A low pressure system moving through the northern Rockies brought heavy rain to portions of western Montana. Higher elevations in Glacier National Park measured anywhere from one to two inches of precipitation.
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The episode as NWS MSO wrote it up.
A low pressure system moving through the northern Rockies brought heavy rain to portions of western Montana. Higher elevations in Glacier National Park measured anywhere from one to two inches of precipitation. This caused some flash flooding and debris flows on the Going to the Sun Road in Glacier Park.
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 13, 2:41 AM MST, 9 hours 14 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MISSOULA MT 341 AM MDT MON JUL 13 2009 .DISCUSSION... TODAY THROUGH TUESDAY NIGHT...ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS ARE POSSIBLE THROUGHOUT THE REGION AS A CLOSED LOW PRESSURE CIRCULATION MOVES ACROSS THE NORTHERN U.S. ROCKIES. AS ADVERTISED IN PREVIOUS DISCUSSIONS...A SURFACE COLD FRONT LOCATED ALONG THE EASTERN EDGE OF WASHINGTON AND OREGON EARLY THIS MORNING WILL BEGIN TO TRACK QUICKLY EASTWARD ONCE THE SUN RISES AND DAYTIME HEATING RESUMES. THUNDERSTORMS WILL EXIST MAINLY ALONG AND TO THE EAST OF THE SURFACE FRONT. CONSIDERING THE PRESENCE OF A FAIRLY STRONG JET STREAK ON THE EASTERN EDGE OF THE CLOSED LOW...THE POTENTIAL EXISTS FOR A FEW STRONG OR SEVERE THUNDERSTORMS DEVELOPING JUST TO THE WEST OF THE CONTINENTAL DIVIDE AS THE SURFACE COLD FRONT ARRIVES DURING EARLY THIS AFTERNOON. ERRATIC AND GUSTY SURFACE WINDS ARE LIKELY AS THE SURFACE COLD FRONT MOVES THROUGH NORTH CENTRAL IDAHO AND WESTERN MONTANA. NOTICEABLY COOLER TEMPERATURES WILL BE EVIDENT BEHIND THE SURFACE COLD FRONT...WITH SHOWER AND THUNDERSTORM ACTIVITY EXPECTED TO CONTINUE FOR THE REMAINDER OF THIS AFTERNOON AND EVENING. THUNDERSTORM POTENTIAL WILL DECREASE SIGNIFICANTLY BEHIND THE COLD FRONT AS WELL. PRECIPITATION CHANCES WILL SLOWLY DIMINISH FROM WEST TO EAST DURING THE OVERNIGHT TONIGHT THROUGH TUESDAY AFTERNOON. NORTHWESTERLY FLOW AT RIDGE-TOP LEVEL DURING TUESDAY WILL FAVOR SHOWER ACTIVITY ACROSS NORTHWEST MONTANA...PARTICULARLY IN THE VICINITY OF GLACIER PARK. BY TUESDAY NIGHT...HIGH PRESSURE WILL BEGIN TO BUILD OVER THE INTERMOUNTAIN REGION...WITH SKIES CLEARING AND PRECIPITATION CHANCES COMPLETELY DIMINISHING WEST OF THE CONTINENTAL DIVIDE. WEDNESDAY THROUGH SUNDAY...NORTHWEST FLOW ALOFT WILL PREVAIL ON WEDNESDAY AS THE RIDGE CONTINUES TO BUILD OVER THE INTERMOUNTAIN WEST. AFTERNOON INSTABILITY ALONG WITH REMNANT LOW LEVEL MOISTURE FROM TUESDAY WILL KEEP A SLIGHT CHANCE OF SHOWERS IN THE HIGHER TERRAIN OF THE GLACIER PARK REGION. A DRYING AND WARMING TREND WILL DOMINATE THE FORECAST THURSDAY THROUGH SATURDAY. THE OVERALL FLOW PATTERN WILL SHIFT AROUND TO THE SOUTHWEST BY FRIDAY AND ADVECT MOISTURE INTO THE AREA. THE BEST POTENTIAL FOR SHOWER AND THUNDERSTORM DEVELOPMENT LIES TO THE SOUTH ACROSS NORTH CENTRAL IDAHO AND SOUTHWEST MONTANA FRIDAY THROUGH SUNDAY...WITH THE BEST AMOUNT OF MOISTURE