Update: A severe thunderstorm has been detected near New Carrolton, according to an 8:04 p.m. report from the National Weather Service. The storm is moving east at 25 miles per hour and capable of producing quarter-sized hail and 70-mile-per-hour winds. "This is a dangerous storm. If you are in its path, prepare immediately for damaging wind gusts, large hail and frequent cloud to ground lightning. Move indoors to a sturdy building and stay away from windows," the NWS warns.
A severe thunderstorm watch has been issued for the Baltimore area through 9 p.m. Friday, the storms marking the end of a three-day stretch of heat above 90 degrees.
A "moist and increasingly unstable" mass of air is moving ahead of a weak cool front crossing into the area today, according to the National Weather Service's Storm Prediction Center. The front is expected to move out to the Atlantic by Saturday.
The storms have the potential to produce damaging wind and locally heavy rainfall, according to a hazardous weather outlook from the weather service's Sterling, Va., office. The forecast calls for a 70 percent chance of storms. The strong winds are forecasters' main concern.
AccuWeather.com, meanwhile, is forecasting thunderstorms as "intense", the second-strongest of its five thunderstorm intensity categories. AccuWeather severe weather blogger Henry Margusity is predicting storms with 40-70 mph wind gusts in some spots along the Interstate 95 corridor from Washington to Boston.
Temperatures are expected to drop into the lower 70s overnight at BWI, slightly cooler than lows of the past few days.
For the weekend, highs will near 90 degrees, but shouldn't surpass the mark. And humidity will be noticeably lower, with dew points falling from the upper 60s and low 70s the past few days to the upper 50s Saturday and Sunday.
Baltimoreans have all but survived their first summer heat wave in a while -- this three-day stretch of 90-degree temperatures is the longest above that mark since Aug. 7-10, 2011.
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