Weather Blog

Was this the gloomiest weekend in Seattle history?

Was this the gloomiest weekend in Seattle history?
View from UW Atmospheric Sciences Building around 8 a.m. on Dec. 12, 2010.
Update: Mark Albright has found a worse weekend. Dec 15-16, 2001 had sunshine ratings of 0.62 and 0.66, as opposed to the 0.77 and 0.80 this past weekend. So it's likely the second-gloomiest weekend.

Combine thick clouds from a major rain storm with the shortest days of the year and you have what might go down as the darkest weekend in Seattle's history!

According to UW research meteorologist Mark Albright, instruments found that Saturday just recorded 0.77 MJ/m2 of sunlight energy while Sunday was just a touch brighter at 0.80. Without getting into gory details, the scale in Seattle typically ranges from low single digits in the winter to a max of about 32-35 on our sunniest summer days. A full sunny day on June 12 this year registered 32.5. Our "sunniest" day this month on Dec. 4 rated 5.36. Albright says individually, 0.77 or 0.80 doesn't rate the lowest, but it is very rare to have two such days back-to-back -- and on a weekend no less. Our lowest measurement in the past two years was Jan. 11, 2010 at 0.73, and in 2009 both Jan. 11 and Dec. 15 were 0.74 (What is it about January 11th and gloomy days?)

He says to truly get the low measurement, you need to be around the winter solstice and Dec. 11 is pretty close. So he figures this was probably the darkest weekend in recent history -- and perhaps ever -- although this is a suspicion and not actually confirmed with data.

So while Seattle didn't set any historical rainfall records, perhaps we just set one for gloom?

It also means we can only go brighter from here, right?