Strong to severe thunderstorms developed ahead of an approaching cold front over the higher terrain of western Montana. 75 inches in diameter reported by trained storm spotters.
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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.
Strong to severe thunderstorms developed ahead of an approaching cold front over the higher terrain of western Montana. The main threat with these storms was large hail, with hail up to 1.75 inches in diameter reported by trained storm spotters.
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 Jul 6, 3:29 AM MST, 8 hours 31 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MISSOULA MT 429 AM MDT MON JUL 6 2009 ...HIGH LIKELIHOOD OF SEVERE THUNDERSTORMS TODAY OVER WESTERN MONTANA... .DISCUSSION...A NUMBER OF METEOROLOGICAL FACTORS ARE COMING TOGETHER TODAY WHICH WILL RESULT IN THE FORMATION OF WIDESPREAD SHOWERS AND THUNDERSTORMS AND THE HIGH LIKELIHOOD OF SEVERE THUNDERSTORMS OVER WESTERN MONTANA. A HAZARDOUS WEATHER OUTLOOK WILL BE UPDATED TO HIGHLIGHT SPECIFIC AREAS OF CONCERN FOR TODAY. A PACIFIC TROUGH OF LOW PRESSURE...WHICH HAS BEEN LINGERING OFF THE WASHINGTON COASTLINE FOR THE PAST 36 HOURS...HAS FINALLY BEGUN TO SWING INLAND THIS MORNING. THIS HAS NUDGED THE AXIS OF THE HIGH PRESSURE RIDGE EAST OVER CENTRAL MONTANA AND ALLOWED A VERY MOIST AND DYNAMIC SOUTHWESTERLY FLOW ALOFT TO DEVELOP OVER THE PACIFIC NORTHWEST AND NORTHERN ROCKY MOUNTAIN STATES. AS THE MORNING PROGRESSES...THE UPPER ATMOSPHERIC FLOW WILL BECOME INCREASINGLY SHEARED...BOTH IN SPEED AND DIRECTION. THIS MEANS THE WIND DIRECTION FROM SURFACE TO 40,000 FEET WILL VARY IN A COUNTER- CLOCKWISE MANNER (WEST AT THE SURFACE TO SOUTH-SOUTHWESTERLY AT 40,000 FEET) AND WIND SPEED WILL INCREASE WITH HEIGHT (10-20 KNOTS AT THE SURFACE TO 70 KNOTS AT 40,000 FEET ASSOCIATED WITH AN APPROACHING ACCELERATION IN THE JET STREAM VISIBLE ON WATER VAPOR IMAGERY THIS MORNING). ALTHOUGH THIS WIND SHEAR IS COMPARATIVELY NOT THAT STRONG...BELIEVE IT WILL BE SUFFICIENT...ESPECIALLY OVER NORTHWEST MONTANA AND ALONG THE CONTINENTAL DIVIDE...TO AID IN THE BUILDING OF SEVERE...HIGH TOPPED THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WIND GUSTS GREATER THAN 60 MPH AND HAIL OF 1 INCH OR LARGER. THIS IS MAINLY BECAUSE FORECAST MODEL SOUNDINGS OVER THIS REGION REVEAL A HIGH AMOUNT OF CONVECTIVE POTENTIAL AND INSTABILITY THIS MORNING THROUGH THE EARLY AFTERNOON HOURS. THE KICKER WHICH WILL GET CONVECTION GOING IS AN APPROACHING SURFACE COLD FRONT...ALREADY SPARKING CONVECTIVE OVER EASTERN WASHINGTON/OREGON EARLY THIS MORNING. THE FRONT WILL ADD THE NECESSARY DYNAMICS TO RAPIDLY LIFT THE UNSTABLE AIRMASS AND ADD TO THE SHEARING PROFILE...HELPING THUNDERSTORMS TO BECOME VERY STRONG AND QUITE LIKELY SEVERE. ALL MODELS SUGGEST THE SEVERE THREAT WILL BEGIN SHORTLY AFTER THE NOON HOUR AND QUICKLY SHIFT EAST OF THE DIVIDE BY 4 PM THIS AFTERNOON WHEN THE FRONT MOVES INTO EASTERN MONTANA. BEHIND THE FRONT SHOWERS AND THUNDERSTORMS WILL GRADUALLY SUBSIDE...WITH ONLY SCATTERED SHOWERS AND THUNDERSTORMS REMAINING UNTIL AROUND MIDNIGHT. A PORTION OF THE COLD FRONTAL BOUNDARY APPEARS TO REMAIN OVER SOUTHWESTERN MONTANA TUESDAY WHICH SHOULD PRODUCE ENOUGH INSTABILITY FOR A CHANCE OF SHOWERS AND THUNDERSTORMS OVER THESE AREAS. TUESDAY NIGHT THROUGH SUNDAY...A DISTURBANCE WILL MOVE THROUGH THE NORTHERN ROCKIES UNDER THIS SOUTHWESTERLY FLOW PATTERN. THIS DISTURBANCE APPEARS TO BE ABLE TO KEEP OFF SOME SHOWERS AND THUNDERSTORMS WHICH COULD PRODUCE LOCALIZED SIGNIFICANT PRECIPITATION. THESE SHOWERS APPEAR TO LINGER THROUGH WEDNESDAY. A RIDGE OF HIGH PRESSURE IS EXPECTED TO BUILD OVER THE REGION THURSDAY THROUGH SATURDAY AS A LOW PRESSURE SYSTEM MOVES ALONG THE PACIFIC NORTHWEST COAST. THE MODELS ARE INDICATING THAT SOME MOISTURE AND ENERGY MAKING OVER THE RIDGE INTO NORTHWEST MONTANA ON THURSDAY. THE AFOREMENTIONED LOW PRESSURE SYSTEM APPEARS TO MAKES ITS WAY INTO THE AREA BY THE BEGINNING OF NEXT WEEK. TEMPERATURES FOR THE MIDDLE OF WEEK APPEAR TO BE 5 TO 10 DEGREES BELOW SEASON NORMALS...THEN WARMING TO 5 DEGREES ABOVE NORMAL BY THE WEEKEND. .AVIATION...WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED THROUGH LATE THIS AFTERNOON. SOME STORMS IN THE VICINITY OF KGPI...KMSO AND KBTM MAY PRODUCE WIND GUSTS IN EXCESS OF 50 KNOTS... HAIL GREATER THAN 1 INCH AND FREQUENT LIGHTNING. THE STRONGEST THUNDERSTORMS ARE ANTICIPATED BETWEEN 1800Z AND 2200Z IN ASSOCIATION WITH AN APPROACHING COLD FRONT. ALL AIRFIELDS WILL EXPERIENCE A WIND SHIFT TO THE FROM SOUTHEAST TO WEST AND GUSTS TO 30 KTS IN ASSOCIATION WITH THE FRONTAL PASSAGE. CONDITIONS WILL GRADUALLY IMPROVE LATE THIS AFTERNOON AND ESPECIALLY DURING THE EVENING. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...NONE. ID...NONE. && SHORT TERM...DICKERSON LONG TERM....SMITH AVIATION...DICKERSON
