Heavy rain from passing thunderstorms caused flooding of urban streets in Dillon. More than one-half inch of rain fell in 15 minutes at some locations.
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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 TFX wrote it up.
Heavy rain from passing thunderstorms caused flooding of urban streets in Dillon. More than one-half inch of rain fell in 15 minutes at some locations.
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 22, 2:12 PM MST, 1 hour 20 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 312 PM MDT TUE JUL 22 2008 .DISCUSSION... TONIGHT THROUGH THURSDAY...ACTIVE WEATHER PATTERN THIS EVENING AS A COUPLE OF STRONG SHORT WAVES MOVE OUT AHEAD OF THE UPPER TROF AND MOVE ACROSS THE AREA. THUNDERSTORMS CONTINUE TO DEVELOP AND SOME MAY BECOME SEVERE WITH HEAVY RAIN AND LARGE HAIL. CONVECTIVE ACTIVITY SHOULD END BY MIDNIGHT WITH ISOLATED SHOWERS POSSIBLE THEREAFTER. ISOLATED THUNDERSTORMS WILL AGAIN DEVELOP WEDNESDAY AFTERNOON AS THE UPPER TROF AXIS MOVES ACROSS THE AREA. RIDGING RETURNS TO WESTERN MONTANA THURSDAY BRINGING DRIER AND STABLE CONDITIONS WITH A FEW LINGERING SHOWERS IN THE EAST. TEMPERATURES WILL REMAIN NEAR SEASONAL AVERAGES. EMANUEL THURSDAY NIGHT THROUGH SUNDAY NIGHT...MODELS FORECAST AN UPPER RIDGE TO DEVELOP OVER THE AREA THURSDAY NIGHT AND CONTINUE OVER THE AREA INTO FRIDAY. WITH THE UPPER RIDGE APPROACHING THE FORECAST AREA THURSDAY NIGHT MODELS DO NOT FORECAST PRECIPITATION AND FEELING CONFIDENT ENOUGH TO REMOVE ITS MENTION FROM THE FORECAST. LATEST MODEL RUNS ARE ALSO DRY ON FRIDAY BUT PREVIOUS RUNS OF SOME OF THE MODELS HAD PRECIPITATION SO WILL LEAVE THE SLIGHT CHANCE OF PRECIPITATION FORECAST FOR SW MT AND THE NW MOUNTAINS. THEREAFTER MODELS FORECAST SW FLOW ALOFT BUT DIFFER ON DETAILS OF WEAK EMBEDDED SHORTWAVES. ALTHOUGH LATEST MODEL RUNS ARE MOSTLY DRY AM RELUCTANT TO DROP THE MENTION OF PRECIPITATION AS IT DOES NOT TAKE MUCH MOISTURE/LIFT THIS TIME OF YEAR TO GENERATE A FEW THUNDERSTORMS. ENDED UP MAKING ONLY SOME MINOR CHANGES TO INHERITED CHANCE OF PRECIPITATION FORECASTS. BLANK MONDAY AND TUESDAY...LATEST MODELS CONTINUE TO DEPICT A WEST TO SOUTHWEST FLOW OVER WEST AND CENTRAL MONTANA DURING THIS PERIOD. MONSOONAL MOISTURE IS EXPECTED TO MOVE IN FROM THE SOUTH AND PROVIDE A CHANCE FOR SHOWERS AND THUNDERSTORMS FOR THE SOUTHWEST MOUNTAINS AND POSSIBLY THE NORTH CENTRAL PLAINS. USED CLIMO POPS THROUGH THE PERIOD AND KEPT TEMPERATURES NEAR SEASONAL. SAUCIER && .AVIATION... UPDATED 2110Z. MAINLY VFR CONDITIONS ARE EXPECTED ACROSS NORTH CENTRAL...CENTRAL...AND SOUTHWEST MONTANA THROUGH WEDNESDAY MORNING. AN AREA OF CLOUDS AND SHOWERS WILL CONTINUE TO MOVE NORTH ALONG THE ROCKY MOUNTAIN FRONT THIS AFTERNOON...BRINGING OCCASIONAL MVFR CONDITIONS TO THE KCTB TERMINAL. A STRONG SHORTWAVE TROUGH WILL ALSO MOVE NORTHEAST OVER THE AREA...BRINGING WIDESPREAD SHOWERS AND THUNDERSTORMS TO THE AREA ALONG AND SOUTH OF A LINE FROM KGTF TO KHVR. SOME STORMS IN THAT AREA MAY PRODUCE HEAVY RAIN AT TIMES... POSSIBLY LARGE HAIL...AND GUSTY WINDS TO 45 KT. THESE STORMS MAY ALSO CAUSE OCCASIONAL MVFR CONDITIONS AT THE KBZN...KHLN...KGTF...AND KLWT TERMINALS. ANY THUNDERSTORMS THAT DEVELOP ACROSS NORTH CENTRAL MONTANA (INCLUDING THE KCTB AND KHVR TERMINALS) WILL BE WEAKER WITH LESS THREAT FOR HAIL. THE SHORTWAVE WILL EXIT THE AREA LATER THIS EVENING AND OVERNIGHT...FOR DECREASING CLOUDS AND STORMS. BREEZY WESTERLY WINDS WILL ALSO DEVELOP IN THE WAKE OF THE SYSTEM. COULSTON && .PRELIMINARY POINT TEMPS/POPS... GTF 54 82 49 81 / 60 20 20 10 CTB 50 78 45 77 / 60 20 20 10 HLN 59 86 55 86 / 50 20 20 10 BZN 53 88 48 88 / 60 20 20 10 WEY 47 77 44 78 / 50 20 20 10 DLN 53 82 48 84 / 40 20 20 10 HVR 58 82 50 81 / 50 10 20 20 LWT 54 80 49 78 / 60 20 20 20 && .TFX WATCHES/WARNINGS/ADVISORIES... SEVERE THUNDERSTORM WATCH UNTIL 9 PM MDT THIS EVENING FOR MTZ008- 015-055. && SHORT TERM...EMANUEL LONG TERM...BLANK/SAUCIER AVIATION...COULSTON WEATHER.GOV/GREATFALLS
HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE GREAT FALLS MT 249 PM MDT TUE JUL 22 2008 MTZ008-015-055-231230- BEAVERHEAD-MADISON-GALLATIN- 249 PM MDT TUE JUL 22 2008 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST MONTANA. .DAY ONE...THIS AFTERNOON AND TONIGHT A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR BEAVERHEAD...MADISON...AND GALLATIN COUNTIES UNTIL 9 PM MDT. SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS SOUTHWEST MONTANA IN ADVANCE OF A VERY MOIST PACIFIC STORM SYSTEM. SOME OF THE THUNDERSTORMS MAY BECOME SEVERE...WHICH MEANS THEY MAY PRODUCE HAIL GREATER THAN THE SIZE OF DIMES AND DAMAGING WINDS GREATER THAN 55 MPH. ALL THUNDERSTORMS WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CONTINUE INTO THE EVENING...BEFORE DIMINISHING AFTER MIDNIGHT. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY ISOLATED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE WEDNESDAY AFTERNOON AND EVENING. SOME OF THESE STORMS WILL HAVE THE POTENTIAL TO PRODUCE WIND GUSTS TO 50 MPH AND HAIL TO THE SIZE OF DIMES. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. MTZ009>014-044>054-231230- NORTHERN ROCKY MOUNTAIN FRONT-EASTERN GLACIER-HILL-CASCADE- CHOUTEAU-CENTRAL AND SOUTHERN LEWIS AND CLARK-TOOLE-LIBERTY- EASTERN PONDERA-BLAINE-SOUTHERN ROCKY MOUNTAIN FRONT- EASTERN TETON-JUDITH BASIN-FERGUS-JEFFERSON-BROADWATER-MEAGHER- 249 PM MDT TUE JUL 22 2008 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL MONTANA...NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA. .DAY ONE...THIS AFTERNOON AND TONIGHT SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON IN ADVANCE OF A VERY MOIST PACIFIC STORM SYSTEM. SOME OF THE THUNDERSTORMS WILL BE CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING WINDS...ESPECIALLY ALONG AND SOUTH OF A LINE FROM HELENA TO GREAT FALLS TO LEWISTOWN. ALL THUNDERSTORMS WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CONTINUE INTO THE EVENING...BEFORE DIMINISHING AFTER MIDNIGHT. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY ISOLATED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE WEDNESDAY AFTERNOON AND EVENING. SOME OF THESE STORMS WILL HAVE THE POTENTIAL TO PRODUCE WIND GUSTS TO 50 MPH AND HAIL TO THE SIZE OF DIMES. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
327 PM MDT TUE JUL 22 2008
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0311 PM HAIL 1 E BOZEMAN 45.68N 111.02W
07/22/2008 E0.75 INCH GALLATIN MT PUBLIC
ALONG INTERSTATE 90 JUST EAST OF BOZEMAN
&&
WILLIAMSON DCPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
418 PM MDT TUE JUL 22 2008
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0410 PM HAIL 4 W DILLON 45.22N 112.72W
07/22/2008 E1.00 INCH BEAVERHEAD MT TRAINED SPOTTER
VERY HEAVY RAIN AND STRONG WINDS PRECEDED LARGE HAIL
0413 PM TSTM WND GST DILLON 45.22N 112.63W
07/22/2008 E65.00 MPH BEAVERHEAD MT TRAINED SPOTTER
&&
MPJThe Missoula radar (KMSX), 226 km away, was scanning. The volume nearest the first event began at 22:30 UTC.
1 flash flood. Local standard time, as filed.
Heavy rain from thunderstorms caused many streets to fill with bumper deep water in the city of Dillon. Rainfall rates of greater than one-half inch in 15 minutes were common.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2008Every state in 2008This day in weather historyWarnings in Montana, July 2008
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: 124084.