The Impacts Of The June 29th, 2012 Derecho On The Mid-Atlantic Region

A historically-destructive derecho swept across the Baltimore/Washington Forecast Area during the late evening hours of June 29, 2012. The impact of this storm system came after a week of record-breaking high temperatures. On the 29th, there was much media focus centered on the record-breaking heat impacting the region. Washington DC's high of 104oF recorded on the 29th set a new all-time high temperature record for June.

The derecho was historic for the region in that it downed tens of thousands of trees, caused damage estimated in the hundreds of millions of dollars, contributed to 5 deaths in the area, shut down a number of Washington Metrorail stations, caused areas of flash flooding, and knocked out power for hundreds of thousands of customers over a multi-day period during a heat wave. Derechoes typically affect the Baltimore/Washington Forecast Area on average once every 2 to 4 years. A significant derecho can leave a lasting impression with area residents, most of whom had never heard of a “derecho”, nor had ever experienced such severe conditions the June 29th derecho produced. A somewhat less intense derecho impacted the DC region on June 4, 2008, though it was much earlier in the day, occurring while most people where either at work or school. A large segment of area residents were unsure about the intensity and impact this June 29th, 2012 derecho would have even hours before it struck. On the 29th, starting in late afternoon, National Weather Service forecasters at the Weather Forecast Office in Sterling began to take the focus off the heat wave and onto the impending and fast-approaching storm. This presentation will discuss some salient events and local meteorology behind the derecho of June 29th, while also highlighting the need for enhanced use of all forms of media to disseminate warnings and alerts to the public ahead of such high-end high-impact events.