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE MISSOULA MT 451 AM MDT MON JUL 6 2009 MTZ001>007-043-070000- 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- 451 AM MDT MON JUL 6 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST MONTANA AND WEST CENTRAL MONTANA. .DAY ONE...TODAY AND TONIGHT ATMOSPHERIC CONDITIONS WILL BE FAVORABLE EARLY THIS AFTERNOON FOR THE DEVELOPMENT OF SEVERE THUNDERSTORMS OVER THE AREA. THE BIGGEST THREATS FROM THESE STORMS WILL BE DAMAGING WIND GUSTS IN EXCESS OF 60 MPH AND HAIL GREATER THAN 1 INCH IN DIAMETER. THE TIME FRAME OF GREATEST THREAT WILL BE BETWEEN NOON AND 4 PM THIS AFTERNOON. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THE PROBABILITY OF WIDESPREAD HAZARDOUS WEATHER IS LOW AT THIS TIME. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE STRONGLY ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. IDZ005>010-070000- NORTHERN CLEARWATER MOUNTAINS-SOUTHERN CLEARWATER MOUNTAINS- OROFINO/GRANGEVILLE REGION-LOWER HELLS CANYON/SALMON RIVER REGION- WESTERN LEMHI COUNTY-EASTERN LEMHI COUNTY- 451 AM MDT MON JUL 6 2009 /351 AM PDT MON JUL 6 2009/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL IDAHO. .DAY ONE...TODAY AND TONIGHT SHOWERS AND THUNDERSTORMS HAVE ALREADY BEGUN THIS MORNING AND WILL CONTINUE THROUGH THE EARLY AFTERNOON HOURS AS A COLD FRONT APPROACHES THE REGION. THE ATMOSPHERE WILL BECOME INCREASINGLY UNSTABLE AND SUPPORTIVE OF STRONG THUNDERSTORMS UNTIL AFTER THE FRONT PASSES. ALTHOUGH MOST CONVECTION WILL BE CAPABLE OF PRODUCING WIND GUSTS TO 50 MPH AND HAIL UP TO THREE QUARTERS OF AN INCH IN DIAMETER...ISOLATED SEVERE THUNDERSTORMS CANNOT BE RULED OUT...CAPABLE OF PRODUCING WIND GUSTS IN EXCESS OF 60 MPH AND HAIL LARGER THAN ONE INCH. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THE PROBABILITY OF WIDESPREAD HAZARDOUS WEATHER IS LOW AT THIS TIME. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
1252 PM MDT MON JUL 6 2009
IDZ009-010-061915-
EASTERN LEMHI COUNTY-WESTERN LEMHI COUNTY-
1252 PM MDT MON JUL 6 2009
...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL LEMHI COUNTY UNTIL 115 PM
MDT...
AT 1250 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
A STRONG THUNDERSTORM 8 MILES SOUTHWEST OF SALMON...MOVING NORTHEAST
AT 40 MPH.
HAIL UP TO THE SIZE OF PENNIES IS EXPECTED WITH THIS STORM.
LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...SALMON AND CARMEN.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
IF THREATENING WEATHER APPROACHES YOUR AREA...GO INDOORS AND STAY
AWAY FROM WINDOWS. IF YOU ARE CAUGHT OUTSIDE...MOVE TO A WELL
PROTECTED AREA.
IN ADDITION...THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR
LOCAL RADIO AND TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS...FOR
ADDITIONAL INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL
WEATHER SERVICE.
&&
LAT...LON 4496 11394 4507 11414 4542 11378 4539 11373
4532 11373 4529 11368 4522 11364 4521 11363
TIME...MOT...LOC 1852Z 219DEG 37KT 4509 11395
ZUMPFEThe Missoula radar (KMSX), 131 km away, was scanning. The volume nearest the first event began at 19:00 UTC.
5 hail. Local standard time, as filed.
Golf ball sized hail accumulated to a 1.5 inch depth on the ground.
Hail up to one inch in diameter reported by a storm spotter.
Report of dime sized hail in Philipsburg.
Weather spotter reported quarter size hail in Philipsburg. Eight miles northwest of Philipsburg, a camper reported half inch diameter hail at 5500 feet.
Weather spotter reported quarter sized hail.
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, July 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: 184047, 184051, 184053, 184064, 184072.