March 04, 2009

Update on cold and snow

Well, its pretty definite now...we are going to experience an unusually cold period for this time of the year...with a real threat of snow showers on Sunday.

Lets start with right now. A cold front is now approaching..and there are clouds and some light showers associated with it. But the flow is sufficiently westerly that central Puget Sound is being rain shadowed (see images). The showers will move through tomorrow am, with improving weather during the day.

On Friday, an upper ridge will move in and it will by dry and sunny. But the fun begins on Saturday as a major Pacific ridge shifts eastward and an upper trough moves southward down its eastern flanks (image). Behind the trough much colder air will flood the region on Saturday into Sunday. On Saturday, the associated showers will probably be rain...but on Sunday things get interesting. The winds will be westerly, so there will be rain shadowing, but the models are insistent about the creation of a Puget Sound convergence zone...and if they are right it will be cold enough for snow (see model snow forecast).
The cold air will hold in for several days...and there will be a substantial pressure difference across the Fraser River Valley...so Bellingham and NW Washington could be raked by strong NE winds and colder temps than anywhere else. This air is cold enough to allow temps to drop into the 20s at night...so there could well be a serious frost that has the potential to damage sensitive plants...particularly those that are budding and vulnerable...so get ready to protect them.
A positive part of the forecast is that the Cascades should enjoy plenty of snow tonight and over the weekend...with up to foot possible tonight and tomorrow.

11 comments:

  1. thanks for the update. I have been refreshing your site every 5 minutes for the last 4 hours. :) seriously!
    -Rob

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  2. Darn, I was hoping for a lot more snow. But at least its better then nothing.

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  3. RobbyRob...

    That is what you call a real 'Cliff Mass blog' fan. :o)

    Over on my blog, I just posted bit of a weather update myself about the cold trough coming over for the weekend.

    It does certainly look cold!

    ---------

    Hey Cliff...earlier today, I went over too the B&N book store here in Woodinvile to see if I could find your book. Thought it might be in the science/nature section but didn`t see it. I went there just to mainly look around. But uh, what section would it be in?

    Or if anyone has picked up his book lately at any of the B&N book stores, what section did you find it in?

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  4. Wahoo for us in Bellingham!! Yet I feel guilty for getting excited over fun weather when it could harm local farmers. At least meteorologists can feel like they are being helpful with information to prepare, while getting excited at the same time!

    Well, since I can't control it...bring it on!!

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  5. Cool, Another Fraser Valley Event...Andy, B&N might have it in the local section. Or just ask.NIce dog riley,love the tennis balls..

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  6. We are getting wintry mix right now on the top of Demery Hill in Sammamish.

    Just saying.

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  7. Andy..just ask them. They generally have it in the NW section..cliff

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  8. Cliff, when you said "They generally have it in the NW section",
    did you mean NW as in New Writings?

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  9. No, the weather will be getting worse throughout the day tomorrow.

    Why don't you say that it will be drying out throughout the day tomorrow with sun appearing, which is what it'll be doing... instead of saying it will be improving - which it won't be?

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  10. Out toward Maple Valley, just got a 2-minute deluge of ice particles, and now the roads, houses, lawns are all white.

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  11. Now it's snow...big, fluffy flakes, and lots of 'em!

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