For days in advance, forecasters had been predicting widespread severe weather for Friday evening, but the skies remained quiet in Central Maryland thanks to a cooling morning rain.
There was what one National Weather Service meteorologist called a "potent" low-pressure system over the Great Lakes earlier in the week that looked likely to spur storms as it passed into the mid-Atlantic and Northeast. But a smaller area of low pressure moved through the area first, causing the rain and releasing some of the instability in the atmosphere.
"The expectation was, as of the middle part of the week, that cold front would come through and we'd have widespread thunderstorms, some of them severe," said Bryan Jackson, of the weather service's Sterling, Va., office.
Those storms did come to pass across New England. Flooding was reported in Rhode Island, a possible tornado was reported in Glastonbury, Conn., while parts of Long Island are reeling from a confirmed tornado across Suffolk County, N.Y.
Isolated storms also passed through Hagerstown and Charlottesville, Va., but there wasn't enough instability in the atmosphere to cause widespread storms in Maryland. That was in part because the rain cooled off the atmosphere and also because there was cloud cover for much of Friday afternoon, preventing things from warming back up, Jackson said.
Some of the most severe storms to strike Maryland this summer -- the June 29 derecho, in particular -- came on days where temperatures soared into the 90s and 100s. When incoming cool fronts reach that heat, they clash, causing the severe storms.
Storms could become less frequent and severe because, as we move into mid-August, the sun is less intense and it becomes more difficult for that heat to stir storms, Jackson said.
Still, there is a chance of some storms with scattered showers expected to pass through the region today. Much of it could be to the east of the Baltimore area, though, Jackson said.