Thursday, November 1, 2012

Variable Winds Modulating Temperatures

1200 UTC Surface Analysis courtesy of Environment Canada
An interesting wind situation has prevailed in the past day over the Fairbanks area, with widespread northeast winds right down to the valley floor. The average wind at the Fairbanks Airport on Wednesday was 14.1 mph. This is most unusual this time of year for a northeast wind event: persistent winds this strong in winter typically occur with southwest flow following a frontal passage. The surface analysis for 4am ADT Thursday from Environment Canada shows the 1039bm high over the Brooks Range, with a decent, though not extreme pressure gradient over Interior Alaska.  The winds Thursday morning have slacked in some valley areas, allowing temperatures to fall smartly: down to 11 below at Woodsmoke near North Pole and 4 below at Fort Wainwright and Fairbanks International. However, one of the usual cold spots, Goldstream Creek, had puffs of wind all night. The temperature dipped to 2 below about 3am, then was back up to 7 above by 730am.


  1. Thanks for posting, I was curious how unusual yesterday's strong winds were.

    It was amazing to see the temperature plummet ("smartly" indeed!) at Fairbanks this morning once the winds finally died down. I'm slightly puzzled by the 12Z sounding, which showed a temperature of -8.5 C at the lowest level, listed as 135 m and presumably essentially at ground level. At the same time PAFA reported -14.4 C, later dropping as low as -22.2 C! I assume this means the cold layer was *extremely* shallow and wonder if this is typical?

  2. Richard,

    Yes, the -8.5C temp was encoded as the surface temperature. The RAOB launch site is just under a mile from the ASOS, so it is possible that there was considerably more wind at the launch site that at the ASOS. However, usually it works the other way around in these kind of situations, with the upper air site colder that the ASOS. The UA site is much more sheltered by trees than the ASOS, which is on the south end of the runway, far from any trees or buildings of any size.

    We are getting to the super inversion time of year, and those kind of vertical temp differences will likely occur over the next few months. I may have posted some point in the past about Fairbanks's most extreme inversions, but I'll try and do up another one sometime soon.