Mother Nature snapped a week of sweltering heat Friday afternoon by dumping rain and hail on the area that reached the size of a baseball.
A tornado appeared briefly, too, touching down near Hermosa.
"It doesn't look like it caused any damage. It just lasted a minute or two," said Susan Sanders, a meteorologist for the National Weather Service in Rapid City.
The twister appeared in an open area, where it didn't have the opportunity to do much damage, Sanders said. The tornado was described as being six miles southwest of Folsom at around 3:45 p.m. on Friday, according to the NWS.
Meanwhile, rain and hail pounded Rapid City and Black Hawk. An inch of rain fell in Rapid City within 45 minutes Friday afternoon, according to Melissa Smith, a meteorologist and hydrologist for the NWS.
"The water was up to the curbs on the major streets," said Smith, adding that water "was running curb to curb" between much of West Boulevard and Mountain View Road.
Other flooded areas included West Main Street and Sioux San Drive, and Saint Joseph Street and West Boulevard, she said.
Near the fairgrounds, Rapid Creek overflowed its banks, according to Smith.
At least one piece of hail the size of a baseball — 2.75 inches in diameter — fell three miles northeast of Hisega. The hail in Rapid City was smaller, about the size of a golf ball, according to Smith. Black Hawk endured 1-inch hail.
The deluge prompted the NWS to issue a series of flood and flash flood advisories for parts of Pennington and Meade counties, prompting sirens in Rapid City to announce the flash flood warning.
The NWS said minor flooding also occurred in downtown Rapid City, Black Hawk, Box Elder, Caputa, Ellsworth Air Force Base, Hayward, Keystone, Rapid Valley, Rockerville and at the Rapid City Regional Airport.