Sep 23, 2021
A slow moving cold front approached the area on the 22nd before passing through on the 23rd. A deep southerly flow allowed for tropical moisture to move into the area ahead of the boundary. This led to heavy rainfall as the cold front approached, and several instances of flooding along with isolated instances of flash flooding occurred.
Source: NOAA National Weather Service Storm Events Database (event 986419). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Frederick County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.