The big threat for lowland snow...if it occurs...is late Monday afternoon/Monday evening...more in a future blog.
Worried about travel on Sunday? Heard stories about lowland snow snarling traffic or massive snow crippling the passes? Don't worry about it...the latest models are far more benign for Sunday.
But another threat looms--very cold air will move into the region on Monday and stick around for much of the week. Cold enough to burst your outdoor hoses, mess up irrigation systems, and do other mischief.
So let's see what is in the meteorological cards, now that we are closer to the cold-wave ground zero.
Thanksgiving Day has been as good as it gets. Clear skies over most of the region, will some fog over Puget Sound and a few valleys (see satellite picture). This time of the year you have a choice: wet and windy or dry, cold and foggy.
Friday and Saturday will be Northwest blah. Clouds, a few sprinkles, highs near 50F. Good shopping weather.
Sunday is a different story. The latest runs bring a strong trough in from the Northwest, but the timing is about 12-h later than a few days ago...and that makes all the difference. And the movement of the trough is not optimal for lowland snow (too easterly motion). Here is the forecast upper level (500 hPA) chart for Sunday at 10 AM. Impressive trough and low to our northwest.
On Monday, modified arctic air will move in to the Northwest (see surface map at 1 PM Monday. At this point it will be cold enough to snow in the Washington lowlands north of Olympia, but will there be any precipitation at this time? The current model runs don't show much, but we need to be careful. In a residual convergence zone, or the leading edge of northeasterly air moving out of the Fraser Valley (into Bellingham and the San Juan's) there could be some snow showers. Don't be shocked if you see some. But right now, no significant lowland snow threat.
You got hoses attached on the outside of your home or apartment? Disconnect them and drain the water. Drain irrigation systems and bring in hummingbird feeders at night.
You don't want this!
Regarding mountain snows, here is the current forecast 48h total ending 4 AM on Tuesday. 1-2 feet in the higher Cascades, less than a foot in Snoqualmie. A nice refresh for the mountains, but not as much as predicted a few days ago.
Happy Chanukah and Thanksgiving.