August 03, 2021

Smoke Will Soon Exit Western Washington As the First Cool/Wet Weather System Approaches

 A thin layer of mainly California smoke is above Washington and Oregon right now, as evident by the latest visible satellite image (below).  Only Northwest Washington is smoke-free.


But as typical of smoke from distant fires, the smoky layer is aloft and air quality at the surface is quite good over the western lowlands, as shown by the AIRNOW website.

The smoke layer aloft has thinned considerably during the past 48h, something illustrated by the view of Mount Rainier from the Crystal Mountain Cam:

Onshore winds will increase during the next few days, and the result will be the removal of smoke both at the surface and aloft.  

Consider the HRRR model forecast for near-surface smoke on Thursday morning.  No smoke over the western WA and Oregon lowlands.  Fires in Washington and southern BC have faded after the cooler/wetter weather and the considerable efforts of firefighting crews. 


But then there is the approaching weather system....it will feel like the first taste of fall, with far cooler temperatures and rain.

But first, I should note the potential for showers and thunderstorms tonight over western WA and the north Cascades, showers associated with a passing upper level disturbance and unstable air.  The simulated infrared satellite image for 5 PM today is impressive!

The rain will hit on Friday, accompanied by a 10-15F drop in temperatures.   To give you an idea of the upcoming rainfall, here is the average of the excellent European Center ensemble of many forecasts for the total rainfall through 11 PM Sunday. Up to 1.5 inches in the mountains.



The UW model showing precipitation through  5 AM Monday also shows bountiful precipitation, particularly over the north Cascades and southern BC, both places where there are some remaining fires.  I expect rapid progress in attenuating these fires with such conditions.



The Seattle Times Hit Piece

I knew this was coming.  

The Seattle Times was upset that I noted problems with their hyped headline and story on the heatwave and they decided to do a personal hit piece on me.   Their story says everything about their attitudes towards science and truthful information.  The bias of the article was pretty obvious, with no attempt to quote the many individuals supporting my viewpoint or to deal with the issues I noted regarding the attribution report.  And then they went over the top, bringing in my comments in social media on completely different topics. 

Anyway, I will write a separate blog on the Seattle Times piece--very poor journalism that demonstrated, better than I ever could, their lack of commitment for communicating the facts and uncertainties regarding global warming.

Global warming is a serious issue that can only be dealt with by a well-informed citizenry.   The Seattle Times has a different view, pushing a politically charged, biased narrative,  that deviates from the best science that in the end will leave our region less prepared for dealing with climate change.  And one that needlessly gives people a sense of doom and desperation.

A few people reminded me of a relevant piece of wisdom:

"When you are receiving flak, you are over the target"



August 01, 2021

Smoke Moves in Aloft, But Precipitation Fell Exactly Where We Needed It

Wildfire smoke from distant fires has now moved in aloft above western Washington, pushed by southerly and southeasterly flow aloft.

The sky again has that hazy look, with the sun taking on orange and red hues.

But air quality remains good near the surface west of the Cascade crest.

The view from Crystal Mountain towards Mount Rainier says it all.  Below is this morning versus July 19th.  Wow.  I'm glad I did my hiking last Sunday.



The NOAA HRRR model shows the forecast smoke over the region around noon.  Red indicates fairly high levels.


But the smoke is staying aloft over western Washington, something shown by an east-west vertical cross section of smoke at the same time.  Not so good at the surface east of the Cascade crest.


Yesterday and overnight some VERY welcome rain fell over the Cascades and northeast Washington...as much as a quarter of an inch (see 24-h totals below).  EXACTLY where we needed it to lessen the wildfire threat (click to expand).


And with all the clouds and smoke hanging around, eastern Washington is RADICALLY cooler today, with some locations 25F cooler than yesterday (the maps shows the 24- temperature change between today and yesterday)


Wildfire threat is way down and this gives firefighters a chance to gain an upper hand.

Finally, the models are converging together on the cool/rainy period starting on Thursday....a period that should greatly lessen the wildfire threat for weeks.

