Another round of precipitation will move in early Friday morning. Snow levels will be pretty low on Friday morning as this will be coming in during the coldest time of day.
From King County south, some light snow could occur near or even below 500 feet and the farther north one goes, the lower the snow level – probably to sea level or close to it from Everett northward. A slushy inch of snowfall could occur in any location but the North Sound from around Everett north and also higher hills above 500 feet have the better chance of a couple inches of snow before it quickly turns to rain mid-morning Friday.
In addition, the Olympia region north around Hood Canal possibly as far north as Shelton and Bremerton could pick up a couple slushy inches Friday morning before precipitation turns to mainly rain by 9-11 a.m.
All-in-all, this looks to present minor impacts to travel in some areas and no impact to travel in others. Still, there is the outside chance for some greater impacts in isolated locations where more than an inch of snow falls Friday morning.
Then, here come wind and rain!
It will become especially breezy across the north and coast on Friday with a High Wind Warning issued for wind gusts potentially over 50 mph north/west of Everett and the coast on Friday. In the Cascades and Olympics, a Winter Storm Warning is out for a half-foot to foot of snow through the Cascade passes on Friday.
We’ll be warmer Saturday with more mountain snow -- potentially another foot or more in spots --- and lowland rain with snow levels above 1,000 feet.
By Sunday afternoon, we’ll have some showers of rain and mountain snow, but as cold air plunges out of British Columbia, snow levels fall again in the late afternoon and we could be flirting with low-elevation snow across Whatcom County and surrounding areas before sunset and other areas after dark. Any accumulation in this scenario should be spotty and most areas won’t have accumulating snow Sunday evening, from present indications.
What happens after sunset Sunday -- and lasting through the week -- is still unclear at this point as it pertains to snowfall potential.
It will absolutely be cold enough for snow at any time and any place starting Sunday night and lasting most of next week. It’s safe to say it is likely there will be lowland snow sometime during next work week -- possibly as early as Monday morning, but just how much moisture is available for snow as dry air plunges in is impossible to know presently. Also unclear is how much moisture from the Pacific might be able to interact with the cold airmass in place once it locks in Monday. I expect that forecast to firm up into the weekend as the nature and trajectory of dry air intruding into our region gets locked in.
Why can we forecast the cold with confidence but we don’t know about snow yet? Cold outbreaks like the one we’ll experience next week are large-scale features -- huge airmasses hundreds or thousands of miles across. And they’re dry. Any weather features that we might expect to bring in some moisture to interact with the cold air and create snow showers are much, much smaller, and the smaller the weather feature, the more difficult they are to forecast days ahead of time.
After highs in the 30s Monday with that snow chance and breezy conditions, Tuesday and Wednesday are shaping up to be the coldest back-to-back days many areas have experienced in more than a decade! As of this writing Thursday night, my forecast highs for Tuesday and Wednesday Jan. 14-15 are in the 20s for Seattle. You have to go back to Thanksgiving 2010 and the day prior to get the last time Seattle had consecutive days where the high temperature did not touch 30 degrees.
I’m expecting Wednesday morning to be the coldest morning with bitterly cold temperatures in the teens in most areas with upper single digits in the coldest outlying spots. A forecast low Wednesday morning of 18 for Seattle (or, the thermometer at Sea-Tac) would be the coldest temperature since -- again -- November 2010.
Most of the region could be below freezing for 48-72 hours straight -- starting Monday or Monday night. This will pose problems for exposed pipes which could freeze up and later burst, for pets and for people -- particularly those living out-of-doors.
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