Flash Flood in Maryland, January 19, 1996

*** Flood/Flash Flood Summary ***A waterlogged snow pack, ranging (roughly) in depth from 3 to 12 inches, was eaten away when subtropical moisture fed into the region ahead of a strong cold front. The warm moist air mass contained temperatures in the upper 50s and lower 60s, along with relative humidity near 100 percent. A deepening storm moving north through the Ohio Valley drew the subtropical air into the region. Minor flash flooding began during the pre-dawn hours, but more significant flooding occurred with the passage of an intense and unusual squall line, which moved through between 0900 and 1200EST. The squall line dumped rainfall amounts of 1.5 to 2.5 inches in less than 3 hours at any one location. Streams quickly overflowed their banks, and water ponded quickly from clogged storm drains and saturated ground.Flash flooding, due to streams and creeks out of their banks, began in northern Montgomery, western Carroll, and much of Frederick Co around 0700EST. The onset of heavy rains, between 0900 and 1000EST over the piedmont, and 1000 and 1200EST elsewhere, produced more substantial flash flooding. In Frederick Co, flash floods caused mud slides, knocked down trees, and closed roads. Numerous rescues were undertaken, mostly due to stranded vehicles. At the height of the storm, 52 roads were closed. Three hundred seventy-eight homes sustained flood-related damage. Fortunately, there were no fatalities, but there were a number of minor injuries. Rapid flooding of the Monocacy River (Frederick Co) caused problems, and there was flooding reported at Point of Rocks. In Carroll Co, 75 acres were reported under water, and several homes were evacuated in Detour, a result of a flood-related HAZMAT incident. Another oil spill also occurred at Owings Mills in Baltimore Co.In Montgomery Co, an elderly woman was in fair condition after her car was submerged along White's Ferry Road near Poolesville. Numerous creeks and streams were out of their banks countywide, including Rock Creek near Kensington. The flooded creek left large deposits of sediment in its wake. In Prince George's Co, over a dozen cars were towed out of high water along federal highway 1, which was temporarily closed.Farther east, in the Baltimore vicinity, several water rescues were reported. Just south of Baltimore City, Interstate 695 was closed briefly near Arbutus. An automobile was swept away in Harford Co.