Washington Daily Snow
By Luke Stone, Forecaster Posted 2 months ago December 7, 2023
The snowpack has taken a big hit over the last day and a half. The heaviest rain is behind us, but showers will continue through Wednesday night before snow levels drop low enough for a changeover to snow. Light snow will continue for a few days with modest accumulations. A stronger storm is possible this weekend starting on Saturday.
Short Term Forecast
I don't know why, but I've been checking the snow depths across several Washington resorts a couple times a day. I check them almost as much as when it's dumping. As of last night, the resorts in western Washington had lost 40 - 55 % of the snowpack prior to the transition to rain on Sunday. I can't sugarcoat that, it's just brutal. There isn't as much available data, but it looks like eastern Washington has lost around 30% of its snowpack.
The only good news is that the heaviest rain is over, we'll transition to snow showers soon, and another snow storm is possible this weekend. Let's get into the details.
This upper-level low sat off shore for the last few days and combined with the jet stream, directed an atmospheric river towards Washington. During this time, Washington was on the warm side of this storm and saw incredibly heavy rain. You can see the upper-level low and atmospheric river on Tuesday below.
Also take a look at the two atmospheric rivers pummeling the Pacific Northwest one after another.
Mercifully, the jet stream is finally shifting, and this storm will make its way inland along with a cold front.
This is already underway, with the approaching cold front beginning to lower snow levels. The same storm responsible for the deluge will bring snow showers later this week as this upper-level low progresses to the east, shown below.
However, the low/cold front won't be far enough inland to reduce temperatures enough for snow at the resorts until Wednesday night.
From Wednesday night through Friday, the dynamics of this storm as it crosses the region will be sufficient to bring widespread snow showers. On Thursday night, the snow may become moderate for a period of time, producing the best accumulation during this period. Totals won't be huge during this time, but resorts on both sides of the state should see 4 - 8 in over a forty-eight hour period.
There may be a Puget Sound Convergence Zone on Thursday night as well that sets up over Snoqualmie Pass, which could bump up the two-day totals to 8 - 16 in. You can see the possible convergence zone below.
We'll likely have only a short break Friday night before the next storm arrives Saturday morning. This is not a perfect storm either, but overall should be quite beneficial. It's sort of a miniature version of what we just experienced, except the warm phase shouldn't be nearly as destructive.
We'll start out the snow from another upper-level low moving in from the west. After heavy snow on Saturday, as the storm progresses eastward it will send another atmospheric river to Washington. This one won't stick around as long, nor be as strong as the previous one. So while snow levels will rise Saturday night, the atmospheric river quickly shifts south and should keep snow levels right around or just below base elevations (3k in the north and 4k in the central/south). They may climb a bit more on Sunday but most the precipitation will be out of here by then.
A back door cold front will try to cross the Cascades Sunday night, while a weak trailing wave moves through the Northwest, which may light up some more snow showers through Monday. The models still have some inconsistencies on this part of the storm, so let's hold off on those details for now.
We may see a brief break in the action through the middle and latter part of next week, before a weak storm is possible around the 13th. Right now the next chance for a big storm looks to be around mid-month.
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