June 28, 2021

Showtime. Temperatures Are Surging to Unparalleled Highs.

What is going to happen during the next few hours can only be described as weather whiplash.

Here is the latest super high-resolution temperature forecast for 5 PM today over western Washington.  Much of the western lowlands away from the water will be above 104F (light brown) and limited areas will surge about 110F.  I expect some localized hot spots around 115F.  Just extraordinary.   You will also note the onshore movement of cool air off the coast: an incipient onshore push of marine air.


SeaTac Airport is now running 8 degrees above normal and with its record-breaking 104F yesterday, it will certainly get near 110F today. Particularly since it is in a particularly favorable area of easterly downslope flow off the Cascades.

The difference between the temperatures at 11:30 AM today and yesterday is quite revealing (see below). MUCH cooler along the southwest coast (15-35F!), but much warmer from Seattle southeastward.  This is the result of the well-predicted southeasterly flow descending the Cascade slopes.



The current visible satellite imagery shows the cloud-laden cool area moving northward up the coast.  Our future comfort depends on it.


The cool-down tonight over Puget Sound still looks good: here are the latest high-resolution ensemble (many forecasts) predictions for SeaTac.  High of 110F this afternoon, but lows below 70F tonight.  Tomorrow will ONLY be in the upper 80s.  And back to normal on Wednesday.


Did you notice the hazy skies?  (see below)  No real wildfires in the region, so it isn't that.



I asked a local air quality expert, Phil Swartzendruber of the Puget Sound Clean Air Agency.   He suggested it is "secondary photochemical formation."   Translation: photochemical SMOG.  

The kind of unpleasant conditions that Los Angeles was so well known for.  The reason for this unpleasant bounty:  lots of sun and very warm temperatures that promote photochemical reactions (interactions of ultraviolet light with organic volatiles and nitrogen oxides).  As shown below, air quality has declined to moderate (yellow colors) around the region.



Finally, where do you think the warm air over us came from?   Well, I was curious and ran some air parcel trajectories back in time (such trajectories show the three-dimensional paths of air parcels reaching a point).  I went back 48 hours.

For this exercise, I traced back the air over SeaTac Airport at 100 meters, 500 meters, and 1000 meters above the surface (see below).  The top panel shows their position and the bottom panel provides their elevation.  

Wow...the air started well above the surface (roughly 3500 to 5000 meters) and then rapidly descended during the last day as it swung around the major high-pressure area over the region.   The air started warmer than normal aloft and warmed rapidly as it descended.


Stay cool.   Marine air is on the way for the west.  But then attention turns east of the Cascades.  Will the all-time high temperature for Washington State be broken (118F)?

48 comments:

  1. Is this "secondary photochemical formation" the same as
    "Biogenic Secondary Organic Aerosol"? And is this perhaps helping to keep us to the lower end of the forecast range?

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  2. Wow! The air parcel trajectory - super fascinating. I SO appreciate that sort of information, for understanding this phenomenon.

    Noon temp today (Monday, Glacier) was 3.1 F higher than yesterday-noon (96.6 ...99.7) so here we go (from the toaster to the roaster). Really looking forward to tonight, tomorrow ...normalcy!

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  3. The past couple of days and even more today, I've been smelling a desert vegetation smell that I've never smelled west of the Cascades before. I wonder if the smell is coming with the hot air from where it originated.

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  4. What are your thoughts on the weather.com model that seems to disagree with a rapid cooldown for Seattle? They are going for 90's in Seattle tomorrow with <70 after 6am which is essentially Tuesday. One likely contributor to smog is that I see a lot of folks sitting in their vehicles running the engine + ac to cool off or just driving around to stay cool.

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  5. Thanks for the frequent posts during this peculiar event!

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  6. considering your research and connection of hot weather with decreased incidence COVID (not sure if i'm saying this correctly), could that be one small positive to the extra warm weather or will this hot spell make no real difference?

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  7. Professor,

    I think other's have noticed the drop(s) in air pressure though this. Is that related to a front or simply "lighter air" (due to the air's dryness)??

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    Replies
    1. The air doesn't seem particularly dry with dew points in the 60s, yet I have the same question.. i.e., what makes the thermal low? Air pressure I had at 1006 mb today and falling late I the day, which seems somewhat low.

