Darkness Strikes Central Puget Sound

It seems almost like winter yesterday around central Puget Sound... the skies were dark and stayed dark most of the day.   And this is the time of the year when the sun is highest in the sky and the day is longest. 

How bad was it?  And why?   

First, how bad.   Quite bad. Here is the solar radiation measurements from the WSU AgWeather network for its northeast Seattle location.  Saturday's value was the lowest since April 14th and is more representative of average values in mid-February.

Same story at the nearby University of Washington solar radiation site.  At Puyallup in the south Sound, the solar radiation was the lowest since mid-March!

 Well, there was clouds--relatively deep clouds.  Here is the visible satellite picture around noon--- an frontal band of right over us

And these clouds were relatively deep, something suggest by the infrared satellite photo (below).  Infrared satellite imagery provides the temperature of the cloud tops and these were relatively cold (and thus high).

There was, in fact, light rain with the front (see radar below), an indicator of the moist lower atmosphere and the depth of the clouds.

The radiosonde sounding at 5 PM (launched at 4 PM) Saturday at Quillayute, on the northern WA coast, showed a completely saturated/cloudy layer in the lower atmosphere, with the temperature (red line) right on top of the dew point (blue dashed line)--that means 100% relative humidity.

And the model simulation of the vertical structure of the relative humidity on the WA coast, showed a very deep layer of saturated conditions (green color) during mid-day (height in pressure, with 700 being about 10,000 ft, time runs forward from right to left, 070100 indicated 5 PM Saturday).

Depressingly, today is not much better than yesterday, with a Puget Sound convergence zone keeping the clouds (and light rain) in place over the central sound (see solar radiation trace at UW below).  I was planning on painting my fence today--the project will be delayed.

But there is one encouraging note.  If you want to escape the murk, the sun is only a short drive away.  Just head across the Cascade crest towards eastern WA.   Just an hour away on I-90 (see visible satellite pictures) and you will be in clear or nearly clear skies.  Sun and  70sF are very close.  Farm stands and desert hikes.

One of the marvels of living here.

from Cliff Mass Weather and Climate Blog https://ift.tt/2tTOzz2