Strong storms developed over portions of Central Montana generating strong outflow winds, dropping mostly small hail, and causing some property damage.
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 TFX wrote it up.
Strong storms developed over portions of Central Montana generating strong outflow winds, dropping mostly small hail, and causing some property damage.
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 Great Falls, MT wrote its last area forecast discussion before the first event at Jul 30, 10:45 AM MST, 2 hours earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 1145 AM MDT MON JUL 30 2012 UPDATED .UPDATE... CURRENT FORECAST LOOKING GOOD. MADE A FEW VERY MINOR TWEAKS TO REDUCE PRECIP CHANCES OVER HILL/BLAINE/ERN CHOUTEAU COUNTIES THIS AFTN. STILL ON TRACK FOR HOT TEMPERATURES TODAY WITH MID 90S EXPECTED ACROSS THE CENTRAL PLAINS AND SOUTHWEST VALLEYS. WARANAUSKAS && .AVIATION... UPDATED 1745Z. EXPECT SUNNY SKIES AT 18Z...TO GIVE WAY TO INCREASING CLOUDS...AND A CHANCE FOR SCATTERED THUNDERSTORMS. THE BEST CHANCE FOR THUNDERSTORM DEVELOPMENT TODAY WILL BE ACROSS SOUTHWEST/CENTRAL MT...ROUGHLY MAINLY ALONG AND SOUTH OF A LINE FROM HELENA TO LEWISTOWN. SOME STORMS COULD PRODUCE GUSTY SURFACE WINDS AND SOME SMALL HAIL. THE STORMS SHOULD EXIT CENTRAL MONTANA AROUND 06Z. GENERALLY VFR CONDITIONS WILL PREVAIL...BUT MVFR CONDITIONS ARE POSSIBLE IN/NEAR ANY THUNDERSTORMS. BRUSDA && .FIRE WEATHER... UPDATED 30/1000Z. THERE IS THE POTENTIAL FOR SCATTERED THUNDERSTORM DEVELOPMENT...SOME WITH STRONG WIND GUSTS...ACROSS THE EASTERN PORTIONS OF THE TFX FIRE WEATHER FORECAST AREA. HOWEVER...RECENT STORMS HAVE MOSTLY BEEN A MIX OF WET AND DRY THUNDERSTORMS...SO THE THREAT FOR RED FLAG CONDITIONS ASSOCIATED WITH DRY THUNDERSTORMS IN THE EASTERN PORTION OF THE AREA IS LOW...AT LEAST AT THIS TIME. THAT BEING SAID...THE SITUATION WILL CONTINUE TO BE MONITORED FOR ANY POTENTIAL CHANGES. COULSTON && .PREV DISCUSSION...(ISSUED AT 400 AM MDT MON JUL 30 2012) TODAY THROUGH WEDNESDAY...A WEAK DISTURBANCE ALOFT WILL MOVE OVER THE UPPER LEVEL RIDGE OF HIGH PRESSURE CENTERED OVER THE CENTRAL CONUS AND ACROSS NORTH CENTRAL MONTANA TODAY. THIS DISTURBANCE WILL COMBINE WITH AN INVERTED SURFACE TROUGH OVER THE AREA AND A MODERATE FEED OF MONSOONAL MOISTURE TO CAUSE ISOLATED THUNDERSTORMS TO DEVELOP OVER THE AREA THIS AFTERNOON. STORM DEVELOPMENT WILL INCREASE TO THE EAST OF THIS TROUGH DURING THE EVENING...WHERE A SLIGHTLY MORE MOIST AIRMASS AND SLIGHTLY GREATER DIRECTIONAL WIND SHEAR WILL RESIDE. ALTHOUGH INSTABILITY IS FAIRLY WEAK...A FEW STORMS COULD BECOME STRONG TO SEVERE OVER THE EASTERN TFX ZONES...AS THE DRIER LOWER LEVELS MAKE STRONG WIND GUSTS THE MAIN THREAT THERE. THESE STORMS WILL THEN DIMINISH OVERNIGHT. THE UPPER LEVEL RIDGE WILL THEN GRADUALLY BEGIN TO BE FLATTENED TUESDAY THROUGH WEDNESDAY AS AN UPPER LEVEL TROUGH OF LOW PRESSURE CURRENTLY OFF THE PACIFIC NORTHWEST COAST APPROACHES THE AREA. THIS PROGRESSION WILL SHIFT THE FLOW ALOFT MORE WESTERLY TUESDAY THROUGH WEDNESDAY...WHICH WILL SHUNT THE MONSOONAL MOISTURE FEED FARTHER SOUTH. THE GENERAL TREND WILL BE FOR A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS...WITH PRIMARY DEVELOPMENT OVER THE MOUNTAINS. HOWEVER...FORECAST MODELS ARE PICKING UP ON A SLIGHTLY UNUSUAL FEATURE. WEAK INSTABILITY PERSISTS OVERNIGHT TUESDAY NIGHT ACROSS CENTRAL MONTANA...ALONG WITH ENHANCED MID-LEVEL LIFT. THIS LIKELY CAN BE ATTRIBUTED TO THE COMBINATION OF WEAK LOW-LEVEL NORTHERLY UPSLOPE WINDS (WHICH WOULD LIKELY CAUSE ISOLATED SHOWER/THUNDERSTORM DEVELOPMENT OVER THE CENTRAL MONTANA MOUNTAINS) AND MODERATE MID-LEVEL SOUTHWESTERLY WINDS (WHICH WOULD LIKELY CARRY THESE SHOWERS/STORMS OVER THE PLAINS OF CENTRAL MONTANA). HAVE THEREFORE INTRODUCED A SLIGHT CHANCE OF