Friday, June 21, 2013

ABC affiliate WJLA: "Surviving Severe Weather"

On Friday, June 21, 2013, ABC affiliate WJLA in Washington DC (actually Rosslyn in Arlington, VA) ran a one-hour special “Surviving Severe Weather” with Brian Van der Graaf, Adam Caskey, and Doug Hill.

The special emphasized the severe weather risks that are more likely in the Washington DC Metro area, and surrounding country from the mountains to the beaches.
The program opened with the severe weather outbreaks that had occurred just a week ago, three of them.

Early, the program covered the big derecho on June 29, 2012.  We had a small, low-end derecho in northern MD Thursday June 13.  A derecho usually starts in the mid-west and can survive the journey across the mountains when the air in the East us very hot and very humid, even without a strong cold front or organized low pressure. 

They did cover the huge tornadoes in Oklahoma in May  Large tornadoes (or anything above F-1) are rare in the DC area, but could increase with global warming.  An F4 tornado occurred in the mountains in Frostburg MD in 1998, and in La Plata MD (in southern MD, in low country near the Potomac River and Chesapeake Bay) in 2002.
Adam Caskey showed a demonstration on the ability of houses to withstand 130 mph winds.  One house in Richburg SC blows away, and the next one has little damage.  They recommend hurricane straps to attach roofs, and certain kinds of nails.  Homes should be routinely built to withstand winds up to 110 mph with little damage. 

In the DC area, many thunderstorm complexes move gradually from SW to NE, and tend to split into distinct sections when hitting the highest, central section of the Blue Ridge (over 4000 feet), about 90 miles directly SW of DC.  The most severe storms seem to go through Harper’s Ferry Gap or the W Va Panhandle into Frederick and northern Montgomery counties and then over into Howard County and toward Baltimore.  The other branch, perhaps even more severe, tend to cross I-95 around Fredericksburg and track into southern Maryland, and game strength from warm water in the Potomac and Chesapeake.  Storms closer to DC may tend to be a little less severe because of the location relative to higher mountains.  But sometimes the mountains can create severe storms (without a line coming from the west), when there is a lot of moisture from the SE that can’t get over the mountains, and then cold air hits it.  In those cases, weather right in DC may be more severe.

A fit adult human being can walk pretty easily in winds over 70 mph, but not 90 mph.  (In nature, animals deal better with storms than do plants.)   Adam Caskey generated the University of Maryland test center that generates 115 mph winds. Later, Caskey demonstrated an experiment creating hailstones in a lab. 

The program moved on to lightning detection.  It covered lightning strikes happening suddenly to people.
I remember the day of Hurricane Sandy.  The highest winds came around 8 PM, and were not as bad as expected, maybe 65 mph at the treetops 75 feet up.  During the storm, pain in an arthritic hip disappeared, and did not come back.  I think low pressure is good for joint problems.  (Washington Nationals's Bryce Harper, take notice.  Prolonged exposure to a severe storm's low pressure will probably help your bursitis.)  
There was little damage, but a few strategic fallen trees on 16th St in Arlington knocked out power in Westover for two days.
Tornado potential has increased east of the Appalachians, particularly from Richmond south and in the coastal plain areas.   This could be because of global warming, or because of improved forecasting.
Tornadoes can develop very suddenly.  So far, sudden development of wide tornadoes has not happened much in the East the way it has in the Plains.  Cooler weather in April and May can delay the tornado season, but make it more severe when it comes.  The program says that the most severe weather in DC occurs in June and July, mostly from little microbursts from "cold fronts" but not from organized outbreaks.  Severe weather in the midwest and Southeast is likely to occur earlier. 

Late in the program, a storm chaser explained the El Reno OK tornado on May 31, 2013, which killed a storm chaser because it went in an unusual direction (to the SE), and exploded from a half mile wide to 2-1/2 miles in 30 seconds, with 296 mph winds at one point.  Fortunately, most of that was over unpopulated areas, but people were killed driving on I-40.

I can remember being caught in severe weather when driving a few times.  I saw a  small tornado from Rt 9  (crossing it) driving west from Rehoboth Beach in August, 2001; it missed me by a half mile.   In April 2005, on a Saturday morning, I was caught by a severe storm on I-95 driving south of Ocoquan; it had been cool and cloudy when  I left Arlington.  A tornado was reported near Richmond from that storm.  In August of 2012, I was caught in a prolonged frightening night storm in northeastern Maryland to the Baltimore Harbor Tunnel;  it disappeared south of Baltimore.  NE Maryland gets the jackpot in my experience for exposure to severe weather.  Then, just last Sunday morning (right after midnight), returning from Baltimore gay pride, and driving on 123 toward Glebe Road in Arlington to return, I missed being hit by a falling tree in good weather (weakened two days before) by about three minutes.  I sent a tweet to WJLA on that one.  
People can try to live in safer areas, but almost any area of the country can have some kind of disaster.  Insurance will take care of people and put them into hotels during repairs, but may not be adequate with very widespread disasters, which can become big social equalizers.
I think that the program should also have covered space weather – solar storms. A Carrington-sized coronal mass ejection (from "solar flares") could pose a severe test of the national power grids.   

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