May 31, 2010
Strong heating of a very moist low level air mass aided severe thunderstorm development during the afternoon and evening over the south central mountains and lower Susquehanna valley. Despite weak upper level support and vertical wind shear, several storms produced damaging winds and hail up to one inch in diameter. In addition, this environment proved to be favorable for slow-moving/training storms which resulted in localized flash flooding in Lancaster County.
Source: NOAA National Weather Service Storm Events Database (event 238258). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Lancaster County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.