AVAILABLE ON SUNDAY. && .AVIATION... SHOWERS AND THUNDERSTORMS WILL BE PRESENT FROM TIME TO TIME ACROSS THE REGION DURING THE NEXT 24 HOURS. A SURFACE COLD FRONT ALONG THE EASTERN EDGE OF WASHINGTON AND OREGON WILL MOVE THROUGH NORTH CENTRAL IDAHO AND WESTERN MONTANA DURING TODAY...WITH THUNDERSTORM ACTIVITY MOST PRONOUNCED ALONG THE FRONT. A HIGH CONCENTRATION OF CLOUD TO GROUND LIGHTNING STRIKES ARE ANTICIPATED JUST AHEAD OF THE COLD FRONT. ERRATIC AND GUSTY WINDS ARE EXPECTED TO ACCOMPANY THE PASSAGE OF THE COLD FRONT AND ARE LIKELY TO BE STRONGEST NEAR KBTM AND KSMN BETWEEN 13/1600Z AND 13/2200Z. AFTER 14/0000Z...THE SURFACE COLD FRONT SHOULD BE EAST OF THE CONTINENTAL DIVIDE...WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRESENT THROUGH THE REMAINDER OF THE FORECAST PERIOD. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...NONE. ID...NONE. && SHORT TERM...ZUMPFE LONG TERM....DEROSA AVIATION...ZUMPFE
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE MISSOULA MT 350 AM MDT MON JUL 13 2009 IDZ005>010-MTZ001>007-043-132200- 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- 350 AM MDT MON JUL 13 2009 /250 AM PDT MON JUL 13 2009/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL IDAHO...NORTHWEST MONTANA AND WEST CENTRAL MONTANA. .DAY ONE...TODAY AND TONIGHT SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED OVER THE REGION TODAY. THERE IS THE POTENTIAL FOR A FEW STRONG OR SEVERE THUNDERSTORMS TO DEVELOP ALONG A COLD FRONT...ANTICIPATED TO MOVE EAST OF THE CONTINENTAL DIVIDE BY LATE THIS AFTERNOON. THE MAIN THREAT FROM THESE STORMS WILL BE FREQUENT LIGHTNING...HAIL AND GUSTY WINDS. THOSE INVOLVED WITH OUTDOOR ACTIVITIES SHOULD BE PREPARED FOR THUNDERSTORM ACTIVITY. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THE PROBABILITY OF HAZARDOUS WEATHER TUESDAY THROUGH SUNDAY IS LOW. .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 717 AM MDT MON JUL 13 2009 MTZ005>007-043-131400- BITTERROOT/SAPPHIRE MOUNTAINS-BUTTE/BLACKFOOT REGION-MISSOULA/BITTERROOT VALLEYS-POTOMAC/SEELEY LAKE REGION- 717 AM MDT MON JUL 13 2009 ...SIGNIFICANT WEATHER ADVISORY FOR WESTERN POWELL...NORTHERN RAVALLI...NORTHWESTERN GRANITE AND SOUTHEASTERN MISSOULA COUNTIES UNTIL 800 AM MDT... AT 713 AM MDT...STORM SPOTTERS REPORTED A STRONG THUNDERSTORM 8 MILES EAST OF FLORENCE...OR 16 MILES SOUTH OF MISSOULA...MOVING NORTHEAST AT 35 MPH. HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...BONNER...QUIGLEY... TURAH...CLINTON...NIMROD...TWIN CREEKS...POTOMAC...GREENOUGH AND GARNET. 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. && LAT...LON 4711 11363 4680 11318 4648 11393 4665 11419 TIME...MOT...LOC 1316Z 228DEG 31KT 4666 11388 KITSMILLER
The Missoula radar (KMSX), 181 km away, was scanning. The volume nearest the first event began at 18:53 UTC.
1 flash flood. Local standard time, as filed.
Glacier National Park officials reported heavy rain that caused rock and debris flows on the Going to the Sun Road. One rock slide sent a rock through a car window.
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: 184727.