SEATTLE, Wash. — Another weather system moving into Western Washington through tonight and Wednesday will bring even colder air than we’ve seen so far. By late tonight, snow levels will start to fall in the mountains as precipitation increases.
In the lowlands tonight, expect a blustery evening, with gusts of 20-25 mph common, along with increasing rain showers. For most areas around Puget Sound, the heaviest and most consistent rain will fall overnight into the first few hours of daylight Wednesday. After that, precipitation will become more scattered.
In the Cascades, snow levels around 4,000 feet will fall toward 3,000 feet in heavier showers after midnight. A Winter Weather Advisory is in effect through much of Wednesday for the Cascades and passes, where accumulating snow will cause some travel impacts.
As expected, the heaviest snow will fall on the higher peaks, but we could see upwards of 6 inches around Stevens Pass and US 2 through Wednesday morning. At Snoqualmie Pass and I-90, temperatures will be more marginal for accumulating snow, so we’re expecting less, generally a few inches of slushy snow through Wednesday morning.
One important note, because of the showery, or “banded,” nature of the snow, amounts could vary quite a bit over relatively short distances. Any sudden heavier burst of precipitation could also put down more snow than the official forecast. Travelers heading through the Cascades should keep an eye on WSDOT road conditions through tonight and Wednesday.
In the Olympics, a few inches of snow is expected around Hurricane Ridge.
Back in the lower elevations Wednesday, we’ll see a little bit of everything -- clouds, sunbreaks, downpours of rain, showers possibly mixed with small hail or ice pellets, and perhaps even a few lightning strikes.
The best chance for thunderstorms looks to be near the coast and mountains, but there could be a few rumbles just about anywhere through Wednesday. A sudden shower of ice pellets or small hail, while not damaging or considered severe, could briefly create slippery travel conditions. Highs will still reach the lower 50s around Seattle.
More showers are expected Thursday and Friday, along with occasional mountain snow. After the first half of Thursday, though, precipitation should begin to very slowly taper. Highs will remain in the lower 50s in the lowlands.
By Friday night into early Saturday, I expect rain showers to taper off, raising the prospect of drier weather for trick-or-treating Saturday evening. However, some forecast data still point to a spotty shower here and there Saturday, so we can’t quite sound the all-clear on rainfall yet!
Weekend highs will just barely reach the lower 50s, with chilly morning temperatures mainly in the upper 30s. Sunday into early next week looks drier, but chilly.