May 03, 2017

70s and Thunderstorms Headed For Our Region

I find it hard to believe I am writing this, but today (Wednesday) and Thursday will bring high temperatures over the western Washington lowlands that will rise into the 70s.   Thunderstorms will be quite possible later on Thursday as unusually moist, unstable air covers the region.

On Wednesday night, a warm front crossed the area, bring light rain and radically warmer temperatures aloft.  The 5 PM surface map on Tuesday shows the warm front  (line with half circles) approaching.

Temperatures above Seattle warmed by around 12F Tuesday night as the front moved through.  The atmosphere should dry out on Wednesday and with a lot of sun and a warmer lower atmosphere, temperatures should soar--here is the forecast temperature at 5 PM Wednesday:  lower 70s over Puget Sound and 80s near Portland and around the Willamette Valley.  Amazing.  There could be a few mountain thunderstorms on Wednesday afternoon.

But the real  weather "fun" will be on Thursday afternoon.  Temperatures will surge into the mid to upper 80s in eastern Washington, and around 80F over the eastern side of Puget Sound.   Much warmer than Maui, Hawaii was on Sunday!   Look closely, and you will see cooler air surging eastward in the Strait and along the coast--an onshore or marine push will be underway.

But wait!  There's more!  The lower atmosphere over western Washington and Oregon (and southern BC) will be unusually unstable, something indicated by large values (at least for around here) of CAPE (Convective Available Potential Energy)--think of it as the "juice" for thunderstorms (see map).  

With the onshore surge of marine air providing lift (and an approaching upper trough providing support aloft) plus lots of instability, the potential exists for significant thunderstorm activity over the region later on Thursday.  (Instability is released by upward motion)  Consistent with this idea, the high-resolution UW WRF model shows lots of showers starting 5 PM on Thursday, increasing by 10 PM, and continuing into Friday AM, progressively moving to the east (see maps).

Friday will be cool, cloudy and showery west of the Cascade crest.  Too bad.  But a few warm days will be a salve to our collective (and chilled) souls.


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  1. I'll just wait around for awhile until I'm told that this wave of warm weather and T - Storms is because of? That's right, the symptom (and cause) of everything - AGW.

  2. Do you think Bellevue is close enough to the foothills to just squeak into the area marked as chance of severe t-storms?

  3. You're totally right Eric B. After all, science is supposedly about inquiry, not "BELIEF". Since when did scientists reach consensus? Isn't the scientific method always being utilized and therefore creating an unlikely scenario that consensus will happen? Well, I suppose that's how it once was, but not when pockets get lined and you keep people distracted on Pokemon Go or what have you. Maybe building a greenhouse and focusing less on cultural nonsense might not be a bad idea hmm? Thanks as always for providing the platform Cliff!

  4. J - Galileo was against the "scientific consensus" when it was widely believed that the earth was flat, if memory serves. Funny how that works out.

  5. So you're saying Thursday morning is the PERFECT time to finally cut the grass and do the desperately-needed spring garden cleanup? Hmmmm I might just do that. :-)

  6. Eric - if by scientific consensus you mean the church, then yes, much like today scientists are forced to defend themselves from misguided people who'd prefer their own made up stories to what science is showing us.


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