3PM in Seattle from the Space Needle PanoCam

Solar radiation on the top of my department roof for the last three days.

Picture at Sea-Tac courtesy of KPLZ

Or to be more exact, the darkest day ever observed at the University of Washington during the twenty years we have recorded solar radiation on the roof of the atmospheric sciences building.Over theday, we receivedof solar radiation over a square meter surface. The old record low was .39 on December 14, 2006 ( a joule is a unit of energy). The runner up was .44 on December 7, 2015. To give you some perspective, in July of this year we had several days reachingConsistent with the UW measurement, here is the solar radiation at the Washington State University AgWeather site in Seattle: December 20th was the lowest over the past year.First, the date. The winter solstice is tomorrow, so solar radiation reaching our atmosphere is about as low as it can be.And then we had a strong atmospheric river, with multi-level cloud decks and loads of precipitation parked over us all day (see MODIS image below). Clouds and precipitation scatter solar radiation back to space (that is why the clouds look white in a satellite image).You may not see a similarly bad day for the rest of your life if you stay here. But you probably won't (stay here).I understand that crowds of visiting and expatriate Californians are rushing to Sea-Tac Airport to get back to sun before it is too late.