Slow moving thunderstorms produced heavy rains that resulted in flash flooding over portions of the Southern Rocky Mountain Front. Mudslides were reported at some trailheads.
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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.
Slow moving thunderstorms produced heavy rains that resulted in flash flooding over portions of the Southern Rocky Mountain Front. Mudslides were reported at some trailheads.
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 7, 4:56 AM MST, 3 hours 34 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 556 AM MDT FRI AUG 7 2009 UPDATED AVIATION .DISCUSSION... TODAY THROUGH SUNDAY EVENING...LARGE UPPER LEVEL TROF EXPECTED TO BE SIGNIFICANT RAINMAKER FOR WESTERN/CENTRAL MT IS CURRENTLY SITUATED OVER THE GREAT BASIN WITH ITS CLOSED LOW CENTER ALONG OR/ID BORDER. MOISTURE WRAPPING NORTHWARD AROUND THE EAST SIDE OF THE LOW HAS BEEN GENERATING AREA OF MOSTLY LIGHT RAIN...WITH A FEW EMBEDDED THUNDERSTORMS...PAST FEW HOURS ALONG THE SOUTHERN ROCKY MTN FRONT AND ADJACENT PLAINS FROM AUGUSTA TO LEWISTOWN. FORECAST MODELS ARE IN GOOD AGREEMENT THAT UPPER TROF WILL MAKE SLOW EASTWARD PROGRESS TODAY...ALLOWING STEADY STREAM OF PACIFIC MOISTURE TO MOVE INTO OUR AREA...PRODUCING WIDESPREAD AREAS OF RAIN THROUGH THE DAY. ISOLATED EMBEDDED THUNDERSTORMS ARE ALSO LIKELY WITH SOME STORMS FROM HAVRE TO LEWISTOWN POSSIBLY BEING STRONG ENOUGH FOR SMALL HAIL THIS AFTN. ALTHOUGH CURRENT MODEL PRECIP TOTALS DECREASED FROM PREVIOUS RUNS...FLASH FLOOD WATCH REMAINS IN EFFECT FOR THE ROCKY MTN FRONT...SEE ADDITIONAL DETAILS IN HYDROLOGY SECTION BELOW. UPPER TROF IS FORECAST TO REACH CENTRAL/EASTERN MT BY SAT EVE BRINGING GRADUAL END TO THE PRECIP FROM WEST TO EAST SATURDAY NIGHT. ON SUNDAY A WEAK SHORTWAVE RIDGE WILL FOLLOW THE DEPARTING TROF...BRINGING DECREASING CLOUDINESS AND JUST A SLIGHT CHANCE FOR RESIDUAL LIGHT RAINSHOWERS. EXTENSIVE CLOUD COVER AND RAIN WILL KEEP TEMPS WELL BELOW NORMAL TODAY AND SATURDAY...BUT TEMPS WILL WARM TO SLIGHTLY BELOW NORMAL VALUES ON SUN. WARANAUSKAS SUNDAY NIGHT THROUGH WEDNESDAY NIGHT...TEMPERATURES WILL RETURN TO SEASONAL LEVELS AND DRIER CONDITIONS ARE ANTICIPATED AS A WEAK UPPER-LEVEL RIDGE BUILDS OVER THE AREA SUNDAY NIGHT AND MONDAY. ZONAL FLOW WILL THEN PERSIST THROUGH WEDNESDAY WITH ONLY SLIGHT CHANCES OF PRECIPITATION ASSOCIATED WITH EMBEDDED SHORTWAVES. ADDED SLIGHT CHANCE POPS FOR BOTH MONDAY AND TUESDAY PM AS A FEW SHORTWAVES CROSS THE AREA...BEST CHANCE HOWEVER WILL BE IN THE MOUNTAINS WHERE TERRAIN-INDUCED INSTABILITY COMBINED WITH WARMER TEMPERATURES WILL PROMOTE THUNDERSTORM DEVELOPMENT. OVERALL...A GENERALLY QUIETER PATTERN IS ANTICIPATED DURING THIS TIME FRAME. MLS THURSDAY THROUGH FRIDAY...MODELS ARE IN ROUGH AGREEMENT DURING THIS PERIOD...WITH SOME DIFFERENCES IN TIMING AND STRENGTH OF FEATURES. A BLENDED SOLUTION FOR THIS FORECAST HAS PERIODIC DISTURBANCES MOVING THROUGH A SOUTHWESTERLY FLOW ALOFT OVER THE FORECAST AREA. ISOLATED ...MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS MUCH OF THE REGION. SHOWERS AND THUNDERSTORMS SHOULD BE A LITTLE MORE NUMEROUS OVER THE HIGHER MOUNTAINS. TEMPERATURES ARE EXPECTED TO BE NEAR...OR A LITTLE ABOVE SEASONAL AVERAGES. EK && .AVIATION... UPDATED 1200Z. WIDESPREAD RAIN SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE ACROSS THE AREA THROUGH THE PERIOD AS A STRONG UPPER-LEVEL LOW PRESSURE SYSTEM PUSHES EAST. LOW CIGS THIS AM WILL CREATE MVFR/IFR CONDITIONS ALONG WITH MOUNTAIN OBSCURATION. OVERALL...MOUNTAIN OBSCURATION AND MVFR CONDITIONS WILL PERSIST THROUGH THE PERIOD WITH OCCL IFR AND LIFR CONDITIONS FOR AREAS NEAR HEAVIER PRECIPITATION. FOR AREAS NEAR THUNDERSTORMS...BRIEF GUSTY WINDS AND VERY HEAVY RAIN ARE ALSO EXPECTED. MLS && .HYDROLOGY...FLASH FLOOD WATCH FOR NORTHERN AND SOUTHERN ROCKY MTN FRONT BEGINS AT 6 AM THIS MORNING AND CONTINUES UNTIL LATE SATURDAY AFTERNOON. WITH RAINFALL TOTALS OF 1 TO 2 INCHES DURING THAT TIME...PRIMARY CONCERN IS FOR DEBRIS FLOWS AND EROSION IN/NEAR AREAS BURNED BY WILDFIRES. ADDITIONAL FLOODING MAY BE POSSIBLE NEAR MTN CREEKS. && .PRELIMINARY POINT TEMPS/POPS... GTF 67 51 70 53 / 80 50 50 30 CTB 61 48 70 50 / 90 90 60 30 HLN 71 52 71 53 / 70 50 40 30 BZN 77 48 72 49 / 60 50 50 30 WEY 60 37 59 36 / 60 60 60 30 DLN 65 44 64 45 / 70 60 50 30 HVR 72 52 73 51 / 80 80 50 30 LWT 71 49 68 49 / 80 50 50 30 && .TFX WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH SATURDAY AFTERNOON FOR MTZ009-014-048. && SHORT TERM...WARANAUSKAS LONG TERM...MLS/EK AVIATION...MLS WEATHER.GOV/GREATFALLS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GREAT FALLS MT 457 AM MDT FRI AUG 7 2009 MTZ008-012-015-050>055-081100- BEAVERHEAD-CASCADE-MADISON-JUDITH BASIN-FERGUS-JEFFERSON- BROADWATER-MEAGHER-GALLATIN- 457 AM MDT FRI AUG 7 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL MONTANA AND SOUTHWEST MONTANA. .DAY ONE...TODAY AND TONIGHT RAIN SHOWERS ALONG WITH A CHANCE OF THUNDERSTORMS WILL BECOME WIDESPREAD ACROSS SOUTHWEST MONTANA AND SOUTHERN PORTIONS OF CENTRAL MONTANA TODAY AND TONIGHT. A FEW STORMS MAY BE STRONG THIS AFTERNOON AND EVENING WITH GUSTY WINDS AND HEAVY RAIN. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO AFFECT THE REGION ON SATURDAY BEFORE TAPERING BY SATURDAY NIGHT. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. MTZ010-011-013-044>047-049-081100- EASTERN GLACIER-HILL-CHOUTEAU-TOOLE-LIBERTY-EASTERN PONDERA- BLAINE-EASTERN TETON- 457 AM MDT FRI AUG 7 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL MONTANA. .DAY ONE...TODAY AND TONIGHT RAIN SHOWERS ALONG WITH A CHANCE OF THUNDERSTORMS WILL BECOME WIDESPREAD ACROSS PORTIONS OF NORTH-CENTRAL MONTANA TODAY AND TONIGHT. A FEW STORMS MAY BE STRONG THIS AFTERNOON AND EVENING WITH GUSTY WINDS AND PERIODS OF HEAVY RAIN. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY WIDESPREAD SHOWERS WILL CONTINUE TO AFFECT THE REGION ON SATURDAY BEFORE TAPERING BY SATURDAY NIGHT. