An impressively moist airmass was in place with dew points well into the 60s across north-central Idaho during the afternoon, contributing to high instability. A vigorous shortwave trough pivoted northwestward through the northern Great Basin, providing strong forcing for ascent.
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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.
An impressively moist airmass was in place with dew points well into the 60s across north-central Idaho during the afternoon, contributing to high instability. A vigorous shortwave trough pivoted northwestward through the northern Great Basin, providing strong forcing for ascent. This forcing, in conjunction with daytime heating and destabilization along the high terrain, initiated supercell thunderstorms that produced large hail and damaging wind gusts across the region.
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 28, 11:57 AM PST, 2 hours 15 minutes earlier.
Area Forecast Discussion National Weather Service Missoula MT 157 PM MDT Thu May 28 2026 .DISCUSSION... KEY MESSAGES: - Warm temperatures and showers/thunderstorms with a few strong storms this afternoon, especially across northwest Montana and through north central Idaho - Prolonged heavy rainfall this weekend in western Montana, elevating risks for hydrologic responses and rockfalls especially near and along the Continental Divide. - High elevation snowfall on Saturday night into Monday could create difficult backcountry conditions. This Afternoon/Evening: This afternoon will bring the warmest temperatures of the week, with valley highs climbing into the upper 80s to near 90 degrees across western Montana and north-central Idaho. Similar to yesterday, thunderstorms will develop by early afternoon and track northwestward. Activity will focus primarily from the Bitterroot Valley northward and across north-central Idaho, including the Camas Prairie. A few stronger storms could produce erratic wind gusts, brief heavy downpours, and small hail. Meanwhile, elevated fire weather concerns persist across southwest Montana this afternoon, particularly south of Dillon due to gusty winds and relative humidity dropping into the teens. Friday: The weather pattern shifts significantly on Friday as an incoming Pacific low-pressure system brings a band of heavy rain. South to north moving showers and storms will bring localized heavy rain and the potential for gusty winds and hail once again. Storms may train over parts of the region particularly the US-12 and US-95 corridors in Idaho, thus localized flash flooding is a concern. Saturday through Monday: By Saturday, the low-pressure system is projected to settle near the Yellowstone region, placing western Montana within a robust deformation zone. Tapping into anomalous moisture, this setup will trigger a prolonged, highly efficient rainfall event into at least Monday. - Hydrologic & Terrain Impacts: Saturated soils from recent rains combined with ongoing high-elevation snowmelt will elevate the risk for significant rises on rivers and streams, as well as rockfalls in steep canyon terrain. - Precipitation Totals: The heaviest totals are forecast near the Continental Divide, where there is a 70 to 90 percent chance of exceeding 1 inch of rain, with localized amounts of 2 to 4 inches possible. - Snow Levels & Backcountry: Sharp cooling aloft will cause snow levels to drop to around 6,000 feet along the Continental Divide by Sunday morning. Backcountry users should prepare for raw, winter-like conditions and difficult travel. Extended Outlook: Looking further ahead, ensemble clusters favor a quick transition back to building high pressure and above- normal temperatures by mid-next week, offering a reprieve from this weekend's wet pattern. && .AVIATION...VFR conditions will prevail across western Montana and north-central Idaho terminals this afternoon, though valley temperatures approaching 90F will contribute to elevated density altitude. Scattered afternoon and evening thunderstorms will focus from the Bitterroot Valley northward and across north-central Idaho, with high-resolution models maintaining coverage trends similar to yesterday. Any developing convective cells could produce short- lived, localized MVFR/IFR conditions due to heavy downpours and low ceilings, alongside erratic outflow wind gusts, hail, and mountain obscurations. Outside of convective activity, terminals in southwest Montana and Lemhi County (including KBTM and KSMN) will experience breezy southeasterly surface winds this afternoon. Patchy fog and low stratus may develop Friday morning in areas that receive rain this evening, ahead of another widespread round of showers and thunderstorms Friday afternoon. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. &&
Special Weather Statement
National Weather Service Missoula MT
330 PM MDT Thu May 28 2026
MTZ007-043-282200-
Butte/Blackfoot Region MT-Potomac/Seeley Lake Region MT-
330 PM MDT Thu May 28 2026
...A STRONG THUNDERSTORM WILL IMPACT WEST CENTRAL POWELL AND EAST
CENTRAL MISSOULA COUNTIES UNTIL 4 PM MDT...
At 330 PM MDT, Doppler radar was tracking a strong thunderstorm 12
miles north of Drummond, moving northwest at 20 mph.
HAZARD...Wind gusts up to 40 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Ovando and Greenough.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Monitor the weather situation closely and be alert for threatening
weather conditions.
&&
LAT...LON 4685 11330 4692 11345 4708 11321 4685 11298
4676 11311
TIME...MOT...LOC 2129Z 136DEG 17KT 4684 11310
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPHSpecial Weather Statement
National Weather Service Missoula MT
354 PM MDT Thu May 28 2026
IDZ008-282230-
Lower Hells Canyon/Salmon River Region ID-
254 PM PDT Thu May 28 2026
...A STRONG THUNDERSTORM WILL IMPACT WEST CENTRAL IDAHO COUNTY UNTIL
330 PM PDT...
At 254 PM PDT, Doppler radar was tracking a strong thunderstorm 10
miles north of Riggins, or 26 miles south of Grangeville, moving
northwest at 20 mph.
HAZARD...Wind gusts up to 40 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Lucile and Slate Creek.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Monitor the weather situation closely and be alert for threatening
weather conditions.
&&
LAT...LON 4546 11626 4552 11654 4555 11653 4556 11651
4558 11648 4559 11648 4560 11646 4561 11646
4565 11649 4568 11653 4570 11654 4573 11654
4575 11655 4578 11659 4579 11658 4566 11623
TIME...MOT...LOC 2154Z 115DEG 19KT 4556 11631
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPHThe Pendleton radar (KPDT), 197 km away, was scanning. The volume nearest the first event began at 22:12 UTC.
4 hail, 1 thunderstorm wind. Local standard time, as filed.
A shattered windshield was reported on Highway 95 just south of White Bird due to golf ball-sized hail.
Severe thunderstorm winds caused power outages for 709 customers across Idaho County. Coincident quarter-size hail was also observed.
A person from the public located near Woodland estimated that the winds were gusting over 60 MPH.
Over 600 customers were reported without power due to this storm.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2026Every state in 2026This day in weather historyWarnings in Idaho, May 2026
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: 1329755, 1329756, 1329758, 1329757, 1329759.