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04/02/2009 FCST: WA (PSCZ)

Billy Griffin

Surprised SPC isn't noting this in their Day Two discussion, but perhaps because it may be such a localized event, it doesn't warrant mentioning at the moment.

Tomorrow's forecast looks tricky for the Puget Sound Convergence Zone (Seattle, Everett, Tacoma area) as convective temps may not even be realized at all.
It's very cold, as we had scattered snow throughout the Seattle area this morning. Warm front now pushing onshore though.

However, models pick up on a rather strong PSCZ forming later in the PM tomorrow, with rather impressive lapse rates over the entire area. Obviously, widespread small hail / grauple events will be possible. In addition, strong convective storms may develop in a defined triple point area between Vancouver, BC, Canada and Seattle/Tacoma, WA. Shear will be rather impressive as well......... appears to be a classic Pacific cold core setup pushing into western WA. If we can manage a few sun breaks here and there, although that's a tall order, a little surface heating could really get the convergence zone cranking! Models show two CZs possible, so it could be interesting.

Bottom line... would not be surprised at all to see some low-topped SVR warned cells and perhaps even an isolated cold funnel / tornado!

It will be a fun day for all types of weather chasing, from thunderstorms to driving maybe 15 miles and be in blinding thundersnow squalls. Will post report if this does actually evolve.

Speed shear will definately be significant. The cold front barrelling through today & upper level temps will definately keep things possible if the PSCZ really acts up!

Here's hoping the southerlies through the Chehalis Gap & Lawrence winds give it some good OOoomph to get things cracking! It's going to need some encouragement (but then again, the good stuff always needs encouragement around here).

I'd be banking on the area tracking from about Kitsap Peninsula straight across to Everett by late afteroon/early eve, just by looking at the winds wrapping off the Olympics.

My biggest concern is yours: No sun, lots of rain & mixing... again.

I'm too far south on a workday to be able to hope for anything within a quick dash from my door... but I'll keep watchin & praying.

OH! P.S. Don't always believe the radar round here - low topped convection oft doesn't register due to terrain.
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Good points on the radar coverage around here, Keith. The Olympics and Cascades really create a challenge.

Taking a look at WVP imagery, I'm starting to get a little concerned on the timing.
As you point out... 'mixing' is now a concern, but it's still 12+ hours out.

Probably an understatement when saying the T word is a long shot, but the environment will certainly be condusive for the classic cold air funnels we often see around here.
I would also suspect that lightning is easily foreseen with -30c 500mb temps!
blown out

Well I think today's been pretty much blown out for anything but a few claps up north.

Here on the south end, winds coming out of the wnw, plenty cold aloft - but with the straight flow at all heights & the PSCZ barely noticeable. Skies completely overcast & rain.

I'll keep my fingers crossed. Strange things happen with the weather on your plateau, you never know what might happen if a chinook shows up and adds a little lower level turning.