No FastCast today…find a current forecast here.
Confidence has increased in the lowland snow potential from late Saturday night through Sunday. NWS Seattle’s Winter Weather Advisory (in effect 4 AM Saturday to 4 PM Sunday) forecasts 2-9 inches of snow from Skagit County southward. Whidbey Island and Skagit/Whatcom Counties have a Winter Storm Warning for 3-11 inches of snow and strong winds.
This blog will take a look at multiple forecast models and how much snow is forecast.
Let’s start with the Euro model.
This prediction is likely on the higher end, representing a snowier situation with multiple bands of snow moving south through (and potentially stalling over) the Puget Sound area on Sunday.
The NAM model shows a slightly less snowier scenario, with highly variable snow amounts based on location, and an average of about 2-4 inches through Sunday evening.
The UW WRF model (below) suggests a similar scenario, with less snow north of Seattle and more south of Tacoma.
The UW model shows 2-4 inches of snow in the metro area, with localized areas with up to 6-8 inches (purple colors).
Finally, the HRRR model (shown below).
This is a less snowier situation that is possible but somewhat less likely. However, as usual in Western Washington, all options are on the table.
Below is a very helpful graphic from NWS Seattle showing the most probable snowfall totals from its NBM model.
This graphic shows the most possible, least possible, and best forecast. 4-6 inches looks likely for the lowlands and coast, with up to 9 inches in the foothills.
Let's take a look at the similarities between these models.
1. 2-6 inches of snow look likely across the Lowlands from late Saturday night to late Sunday.
2. Most of this snow will stick, since it will fall while temperatures are in the mid 20s to near freezing.
3. It is possible that snow will fall overnight Friday into Saturday, but the Seattle area will be in the "snow shadow" with westerly winds. Accumulations of 0.5-1 inch are possible in the Lowlands, but will likely melt away during the day.
There will be areas that receive more snow than others. Some of these localized areas with more snow will be determined by where showers set up. Others we can likely predict.
Whatcom County will likely receive higher amounts (up to 8-10 inches) due to an earlier onset of colder temperatures. Similarly, due to exposure to Fraser Gap winds and colder temperatures, the northern Olympic Peninsula (Port Angeles area) will receive more snow (4-8 inches). The Cascade foothills will also receive 5-10 inches due to their higher elevation and therefore colder temperatures.
Additionally, very cold temperatures are still in the forecast. The models have backed off from some of the more extreme temperatures, but lows in the mid to upper teens are still expected, with single digits in Whatcom County, and low teens in outlying lowland areas. Expect the coldest temperatures on Monday, Tuesday, and Wednesday mornings. Highs on these days will likely only be in the 20s to near 30.
Wind chills will keep temperatures even colder, with feels-like temperatures as low as 5-15 degrees in the Lowlands and -5 to 5 degrees in Whatcom County.
Below is an important graphic from NWS Seattle about how to stay safe in the cold.
Stay tuned for updates on Twitter (a link to my page is found on the upper right of the blog site) and for video updates on Michael Snyder's Pacific Northwest Weather Chasers YouTube channel.
Stay safe & keep warm!!
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