Thursday, February 25, 2016

Were the February mid-Atlantic tornadoes a result of "only" El Nino? Or climate change? Will this become more common?

An unusually violent late winter (February) low pressure system, moving up the Ohio valley, spawned tornadoes from Louisiana up to eastern Pennsylvania through yesterday. It behaved almost like a land tropical storm, spawning twisters on its northeast side.  Three died in a small town southeast of Richmond.  That turned out to be an EF1 in the earlier "warm front" portion of the storm, which would be unusual enough. In the later afternoon or early evening, there were longer tracking and wider EF3 tornadoes near Appomattox and then Tappohannock (60 straight line miles from DC). 
The storm was said to be fueled by El Nino.  Let’s hope so, because if associated with climate change instead, this could become a much more common event along the East coast, and would longer tracking, higher end tornadoes.

But what was shocking was the ability to generate miniature bows and Doppler tornado signatures even without much sunlight and normal heat.  However, most of the tornado generation stopped about 40 miles south of Washington as evening came on.   When the storm hit DC, it spread out, lasted longer, but became less intense, with most treetop winds under 45 mph,, but lots of dangerous lightning. The high temperature in Arlington reached “only” 65 degrees about an hour before the storm and fell into the upper 50s quickly.  Had there been more sun, or a longer day (had this storm occurred a month later), the results could have been much worse locally.

A day before, we were under “marginal risk” and then that got upgraded to “slight” and then “enhanced”.  WJLA has an explanation here

Before the storm, hit, weather maps showed a malignant, angry dark red welt running south to northeast, looking like Kaposi’s sarcoma.
The major tornado outbreaks of big tornadoes in the DC area occurred in 1998 (Frostburg, MD, a bizarre EF4 in the mountains), College Park MD (an EF3, with an EF4 in the VS Piedmont and an EF0 on the Mall, in late September 2001), and an EF4 in La Plata MD in 2002.  The Chesapeake Bay, with SE winds, can provoke small tornadoes to the NW around Baltimore sometimes.  

Homeowners should prepare for storm damage and floods with proper insurance (and homeowners should seriously consider whether they need flood insurance, even if not near water;  look at the possibility of hidden covered streams in the area).  Protect electronics and data by unplugging and taking to a safer place if possible during violent weather.   A normal policy should cover extended stay apartment housing during repairs.  But in case of a major area disaster (EF4 and higher), people will learn what it is like to be in shelters. 
On a tangential matter, climate change might have something to do with the increasing consequences of the Zika virus, and the possibility of sexual transmission needs to be closely watched.  

First picture: Tupelo MS tornado devastation, 2014, my picture. 

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