Double Convergence Zone and Snow Hits the Area!

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As last night's run correctly forecast, the front did not bring any snow to the lowlands.  As noted yesterday, it was a really interesting situation in which a small change in the configuration of the front caused a huge change in the snow prediction.  An indication of how snow often requires getting everything right around here, particularly when temperatures are marginal.

But we did get some snow today  after frontal passage and in fact it is snowing over NW Washington as a write this blog.

Today, as the front moved past, the winds turned northwesterly on the coast--the direction that sets up the Puget Sound convergence zone.  Did you know that convergence zones are often double?   One in the lee of the Olympics and the other in the lee of the mountains of Vancouver Island?   Here is a nice visible satellite shot today that shows this clearly:

You will also notice how CLEAR is it north and south of the convergence zones...that is due to air sinking down the slopes of the two barriers.  The picture also clearly shows the retreating front, stretching from the north Cascades across NW Oregon.  You can also see the double convergence zone in the surface winds:
 Here is the radar image at 1 PM:  you can see the convergence zone and some of the frontal precipitation.

The air cooled down behind the cold front and in the areas of heavier precipitation within the PS convergence zone melting and evaporation pushed the snow level down to the surface.  You can see some of the convergence zone cooling in this plot from Seattle SNOWWATCH at noon...mid-30s in Mountlake Terrace and Lynnwood within in the convergence zone precipitation zone.  Ten degrees warmer to the south.
Within the convergence zone many saw snow showers and then continuous snow--up to an inch in places.   Here is the proof from WSDOT cameras:

The image looks like the arctic!

Tonight the convergence zone has weakened, but a band of showers is moving across NW Washington--with lots of reports of snow, freezing rain, and ice pellets.  Enough to melt the crystalline heart of the Salt Guru.  Here is the radar image and a snowy shot from a Bellingham cam to show what is happening.  Some snow showers will continue across the region into mid-mrning and then end for the day over the lowlands.

Dog Spotted Again: A report by someone last night at Horizon View Park in Lake Forest Park.   Another person claimed to see our dog, all trimmed and cleaned up on someone's leash at the playground at Terrace Creek Park

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