Sunday Morning Snow Update

More serious snow this morning in many locations....and a very different situation.  Looking outside my window in north Seattle the scene is completely white, moderate snow if falling, and there is perhaps 3/4 inch on the ground.  Really pretty.

Yesterday the snowfall was quite varied...with nothing to an inch over much of the lowlands, but several inches in the convergence zone (e.g., 3 inches in Snohomish).  Here is a snow map 7 AM this morning from the CoCoRahs network (click to expand)

 

Here is the 24-h precipitation from Seattle Rainwatch--probably corresponds well to the snow distribution right now:

The temperature of the atmosphere is much cooler this morning than yesterday and virtually all precipitation is going to be snow.  Here is the latest temperature structure from Seattle SnowWatch:

Now I will show you something NEVER seen before on this blog or anywhere else..the precipitation type output from the dual-polarization capability of the new coastal radar and the old Camano radar. Light blue (DS) indicates dry snow.  Remember the beam increases in height away from the radar.

Looking at the radar loops and the latest surface reports indicates a low is now centered south of Grays Harbor--a location that allows precipitation to circle back up into western Washington. At the same time there is a band of snow down the Strait towards Whidbey.
Each forecast run the last few days increasingly suggested this location for the low ...and this morning's run shows it clearly.  Looking at the latest Langley Hill radar image we can
 see showers offshore circling around and then moving up into western Washington.  Snow on the coast, of course.  The band down the Strait into NW WA is fascinating...it represents the convergence between southerly flow moving up the Sound and northerly or weak flow moving out BC.  What makes it exciting to me is that the models were suggesting this yesterday.

There is a gradient of snow east-west across the Sound..more on the east side, due to Olympic "snowshadowing"

This situation will keep up for a few more hours, but the low and the snow will slowly move south, causing a drying out this afternoon...from Olympia north.  Sorry snow lovers!

But the best is yet to come.  We will have a break the second half of today and much of Monday.  But later Monday afternoon into Tuesday morning another batch of snow will come in with another upper trough and this could be considerably heavier.

And then Wednesday morning we may have snow/rain SLUSHMAGEDON. A very warm, wet system will approach...first we could have heavy snow and then heavy rain.  Possibly a big mess.

And remember the mountains are getting lots of snow...over a new foot at Stevens. They needed more snow and will get it.  But the avalanche risk will be increasing.

So to summarize:  This situation has four stages:

Stage 1:  Snow with the front yesterday, with convergence zone snow.
Stage 2: Today's snow with the coastal trough
Stage 3.  Later tomorrow snow with another trough
Stage 4:  SLUSHMAGEDON on Wednesday AM.

The current model runs suggest that the next week will bring some of the most intense and active weather in a long time...windstorms, rain, snow....the trifecta of NW weather.

Do you Live In or Near Mountlake Terrace?
If so, please keep you eye out for my lost dog..see the picture and more information in the right panel.  Thanks. Also message for the City of Mountlake Terrace:  Please Don't Pull Down and Tear Up Our Lost Dog Signs!