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  8. A friend in Hoquiam reported a cool breeze developing around 1pm.

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  9. To repeat my question from yesterday: how does one explain the considerable discrepancy between the temperatures shown in these model runs and the NWS prediction that overnight cooling will be “poor” and that tomorrow’s highs will be in the upper 90s?

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    Replies
    1. one of the predictions is wrong.

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    2. Incisive & direct - a great answer!

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    3. who said tomorrow (Tuesday?) highs would be in the upper 90s? Where?

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    4. And…it looks like NWS gets the booby prize. Although they haven’t rescinded their Excessively Heat Warning, they’ve toned down the terms of it significantly (heat Index of up to 101 instead of the original 111, no mention of highs in the upper 90s or “poor” nighttime cooling in the Eastern Puget Sound, etc ).

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  10. TUCW1 Tucannon River near Starbuck; Provider HADS; 28 Jun 1:30 pm 120F
    https://www.wrh.noaa.gov/mesowest/timeseries.php?sid=TUCW1&num=72&banner=gmap&raw=0&w=325

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  11. 109 at 3pm
    500 feet elev. above Hood Canal near Dabob.

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  12. There is a fire near Mt. Lassen and the smoke is blowing to the NW. Is this adding to our smog?

    Marine push in Hoquiam currently. Was in the mid to upper 90s at 11AM and is now in the upper 60s

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  13. So you're saying the marine layer has an effect? Quillayute (north of the cloud deck), 109 F. Queets (south of the cloud deck), 67 F. The two are less than 30 miles apart!!

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  14. What are your thoughts on the weather.com model that seems to disagree with a rapid cooldown for Seattle? They are going for 90's in Seattle tomorrow with <70 after 6am which is essentially Tuesday. One likely contributor to smog is that I see a lot of folks sitting in their vehicles running the engine + ac to cool off or just driving around to stay cool.

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  15. I don't think I will complain about rain for a long time. I do appreciate the commentary. It allowed me to prepare for the heat. Even though the models seemed to exaggerate everything last week, they were really close to what did happen.

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    1. Indeed they were! Impressive. The European model was quite close almost a week ahead of time!

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  16. Cliff - how many years or other measurement periods outside the temperature standard deviation will it take for our region to confirm climate change?

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    1. When we have our next heat wave, it will no longer be showing this as a 1 in 1,000 or 10,000 event, using the past 200 years of data. I wonder what the stats would say if we only had data from 10,000 years ago to 200 years ago to compare with this past weekend. This is all compounded by the fact that we had three successive 1 in 1,000 to 10,000 daily events. There are better statistical methods to analyze this. Looking at standard deviations alone only tells a small part of the story.

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  17. Cliff - is latitude and higher temp trends a good measure of climate change? The media seems to be making a connection with the temps in BC to the north of us. How many years of higher latitudes setting records will it take to confirm climate change?

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  18. Safe food handling tier surface temp today

    https://kitsap.s3.us-west-2.amazonaws.com/public/20210628_120810.jpg

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  19. So, when the marine air hits our superheated valley- and with quite high dewpoint (looks like about 64 degrees)- will that be sufficient condition to touch off a line of thundershowers (and do I need to put up the rainfly over the tent outside where I'll be sleeping?) Any rain is welcome, obviously- if this will not be sufficient triggering event for deep convection, why not?

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    Replies
    1. It's pretty warm air aloft too, which is bad for convection.

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  20. So when do you think someone who lives in downtown Kirkland, a half mile or so from the water, will see this coveted 70 degree temp? My weather app (Not-So-AccuWeather as I call it) has it out for me and says it will still be 80 at 1am. Of course the tubing to our bedroom AC unit cracked and was spilling hot air into our room last night. I think it’s time I have a discussion with our apartment building about some custom solar blinds or something! This is too much heat!! (Thanks!!!)

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  21. Partially related, but it looks like we are seeing a lot of these peak temperatures all the way through to BC, could this help with the Murder Hornet "invasion?" I think I learned that Japanese honeybees kill murder hornets by swarming them and heating them to 108f.

