Thursday, February 26, 2015

Is There Snow in our Future?

It's been so long since we've seen snow around here, that most of us have put away the boots and snow shovels for the season.  Is there any chance we'll have to get them back out of storage?  It's not likely, but there is a chance.  Let's take a look.

First, the stage will be set in the next couple of days.  A somewhat weak storm is moving down from the north today (Thursday), but this will largely miss our area to the west.  Some folks are getting some rain and high elevation snow, but mostly it's just clouds.  As this storm moves south of the region on Friday, it will pull down some cold and dry air from Canada.

GFS forecast precipitation (green shading) and surface pressure (thin black lines) for Saturday morning

Saturday  will be a rather raw day, with temperatures in the upper 30s to lower 40s and a brisk north wind.  This new air mass will mean that any precipitation from the next weather system will fall as snow instead of rain.  That next system will arrive Monday and Monday night.  There are three computer models that we look at for the weather 5 days out: the GFS (US model), the GEM (Canadian model) and the ECMWF (European model). 

Here's the GFS forecast for Monday night:
GFS forecast precipitation (green shading) and surface pressure (thin black lines) for Monday night
The GFS shows the majority of the next system sliding down east of the Rockies, which is what most of these storms do.  But you can see that the GFS does indicate some snow making it into the Panhandle and extreme eastern Washington.

Now take a look at the GEM model for this same time:

GEM forecast precipitation (shaded) and surface pressure (solid lines) for Monday evening

Not identical to the GFS, but similar.  The ECMWF (not shown) actually has a bit more precipitation for eastern Washington than the GEM or GFS.  Earlier runs of the ECMWF were showing a more significant storm for the Inland Northwest, but the more recent model forecasts have backed off on that idea.

Unlike storms in December or January, this system will be more spring-like.  What does that mean?  In the heart of winter, our atmosphere is typically very stable.  Snow tends to be more widespread and light.  But in the spring, the surface is warmer while the upper-atmosphere is colder.  This causes a more unstable atmosphere.  The result is precipitation which is more showery but can be heavier.  But it also can be more difficult to accumulate snow on the ground during the afternoon hours.

Temperatures on Tuesday might be rather chilly, with some locations not making it above the freezing mark.  If this happens, it would be the coldest day since January 3rd.

GFS forecast high temperatures for Tuesday March 3rd

Thus, at this point it doesn't look like a widespread heavy snow event.  Rather, some locations in the Panhandle and extreme eastern Washington could see a few inches of snow.  It's too early to have much confidence in this scenario.  In fact, it's more likely that this storm will stay to the east of our area, as they typically do.  

Stay tuned and we'll update this blog in a day or two as the forecast becomes clearer.

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