Flash Flood and Damaging Winds in Maryland, June 26, 1997

A pre-frontal squall line, progressing into a very unstable atmosphere, generated widespread but scattered tree and wire damage across central and lower southern Maryland during the mid to late afternoon of the 26th. Tree damage was most pronounced in Montgomery Co, where over 3 dozen large limbs and trees were knocked down between Poolesville and Rockville. In Gaithersburg, the 200-year-old famed Forest Oak's demise was aided by the winds, although it had been gradually rotting. In Bethesda, winds along the gust front (estimated between 50 and 60 mph at their peak) blew a large oak onto a home, causing substantial roof damage. In one Germantown neighborhood, seven trees were reported down, including one onto a vehicle. In the northeast portion of the county, a man was trapped in his automobile by downed power wires. Several roads were blocked during the height of the storm; the combination of lightning, wind, and excessive load on the power grid from air conditioning left approximately 41,000 customers without electricity at the height of the storm.The lightning may have contributed to 4 knocked out substations in the county; lightning also struck and felled a tree in Gaithersburg.Similar damage occurred in lower southern Maryland, from Prince George's Co through Calvert and St. Mary's Cos. Lightning-related fires caused substantial damage to at least four homes in central Prince George's, including one with an estimated $250,000 in damage. Four fire fighters were injured battling the blaze. Other homes were struck by lightning in Clinton, Ardmore, and Forestville. Large limbs and wires were blown down in Beltsville, with one limb onto an automobile. Other tree damage was noted in Upper Marlboro. Farther south, scattered tree and wire damage was seen in Chesapeake Beach, and estimated winds of 60 to 70 mph knocked down large limbs/trees in Waldorf. the storms passed across the Chesapeake Bay shortly after 5 PM.Downpours associated with one of the more intense cells may have dumped as much as 2 inches of rain in an hour in central Prince George's Co. Two creeks spilled over their banks in Croom and Upper Marlboro. In both cases, low-lying bridges were flooded by rapidly rising water. Along Croom Road, an automobile unsuccessfully attempted to navigate through the flooding Charles Branch. The vehicle stalled, and the motorist was rescued by volunteer fire and state highway personnel when the water level reached the hood of his car. The flood waters receded on all creeks within an hour after the storm's passage.