Heavy Rain in Delaware, May 8 to 12, 1998

A series of low pressure systems that passed through the Middle Atlantic States and then stalled offshore gave Delaware nearly five days of continuous rain from when it started Friday morning the 8th until it exited state from north to south on Tuesday the 12th. Storm totals ranged from 2.6 to 4.2 inches. Overall there were few periods of heavy downpours and there were sufficient lulls of light rain or drizzle to keep most small streams and creeks within bankfull. Flooding problems were confined to flooded basements, backyards and some poor drainage areas. The heaviest rain for any given day during this event was mainly Friday the 8th. The axis of heavy rain slowly shifted north over the weekend into Pennsylvania. A second shot of heavy rain fell on Tuesday the 12th as the system was finally leaving the area. Storm totals included 4.23 inches in Dover (Kent County), 3.73 inches in Georgetown (Sussex County), 3.61 inches in Wilmington (New Castle County), 3.41 inches in Lewes (Sussex County), 3.00 inches in Odessa (New Castle County), 2.65 inches at the New Castle County Airport and 2.60 inches in Newark (New Castle County). In addition to the heavy rain, as the low departed the area and the high pressure system moved in, strong winds occurred during the daylight hours on the 12th. The loose ground from the rain left the trees vulnerable and some of the weaker ones were knocked over and caused scattered outages mainly in Sussex County. Peak wind gusts included 58 mph at the Pilot Tower at Cape Henlopen and 47 mph at the Indian River Inlet. A low pressure system heading toward the Middle Atlantic States was in the lower Ohio Valley the morning of the 7th. By the morning of the 8th, it moved into northern Indiana as a secondary low was forming in Virginia. On the morning of the 9th, this secondary low was located about 275 miles eastsoutheast of Indian River Inlet. But, it became trapped by a low at upper levels of our atmosphere and drifted slowly south through the morning of the 10th. Meanwhile, a large high pressure system started building into Northern New England. Yet another low pressure system developed over the Southern Plains on the 9th and was in the Tennessee Valley the morning of the 10th. On the morning of the 11th, two low pressure systems, one trapped under the closed low in the western Atlantic and the other just east of Charleston, South Carolina continued the wet onshore flow. These two lows merged into one by the morning of the 12th about 275 miles east of Cape Hatteras, North Carolina and remained nearly stationary through the 14th. The high pressure system over Northern New England slowly built south and brought drier air into the region and gave the state its first prolonged rain-free period of the month from the 13th onward.