

Walking my dog yesterday, I ran into a neighbor who asked whether July 4th temperatures in our area had changed much under global warming. I promised to run the numbers... and here are the results. **Be prepared to be surprised 😀.** Starting at Olympia, on the western side of the state, there is almost no trend in July 4 daily average temperatures since the 1940s! (The purple line is the linear trend). What about the highest temperatures each year on July 4 in Olympia? **No trend!** OK, now let's check Yakima in eastern Washington! The July 4 average temperature trend is slightly upward (a little less than 2 F over 75 years). The trend in the maximum temperatures at Yakima is similar. Modest upward increase. And then there is Spokane, over the northeast side of Washington (below). Very little trend in average July 4th temperatures or in the highest temperatures on that date. _ _ What about precipitation on July 4th in Olympia? As shown below, there is little evidence of a long-term trend. **Anyway, a big yawn is appropriate for the July 4 trends in temperature over Washington State.** ** ** The planet is slowly warming for sure, but the temperature trends in Washington State are very, very modest. **But you might get a different answer if you relied on AI.** I asked Google's AI to create a graphic summarizing the July 4 temperature trend over Washington. It created the graphic below, with a dramatic upward trend over Washington from 26F to 80°F since 1990 (below). Was it really below freezing in July in 1990? Total nonsense.

**With an _extreme heat watch_ over much of the central and northeast U.S., including temperatures reaching near 100 F (see below), it is good to know that the weather over the Northwest will be near perfect over the holiday weekend.** Temperatures will rise into the mid-70s in Seattle on Friday through Sunday, while temperatures in eastern Washington will reach about 90F. A forecast map of surface air temperatures around 8 PM on Saturday, July 4, shows the mild temperatures in western Washington, with reasonable warmth in the Columbia Basin. Cool in the mountains. No worries about precipitation on July 4th, as illustrated by 3-h precipitation totals ending 11 PM that day (below). Obscuring clouds on Independence Day? Here is the cloud prediction for 5 PM Saturday. Mostly clearly, except for high terrain in the Olympics. To make things even better, the cool/wet conditions this week have made regional fuels less flammable, reducing fire risk this weekend (when all kinds of crazy fireworks activity will occur). See the predicted ERC and Fuel Moisture values below. There are no reds (serious risk) and only some marginal values (orange). But please be careful.