Jul 28, 2013
A slow moving cold front coupled with a deep southerly flow of very moist air caused slow moving and in some instances back building thunderstorms to occur during the afternoon and evening of the 28th. This caused an all-time record breaking rainfall in Philadelphia as well as flash flooding in Philadelphia and Delaware Counties and also in parts of the Poconos and Lehigh Valley. Doppler Radar storm total estimates and or actual measurements reached around 4 inches in parts of the Lehigh Valley,
Source: NOAA National Weather Service Storm Events Database (event 468025). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Philadelphia County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.