Parts of Eastern Montana saw hail Thursday evening, like this tennis ball-sized hail in Roundup.
A severe thunderstorm that pummeled Roundup and other parts of Musselshell County Thursday evening brought with it tennis ball-sized hail that shattered windows and damaged property, the National Weather Service in Billings reported.
The storm originated in southeastern Wheatland County and held together as it traveled across Golden Valley County and on to Musselshell County, said Tom Humphrey, an NWS forecaster.
The storm reached the Roundup area shortly before 6 p.m.
The storm was severe enough to produce what Humphrey called a "rotating wall cloud," which in some cases can be a precursor to a funnel cloud and ultimately a tornado. Rotating wall clouds are often a characteristic of larger supercell storms.
"People could look up and see the thunderstorm rotating clearly," Humphrey said.
Speaking shortly after 7 p.m., Humphrey said Roundup wasn't in the clear yet. At about 7:30 p.m., a severe thunderstorm warning was issued for Roundup and Klein, this one capable of producing quarter-sized hail and winds up to 60 mph.
The initial round of thunderstorms that passed through the area early Thursday evening mostly missed Billings.
At about 2 p.m., the weather service issued a severe thunderstorm watch until 10 p.m. extending from west of Butte and continuing east of Miles City, with storms poss ...