Take a look at the 48-h total precipitation ending 5 AM Sunday.  Unbelievably wet, with some areas getting over 2 inches of rain.  If this verifies, the fires near Winthrop and southern BC will get radically knocked back.  


All and all, a very favorable situation.


July 31, 2021

Monsoon Moisture Reaches Washington and Oregon

When one thinks of the Northwest during the summer, the word monsoon is not the first thing that comes to mind.  But during the last day, Southwest Monsoon moisture has spread from the southwest U.S. into our region.

It has already rained at Sea-Tac Airport and clouds have spread over western Washington.  

The water vapor channel of the NOAA GOES satellite clearly shows the plume of moisture heading directly over the Northwest.


And the visible satellite image this morning highlights the associated clouds over western Washington and northern Oregon


The radar image around 7AM indicates some showers moving up into our region.   My newspaper was a bit soggy this morning.


This moist air will be around this weekend and the air is unstable enough for more showers this afternoon, particularly over and east of the Cascade crest.

Over the 24h ending 5 AM Sunday, most of the showers will be over eastern Oregon (see 24-h accumulated rainfall below.  And some of these showers will be associated with thunderstorms. A few light showers could hit western Washington.


But Sunday is a different story, with northeast Washington and southern BC getting more moisture. Serious rain over some of the wildfires near Winthrop.


After today, there will be four warm days before the bottom drops out of our weather.   

Below are the forecasts for the NOAA GFS ensemble system showing the temperature at Seattle.  In an ensemble system, the model is run many times, each slightly differently.  

Today gets to around 80F, and the next four days are slightly warmer.  But then comes Thursday and BOOM...a big decline (the black line shows the average of the many forecasts).   There is some uncertainty in the forecasts, with a range of solutions, but most are MUCH cooler.   Same for Friday and Saturday.

Rain?  Chance of some very light errant showers over the weekend, but the rain chance really revs up on Thursday onwards, with many of the simulations showing rain.


As I noted early, this is quite a vigorous cool/wet event for midsummer, but I suspect it will be welcomed by many.  And it will reduce the wildfire threat for a while, assuming we don't get many lightning starts.








July 30, 2021

New Podcast: Weather Whiplash Week. From Heatwave to Thunderstorms to the Big Cool

My podcast today will review the major shift in our weather that will occur this week.   And in the second segment, I will talk about Northwest thunderstorms.

We start with a minor heatwave today with temperatures zooming to around 90F in western Washington away from the water and into the upper 90s in the Willamette Valley.

But at the same time, a major plume of moisture will move northward into eastern Washington and Oregon, bringing thunderstorms (the image below shows the predicted rainfall through 5 PM Sunday).


Wildfire smoke will move in overhead during the weekend but not reach the surface in western Washington, so you can breathe easily.  But the plot of total smoke above us on Sunday night is scary:


Finally, there is the BIG change at the end of the week.  Clouds, precipitation, cooler temperatures.  Way earlier than normal.  The 48h total rain ending at 5 PM Friday is shockingly wet.


My podcast will not only describe this forecast but give you an essential background regarding Northwest thunderstorms.

To hear the full story, listen to my podcast below or select your preferred streaming service



 HTML tutorial HTML tutorial



July 29, 2021

Super Moisture Plume Headed for the Northwest.

Many of you will need umbrellas during the next week.   And perhaps a lightning rod.  

The cause? 

A dramatic plume of moisture will be heading into the Northwest from the south.  

Southwest Monsoon moisture will be entering our region, and our chances of breaking any dry spell records are dimming fast.

The latest water vapor satellite image shows the impressive moisture plume over the Southwest---and it is heading our way.


Let me start by showing you the latest precipitation forecasts from the UW WRF model.  For the 72 hours ending 5 PM Tuesday, the interior gets wetted down well, with some favored locations enjoying over an inch of rain.  This precipitation is from the plume of moisture from the southwest U.S.  


