December 11 storm takes a different track to bring area a blizzard

The storm that affected much of the region on December 11 with blizzard conditions will be memorable.  Visibilities were less than a quarter mile due to snow and blowing snow as winds gusted over 50 mph for several hours.  This made many roads impassable during the afternoon and evening.  In addition, snowfall along and east of Interstate 29 ranged from 4 to 10 inches.  Even heavier snowfall was observed over the remainder of central Minnesota into western Wisconsin where several places near the Twin Cities were well over 12 inches.

What makes this storm unique for the eastern plains is that it took a very different path to get here.   The figure below shows the path of the "normal" snowstorm which affects eastern South Dakota (purple arrows and L)), the Christmas 2009 blizzard which brought 1 to 2 feet of snow to the region (red arrows and L) and for December 11, 2010 (blue arrows and L).

For the "normal" snowstorm, the low will develop over Texas and then move northeast into Missouri and into Wisconsin.  In this case, as the low moves northward, south winds ahead of the low will bring moisture from the Gulf of Mexico into the northern plains.  This is the source for the heavy snow which eventually falls to the north and west of the low track.  For more information on the climatology of heavy snowstorms that affect the region, please see this web article.  Notice that the Christmas storm of 2009 followed a very similar track.  The low started out in western Texas and then moved northeast into northern Missouri.  At that point, the storm turned north into Iowa and eventually ended up near Spencer Iowa by 6 pm on Christmas Day. 

The storm that affected the region on December 11 took a much different path.  It began in the northern Montana and moved rapidly southeast into southwest South Dakota.  Then the storm turned to the east and moved through northern Nebraska, northern Iowa and into southwest Wisconsin.  This is a track more typical of an Alberta clipper.   An Alberta clipper is a storm that is typically fast-moving and also associated with very strong winds.  In many cases, the eastern Plains will see winds gusting over 40 mph with a strong Alberta clipper and can be produce ground blizzard conditions if there is snow on the ground.  However, because these storms move out of the northern Rockes, they typically cannot get moisture from the Gulf of Mexico so that snowfall with Alberta clippers is generally 4 to 6 inches.  A few stronger Alberta clippers may produce over 10 inches of snowfall.   For a low pressure system to move out of the northern Rockies and produce a widespread area of 6 to 18 inches of snow is very unusual.  But when it does, these can be significant blizzards because they are typically associated with very strong winds.

 Image under development...



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