Incoming chill to bring low snow levels to Western Washington
SEATTLE -- Apparently Mother Nature has no use for November and is skipping right to December with an incoming chilly pattern that might have you thinking about egg nog lattes a bit early. (Or, maybe not so early.)
How chilly? Some spots in the lowlands could even see their inaugural snowflakes of the season. (Spoiler Alert in the interest of not over-hyping: It's not Seattle.)
A low pressure center is working its way down from the Gulf of Alaska -- already triggering a little bit of rain Wednesday, but will make for a wetter day Thursday as the low swirls offshore. But as the low approaches, so does some cold air from Alaska that will be moving into British Columbia.
As the low moves south on Thursday night and Friday, it will draw in that colder air through the Fraser River Valley and into Western Washington -- and if this sounds like something we Seattle weather people usually talk about in the heart of winter right before we start typing about snow, you'd be right. But before you snow fans get too excited, remember we just came into November so it's a bit early for lowland snow, and that's the case for most this time too.
However, those cold northeast winds Thursday night and early Friday could make it locally cold enough for fringe or wet snow down to a few hundred feet in western Whatcom County, the San Juan Islands, and maybe even the northeastern Olympic Peninsula where those Fraser winds run into the Olympic Mountains (that creates convection and can bring a localized snow from about Sequim east to Quilcene along US 101 and western SR 104). Conditions are still marginal at best (boy, had this been December 3rd instead of November 3rd though...) but there is potential for some minor wet accumulations in those specific locations.
In addition, those Fraser winds could gust as high as 30-40 mph across Whatcom County Thursday night into Friday morning before easing, knocking wind chills down into the 20s.
For everyone else, it will be a very chilly, November rain Thursday night into Friday with snow levels around 1,000 feet -- safely above the populated lowland areas but maybe some mixed rain/snow in the higher Cascade Foothills. Showers will decrease Friday. For the greater Seattle/Puget Sound area, this system is no big deal aside from the noticeable chill.
Once place where snow is a slam dunk is in the mountains Thursday night through Friday with some models suggesting 8-10" of snow around Snoqualmie Pass and around a foot at Stevens so keep that in mind for any mountain travel.
We'll dry out Friday night and remain relatively dry on Saturday, but still chilly with highs in the 40s and lows in the 30s. Our next wrinkle comes on Sunday where another low pressure system again swings down from the north. Right now, most forecast charts have this system dodging much of our region as it drops by to our west offshore, the moves into Northern Oregon/Southwestern Washington.
The moisture will be mostly focused south of the Puget Sound region, but Southwestern Washington could see some low snow levels and potential wet lowland snow depending on the temperatures and how effective the Fraser Winds were at cooling and drying out the region. It'll bear watching -- you're still fighting the calendar but it'll be close! The Puget Sound region will likely again be in the "scattered cold rain showers" territory.
Long range models moderate us a touch as we get into next week to bring the snow levels out of the lowlands and back up a bit into the mountains, but still low enough that subsequent systems should keep adding to a mountain snow base. Skiers and snowboarders, the pattern is looking quite favorable for an early start -- cross fingers! This cool, wetter pattern overall does resemble what we'd expect in a budding La Nina winter, it's just a bit early. We'll see if it's just a preview or if we're kicking off our cool/wet winter in November.