Very Uncertain Snowstorm Forecast for Western Washington

No FastCast tonight. Continue reading below as we analyze forecast models to see what areas will receive snow, and how much may fall in this highly uncertain setup.

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Forecast models are having a hard time agreeing on the placement of a low pressure system that will move through the region on Tuesday. The placement of the low pressure system will determine what areas receive rain, and which receive snow.

We will go through all the forecasts available and take a look at snow through Wednesday afternoon. The general idea is that areas from Seattle south will go from snow on Monday night to brief rain or rain/snow mix early Tuesday morning and back to snow midday/early afternoon Tuesday.

Snow amounts vary wildly between models, so we'll take a look at all the latest forecasts. But below, let's take a look at a general consensus, from south to north.

Olympia southward: 0-2"

Seattle to Pierce/Thurston Line: 0.5-6"

Seattle: 1-6"

Everett to Mount Vernon: 6-8"

Mount Vernon northward: 8-10"

Now...for all the forecasts, hence the large range of snow totals. Let's start with the GFS model, which is by far the snowiest (likely too snowy).

This is almost certainly far overdone for the Seattle area. However, totals of 6-8 inches aren't out of the question, but anything over 10" south of Everett is highly unlikely. Areas south of Seattle would receive 6-8 inches in this model, likely too high.

Now, let's look at the ultra-high resolution UW WRF forecast. This is a snowy solution for the region.

The UW high resolution forecast shows 5-7 inches for most areas from Tacoma northward, with isolated spots of 8-10 inches. Areas from Tacoma south get 2-4 inches.

However, these are the snowiest models, and others show significantly less. Let's take a look at the European model.

The European model is much less snowy, with 0.5-2 inches from Everett southward, and 3-9 inches from Mount Vernon north. 

Now, let's take a look at the American high-resolution models. First is the NAM model, shown below.

The NAM model is in the middle, showing 1-3 inches from Everett southward and 4-10 inches from Mount Vernon northward, an impactful snow for the North Interior.

Next, the National Weather Service NBM forecast.

This forecast is a bit snowier than the NAM, showing 3-4 inches from Seattle south, and 5-8 inches from North Seattle northward.

So, essentially, there is massive uncertainty among different forecasts. Some lean snowier, while others scour out cold air completely. The best thing to do is stay updated.

Updates are available on Twitter (link on top right of blog site), on local news stations, and on the Pacific Northwest Weather Watch YouTube channel. Stay tuned and stay safe! Much more winter weather is ahead this week...