A rather potent storm is set to roll in off the Gulf of Alaska on Sunday, and it's bringing some very cold air behind it.
The front would first bring a steady rain and gusty winds, and then taper off to showers as the front passes and snow levels drop to near the surface, if not all the way to sea level.
That scenario is holding steady in the weather forecast models, but there are still some timing differences between whether the cold air gets here Sunday afternoon, Sunday night, or Monday. That of course could have some major impacts on returning Thanksgiving travel plans Sunday, so we'll be keeping a very close eye on it.
Right now though, I'd put higher odds on a late Sunday night or during-the-day Monday time frame for the cold air to arrive, allowing better lowland travels on Sunday, in exchange for a potentially messier Monday commute/work/Monday Night Football game.
No matter when this happens, this would probably not be a widespread snow event because by the time the cold-enough-to-snow air gets here, the steady "rains" will be over. But there does look to be some hit-and-miss showers in the front's wake, as we typically get after a storm passes. So we could be looking at pockets of minor accumulations.
But this pattern is ripe for a Puget Sound Convergence Zone, so those of you who live between Northgate and Everett need to really pay attention here as you have a higher chance than others for snow at times -- initial model indications are hinting at a potential of 2-4 inches in Snohomish County, but the event is several days away so changes are possible. The Cascade foothills could also be looking at a few inches.
Also who need to pay close attention to forecasts: Mountain pass travelers. Sunday will be a VERY busy time in the passes and as I mentioned, some models have sped up the timing of the cold air to Sunday, meaning we could see some very heavy snow in the mountains on Sunday, especially toward the afternoon and evening and especially Snoqualmie and Stevens Pass if a convergence zone is going.
If heavy snow is something you really want to avoid, I'd at least start thinking of an option for crossing on Saturday as snow levels will be above pass level, and keep monitoring forecasts this holiday weekend.
We'll quickly run out of moisture by Tuesday, if not by Monday, leaving us partly sunny but very cold and icy. If we clear out fast enough, lows Monday night could be in the teens to mid 20s. Tuesday is looking dry with highs only in the low-mid 30s. Tuesday night's low temperatures would also be a hard freeze.
Now, the super long range models have been showing occasional signs of keeping this arctic air around for an extended period. There is zero agreement on when or if we have any more bouts with snow, which makes sense that far out, but I will say it looks like "the door is open" for additional snow events in the 7-14 day period, so stay tuned.