Severe storms in Flathead and Sanders counties produced hail up to one inch in diameter.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS MSO wrote it up.
Severe storms in Flathead and Sanders counties produced hail up to one inch in diameter.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Missoula, MT wrote its last area forecast discussion before the first event at May 11, 1:16 AM MST, 10 hours 11 minutes earlier.
Area Forecast Discussion
National Weather Service Missoula MT
216 AM MDT Sun May 11 2025
.DISCUSSION...
KEY MESSAGES:
- Scattered thunderstorms are expected today with a 5 percent
chance of severe storms in portions of southwest Montana and
Lemhi County, ID.
- Snow levels will start to decrease tomorrow adding more snow in
the Anaconda and Pintlar mountains as well as along the
Continental Divide.
- Cooler and showery conditions continue through the week and into next weekend.
A large Pacific trough is moving onshore and already causing some
showers and thunderstorms across northwest Montana this morning.
The cold front associated wit this trough will slowly move across
the region today. That front will provide a consistent source of
lift and shear, which will help keep consistent showers and
thunderstorm coverage today. Increased cloud cover will keep solar
heating down, so we don't expect the storm updrafts to get strong
enough to produce severe winds or hail today across most of the
region. Portions of southwest Montana, including Silver Bow
county, and the southern portions of Lemhi County, ID are far
enough ahead of the front though, that there is a low, roughly 5%
chance of storms in that area becoming severe.
The southwest to west winds ahead of the cold front will be
unusually strong for this time of year. Wide spread gusts over 40
mph are expected, with higher elevations seeing frequent wind
gusts today over 50 mph.
Snow levels will fall Monday as the trough forms into a cutoff low
over southern Idaho. By mid-week we expect snow levels between
5,000 and 6,000 feet. Most of Monday they will remain around 6,000
feet and above. This means any showers during that time will bring
snow to the mountains. Currently we're expecting minimal impacts
to the mountain passes, but if you're already in the back country,
be prepared for very raw conditions. Current forecasts have the
most snow in the Anaconda and Pintlar mountains with an inch or
two expected along much of the Continental Divide.
The cut off low will take most of the week to move across the
region, and once it does, it leaves a broad trough in its wake. As
a result, this next week will remain cool and moist with breezy
conditions.
&&
.AVIATION...A cold front moving across the region today will keep
the weather active with strong winds ahead of the front and plenty
of thunderstorms. Steep lapse rates through the lower atmosphere
will allow plenty of convection today. The HREF indicates storm
initiation around 19 to 20Z. Due to the presence of the front in
the region, there will be enough shear available to produce some
hail with these storms.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...Wind Advisory from 1 PM this afternoon to 9 PM MDT this evening
for Eastern Lemhi County...Western Lemhi County.
&&The Missoula radar (KMSX), 149 km away, was scanning. The volume nearest the first event began at 18:26 UTC.
3 hail. Local standard time, as filed.
A trained spotter reported one inch diameter hail. A flight into Kalispell was diverted to Spokane due to the storm.
A trained spotter reported 0.88 inch diameter hail.
A trained spotter reported pea to golf ball sized hail.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2025Every state in 2025This day in weather historyWarnings in Montana, May 2025
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1251472, 1251471, 1251475.