Hooked on a Pattern: The Spring and Summer Floods of 2018 in the Mid-Atlantic Region

Over a nearly four-month period during the spring and summer of 2018, multiple significant flooding events occurred in the Mid-Atlantic Region, and more specifically, the National Weather Service (NWS) Baltimore/Washington Weather Forecast Office (WFO) area of responsibility. Many areas observed 20 to 40 inches of rain during this period, which is nearly what is typically expected in an entire year. For much of the urbanized corridor between metropolitan Washington, DC and metropolitan Baltimore, Maryland, 10 to nearly 20 inches of that total fell in less than two weeks.

Flash floods with fatalities occurred in Ellicott City, Maryland; Charlottesville, Virginia; and Syria, Virginia; while other significant floods affected many other communities, with flooding severity not observed in a generation or more in some cases.

This study will analyze the atmospheric conditions during each of the significant events, as well as during an anomalous period for the first half of July 2018 when virtually no rain occurred at all.

Further historical perspective will be provided on some of the events and the period as a whole to provide context on the relative rarity of this lengthy and repetitive pattern.