Coldest Temperatures in Years and the Next Snowstorm

A number of local observing stations experienced their record low temperatures for the date yesterday and the minimum temperatures this morning were chilling (see below, click to enlarge).  Teens were widespread over the region away from the water, and there were single digits north of Bellingham, in the north Cascades and over eastern WA.

At Boeing Field, the low temperate this morning (16°F) was the coldest in at least 5 years (see plot below)

This is one cold wave that is not going away, with the entire week being far cooler than normal. Ice and snow on non-arterial roadways are not going anywhere fast.

But now the serious stuff.  There is a real chance for a major snow event late Friday into Saturday--one with the potential to drop as much snow, or even more, than the event on Monday morning.  At this point there is substantial discrepancy among the model systems, and thus great uncertainty for the specific amounts and their distribution.

Let me start by showing you the accumulated snow totals for the Friday night/Saturday event from the European Center Model....one of the best in the world (but lower resolution than the UW model I show you frequently).  The EC model starts the snow on Friday afternoon and the 48-h totals ending 4 AM Sunday are substantial:  roughly 6 inches over Seattle and more on the western slopes of the Cascades of southern WA and Oregon.  Lots of snow in eastern WA.

The European Center ensemble of 51 separate forecast gives some idea of the uncertainty in the forecast.  Here is their snow forecast for Seattle as a function of time (graphic courtesy of WeatherBell--an excellent service to sign up for, by the way).  Most the forecasts are going for 2-6 inches of snow, with the ensemble mean about 4 inches.  Their high resolution forecast (shown above) has more snow.  But a few of the solutions have little snow (about 20% of them), while others are going for 6-12 inches.

The U.S. model (the GFS) is quite different, mainly because it moves the low center associated with the snow farther offshore.  We will examine the situation further in future days, but at this point, be warned of a potential snowstorm early in the weekend. 




from Cliff Mass Weather and Climate Blog http://bit.ly/2DaYvbS