Wednesday, August 10, 2016

Statewide Thaw

The exceptionally persistent and unusual warmth across Alaska in recent months and years (since mid-2013) has been well-publicized on many fronts, and deservedly so.  Here's another angle on the amazing warmth that I haven't seen discussed elsewhere (although perhaps I missed it): it is now very likely that Alaska's statewide 12-month running average temperature will rise above freezing for the first time on record within the next 2 months.  This is according to NOAA's climate division data for Alaska.

We're already very close to the 32°F threshold, as the 12-month average was 31.9°F for periods ending in both April and July of this year.  Last year both August and September were cooler than normal statewide, so if this year continues warm or even normal, it will be easy to bump the 12-month average above freezing.  For example, an August-September mean temperature of 44.65°F would be needed to push the 12-month average up to 32°F, and only 7 out of the past 35 years were cooler than this (most recently last year).

The charts below illustrate the likely range of 12-month running mean temperatures through the end of this year by appending the 1981-2015 distribution of multi-month means to the preceding averages.  Note that anything except continued very unusual warmth will bring the 12-month running average back down below freezing by early winter; it's rather unlikely that the annual mean temperatures will remain above freezing for more than a month or two.  After all, the 1981-2010 normal is 27.2°F, and presumably more normal temperatures will return, at least for a spell, sooner or later.

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