August 05, 2021

California Smoke Overhead But MUCH Cooler Temperatures and Rain are Ahead

Today is the last warm day for the region for a while--before the weather abruptly shifts to cooler, moister onshore flow.    And the California smoke over two-thirds of WA State this morning will soon be blown to the east.

The regional satellite image this morning is very dramatic, with a thick plume of California wildfire smoke moving across western Oregon into central and eastern Washington.  Only the northwest part of the domain is clear.


The California origin of the smoke is made clear by the NOAA HRRR model simulation, with the forecast for 2 PM shown below.


Fortunately for the residents of western Oregon and Washington, the smoke is aloft, with little of it reaching the surface.   

An east-west vertical cross-section from the NOAA model simulation shows this fortunate situation (below).  No smoke at the surface over western WA, but serious smoke aloft.  So if you are in the western lowlands from Eugene OR to Vancouver BC,  you can breathe easily.  And the smoke aloft will provide some cooling so today will be a few degrees cooler than yesterday.


But tomorrow EVERYTHING changes!  You better have your sweater or jacket handy.

A strong upper-level trough of low pressure will approach and move through on Friday and Saturday, something illustrated by the upper-level (500 hPa pressure, about 18,000 ft) map for 11 AM Friday.


The increased onshore flow through depth produced by this disturbance will push the smoke out of much of the Northwest, something illustrated by the vertical cross-section of smoke forecast for 5 AM tomorrow.  


And temperatures will fall.  Here are the temperature predictions from the University of Washington high-resolution ensemble (many forecasts) for Seattle.  Today will rise to the lower 80s, around 75F tomorrow, and around 70 on Saturday.  Where the forecasts are the same, there is less uncertainty.  


Rain?   You bet.  Here are the predicted totals through 5 AM Sunday  Good wetting in the mountains and southern BC.


Of particular importance will the cooling in eastern Washington, where high temperatures will drop into the 80s by Saturday.   And relative humidity, a key factor for wildfires, will rise substantially (see the prediction for Ephrata below for the next several days).  Low relative humidity today (only peaking around 40%), but rising to around 70% for the next four days.  Expect major progress in getting control of current wildfires in the state.


Finally, let me provide you with a visual treat.  Greg Johnson's cam at his wonderful Skunk Bay Weather site on north Kitsap captured the plume of smoke moving in this morning.  Absolutely spectacular.  View it below.  Enjoy.




20 comments:

  1. So Accuweather came out with their Fall/Winter projections for the expected La Nina conditions. Talk about gloomy for the PNW, they only left out the Four Horsemen of the Apocalypse.

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    Replies
    1. I welcome any rain and gloomy , bring it on !

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    2. I welcome any rain and gloomy , bring it on !

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    3. I welcome any rain and gloomy , bring it on !

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    4. That's exactly what I was hoping would develop. More rain than average, cooler temps, more cloud cover and hopefully more snow in Winter will help recover from/prevent drought in the PNW. The sooner the better, although they aren't predicting La Nina until December. Mostly neutral conditions until then.

      But here's hoping. The modeling is early, and Winter skill might not be so great in early August, but it is something to hope for. In a time when climate change may be starting to become noticeable, sunshine and dry are not our friends. Clouds and rain are.

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    5. You misunderstood my point, my bad. If you read their summary, they're calling for the drought to continue, perhaps into the winter months. That's what I call a gloomy forecast!

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    6. Accuweather is notoriously inaccurate with anything long-range (as are pretty much all long-range outlooks). I wouldn’t put any stock in their forecast at all.

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    7. According to NOAA's Climate Prediction Center, the source of ENSO forecasts, our precip probabilities are normal (EC) through November and then go Green (wetter) for November and December, then back to EC for the rest of the winter. Not sure they've cranked in the latest ENSO forecast (just came out yesterday) yet, which likely takes us wetter yet starting in December.

      That's for Western WA.

      Way drier forecast for Eastern WA.

      Location is everything.

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  2. My phone begs to differ. It’s showing low-mid 70s with no rain. What gives ?

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  3. Do you have any insight into the upcoming heat wave next weekend? I’ve seen some meteorologist on Twitter stating we could see temps in the 100s again?

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    1. If they are telling you 100F, I would find another meteorologist.

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    2. I hope you're right, Cliff. They're forecasting another string of 100 degree days here in Portland next week. Yikes.

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    3. So, Weather Underground is a poor source for weather forecasts, then? I'm seeing 99°F late mext week using their forecast.

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    4. I just checked weather underground for Seattle.... 91F. Perhaps you are looking at a different location. In eastern WA or Portland, 99F would be a reasonable forecast

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    5. I should've included the location... Olympia area a few miles from the water.

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    6. Weather.com is going for 98 here in N. Bend. I know you have spoke very highly of their model. This rapid swing to high temps seems like it will quickly negate any dampening effect of the rain.

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  4. What modeling do our local TV meteorologists use? The 2 stations I watch are calling for very little if any rain in Seattle (but a better chance Sat night). Thanks - I'm a huge fan of yours.

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  5. "Mostly neutral conditions until then." Doesn't that mean strong storms? I hope you have a generator.

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  6. How does this year's drought stack up to prior dry spells?

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Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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