Wednesday, November 13, 2013

NatGeo map shows mid-Atlantic states, New England at more tornado risk than generally believed

The November 2013 issue of National Geographic traces the activities of tornado chaser Tim Samaras, with particular emphasis on the May 31, 2013 tornado that took a bizarre course near El Reno, OK and barely missed Oklahoma City.  At one point it was almost 3 miles wide with wind speeds of almost 300 mph (the typhoon in the Philippines topped at around 220 possibly, but probably that was well off shore).  Curiously, the tornado dissipated four minutes after its maximum fury. The article is called “The Last Chase” by Robert Draper (like the 1966 movie “The Chase”).

There are graphic photos of the storm.  On pp. 48-49 there is, besides a drawing showing how supercells evolve, a US map showing the relative frequency of tornadoes, with the largest in “tornado alley”, especially Oklahoma. In the late winter and early spring there’s a patch from east Texas all the way to north Georgia.  I was surprised that there is a little “mini tornado alley” in the mid-Atlantic, stretching from SE Maryland, up by Annapolis and Baltimore, and into southeastern PA and southern New Jersey.  The risk diminishes quickly from Washington DC to the West,  There is another little alley in Connecticut and central Massachusetts.  I wasn’t aware that these areas have some heightened tornado risk.  The position of the mountains in the Blue Ridge (gaining in elevation quickly to the south) seems to funnel some severe storms through Harper’s Ferry gap into the Frederick area, but protects a lot of the Virginia suburbs directly west of DC somewhat, as some severe storms “divide” as they approach DC.
Try this link at NatGeo (“direct hit”), link
A few of the most severe storms I have encountered driving were north of Fredericksburg in April 2005, and (particularly heavy) northeast of Baltimore on I-95 in August 2012., and perhaps southern New Jersey in July 2011.   

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