Friday, December 13, 2013

Unusual Wind

Thursday was one of the windiest days in recent decades in Fairbanks, and remarkably this occurred in the least windy month of the year, climatologically speaking.  The mean daily wind speed was 20.3 mph, which is higher than all but two other days in the 1984-present history of this weather variable.  The chart below shows the maximum daily mean wind speed and the 90th percentile of all daily mean values, categorized by month.  Ninety percent of days in December have daily mean wind speeds below 5.6 mph, and the previous highest value observed in December was 14.1 mph on December 4, 1991.

The culprit for this outcome was an intense synoptic-scale pressure gradient over Alaska, as seen in the 3 am AKST surface analysis from yesterday: a very strong anticyclone was located over the North Slope, while a strong low pressure system was affecting the Gulf of Alaska.  The unusual aspect of this is the intensity of the high pressure in the north.

1 comment:

  1. The synoptic we experienced is very typical for March...and to paraphrase an aviator's term (used for observing the altimeter when flying between pressure zones), but for a different reason...High to Low look out below.

    My garbage container scooted across the driveway three times yesterday.