But our wet bounty is not over: during the next 48 h the first Pacific disturbance of the season moves in from the west and provides precipitation for western Washington and southwest BC. This system is a bit earlier than normal (normally the first wet system occurs during the third or fourth week of August), but no one is going to complain.


Now back to the superplume of moisture coming up into our region.  

Below is the forecast total moisture in the atmosphere predicted by the European Center model for Sunday evening. Known as precipitable water, it represents the depth of water that would occur if all water vapor was condensed out of the atmosphere.  The colors represent the percent of normal.  Blue is high (over 160% of normal, gray is VERY high (over 250% of normal).  Lots of moisture moving northward east of the Cascade crest.


How unusual is this moisture plume?  The predicted values over eastern WA and southern BC on Monday morning will be up to FIVE standard deviations from normal for that date (see image below, dark gray).  A standard decision is a measure of deviation from the mean.  Five standard deviations indicate essentially unprecedented conditions over the past several decades.

So we will go from extreme heat to extreme moisture in a little over a month!

This moist air will be relatively unstable, which means a good chance of thunderstorms east of the Cascade crest.   The simulated infrared satellite image on Saturday night suggests a number of storms in eastern Oregon (see below).  Thunderstorms can bring needed rain, but they can also start wildfires.


With the lack of thunderstorms and wind, wildfire activity has actually declined in recent days.  So this situation will be one to watch carefully.

Reminder:  new podcast tomorrow morning.  Perhaps it is time to talk about Northwest thunderstorms!


July 27, 2021

The Most Perfect Weather Month in Western Washington History

One can make a pretty compelling argument that July 2021 will go down in the record books as the most perfect weather month in western Washington history.

Perfect in every way

Moderate, but warm temperatures.  Cool enough at night for sleep.  Lots of sun. No wildfire smoke.  Good air quality.  No rain.

Picture today over Puget Sound, courtesy of Ben Slivka

Temperature:

Consider Boeing Field in Seattle.  Every day has had maximum temperatures between 69 and 84F.    Never too cool or too hot! And enough variation to keep it interesting.  But wonderful for outdoor recreation.


Cool enough to sleep at night?  You bet!   

Every day at Boeing Field had low temperatures below 65F and most days dropped to around 60F or the upper 50s.  And that is in the middle of the urban heat island.  Most folks enjoyed even cooler nighttime minimum.    You could sleep well without AC!

What about sticky conditions?  Humidity that can make life so unpleasant in much of the U.S.?

Not here in western Washington!  A very good measure of unpleasantly "sticky" conditions is when the dew point gets above 63-65F.    Remember that the dew point is the temperature at which the relative humidity gets to 100% when the air is cooled.   

Look at the dew point this month at SeaTac Airport (below).  Never above 59F and for much of the month it has been less than 55F.   No wonder it has felt so comfortable!


What about wind?   A little wind is a good thing, making conditions more pleasant.  And as shown by the winds at the UW Atmospheric Sciences Building, most days had just around the right amount, with sustained winds during the afternoon getting up to around 12 knots...and sometimes a bit more.

Many afternoons have brought a highly pleasant Sound Breeze to Puget Sound, with excellent conditions for those with sailboats.  Just ideal

Sunshine?   Most days were at nearly full sun, which means few clouds and NO SMOKE (see solar radiation at Seattle below).


And let's talk about smoke, which is both depressing when it hazes the sky and which is unhealthy when it reaches the surface.

Basically, western Washington has escaped smoke this summer as onshore, westerly flow has pushed any smoke away from western Washington.   A visible satellite image from yesterday illustrates this smoke-free boon:


Air quality at the surface has been excellent in July around western Washington, as illustrated by today's evaluation by the excellent Puget Sound Clean Air Agency (see below).


But what about Tacoma?  Low particulate levels (under 15 micrograms per cubic meter), except for the July 4th fireworks.   Excellent air quality.  No smoke.


 Finally, what about rain, which can dampen outdoor activities and ruin that trip to the mountains.  

Little rain...just a few hundredths in the interior and a quarter inch on the coast.  Much drier than normal.  The monthly totals are below (click to expand).


