A cold front pushed over Western Montana on the afternoon and evening of 08/09/2008. Strong shear, instability and good upper level jet support provided a good thunderstorm environment and resulted in several storms producing hail and thunderstorm wind 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 MSO wrote it up.
A cold front pushed over Western Montana on the afternoon and evening of 08/09/2008. Strong shear, instability and good upper level jet support provided a good thunderstorm environment and resulted in several storms producing hail and thunderstorm wind 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 Missoula, MT wrote its last area forecast discussion before the first event at Aug 9, 9:02 AM MST, 3 hours 18 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MISSOULA MT 1002 AM MDT SAT AUG 9 2008 .UPDATE...INCREASED POPS...THUNDERSTORMS AND CLOUDS ACROSS NORTH- CENTRAL IDAHO THIS MORNING. && .DISCUSSION...CONVECTION CONTINUES ACROSS PORTIONS OF NORTH- CENTRAL IDAHO AND NORTHWEST MONTANA. HAVE INCREASED THIS THREAT ACCORDINGLY FOR THIS MORNINGS FORECAST. SO FAR...MODERATE RAINFALL HAS BEEN ASSOCIATED WITH STORMS. THE SYNOPTIC PATTERN FAVORS STRONG CONVECTION WITH SOME STORMS CAPABLE OF PRODUCING LARGE HAIL...STRONG GUSTY WINDS...AND BRIEF BUT HEAVY RAINFALL. AN UPPER-LEVEL NEGATIVELY-TILTED TROUGH OF LOW PRESSURE WILL SWEEP ACROSS THE NORTHERN ROCKIES TODAY PROVIDING STRONG LIFT. THE ATMOSPHERE IS VERY UNSTABLE AND MOIST WITH PRECIPITABLE WATER VALUES NEAR ONE INCH. IN ADDITION...WIND SHEAR FAVORS SOME STORMS BECOMING ORGANIZED AND LONG-LIVED...THUS PROVIDING TIME FOR CELLS TO DEVELOP STRONGLY AND MAINTAIN THEIR STRENGTH FOR EXTENDED LENGTH OF TIME. EXPECT CONVECTION TO INCREASE IN INTENSITY AND COVERAGE DURING THE DAY...PEAKING ABOUT MID AFTERNOON THROUGH THE EARLY EVENING HOURS. && .AVIATION...NORTHWEST MONTANA AND NORTH-CENTRAL IDAHO AIRFIELDS WILL BE INFLUENCED BY SCATTERED THUNDERSTORMS THROUGH THE EARLY MORNING HOURS. AN INCREASING TREND IN COVERAGE/INTENSITY OF STORMS IS EXPECTED THIS AFTERNOON...THEN CONTINUING THROUGH THE EVENING HOURS. STORMS WILL CAPABLE OF PRODUCING HAIL...STRONG WINDS...AND BRIEF HEAVY RAIN. HIGHER TERRAIN WILL BE OBSCURED IN CLOUDS/PRECIPITATION WHERE STORMS DEVELOP AND TRACK THROUGH THE REGION. && .PREV DISCUSSION... /ISSUED 353 AM MDT SAT AUG 9 2008/ ..SEVERE WEATHER LIKELY ACROSS WESTERN MONTANA AND PORTIONS OF NORTH CENTRAL IDAHO TODAY... DISCUSSION...SHOWERS AND THUNDERSTORMS CONTINUE TO RUMBLE ACROSS PORTIONS OF WESTERN MONTANA AND NORTH CENTRAL IDAHO EARLY THIS MORNING IN RESPONSE TO A SHORT WAVE PROPAGATING THROUGH THE FLOW. OVERNIGHT CONVECTION PRODUCED CLOUD COVER WHICH HAS KEPT MANY LOCATIONS QUITE WARM. HOWEVER THE LATEST SATELLITE TRENDS POINT TOWARDS SOME CLEARING THIS MORNING WHICH WILL ALLOW TEMPERATURES TO WARM THROUGH EARLY AFTERNOON. THATS WHEN THINGS GET REALLY INTERESTING. WIDESPREAD THUNDERSTORMS ARE EXPECTED THIS AFTERNOON WITH SEVERE WEATHER LIKELY IN MANY LOCATIONS. A STRONG COLD FRONT IS CURRENTLY COMING ASHORE IN WESTERN WASHINGTON. AS THE FRONT APPROACHES... INCREASING INSTABILITY (CAPE IN THE 1000-2000J/KG RANGE...LIS BETWEEN -3 AND -6 AND VERY STEEP LAPSE RATES OF 8-9 C/KM) WILL INTERACT WITH STRONG VERTICAL SHEAR (BULK SHEAR VALUES OF 25-50 KTS) AS WELL AS MID AND UPPER LEVEL JET MAXES TO PRODUCE ORGANIZED AND POTENTIALLY LONG LIVED THUNDERSTORMS. THE MAIN THREATS WITH THESE STORMS WILL BE STRONG...POTENTIALLY DAMAGING WINDS AND LARGE HAIL. THERE WILL ALSO BE THE THREAT FOR PERIODS OF HEAVY RAINFALL WITH THUNDERSTORMS GIVEN PRECIPITABLE WATER VALUES REMAINING NEAR 1.00 INCHES. BUT STORM MOTIONS SHOULD BE FAST ENOUGH TO AVOID MAJOR FLASH FLOODING ISSUES. THUNDERSTORMS