December 04, 2021

Monday's Snow Event

 Before I discuss the potential snow event on Monday, let me note that as predicted, some light snow fell over Northwest Washington. illustrated by the WSDOT cam north of Bellingham.

Perhaps the most interesting snow reports were received from downtown Kirkland.  Since I am particularly interested in highly localized snow events, I checked it out myself (picture below).  Have not figured out the complex meteorology of that situation yet.

Now, let's turn to the Monday "event".

That morning, a weak upper trough will be moving through (see attached).  From my experience, too far northeast and too weak to produce a significant snow event over western Washington.

4 AM Monday 500 hPa (~18,000 ft)

Near the surface at 4 AM, the air will be plenty cold enough for snow east of the Cascade crest, but very marginal over western Washington and Oregon (green colors)

The latest UW forecast run (initialized at 4 PM Saturday) provides the predicted snowfall total through 4 PM Monday (below). With the exception of northwest Washington around Bellingham, the lowlands get nothing or perhaps a few flakes mixed with the rain.  Bellingham and vicinity might get an inch or two of SNOWFALL.

It is VERY important to distinguish between snowfall (snow amounts falling out of the sky) and snow accumulation on the ground.   The difference is particularly acute this time of the year when the soil temperatures are relatively warm..... particularly after our recent warm stretch.   

Here are the latest soil temperatures from the WSU AgweatherNet website.  Upper 40sF around western Washington and mid-40s in the east.

With these warm soil temperatures in mind, take a look at the predicted snow depth at 4 PM Monday based on the same forecast as above.  Lowland snow only accumulated on the ground around the  Bellingham area.

You have to admit, the Bellingham folks have been ground zero for active weather lately.

For eastern Washington, only the northern portion will end up with light snow on the ground (see below)

We have now switched into a much cooler, wetter configuration and expect snow to pile up in the mountains.

And if any of you are disappointed with the lack of snow, you have a new option! 

There is a blizzard warning for the Big Island of HAWAII.   I kid you not.  Check the latest National Weather Service Forecast graphic:

And the forecast for Honolulu is bound to disappoint some vacationers (see below).  The cause?  An infamous Kona Storm.

December 03, 2021

New Podcast is Out: Monday's Snow Event and the Meteorological "Trick" Required for Western Washington Snow

We have a major change in our weather ahead, with cooling temperatures, heavy snow in the mountains, and snowflakes reaching sea level over portions of western Washington.

 One system comes through on Saturday, laying down 6-11 inches over the central and northern Cascades and substantial snow over the northern section of eastern Washington (see snowfall totals through 1 PM Saturday).   Northwest Washington gets a piece of it (particularly from Bellingham towards the Fraser River Valley).  A few flakes in the air over Puget Sound.

Sunday will be dry, followed by a potent low moving through on Monday (see the sea level pressure map at 4 AM Monday).  Strong winds will occur along the coast and cold air in place over the interior.

The low will track southeastward on Monday producing lots of snow in the Cascades and more than a dusting over Northwest Washington, with Bellingham also getting strong northeasterly winds out of the Fraser River Valley (the 24-h snowfall accumulation ending 4 PM Monday is shown below).  Puget Sound will be fine.   Skiers should prepare their gear.

More detail about the event is found in my podcast, which also describes the unusual conditions needed to produce a major western Washington or western Oregon snow event.

You can listen to the podcast below or through your favorite podcast server.

Some major podcast servers:

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Monday's Snow Event

 Before I discuss the potential snow event on Monday, let me note that as predicted, some light snow fell over Northwest Washington. illustr...