Thunderstorm Wind in Powell County, Montana

A trained spotter reported estimated wind gusts of 60 MPH. Smaller tree branches were down with the largest branch estimated at four inches in diameter.

The atmosphere had warmed and dried from the first 90 degree day of the summer on Monday June 28. By Tuesday June 29, very unstable air associated with increasing southwesterly flow and moisture aloft provided the ingredients for a severe weather event. A strong shortwave associated with an approaching jet stream approached the area. The first severe storm developed Tuesday afternoon over Ovando in Powell County with wind gusts up to 60 mph blowing trees down. By early evening, the transition had already taken place for large hail producers as large hail was noted first near Condon. Two severe storms passed near Missoula and Lolo at 940 PM and again at 11 PM with large hail and wind. The most significant severe weather occurred between Stevensville and Florence, as a line of storms produced outflow damaging winds estimated at 88 to 100 mph between 1045 PM to 1130 PM.