On the second day of a developing heat wave, under a sunny sky, afternoon temperatures reached the upper 90s to above 100 degrees across most of southeast Ohio. For example, Waterloo in Lawrence County reached 104 degrees that Friday afternoon. Marietta had 100 degrees. Meanwhile, an area of multi-cellular convection had moved out of northern Illinois that morning. It continued to organize and strengthen, as it propagated east and southeast across northern Indiana into western Ohio during the afternoon. As it moved toward southeast Ohio, it had already formed into a large arch of storms, or bow, with a developing cool pool in its wake. The temperature contrast between the air ahead of the developing derecho, compared to that in its wake was reaching 30 to 35 degrees. The resultant wind shift in the cool pool resulted in strong moisture convergence on the leading edge of the complex. This in turn, helped drive the storms further southeast, away from the mid and upper level wind support. However, the complex was diving right into that hot air that had obtained large convective available potential energy (CAPE), on the order of 4000 to 5000 j/kg.
The derecho reached southeast Ohio near the hottest time of the day, after 1600E. It was racing southeast around 65 mph. The outflow or gust front began to outrace the rain as it moved into southeast Ohio. As the system matured, the strong gusts were longer in duration, in some cases around 10 minutes. That gust front then crossed the Ohio River into northeast Kentucky and western West Virginia on either side of 1730E. The storms and showers only provided about a quarter to a half inch of rain.
Widespread wind gusts of 60 to 85 mph were likely with the leading gust front across southeast Ohio. A department of highways garage in Perry County measured 62 mph at 1650E. Ohio University at Athens measured 64 mph at 1712E. The airport near Albany of Athens County had a gust to 59 mph at 1715E. The department of highways garage in Gallia County near Kerr had 62 mph at 1731E.
The wind caused trees and large branches to fall in scattered locations throughout the 9 counties in southeast Ohio. There was some structural damage. Corrugated metal and siding were ripped off a few buildings. Trees fell onto houses and vehicles. Out of the 9 counties only 4 counties reported individual damage to the state. Those counties were Athens, Jackson, Lawrence and Meigs. The fallen trees and power lines also caused roads to be temporarily blocked. However, the largest impact was on the electric power grid. Prolonged power outages occurred. Some areas were without electricity for 4 to 7 days.
Luckily there were no direct deaths or injuries. One indirect death can be attributed to the storm.
The lack of electricity in the midst of the heat wave, disrupted the daily routines of most citizens for several days. Water and ice were in high demand. An emergency declaration by President Obama allowed federal supplies to be quickly delivered. Family and retail refrigerated food lost was substantial. Rural citizens with private wells may have been hit harder than those living in towns on public water systems. Citizens that relied on well water had no power to pump the water from their wells. Water had to be hauled just to flush the toilet. Some people slept outside on porches where it was cooler. With limited gas stations available to pump gas, long lines developed for a few days in the wake of the storm. Workers trying to restore the electricity had to take frequent breaks due to the heat and the safety equipment they had to wear.
Due to the public damage, a federal major disaster was eventually declared for this episode. A few others episodes during the first few days of July were also included. See FEMA disaster number 4077 for more details.