 I have gone back many decades into the meteorological records of the region and no July or ANY OTHER MONTH has offered such consistent meteorological perfection.

But Some Have Another View

Now in the current psychological state of the world, the media, social media, and politicians are totally obsessed with the negative, particularly in environmental matters.

During the last month, major media has been obsessed with meteorological disasters from floods and heatwaves to wildfire smoke and drought...to name only a few.  Just one front-page disaster after another.

So where are the banner headlines about our wonderful weather:  the envy of the world?  

In fact, the Seattle Times, with a tendency for apocalyptic (and generally ill-founded) global warming stories, had a front-page story about THE BIG DARK.   About how miserable we will all be in the upcoming period of darkness.  I thought it was a Seattle Times joke when I first saw it, but they were serious (see sample below).  All in the middle of meteorological nirvana.


Western Washington generally has the best summer's in the nation and this month was off the charts wonderful.   Time to recognize it.




July 25, 2021

The Southwest Monsoon Brings Thunderstorms and Wildfires to the Northwest: Will This Change Under Global Warming?

Every summer starting around mid-June and ending by the beginning of September, moisture streams northward out of the Gulf of California into Arizona, Nevada, and the eastern portions of the Pacific Northwest.

Known as the Southwest Monsoon or the North American Monsoon, this phenomenon is associated with the river of moist unstable air that brings thunderstorms into the southwest U.S. and occasionally into eastern Oregon and Washington.


This moist current, with an origin over the warm Gulf of Mexico, is the result of high pressure that develops during the summer over the Southwest U.S. When this high shifts to near the Four Corners area of the SW (where AZ, NM, CO, and UT meet), the moisture can surge into the eastern portion of the Pacific Northwest.  This should happen later this week.

To see an example, lightning moved into eastern Oregon on July 20th (see below)


This was associated with the Southwest Monsoon and the Four Corners high, bringing moisture in from the south and southwest ( see upper level (500 hPa, 18,000 ft) weather map below for mid-day on July 29th.:


A plume of moisture associated with the Southwest Monsoon will move northward later this week out of the desert southwest.  To illustrate, this image shows you the atmospheric moisture pattern on Saturday, with blue, white, and red being the highest values (in that order.)


The 24-total precipitation ending late Sunday shows a typical SW Monsoon distribution, with precipitation extending northward into southeastern Oregon.


More on the weekend precipitation (which will include lots of thunderstorms) will be found in a future blog.

The importance of the mid-summer thunderstorms from the Southwest Monsoon is evident in the climatology of many stations in the southwest U.S.  Here are record daily precipitation totals in Phoenix, AZ...the biggest amounts are in July through September...that is the Monsoon.



You can see a weakened, but similar, effect at Las Vegas.


Thunderstorms associated with the Southwest Monsoons are potent sources of wildfires east of the Cascade crest.   Some of these thunderstorms are high-based and little precipitation reaches the surface.  Thus, a lightning stroke can start a fire if the vegetation is dry, as it usually is by midsummer.  Even if there is substantial rain, the lightning stroke can initiate a smoldering fire, that bursts out when the weather subsequently improves.

What about global warming?  Will it bring more or less Southwest Monsoon precipitation to our region?

I am, in fact, working on this problem with Professor Eric Salathe of UW Bothell, using very high-resolution regional climate simulations.

The answer appears to be that there will be more summer precipitation from the monsoon reaching eastern Washington (see a map showing you the difference between the end of the 20th and 21st centuries assuming very rapid increases in greenhouse gases).  Green indicates a wetter summer under global warming.  There is a number of reasons why global warming might stoke eastside thunderstorms, such as greater availability of water vapor.

But there is a dark side to a wetter summer:  more lightning, which can ignite wildfires.   
Stay tuned....we have a lot more work to do on it.





Smoke Will Soon Exit Western Washington As the First Cool/Wet Weather System Approaches

 A thin layer of mainly California smoke is above Washington and Oregon right now, as evident by the latest visible satellite image (below)....