Has Eastern Washington Gotten Drier or Warmer?

 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.

Are the Recent Northwest Wildfires a Sign of Global Warming? The Science Says No

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.

The Meteorology of the Kenmore Air Crash near Sucia Island

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.

The Weather Pattern is Stuck: Temperate, Mild Weather Ahead

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.

Thunderstorms Possible This Evening in Western Washington

 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.

Tropical Storm Moisture Will Bring Precipitation to the Northwest During the Driest Time of the Year

 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...the 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.  

Warming Temperatures.....But Western Washington And Oregon Will Miss Low-Level Smoke

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.