A strong thunderstorm developed near Hot Springs and produced heavy rain, localized flooding and nickel size hail.
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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.
A strong thunderstorm developed near Hot Springs and produced heavy rain, localized flooding and nickel size hail.
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 25, 9:00 AM MST, 4 hours 29 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MISSOULA MT 1000 AM MDT MON MAY 25 2009 .UPDATE...INCREASED CLOUDS AND SHOWER POTENTIAL ACROSS NORTHWEST MONTANA THIS MORNING. AT THE SAME TIME...REDUCED CLOUDS AND SHOWER ACTIVITY ACROSS NORTH-CENTRAL IDAHO AND WEST-CENTRAL MONTANA FOR THIS MORNING ONLY. && .DISCUSSION...A WEAK DISTURBANCE IS MOVING ACROSS THE NORTHERN IDAHO PANHANDLE AND NORTHWEST MONTANA TRIGGERING SCATTERED SHOWERS. ELSEWHERE CLOUDS/SHOWERS HAVE DISSIPATED DUE TO THE LACK OF ANY LIFT THIS MORNING. HOWEVER...THE AIR MASS REMAINS QUITE MOIST AND UNSTABLE. AS HEATING TAKES PLACE THIS AFTERNOON...CLOUDS AND SHOWERS ARE EXPECTED TO INCREASE. ISOLATED THUNDERSTORMS ARE ALSO POSSIBLE THIS AFTERNOON. NO OTHER CHANGES PLANNED THIS MORNING. && .AVIATION...MOIST UNSTABLE AIR MASS AND A WEAK DISTURBANCE WILL RESULT IN SCATTERED SHOWERS THIS MORNING ACROSS NORTHWEST MONTANA THIS MORNING. THE ATMOSPHERE REMAINS QUITE UNSTABLE AND EXPECT LOW-LEVEL MOISTURE TO BE LIFTED THIS AFTERNOON. CLOUDS AND SHOWERS WILL BE DEVELOPING THIS AFTERNOON WITH ISOLATED THUNDERSTORMS ALSO IN THE WEATHER PICTURE. SOME STORMS MAY HAVE HEAVY PRECIPITATION CORES WHICH REDUCES THE VISIBILITIES. THE THUNDERSTORM ACTIVITY IS EXPECTED TO DECREASE AFTER SUNSET. && .PREV DISCUSSION... /ISSUED 337 AM MDT MON MAY 25 2009/ DISCUSSION...A PLUME OF SUBTROPICAL MOISTURE CONTINUES TO AFFECT THE NORTHERN ROCKIES TODAY. CURRENTLY A WEAK DISTURBANCE IS MOVING ACROSS NORTHWEST MONTANA THIS MORNING CAUSING AN INCREASE IN SHOWER ACTIVITY...ESPECIALLY ACROSS THE GLACIER PARK REGION. THIS AFTERNOON THE ATMOSPHERE APPEARS TO BECOME UNSTABLE ENOUGH TO SUPPORT THE DEVELOPMENT OF THUNDERSTORMS. THE GREATEST POTENTIAL OF THUNDER WILL BE ALONG THE CONTINENTAL DIVIDE. HEAVY RAINFALL IS ANTICIPATED WITH THESE STORMS. THE CONVECTION IS EXPECTED TO DECREASE THIS EVENING AS THE SUN SETS. A BROAD RIDGE BUILDS OVER THE REGION ON TUESDAY CAUSING A WARMING AND DRYING TREND. TEMPERATURES FOR TUESDAY ARE EXPECTED TO BE 5 TO 10 DEGREES ABOVE SEASON NORMALS. WEDNESDAY THROUGH MONDAY...HIGH PRESSURE WILL AGAIN BUILD AND STRENGTHEN OVER THE WESTERN UNITED STATES FROM WEDNESDAY AND INTO THE WEEKEND. TEMPERATURES WILL WARM TO WELL ABOVE SEASONAL AVERAGE READINGS THROUGH THE WEEKEND. ALTHOUGH MODEL GUIDANCE AGREE ON HIGH PRESSURE THROUGH THE WEEK...UNCERTAINTY DOES EXISTS. ONE OF THE UNCERTAINTIES IS WHEN THE RIDGE WILL BREAK DOWN...AND ANOTHER IS THE AMOUNT OF SUBTROPICAL MOISTURE THAT WILL PASS THROUGH THE CLOCKWISE CIRCULATION OF THE HIGH PRESSURE RIDGE. MOISTURE LOOKS TO BE SUFFICIENT FOR HIGH BASED AFTERNOON CONVECTION...SO INCREASE THE PROBABILITY OF PRECIP FOR EACH AFTERNOON...ESPECIALLY FOR SOUTHWEST MONTANA AND EAST CENTRAL IDAHO. HYDROLOGY...CONTINUED WARM TEMPERATURES THE NEXT FEW DAYS COMBINED WITH THE LIGHT TO MODERATE RAINFALL FROM THE PAST FEW DAYS WILL CAUSE AREA RIVERS AND STREAMS TO CONTINUE TO RISE. THE BITTERROOT RIVER NEAR DARBY COULD REACH FLOOD STAGE BY MIDDAY TODAY...AND DOWNSTREAM LOCATIONS POSSIBLY TUESDAY OR WEDNESDAY. THE CLARK FORK NEAR MISSOULA COULD SEE FLOOD STAGE BY WEDNESDAY MORNING. WHILE ROCK CREEK NEAR CLINTON IS A LOCATION THAT MAY SEE AT LEAST BANK FULL LEVELS. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...NONE. ID...NONE. && SHORT TERM...MSJ LONG TERM....KITSMILLER AVIATION...MSJ
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE MISSOULA MT 323 AM MDT MON MAY 25 2009 IDZ009-010-MTZ002-006-007-043-252100- WESTERN LEMHI COUNTY-EASTERN LEMHI COUNTY-WEST GLACIER REGION- BITTERROOT/SAPPHIRE MOUNTAINS-BUTTE/BLACKFOOT REGION- POTOMAC/SEELEY LAKE REGION- 323 AM MDT MON MAY 25 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL IDAHO...NORTHWEST MONTANA AND WEST CENTRAL MONTANA. .DAY ONE...TODAY AND TONIGHT A PLUME OF SUBTROPICAL MOISTURE CONTINUES TO AFFECT THE NORTHERN ROCKIES. THIS AFTERNOON A FEW THUNDERSTORMS ARE EXPECTED TO DEVELOP. THESE STORMS COULD PRODUCE SIGNIFICANT RAINFALL. THIS ADDITIONAL RAINFALL COMBINED WITH SWOLLEN STREAMS AND SMALL RIVERS COULD CAUSE LOCALIZED FLOODING. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY A RIDGE OF HIGH PRESSURE IS EXPECTED TO BUILD BACK OVER THE REGION WITH TEMPERATURES WELL ABOVE SEASON NORMALS. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Missoula radar (KMSX), 83 km away, was scanning. The volume nearest the first event began at 20:27 UTC.
1 heavy rain, 1 hail. Local standard time, as filed.
Hot Springs RAWS reported 1.36 inches of rainfall in one hour at 3:29 PM MDT. Hot Springs Fire Department reported localized flooding of streets in Hot Springs.
Public reported nickel size hail and heavy rain from thunderstorm over the Irvine Flats area.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2009Every state in 2009This day in weather historyWarnings in Montana, May 2009
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: 164182, 164185.