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. MTZ009-014-048-081100- NORTHERN ROCKY MOUNTAIN FRONT- CENTRAL AND SOUTHERN LEWIS AND CLARK- SOUTHERN ROCKY MOUNTAIN FRONT- 457 AM MDT FRI AUG 7 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA. .DAY ONE...TODAY AND TONIGHT PERIODS OF HEAVY RAIN AND STRONG THUNDERSTORMS ARE EXPECTED ALONG AND EAST OF THE ROCKY MOUNTAIN FRONT WITH AMOUNTS POSSIBLY EXCEEDING ONE INCH IN SOME LOCATIONS. THE HEAVY RAIN WILL INCREASE THE THREAT OF FLASH FLOODING...ESPECIALLY IN AREA BURNED BY CURRENT AND PREVIOUS SEASON WILDFIRES...AND A FLASH FLOOD WATCH IS IN EFFECT THROUGH SATURDAY AFTERNOON. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY A FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH SATURDAY AFTERNOON. WIDESPREAD HEAVY RAIN WILL CONTINUE THROUGH SATURDAY AFTERNOON BEFORE TAPERING BY SATURDAY NIGHT. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREAT FALLS MT 639 AM MDT FRI AUG 7 2009 MTZ012>014-049-071330- CASCADE MT-CENTRAL AND SOUTHERN LEWIS AND CLARK MT-CHOUTEAU MT-EASTERN TETON MT- 639 AM MDT FRI AUG 7 2009 ...SIGNIFICANT WEATHER ADVISORY FOR EASTERN LEWIS AND CLARK... SOUTHEASTERN TETON...NORTHERN CASCADE AND SOUTHWESTERN CHOUTEAU COUNTIES UNTIL 730 AM MDT... AT 636 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM 9 MILES WEST OF CASCADE TO 14 MILES SOUTHWEST OF BELT...AND MOVING NORTH AT 25 MPH. WIND GUSTS UP TO 50 MPH AND PENNY-SIZED HAIL ARE EXPECTED WITH THESE STORMS...ALONG WITH HEAVY RAIN. LOCATIONS NEAR THE PATH OF THESE STORMS INCLUDE...CASCADE...GREAT FALLS...BELT...FORT SHAW...BLACK EAGLE...STOCKETT...CENTERVILLE... SAND COULEE...TRACY...ULM...MALMSTROM AFB...SUN RIVER...SUN PRAIRIE AND VAUGHN. IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A STURDY BUILDING. LAT...LON 4766 11185 4764 11081 4715 11101 4716 11205 TIME...MOT...LOC 1239Z 195DEG 24KT 4726 11187 4724 11111 MLS
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
909 AM MDT FRI AUG 07 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0830 AM HEAVY RAIN 10 W CHOTEAU 47.81N 112.40W
08/07/2009 M2.30 INCH TETON MT PUBLIC
SPOTTERS SON MEASURED 2.3 INCHES OF RAINFALL FROM
THURSDAY NIGHT INTO FRIDAY MORNING.
0830 AM HEAVY RAIN 7 W FAIRFIELD 47.62N 112.13W
08/07/2009 M1.20 INCH TETON MT TRAINED SPOTTER
SPOTTER REPORTED 1.2 INCHES OF RAINFALL FROM THURSDAY
NIGHT INTO FRIDAY MORNING.
0842 AM HEAVY RAIN 4 S CASCADE 47.22N 111.71W
08/07/2009 M1.70 INCH CASCADE MT CO-OP OBSERVER
RAINFALL TOTAL SINCE MIDNIGHT.
&&
DBERNHARThe Missoula radar (KMSX), 98 km away, was scanning. The volume nearest the first event began at 15:27 UTC.
1 flash flood. Local standard time, as filed.
Heavy rain from slow moving thunderstorms produced flash flooding near Crown Mountain in the Bob Marshall/Scapegoat Wilderness Area. The flash flooding produced a mudslide near the Crown Mountain trailhead which is located near Benchmark, off of Road 235.
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, August 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: 195564.