The historic derecho of June 29, 2012
Corporate Authors:United States, National Weather Service,
Effect Of Storms On
Natural Disaster Warning Systems
Electric Utilities/Effect Of Storms On/Atlantic Coast (U.S.)
Natural Disaster Warning Systems/Evaluation/Atlantic Coast (U.S.)
Thunderstorm Forecasting/Analysis/United States
Description:Derecho science and climatology -- Event overview -- Facts, findings, recommendations, and best practices. Model performance ; SPC products and services ; WFO pre-event services ; WFO warning services ; NWSChat and social media ; Service backup ; Spotter activation and training ; StormReady program ; Equipment failures ; Post-event heat -- Societal responses and impacts. Public opinion survey ; Impacts of waring language and lead time ; NOAA weather radio all hazards and siren system -- Appendix C. Direct fatalities from the derecho -- Appendix D. Heat-related fatalities in areas affected by the derecho.
"On June 29, 2012, a devastating line of thunderstorms known as a derecho (deh REY cho) moved east-southeast at 60 miles per hour (mph) from Indiana in the early afternoon to the Mid-Atlantic region around midnight. The states most significantly impacted were Indiana, Ohio, Kentucky, Pennsylvania, West Virginia, Maryland, Virginia, Delaware, New Jersey, and North Carolina, as well as Washington, D.C. Nearly every county impacted by this convective system suffered damages and power outages. Winds were commonly above 60 mph with numerous reports of winds exceeding 80 mph. Some areas reported isolated pockets of winds greater than 100 mph. The storm resulted in 13 deaths, mainly a result of falling trees. One major impact from the derecho was widespread power outages. More than 4 million customers were without power, some for more than a week after the storms moved through. To make matters worse, the area affected was in the midst of a prolonged heat wave. There were 34 heat-related fatalities in areas without power because of the derecho. The National Weather Service (NWS) formed a Service Assessment Team to evaluate performance during this event. Due to the widespread nature of this derecho, the team chose to visit the sites and review products and performance only at NWS Weather Forecast Offices (WFO) most impacted by the storms: WFOs Syracuse, IN (hereafter WFO Northern Indiana); Wilmington, OH; Pittsburgh, PA; Sterling, VA; Charleston, WV; and Blacksburg, VA. The team collected data from five other sites on the periphery of the damage path: WFOs Indianapolis, IN; Cleveland, OH; Jackson, KY; Mount Holly, NJ; and Wakefield, VA. A review of the products and services provided by the Storm Prediction Center (SPC) was also conducted along with numerous SPC staff interviews. Unlike many major tornado outbreaks in the recent past, this event was not forecast well in advance. Warm-season derechos, in particular, are often difficult to forecast and frequently result from subtle, small-scale forcing mechanisms that are difficult to resolve more than 12-24 hours in advance. The National Centers for Environmental Prediction (NCEP) operational forecast models, such as the North American Mesoscale (NAM) and Global Forecast System (GFS), provided little assistance in forecasting this event more than 24 hours ahead of time. However, on the morning of June 29, some high-resolution, convection-allowing models began to provide clues that an intense line of thunderstorms could take the path that was later observed."--Page ix.
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