Wednesday, October 23, 2013

Gradual Cooling

Surface temperatures have cooled off quite a bit across the eastern interior in the past couple of days, with overnight minimum temperatures in the single digits and teens in many places, as befits the season.  The Chicken COOP observer reported 0 °F for the first time this morning, which is about 10 days later than normal; the climatological normal low temperature drops to zero in only three days from now at Chicken.  A number of higher elevation RAWS locations also reported 5 °F or lower, and Arctic Village in the northeast reached 0 °F.

Despite the surface cooling, above-freezing air was still observed in this morning's 4 a.m. sounding at Fairbanks.  The chart below shows that the 925 mb temperature (around 700 m above ground) has been above freezing at each 12-hourly measurement since early on October 11.  With gradual cooling continuing aloft today, and surface temperatures just below freezing, the column will soon drop below freezing if it hasn't already.  However, this won't last long, with warmer air returning soon.

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