Those at or near Aberdeen Proving Ground late Saturday afternoon got a surprise when a thunderstorm dumped more than 2 inches of rain over the installation.
Everyone else in the county, however, stayed relatively dry.
"A thunderstorm developed over the proving ground and moved off north from the Aberdeen area," Gerald Luft, a meteorologist with APG, said Tuesday. The area received 2.34 inches of rain.
The storm, he continued, "didn't move very much," and was intensified over the APG area for about an hour between 4 and 5 p.m.
During that time, a severe storm warning was issued just for APG and had estimated 2 to 5 inches of rain for the area.
Luft explained that thunderstorms during the summer are "very small scale in nature" and can cover just a 5-mile radius at a time. This would explain why the installation had significant rain while nearby areas did not.
The surface heating makes the atmosphere unstable, he continued. Then, some sort of "upper-level disturbance," Luft said, or a trigger, such as a cold front coming through the area, makes the hot air rise. As the two mix, the air cools and condenses to create clouds, which can create convectional thunderstorms.
According to the National Weather Service, no precipitation was recorded at BWI Airport in Baltimore Saturday. Observers in Norrisville reported a trace amount of rain to NWS.
Along with the rain, some tree damage occurred between 4:30 and 5 p.m., a meteorologist at NWS said.
