Snow Possible This Weekend

As mentioned in the previous blog, snow is a  possibility this weekend.  There's a couple of chances, both on Saturday night as well as Sunday night.  Below is the chances of rain and snow over the next 10 days.  You can see the chance of snow late on Saturday, changing to a better chance of rain on Sunday, and then another lesser chance of a little snow on Sunday night.



Why is this storm different than the previous rain storms?  Namely, it's where the storm is coming from.  The weather map below shows the storm that came through our area last Monday.  But it also shows another storm south of the Aleutian Islands, which is the wet storm that came through the Inland Northwest on Wednesday.  Both of these storms essentially are moving west to east.


This next weather map shows the Wednesday storm in the West.  But you can also see the next storm that will affect our area this weekend.  Notice that this storm is coming from an area north of the Aleutian Islands, and thus is going to be colder than it's predecessors.


How much snow could we be looking at?  Here's forecasts from the European, Canadian and US computer models.  They all three show a similar pattern to the snowfall, confined mainly to the northern mountains and valleys.  







The US model (the GFS) is the snowiest of the forecasts.  But it has been consistently showing snow for each of our past rain storms this fall, so it's been over-forecasting snow.  The Canadian model is typically a little colder than other computer models.  The European model is probably the most conservative forecast.  It would predict about 1" of snow for Spokane and the West Plains, and 1-2" in the valleys to the north.  Possibly up to 4" for northern locations like Priest Lake.

Saturday will be a cold day ahead of the storm, with daytime temperatures remaining in the 30s.  Timing will be important to accumulation.  If the snow starts on Saturday afternoon, it probably won't accumulate on the ground until after sunset.  The snow should change to rain on Sunday afternoon as temperatures warm into the upper 30s and a cold front moves through.  This should melt most if not all of the snow that falls in the morning.

As a matter of reference, on average Spokane receives its first inch of snow on about 15 November.  So this weekend snow is right about on schedule.

After our weekend storm, a strong area of high pressure will build over the West.  At this time, this high pressure looks like it could hang around a week or more, bringing us dry but cold weather starting on Tuesday 19 November.










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