The_Weatherman2 Weather Blog: Friday Night Snowstorm Update

Friday, February 12, 2021

Friday Night Snowstorm Update

After a cold day on Friday, with highs barely making it above freezing, the next storm is here. As of 6:45 PM, snow is falling across most of the areas south of Seattle.

A Winter Storm Warning is in effect from 10 PM Friday to 4 PM Saturday. The alert is posted below.

Now for the forecast. Snow will battle dry easterly winds, just like yesterday's system. However, this storm is stronger, and snow will be more widespread.

The forecast graphic below from NWS Seattle shows the snow forecast and the uncertainty surrounding snow totals.

This forecast gives roughly 3-8 inches of snow to the South Central Sound (aka: Tacoma/Puyallup/Lakewood/South Hill/Federal Way/Auburn).

Before we settle on totals, we will take a look at a few more forecasts to get a better idea of how much snow could fall.

The high-resolution University of Washington WRF forecast model shows snow totals through Saturday night.

The South Central Sound gets 5-9 inches in this forecast model. Notice the distinct line separating greater and lesser snow totals. This line, likely over King County, will play a big part in determining where the most snow will fall.

The National Weather Service's HRRR (Rapid Refresh) model, (no image) gives the South Central Sound 3-8 inches of snow, with a significant decrease near the influence of the easterly wind (8" in Tacoma, 3-5" north of there).

Finally, the European Model's forecast for snow through Saturday evening.

Image from Cliff Mass Weather Blog and WeatherBell.

The Euro gives the most snow area-wide, and the South Central Sound receives 7-10 inches.

So, how much snow can we expect?

That will depend on the dry easterly winds. As you can see in most of the forecasts above, the areas just west of the Cascades have less snow. That's the impact of easterly winds on snow totals. Since the easterly winds are dry, they dry out the air and in turn stop precipitation from falling.

The most likely snow amount for the South Central Sound is 3-8 inches. Isolated higher totals are possible.

Since it is already quite cold (25-32 degrees) across the area, expect snow to stick to roads, especially once traffic decreases this evening. Be ready for winter driving conditions.

If you are going to measure the snow that falls at your location, follow these general guidelines below from NWS Seattle!