WILL FIRST FORM OVER THE MOUNTAINS OF IDAHO LATE THIS MORNING IN ADVANCE OF THE FRONT AND THEN MOVE EAST AND NORTH ACROSS WESTERN MONTANA THROUGH THE LATE AFTERNOON AND EVENING HOURS. STORMS SHOULD BE EAST OF THE DIVIDE SHORTLY AFTER 06Z (MIDNIGHT MDT) WITH SKIES BECOMING PARTLY CLOUDY FOR THE REMAINDER OF THE NIGHT. COOLER...POST FRONTAL CONDITIONS ARE EXPECTED ON SUNDAY WITH SOME WEAKER SHOWERS AND THUNDERSTORMS FORMING DURING THE AFTERNOON. SUNDAY NIGHT AND MONDAY...THE NORTHERN ROCKIES WILL STILL BE UNDER THE INFLUENCE OF THE EXITING UPPER TROUGH. BUT MOST OF THE ENERGY WILL BE CONFINED TO THE EXTREME NORTHERN BORDER AND ALONG THE DIVIDE. FOR MID WEEK...A WARMING AND DRYING TREND IS EXPECTED AS THE UPPER RIDGE ONCE AGAIN AMPLIFIES OVER THE REGION. THE MODELS ARE STRUGGLING IN THEIR DEPICTION OF THE SLOW MOVING NEARLY STATIONARY UPPER TROUGH OVER THE CENTRAL CANADIAN PROVINCES. SOME MODELS ARE NOW SUGGESTING SOME OF THIS ENERGY WILL RETROGRADE BACK INTO THE INTERMOUNTAIN WEST BY THE END OF THE WEEK. SINCE THIS IS A NEW SCENARIO AND VERY DIFFERENT FROM PREVIOUS RUNS...HAVE MADE NO CHANGES TO GOING FORECAST WHICH KEEPS A MAINLY DRY AND WARM FORECAST UNDER A RIDGE. WILL CONTINUE TO MONITOR LATER RUNS FOR BETTER CONSISTENCY BEYOND WEDNESDAY. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...NONE. ID...NONE. && SHORT TERM...MSJ LONG TERM....DICKERSON AVIATION...MSJ
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE MISSOULA MT 815 AM MDT SAT AUG 9 2008 IDZ005>010-MTZ001>007-043-100600- NORTHERN CLEARWATER MOUNTAINS-SOUTHERN CLEARWATER MOUNTAINS- OROFINO/GRANGEVILLE REGION-LOWER HELLS CANYON/SALMON RIVER REGION- WESTERN LEMHI COUNTY-EASTERN LEMHI COUNTY-KOOTENAI/CABINET REGION- WEST GLACIER REGION-FLATHEAD/MISSION VALLEYS- LOWER CLARK FORK REGION-MISSOULA/BITTERROOT VALLEYS- BITTERROOT/SAPPHIRE MOUNTAINS-BUTTE/BLACKFOOT REGION- POTOMAC/SEELEY LAKE REGION- 815 AM MDT SAT AUG 9 2008 /715 AM PDT SAT AUG 9 2008/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL IDAHO...NORTHWEST MONTANA AND WEST CENTRAL MONTANA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS WILL INCREASE IN COVERAGE AND INTENSITY LATE THIS MORNING AND THIS AFTERNOON AS A VERY MOIST AND UNSTABLE ATMOSPHERE INTERACTS WITH A COLD FRONT APPROACHING THE REGION. SOME STORMS MAY BECOME SEVERE PRODUCING LARGE HAIL AND DAMAGING WINDS. FLASH FLOODING IS POSSIBLE WITH THE ABUNDANT MOISTURE IN THE ATMOSPHERE...HOWEVER STORM MOTIONS WILL BE FAST ENOUGH TO MINIMIZE ANY WIDESPREAD POTENTIAL. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY THE PROBABILITY OF WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Missoula radar (KMSX), 43 km away, was scanning. The volume nearest the first event began at 19:18 UTC.
3 thunderstorm wind, 1 heavy rain, 1 hail. Local standard time, as filed.
National Weather Service employee reported 2 tree tops blown off with structural damage to a neighbor's roof. Winds estimated to be 53 mph.
National Weather Service employee reported the metal roof on the Rock Creek Lodge was blown off from thunderstorm winds.
National Weather Service employee reported several cottonwood trees blown down along Interstate 90, 4 miles west of Nimrod. The trees fell onto the highway obstructing traffic.
National Weather Service employee reported that heavy rainfall from a thunderstorms caused a rock and debris slide with some overwash onto the frontage road near Bearmouth Lodge.
National Weather Service employee reported 1.25 inch diameter hail on Interstate 90 between Clinton and the Rock Creek Road exits.
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, August 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: 128454, 128464, 128469, 128472, 128474.