Severe thunderstorms developed over portions of Southwest Montana during the late afternoon hours of the 18th. Hail the size of half dollars as well as winds in excess of 60 mph was reported.
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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.
Severe thunderstorms developed over portions of Southwest Montana during the late afternoon hours of the 18th. Hail the size of half dollars as well as winds in excess of 60 mph was reported.
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 Aug 18, 1:52 PM MST, 6 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 252 PM MDT SAT AUG 18 2007 .DISCUSSION... TONIGHT THOUGH MONDAY...SHORTWAVE IN SW FLOW ALOFT WILL MOVE NE THROUGH CENTRAL MT THIS EVENING...BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS TO CENTRAL MT THROUGH THIS EVENING. STILL SEEING ENOUGH INSTABILITY AND SHEAR FOR A SLIGHT RISK OF SEVERE STORMS WITH MAIN THREAT BEING STRONG WINDS AND HAIL. UPPER LEVEL TROUGH COMES ONSHORE SUNDAY WITH A STRONG COLD FRONT REACHING THE CONTINENTAL DIVIDE BY LATE AFTERNOON. EXPECT INCREASING SW WINDS AHEAD OF THE FRONT WITH TEMPS REMAINING WARM AHEAD OF THE FRONTAL BOUNDARY. WILL SEE A SLIGHT CHANCE OF CONVECTION WITH THE FRONTAL PASSAGE IN THE EVENING...MAINLY OVER EASTERN ZONES. WINDS SHIFTS TO THE WEST AND REMAIN BREEZY BEHIND THE FRONT SUNDAY EVENING WITH COOLER BUT CONTINUED BREEZY CONDITIONS ON MONDAY. HOENISCH MONDAY NIGHT THROUGH THURSDAY NIGHT...MODELS CONTINUE TO BE IN GOOD AGREEMENT. UPPER LEVEL TROF MOVES THROUGH THE AREA FOR COOLER TEMPERATURES AND A CHANCE OF PRECIPITATION. TIGHT GRADIENT OVER CWA FOR STRONG WESTERLY SURFACE WINDS MONDAY NIGHT AND INTO TUESDAY. NORTHWEST FLOW ALOFT ON TUESDAY AND WESTERLY FLOW ON WEDNESDAY. ANOTHER UPPER LEVEL TROF TO MOVE THROUGH ON THURSDAY. CAMP FRIDAY THROUGH SATURDAY...MODELS REMAIN IN BASIC AGREEMENT DURING THIS PERIOD. A BROAD UPPER LEVEL RIDGE BUILDS OVER THE REGION RESULTING IN A WESTERLY FLOW OVER THE FORECAST AREA. WITH ONLY LIMITED MOISTURE IN THIS FLOW...ONLY A FEW SHOWERS OR THUNDERSTORMS ARE EXPECTED ALONG THE CONTINENTAL DIVIDE AND OVER THE SOUTHWESTERN MOUNTAINS. SKIES WILL BE CLEAR TO PARTLY CLOUDY. TEMPERATURES ARE EXPECTED TO WARM A LITTLE ABOVE SEASONAL AVERAGES. EK && .AVIATION... UPDATED 1730Z. AN UPPER LEVEL DISTURBANCE WILL MOVE THROUGH A MOIST SOUTHWEST FLOW ALOFT THIS AFTERNOON...SCATTERED THUNDERSTORMS WILL BE OVER THE SOUTHWEST THIS AFTERNOON...SPREADING INTO NORTH CENTRAL MONTANA LATER THIS AFTERNOON INTO EARLY TONIGHT. SOME OF THESE STORMS MAY BE SEVERE WITH DAMAGING WINDS AND LARGE HAIL. IN ADDITION...SMOKE WILL CONTRIBUTE TO MVFR VISIBILITY AT TIMES...ESPECIALLY AT NIGHT. VFR CONDITIONS WILL PREVAIL WITH MVFR IN SMOKE AND IN AND NEAR THUNDERSTORMS. WILLIAMSON DC && .FIRE WEATHER... && .PRELIMINARY POINT TEMPS/POPS... GTF 54 88 51 73 / 20 10 10 10 CTB 51 82 49 72 / 0 10 10 10 HLN 54 87 54 76 / 10 10 10 10 BZN 51 90 49 77 / 20 10 10 10 WEY 44 79 39 72 / 30 30 20 20 DLN 51 85 47 74 / 20 10 0 10 HVR 58 94 57 77 / 30 10 20 10 LWT 55 90 52 72 / 40 30 20 10 && .TFX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FROM 12 PM SUNDAY TO MIDNIGHT MDT SUNDAY NIGHT FOR MTZ112>118. && SHORT TERM...HOENISCH LONG TERM...CAMP AVIATION...DC WILLIAMSON WEATHER.GOV/GREATFALLS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GREAT FALLS MT 455 AM MDT SAT AUG 18 2007 MTZ008>015-044>055-191100- 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- 455 AM MDT SAT AUG 18 2007 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL MONTANA...NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA. .DAY ONE...TODAY AND TONIGHT SMOKE WILL LINGER OVER MUCH OF THE AREA THIS MORNING...REDUCING VISIBILITY AND AIR QUALITY AT TIMES. PEOPLE WHO ARE SENSITIVE TO THE SMOKE SHOULD AVOID IT AS MUCH AS POSSIBLE. SCATTERED THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND EVENING. SOME STORMS MAY BE SEVERE WITH DAMAGING WINDS AND LARGE HAIL. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY A COLD FRONT MOVING THROUGH THE REGION SUNDAY WILL BRING VERY GUSTY WINDS TO THE AREA THROUGH SUNDAY NIGHT. THE STRONG WINDS WILL COMBINE WITH LOW RELATIVE HUMIDITIES TO CREATE DANGEROUS FIRE WEATHER CONDITIONS. A FIRE WEATHER WATCH IS IN EFFECT FOR ALL OF NORTH CENTRAL AND SOUTHWEST MONTANA SUNDAY AFTERNOON AND EVENING. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Missoula radar (KMSX), 227 km away, was scanning. The volume nearest the first event began at 20:58 UTC.
6 hail, 1 thunderstorm wind. Local standard time, as filed.
A severe thunderstorm dropped .88 inch diameter hail at Dillon. Brief heavy rain was also reported with water topping some curbs in town.
A severe thunderstorm dropped 1 inch diameter hail at Dillon 3N. Rainfall amounts of .61 inches was also reported.
A severe thunderstorm dropped .88 inch diameter hail at Virginia City 2W. The hail damaged 30 windows in Nevada City and caused minor injuries to passengers traveling in an open car train between Nevada City and Virginia City. Wind gusts were reported between 50 and 60 mph.
A severe thunderstorm produced a wind gust to 60 mph at Virginia City 2W. The strong wind blew a sign (2 feet by 2 feet) through a windshield of a car, injuring the driver.
A severe thunderstorm dropped .88 inch diameter hail at Dillon 3N.
A severe thunderstorm dropped 1.25 inch diameter hail at McAllister.
A severe thunderstorm dropped .88 inch diameter hail at Whitehall 12W.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2007Every state in 2007This day in weather historyWarnings in Montana, August 2007
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: 47328, 47330, 47332, 47334, 47335, 47336, 47337.