Darkest Day and Possible Snow

This will be a blog about contradictions. Yesterday was very dark over much of the NW, in fact in Seattle it was the darkest day since January 10th of this year based on the solar radiation measurements at the UW (this fact was communicated by Mark Albright, past state climatologist). First, we start with the darkest period of the year based on the amount of solar radiation reaching the top of the atmosphere (of course, the darkest day by that aspect is December 21st). Then we add unusually thick clouds with lots of water content that scatter and absorb the radiation we do get. Between the two, not much got in. Here is the plot of observations and solar radiation at the UW for the last three days...the last line is solar radiation.....pretty pathetic yesterday!So how do we brighten things up? Snow, of course. And the latest runs are suggesting the potential for lowland snow next Wednesday. Here is the forecast for 10 AM next Wednesday: cold air in our vicinity and a low center off the SW coast of WA. This pattern, and the upper level flow associated with it, are close enough to the canonical pattern for lowland snow to be concerned. And the model explicitly is indicating snow near sea level. But I would not get too excited yet--this could change. But local municipalities should go into a watchful waiting mode, insuring that their crews are rested, the salt and deicer bins are full, and the reversible lanes of I5 are ready to go.

And I hope everyone has a relaxing holiday weekend.