The National Weather Service is warning southwest and central Montana of severe thunderstorms, potentially damaging hail and snow in higher elevations on Thursday and Friday.
From the NWS:
What to expect: One inch sized hail, lightening accompanying some of those T-storms, wind gusts 20-35 mph.
Areas impacted: The severe storms are most like east of a line from Dillon, to Helena, to Great Falls to Harlem.
For snowfall, the mountains around Glacier Park, along with Central and Southwest MT are most likely to have the higher snowfall accumulations. Elevations above 5000 feet will see some snow.
There's also high confidence for 1 or 2 strong thunderstorms to develop later this afternoon over the southern Bitterroot Valley and track northeast towards I-90. Isolated wind damage from 60 mph or greater is possible. Severe cross-winds are possible on Highway 1 and Interstate 90 especially between 5 and 9 pm. Hail is also possible and would damage vegetation.
Duration: The best time frame for the severe storms to occur on Thursday is from 1 PM until about 9 PM. Rain and snow is the then expected to develop on Friday, with periods of rain and snow Friday night through Saturday.