Rainy, blustery Tuesday on tap, with maybe a dash of snow in spots?
SEATTLE -- The first half of December has been a figurative snooze-fest for weather but Mother Nature is ringing an alarm clock for Tuesday that will feature some moderate rain, gusty winds, mountains snows - and maybe even some slushy snow on the higher hills.
A moderately potent low center will swirl ashore across the Washington coast into northern Washington Tuesday morning. The track is a decent windstorm track, but the storm strength isn't too concerning. Still, it's enough to warrant a Wind Advisory for the Puget Sound, Southwest Washington and central coast for potential southerly gusts reaching 45 mph. The coast's advisory is in effect from 3 a.m. to 10 a.m. while the interior's advisory runs from 6 a.m. to 4 p.m.
Up in the mountains though, it's gobs of snow as the first huge dump of snow comes to the mountains in several days. A Winter Storm Warning is in effect for much of the Cascades from 6 p.m. Monday through 10 p.m. Tuesday. This is a bit complex -- snow levels will be around 2,500 feet in the North Cascades for as much as 2-3 FEET of snow. In the Central Cascades, snow levels will be around 3,500 feet with 14-24 inches expected above that level.
That warning includes Stevens Pass, but not Snoqualmie Pass, where lower snow amounts are expected due to some period of a switch to rain on Tuesday as snow levels rise just above pass level. However, there is some wiggle room in the forecast models that could lead to a lower snow level and heavy snows at Snoqualmie. So be sure to check the pass conditions before heading across I-90.
Then, Tuesday night, colder air moves in as the storm begins to move away. How cold? Snow levels could drop to around 500 feet Tuesday night after midnight and while we're marginal on both temperatures and moisture for making lowland snow (aren't we always?) there is a chance for some wet accumulations to around 1" at 500 feet or higher -- especially in the Convergence Zone areas between around Shoreline/Redmond north to Everett-Monroe.
That includes the Alderwood Mall, Mukilteo, Lynnwood, Mill Creek, Bothell and south Everett areas. The Euro model from Monday morning paints about 0.8-1.2" of snow possible in those areas. The Seattle proper area should be snow-free or maybe just a visual non-sticking snow, but the Cascade foothills could see a slushy inch as well. Lows Tuesday night will be in the low-mid 30s.
The marginal snow threat ends Wednesday morning as we go dry and cold for a few days. That sets up a couple of very cold nights, starting Wednesday night with temperatures dropping into the mid-upper 20s. Another sunny but chilly day expected Thursday with highs in the upper 30s and lows in the 20s.
Forecast models are toying with the idea of another weak system coming into this cold air Thursday night into early Friday. We're cold enough here for snow but very limited moisture is available. So maybe some flurries or light snow showers Thursday night into Friday but no significant accumulations expected. Moisture leaves early Friday morning and we clear out to sunny skies with highs near 40.
We'll stay sunny and chilly through the weekend and through Christmas Day with highs in the mid-upper 30s ad lows in the low-mid 20s.