Heat — Cecil, Maryland

1999-07-04 to 1999-07-06 · Cecil, Maryland

Wider weather episode

A very strong and oppressive high pressure system that extended from the surface to aloft gave the Maryland Eastern Shore a brutal heat wave that included the entire Independence Day weekend. High temperatures reached the 90s for the first time of the 3rd, but sweltering humidity and record breaking maximum temperatures of around 100 degrees occurred from Independence Day through the 6th. The combination of the temperature and humidity produced heat indices of around 110 degrees during the afternoon of each day. A cold front moved through the region early in the morning on the 7th. While high temperatures continued to reach the 90s from the 7th through the 10th, humidity levels were lower. A stronger cold front moved through the region during the afternoon of the 10th brought an even cooler and drier air mass. This ended the run of 90 degree highs.About 10 people were reported to suffer heat exhaustion during this heat spell. Most were not avoiding strenuous activities. The heat killed tens of thousands of chickens throughout the Delmarva Peninsula. One company alone lost around 33,000 chickens. The record heat led to record demand for power. Conectiv Energy reported a record power usage of 3,418 megawatts within an hour on the 5th. The PJM Interconnection, a power pool that links electric utilities throughout the area churned out a record 52,000 megawatt hours of power on the 6th. The excessive demand for electricity strained electrical systems. Conectiv Energy instituted rolling blackouts to 40 percent of its 1.1 million customers in Maryland, Delaware and New Jersey at 1040 a.m. EDT on the 6th. A generator at Conectiv's Indian River Power Station failed. The blackouts affected 20,000 customers for 20 minutes at a time and included all of the Eastern Shore. Area wide, the PJM reduced voltage by 5 percent at 2 p.m. EDT on the 6th to deal with the huge demand that was straining the electrical system. Locally Choptank Electric reported only a few overloaded related outages on the weekend.The highest temperatures during this hot spell occurred mainly on the 5th. They included 103 degrees in Havre De Grace (Harford County), 102 degrees at the Baltimore Washington International Airport, 101 degrees at Easton (Talbot County), 100 degrees in Salisbury (Wicomico County) and 97 degrees at Rock Hall (Kent County). Many daily record high temperature records were set on the 5th and the 6th.

Source: NOAA Storm Events Database, event_id 5715358. Narrative written by the NWS forecast office that issued the report.