Today's frost was one week earlier than normal and the earliest at the airport since 2005; but 28 °F or lower is not typically observed until September 23 (1981-2010 median), so in that respect we're nearly three weeks ahead of schedule.
In more rural areas of the interior much cooler temperatures were observed this morning, including:
Norutak Lake RAWS in Kobuk National Preserve 14 F
Circle Hot Springs 15 F
Chicken 17 F
Eagle airport 18 F
Goldstream Creek 19 F
Bettles 21 F
Tanana 22 F
Local temps can be driven by a lack of cloud cover and brief pre-dawn AM winds this time of year. The reported low at 1453Z of 28 was accompanied by high scattered to few clouds and a slight NE wind. The light wind can move colder air over the airport from low lying spots nearby. The Sun soon warmed things up nicely.
ReplyDeleteThose morning low level winds can be both seen (via bent furnace and vehicle exhaust) and felt while out walking with the dog.
Gary
Oops, bad calculation Gary. Here are the actual sky conditions at PAFA so far in 2014. The "CLR" condition seems pretty underrepresented in my opinion.
DeleteOVC: 21%
BKN: 46%
SCT: 13%
FEW: 13%
CLR: 8%
VV: 0%
Gary, I wouldn't put too much faith in the PAFA ASOS cloud ceiling data. Here is the percentage of sky conditions so far in 2014. As you can see, it has been overcast only 1% of the time!
ReplyDeleteBKN: 16%
CLR: 8%
FEW: 49%
OVC: 1%
SCT: 26%
Good point Brian. It's unfortunate that in these days of aviation safety awareness that we may no longer be able to depend upon reliable observations of cloud ceiling data. Maybe a discussion on what drives the sensitivity of the ASOS' reports is in order?
DeleteHowever, I was out a little after 8 this morning, and as is my habit, did look up for circling predators. It was pretty clear overhead and there was a slight NE breeze with at local temp around 26F.
Radiation cools as does sub-freezing 850 mb temps and declining photoperiod.
Gary