Jul 18, 2021
During the evening of July 17th an area of low pressure slowly moved east along a stationary boundary that stretched from New York to Massachusetts. The front briefly lifted northward into southern New Hampshire pulling ample moisture with precipitable water values over 2 inches, anomalously high, even for July. Additionally, much of this region had seen 300%+ of average rainfall over the preceding few weeks. This caused soil moisture values and streamflow conditions to be well above average.
Source: NOAA National Weather Service Storm Events Database (event 975656). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Hillsborough County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.