Updated Tuesday 3:55 p.m.
Brrrrrrrrr!
Yes, it's a 9-'r' Brrrrr!
The area's frigid temperatures are rivaling the great cold snap over Thanksgiving weekend in 1985. Highs today have been in the mid 20s and lows tonight are dropping to eye-popping levels.
Seattle's preliminary high was 25 degrees and the 49-degree swing between that and the record 74 degrees we had on Nov. 3 has smashed the record for largest range of high temperatures in the month of November -- and the second closest that I found was 39 degree spread in 1955 (21 low, 60 high).
But 25 will seem toasty compared to where we're heading tonight as clear skies, fairly light winds and snow on the ground is the hat trick of ingredients needed for record low temperatures. Lows will drop into the mid teens in Seattle (record low: 16 set in 1985. Forecasted low: 15) but we're looking at single digits for usual cold spots like Olympia, North Bend, Arlington and Shelton. So road ice will continue to be of high concerns and take great care in that any melted snow from the sun today will freeze very hard tonight.
(One minor note: we've had a few reports of flurries down around Tenino and Tumwater. It's just a little moisture that snuck up from Portland area. It'll pass and shouldn't amount to anything and you should clear out afterwards.)
The region will awake again Wednesday still in Mother Nature's ice box, with afternoon temperatures perhaps managing a few more degrees' warmth, but still likely to come up short of the freezing mark. Meanwhile, clouds will increase through the day. But I don't see any new weather problems for the big Thanksgiving traffic exodus on Wednesday evening, aside from any lingering ice/road problems from Monday.
By Wednesday night, we begin the transition to more familiar autumn weather in the Northwest as the winds turn from the north to the west, ushering in milder air off the Pacific Ocean. In addition, a weak warm front will approach the area late Wednesday night into Thursday morning. This storm has no arctic bones about it -- it's a rainy-and-45 storm at its core, but we still have some cold air entrenched to deal with.
So this will be our next forecast challenge because of those pockets of lingering cold air, and it'll be a race between whether we can warm up enough before the moisture arrives as to whether it starts as snow or rain, and whether it'll even be wet enough to bring anything until Friday.
Scenario A as of this moment brings some light precipitation from about Seattle north to the Canadian border, reaching Seattle around late morning/midday Thursday. This will be close as it might briefly start as snow before changing to rain, especially if it arrives earlier in the morning when we're colder. But if it truly is midday arrival, we'll probably be pretty close to being warm enough to rain -- maybe a little period of snow before the changeover. Sounds scary, but unlike Monday, conditions will improve, not deteriorate, as we go forward.
Scenario B keeps the warm front moisture even less and well to the north of Seattle -- just mainly affecting areas near the Canadian border. That would allow the Puget Sound region a safe transition to warmer weather without the moisture. That doesn't have any rain until late Thursday night into Friday for Puget Sound area, and it's all rain by then. Either way, highs on Thanksgiving should make it well into the 40s.
So we'll keep an eye on it. Bottom line: Wednesday evening travel should be dry, but still around freezing temperatures. We could see a period of snow on Thanksgiving day in spots, but it will change to rain with temperatures safely into the 40s.
Forecast models are pretty consistent that Friday will be back to Seattle normal: Rainy and breezy with highs in the 40s.
Saturday will see some scattered rain showers with highs still in the 40s. Sunday actually looks dry and what we'll pass for pleasant with highs in the low-mid 40s.
Long range models look like we can temporarily retire #snomg and go more with regular Seattle weather. The pattern will remain relatively cool, but not *that* cool with temperatures in the low 40s for rain, but snow levels well below the passes.
Maybe just enough for a 3-'r' Brrr! :)
Scott Sistek
KOMONews.Com Meteorologist
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