January 11, 2015

The Most Boring Weather Day in Seattle History? Did it Influence the Playoff?

Although there was plenty of excitement at Seattle's CenturyLink Stadium as the Seahawks triumphed over the Panthers, Seattle's weather was just the opposite: one of the most BORING weather days in memory.  And it was one of the darkest days in a long time as well.

Here is a plot of the observations on the roof of the atmospheric sciences building at the UW in north Seattle.  The time axis on the bottom is in Greenwich Mean Time (GMT or UTC), but just consider it the last three days ending 9 AM Sunday. The third panel is temperature (black line) and dew point (red line).  Thursday and Friday showed the normal increase in temperature during the day, but Saturday was amazingly boring, with practically no daily (diurnal cycle) and a very slow warming of perhaps 1.5F.    You don't see days like that very often.  It is if the sun did not exist!

Talking about the sun, the last panel shows the amount of solar radiation reaching the surface.  Nice daily variation on Thursday, somewhat less on Friday, but VERY LITTLE ON SATURDAY.  It was a very dark day, with thick, drizzly low clouds over the entire period.

Winds?   Forget it.  They GUSTED to 4 knots yesterday!

In fact, Seattle was the darkest place in western WA on Saturday as shown by the solar radiation observations (SolRad) taken by the Washington State University AgWeatherNet sites (see below).  There was nearly three to four times more solar radiation on the coast! (GRAYL).

The cause of this darkness and unchanging temperatures was persistent low clouds over the Puget Sound region (see visible image at 11 AM).  Thick, low, drizzly clouds.  And lots of fog (but without the stink!).  Thick low clouds act as a reflective blanket:  solar radiation can't get in and infrared radiation from the surface can't get out.  The result is little diurnal temperature variation.

Why no stink?  Because the passage of weak disturbance destroyed the inversion that was capping a shallow layer of cold air near the surface.  The smell lid was taken off Seattle...thank god.

Did the weather aid the Seahawks?   It couldn't hurt.  The Panthers are used to sunny, temperate Charlotte, North Carolina and the dark, dank, drizzly Seattle environment, with the real threat of exotic smells, was certainly intimidating.   Seattle's weather is the Seahawk's 13th man (or woman), particularly since most competing teams are from sunnier locations.


  1. By the way, the scale on the 3day pcp has been broken for some time now hence always shows a flat line. Could you notify the appropriate person to fix it?

  2. Check out the last few seconds of the UW AtmoSci west-facing webcam for Jan 12 - a nice little train of KH waves in the stratus deck as twilight falls.


  3. I'd love to see some comparison of the sunlight output to a summer day or a more sunny location. What's a summer day at the tropic of cancer looks like, a winter day in Phoenix? A normal winter day in Seattle and last weekend(which was notably grey/dark)

  4. http://www.popularmechanics.com/science/environment/climate-change/us-weather-satellite-noaa-goa-report-2015-17640539

    A fascinating (and sad) article like what we often find reported on this blog.


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