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  22. I drove to Twin Harbors state park along the coast near Westport to escape the heat. Didn't happen. At the ocean, on Sunday morning it was 90 before 11 am. I heard that Aberdeen even got to 104 on Sunday. But, I saw that it was only 80 there today and upper 60s Tuesday.

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  23. I took off from SeaTac on my way to LAX and at 15,000 feet it was 75 degrees! Even the top of Mount Rainier was hot!

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  24. I learned three things from this to help keep cool. 1, if you have a sprinkler, be a kid, especially before bed. 2, a tub filled with cold water (not necessarily full) makes a great indoor pool for a quick cooling dip. 3, cold water towels on my hot dog seem to work at helping them cool down too.

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  25. It seems like this call comes back to the "Ridiculously Resilient Ridge" (NW version) and whether the RRR is more likely to form because of climate change. That's the question I'd really like answered, to the extent possible. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015GL066628

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  26. I lost internet along with quite a few others. So can I assume that equipment can be sensitive to heat? Do places like Phoenix prepare for that or protect equipment somehow?

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  27. I don't remember seeing you talk about Purple Air, but for local air quality you can see the dozens of air quality sensors in the Seattle area:
    https://www.purpleair.com/map?opt=1/mAQI/a10/cC0#11/47.6268/-122.3132

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  28. 9:00 p.m. in Olympia and the wind is gusting from the SW. As Cliff predicted, the temp has dropped around 40 degrees in just a few hours. So nice to feel comfortable outside!

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  29. Been following the marine air—-via weather link—as it makes its way through the Chehalis Gap,splitting to go around the Black Hills: black dots turn red then orange then yellow. Our station has just turned orange, now 78°. In less than 2 1/2 hours we dropped 30°.

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  30. You were tight about the rapid cooling. In Gig Harbor it went from 90 to 68F at our place from 9pm to 11pm Monday. Really nice cool breeze coming out of the west. I'm sure it's a relief to many people.

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  31. Marine push hit Ucluelet ~10pm tonight - went from 35'C earlier this eve to 15'C, fog and 30-40 km/hr wind now.

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  32. Yes. Noticed the haze. Deep orange red sunset like smoke season. So, this hot air actually came from Canada!? Where/ how did take on all the heat? Just solar radiation in the desert?

    How is this different from 2009? Other than being a few to several degrees hotter. I recorded 104.2 in Shoreline vs. 102.5 in 2009. I am definitely hoping this is a one off that doesn't come around again for another decade or so,. but still wondering-- could this happen more often?

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  33. I moved from Phantom Lake in Bellevue (109-111F) today to Gilpin County, CO, at 9100 feet two years ago, and today our high was 57.2F and we had 0.6" of rain, rather like traditional Seattle "Junuary" - it's 41.7F now at 2 am. Will this hot bubble push from Seattle over to us, or will it dissipate after Eastern Washington?
    Our weather forecast for the next 10 days shows a 20+% chance of rain each day (HIGHLY unusual for this time of year; today historically we have a 12% chance of measurable precip) and highs in the mid to upper 60s, unusually cool.
    My Ambient Weather WS-2902c is on Weather Underground as KCOBLACK86.

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  34. Haven’t benefitted yet from the huge marine air push here in north Whatcom County as temps stayed above 70 overnight. Still, it’s clear things are moderating & today will be more comfortably normal than yesterday!

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  35. You were spot on with your North Tacoma forecast. Almost exactly at 5:00 PM a breeze kicked up---by 7:00 PM it was very comfortable

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  36. Sunlight this evening seems orangish, similar to what we see during forest fire smog, and yet air quality is showing good to moderate. Any idea?

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  37. I will say, having been in Spokane on 6/29 with temp of 108 and RH of 15% and then in DC on 6/30 with temp of 96 and RH of 80+% - I’ll take Spokane!!!

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  38. Hey Cliff WTPuck.
    Lytton BC erased Las Vegas highest Tc you didn’t even Discuss this…!
    We were baking up here & now had 10,000 sparks of lightning setting off forest fires. Lytton is likely ashes this morning. Be nice if you would be a regional geographical perspective meteorologist and not just a loco poco…

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