Very Snowy and Cold Next Week

As we discussed in our previous blog, our mild winter weather is coming to an end.  We'll see some light snow tonight (Friday night), but then it should be snowing most of the day on Saturday, with snow showers continuing Saturday night and into Sunday morning.  

The European model isn't too excited about the snowfall amounts with this system for the Spokane area (0.7"), but gives a healthy 3-5" to the northern valleys.  It has been very consistent with this forecast over the past couple of days.

Meanwhile the GFS is much more excited about this storm, bringing 6" to Spokane and Sandpoint.  The difference is that the GFS lingers the storm over our area much longer than the European model.  

There are lots of other models that give us snowfall amounts somewhere between the GFS and ECMWF forecasts above.  With temperatures right around freezing, this snow will be on the heavier wetter side.  Snow-liquid ratio (SLR) will be around 10:1, which means if you get 0.25" of liquid, you'll get 2.5" of snow.

After a break on Sunday afternoon and night, the next storm system will spread snow into our area Monday and continuing into Tuesday morning. Expect some southwesterly wind on Tuesday at temperatures warm into the mid 30s.

The consensus of the computer forecasts is that we'll get more snow from this second storm than the first.  The snow will be a little fluffier than Saturday's storm.

Again, here is the ECMWF forecast.  Not a lot of snow for the Spokane metro, but about 8-10" for the northern valleys.

The GFS is also bullish on this storm with heavy snow for Spokane and all locations north and east.

But wait, there's more!  After our Monday/Tuesday storm system, temperatures aloft (18,000 foot elevation) get REALLY cold.  Our temperatures at ground level will also get colder, but not as much.  This creates a very unstable atmosphere.  This is the kind of situation where we can get a LOT of snow.  But this is the dry fluffy snow, with snow-liquid ratios of 20:1 or higher.  In this kind of a set up, we should expect to see reports of 12" or more overnight.  This is a more showery regime, so we won't all see these kinds of snowfalls each day.  

The best chance of heavy snow next week looks like it will be around Thursday or Friday.  I'll show you a couple of examples.  Don't get hung up on the exact timing or placement of the snow in these graphics.  The details will vary widely and we probably won't be able to pin down the details even just before it happens.

First, the ECMWF forecast.  A widespread 1-2 feet of snow north and east of Spokane on Thursday and Thursday night.  Again, this is just one out of 150 forecasts.

From the GFS, a fairly similar story.

After all of this snow, temperatures will get colder and could get really cold.  But the uncertainty level with this part of the forecast is extremely high.  First, I'll show you the most likely forecast of temperature (solid line) and wind chill (dashed line) for Newport, WA.  You can see that by the end of next week the forecast is for high temperatures around 10F and lows around -5F, with wind chills down to -15F.

But there is a HUGE amount of disagreement on this forecast.  Some of the computer forecasts don't see any cold air for us, keeping us in the 30s and even 40s next weekend.  But other computer runs expect our nighttime lows to drop as low as -27F.  These forecasts are both outliers and likely won't happen.  But in a cold atmosphere with snow on the ground, any low temperature is possible.

One concern with these cold temperatures in the impact they could have on alfalfa or winter wheat.  In this case, it's almost a sure bet that most fields will have anywhere from 6" to three feet of snow on them.  As usual, the most likely location for bare ground and frigid temperatures will be in the Columbia Basin.