Derecho Assessment

Left:  Progress of the June 29, 2012 as it decimated the landscape. (It was something like a science fiction movie disaster come to life!)

Jerry notes an interesting and important document, just released by the National Weather Service, assessing their performance regarding the June 29, 2012 derecho. As the report notes:

A historic derecho impacted the Ohio Valley and Mid-Atlantic states on June 29, 2012. The event originated in northeast Illinois as a small cluster of thunderstorms. The derecho became organized over northeast Indiana during the afternoon and raced southeastward across Ohio and West Virginia at 60 mph. The derecho remained intact crossing the Appalachians, a climatological rarity, and caused widespread damage in the Washington, D.C., metropolitan area during the late evening. The derecho moved offshore shortly after midnight on June 30, 2012. In its wake, 13 people were killed and several million customers were left without power, many for several days. Tony Cavalier, Chief Meteorologist from WSAZ-TV Huntington-Charleston, WV, was quoted as saying, “The derecho was one of the top two impacting events in my 25 year career.”

This derecho was not forecast until the day of the event. Summertime derechos are often difficult to forecast because they respond to smaller-scale forcing mechanisms.

That HRRR model looks like it is useful. It’s interesting how the derecho tries to stay north and hew to the frontal boundary, even the higher values of CAPE might be further south. I guess it’s the rain-induced cooling that is so important!