SHOWER/THUNDERSTORM DEVELOPMENT TUESDAY NIGHT INTO WEDNESDAY MORNING TO REFLECT THIS...AND WILL CONTINUE TO MONITOR THE SITUATION. TEMPERATURES TODAY WILL WARM TO NEAR 10 DEGREES ABOVE SEASONAL AVERAGES ONCE AGAIN...BUT THE GRADUAL WEAKENING OF THE RIDGE WILL CAUSE TEMPERATURES TO COOL ABOUT 5 DEGREES BY WEDNESDAY. COULSTON WEDNESDAY NIGHT THROUGH MONDAY...MODELS CONTINUE TO FORECAST A BREAKDOWN OF THE UPPER LEVEL RIDGE DURING THE WEDNESDAY NIGHT THROUGH FRIDAY PERIOD AS AN UPPER LEVEL TROUGH TRACKS SOUTHEASTWARD FROM BC INTO THE NORTHERN PLAINS STATES. TEMPERATURES COOL SLIGHTLY BUT REMAIN ABOVE AVERAGE ON THURSDAY BEFORE A CANADIAN COLD FRONT DROPS SOUTHEAST ACROSS THE REGION THURSDAY NIGHT...USHERING IN A COOLER AIRMASS FROM THE NORTH. BEFORE THE COOLER AIRMASS ARRIVES...WILL NEED TO MONITOR THURSDAY FOR POTENTIAL FIRE WEATHER CONCERNS AS WEST WINDS ALOFT PICK UP IN ASSOCIATION WITH THE FLATTENING UPPER LEVEL RIDGE. WINDS SHIFT TO NORTH/NORTHWEST THURSDAY NIGHT AS THE CANADIAN FRONT PUSHES SOUTH THROUGH THE AREA WITH TEMPERATURES LOOKING TO COOL TO JUST BELOW SEASONAL AVERAGES ON FRIDAY. BEST CHANCE FOR PRECIPITATION WILL OCCUR THURSDAY NIGHT INTO FRIDAY MORNING...MAINLY OVER NORTH AND NORTHWEST PORTIONS OF THE FORECAST AREA. COOLING IS SHORT- LIVED HOWEVER AS THE UPPER TROUGH MOVES EAST AND RIDGING REBUILDS FORM THE GREAT BASIN TO THE NW ON SATURDAY ALLOWING TEMPERATURES TO WARM BACK UP. MODELS DIVERGE LATER THIS WEEKEND INTO EARLY NEXT WEEK WITH GFS AND CANADIAN MODELS MAINTAINING A NW FLOW OVER THE REGION WHICH ALLOWS FOR ADDITIONAL COOLER AIRMASSES TO CLIP NORTHERN PORTIONS OF THE FORECAST AREA WHILE THE ECMWF MODEL SHOWS A MUCH WARMER SCENARIO DUE TO A STRONGLY AMPLIFYING UPPER LEVEL RIDGE OVER THE ROCKIES. WITH LOW CONFIDENCE THIS LATE IN THE FORECAST PERIOD HAVE KEPT POPS/TEMPS CLOSE TO CLIMATOLOGICAL AVERAGES. HOENISCH && .PRELIMINARY POINT TEMPS/POPS... GTF 95 60 93 57 / 20 20 10 20 CTB 92 56 87 52 / 20 20 10 20 HLN 94 59 92 57 / 20 20 10 20 BZN 95 52 93 51 / 20 20 20 20 WEY 85 40 83 40 / 20 10 20 10 DLN 91 53 89 51 / 20 20 20 20 HVR 96 61 93 56 / 10 30 10 20 LWT 91 57 89 54 / 20 40 20 30 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && WEATHER.GOV/GREATFALLS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GREAT FALLS MT 311 AM MDT MON JUL 30 2012 MTZ008>015-044>055-311200- BEAVERHEAD-NORTHERN ROCKY MOUNTAIN FRONT-EASTERN GLACIER-HILL- CASCADE-CHOUTEAU-CENTRAL AND SOUTHERN LEWIS AND CLARK-MADISON- TOOLE-LIBERTY-EASTERN PONDERA-BLAINE- SOUTHERN ROCKY MOUNTAIN FRONT-EASTERN TETON-JUDITH BASIN-FERGUS- JEFFERSON-BROADWATER-MEAGHER-GALLATIN- 311 AM MDT MON JUL 30 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL MONTANA...NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA. .DAY ONE...TODAY AND TONIGHT THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
The Great Falls radar (KTFX), 126 km away, was scanning. The volume nearest the first event began at 19:43 UTC.
5 thunderstorm wind. Local standard time, as filed.
Strong outflow winds gusted to an estimated 50KT (58MPH) and knocked down up to 20 power poles 1 mile N of Townsend.
Strong outflow winds generated a gust to 64KT (74MPH) as measured by the Great Falls Airport ASOS. A billboard along the highway near the airport was badly damaged as well.
Strong outflow winds generated a gust to an estimated 52KT (60MPH) and damaged a roof in Great Falls.
Strong outflow winds generated a gust to 63KT (72MPH) as measured 1 mile NW of Cascade.
Wind gust of 58KT (67MPH) was reported at the Millegan station 20 miles SE of Cascade.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2012Every state in 2012This day in weather historyWarnings in Montana, July 2012
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: 398280, 398282, 398283, 398285, 398287.