Cooling off

Angel Galliano, 2, jumps on the back of brother Jeffrey Galliano, 11, who floats in the cool, clear water of the Patapsco River at Patapsco State Park. (Baltimore Sun photo by Karl Merton Ferron / July 18, 2012)

Record-breaking heat fueled severe storms that swept across parts of Maryland on Wednesday.

Though not an official record-keeping location, Maryland Science Center reached 107 degrees, tying the hottest mark ever recorded in Baltimore, on July 10, 1936. At that time, weather records were kept at the U.S. Custom House downtown, but the point of record for Baltimore moved in 1950 to what is now Baltimore-Washington International Thurgood Marshall Airport.

BWI, meanwhile, reached a high of 104, breaking the previous official record for July 18, set in 1887 at 102. That had been Baltimore's longest-standing high-temperature record for July.

The storms packed dangerous winds, hail, lightning and torrential rains as a cool front met the mass of hot, humid air over the state. Cold downdrafts of air then spread out ahead of the storms, meeting the hot air and causing more storms to form, said Kevin Witt, a meteorologist with the National Weather Service in Sterling, Va.

Trees and branches came down throughout the region as water pooled in low-lying areas.

Planes were grounded at BWI for about an hour, between 5 p.m. and 6 p.m., while thunderstorms swept through the area, a spokeswoman said.

The Bay Bridge was closed in both directions about 5:30 p.m. because of high winds, which reached 59 mph, according to a Maryland Transportation Authority spokeswoman. Eastbound lanes reopened shortly after 6 p.m.

One westbound lane reopened shortly before 7 p.m., a second opened about 7:30 p.m. and a third remained closed late Wednesday as crews checked for wind damage, a spokeswoman said.

The lane closures caused traffic backups for miles on either side of the bridge, the spokeswoman said.

More than 9,200 BGE customers lost power in the storms, with more than 8,000 of them restored as of 8:45 p.m.

The heat prompted Baltimore Gas and Electric Co. officials to activate the utility's Peak Rewards program for the second time this summer. The program cycles participating customers' air conditioners in exchange for bill credits.

BGE officials activated the program about 12:30 p.m. in response to high electricity prices. Turning off customers' air conditioners lowers demand for electricity and helps to lower prices. About 3 p.m., officials with the PJM Interconnection, the power grid that includes Maryland, ordered BGE to begin an emergency activation of the program because the high heat strained the grid.

BGE officials activated the program for the first time this summer on Tuesday in response to high electricity prices.

More heat and humidity are in the forecast for Thursday, with highs expected in the low- to mid-90s, according to the National Weather Service. More thunderstorms are possible Thursday and Friday throughout the day. Temperatures are expected to cool to the mid-80s Friday and through the weekend.

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