Masters student in tropical meteorology at FSU. Raised in Alaskan blizzards, but drawn toward tropical cyclones by their superior PGF.
By: Levi32 , 5:53 AM GMT on November 28, 2007
A major pattern change is beginning, not just for Alaska, but for the rest of the US as well. A sudden pulse of the SOI is partly to blame for this, although La Nina remains firmly in place across the tropical Pacific. A strong low currently south of the Kamchatka Peninsula in Russia will be moving into the Bering Sea during the next couple days. An enormous ridge will build ahead of this low and up into Alaska, bringing very warm air and clear skies ahead of the low. Temperatures will be running 15-20 degrees above normal for about 4 days as this ridge sits overhead. At the same time as this ridge moves in, cold air will be massing over Canada and pouring into the US plains, feeding a potentially potent snow storm for the eastern seaboard. Over the course of the following week, that cold air will make it's way west into Alaska, nudging out the ridge. The ridge will split leaving a blocking anticyclone over NW Alaska that will slowly retreat towards Asia. This is key because blocking highs in that position force lows south of them to come underneath before turning north. This means that lows that would typically curve north well west of Alaska will have to pass underneath the block and much further east before coming north. As the cold air takes a foothold in the interior of Alaska, the storm track will be simultaneously directed into the gulf. The GFS has been hinting consistently at a strong sub-970mb storm in the gulf next week running right up against that cold air. This would be a major snow event over a large area if this plays out.
This general pattern with a more south and east storm track and lots of troughiness over the Gulf of Alaska will be the story for most of December. The pattern for the lower 48 will start cold in the plains to the eastern seaboard but rapidly reverse with a strong warm ridge setting in as the dominant pattern for much of the rest of the winter.
We shall see what happens!
GFS 168 hour forecast showing a potential snowstorm for southern Alaska.
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