Swollen tributaries contributed to high river levels on the Milk, mainly in the Glasgow area.
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 GGW wrote it up.
Swollen tributaries contributed to high river levels on the Milk, mainly in the Glasgow area.
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 Glasgow, MT wrote its last area forecast discussion before the first event at May 11, 3:20 AM MST, 5 hours 6 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 420 AM MDT WED MAY 11 2011 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH FRIDAY... STRONG SURFACE LOW PRESSURE SYSTEM HAS LIFTED INTO SOUTHERN MANITOBA WITH PRECIPITATION ENDING RATHER QUICKLY LAST EVENING. LOW CLOUDS PERSIST MAINLY IN THE YELLOWSTONE VALLEY AND A FEW LIGHT SHOWERS STILL MAY OCCUR UNDER THESE CLOUDS THIS MORNING. FURTHER NORTHWEST...CLOUDS HAVE CLEARED WITH DRY AIR MOVING INTO THE REGION. UPPER PATTERN PUTS A WEAK COL OVER MONTANA WHICH TRANSITIONS INTO AN OMEGA BLOCK RIDGE BY THE WEEKEND. THIS IS THE RESULT OF STRONG LOW DIGGING ALONG THE WEST COAST AND THE SPLIT LOWS OVER THE PLAINS GRADUALLY MERGING. BOTH THESE TROFS ARE BEING PREVENTED FROM MOVING EAST BY BLOCKING LOW OFF THE ATLANTIC COAST. AT THE LOW LEVELS HIGH PRESSURE PUSHES SOUTH FROM CENTRAL CANADA FOR GENERALLY DRY WEATHER THROUGH THE SHORT TERM PERIOD. TEMPERATURES WILL RECOVER DUE TO PLENTY OF SUNSHINE OVER THE NEXT FEW DAYS...WHILE LOW LEVEL EAST TO NORTHEAST FLOW AND RIDGE AXIS TO THE WEST WILL BE LIMITERS TO WARMING. EBERT .LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY... FRIDAY NIGHT THROUGH MONDAY...THE NORTHERN HIGH PLAINS WILL HAVE A WELL AMPLIFED UPPER LEVEL RIDGE OVER IT SO EXPECT GOOD WEATHER. AT THE SAME TIME MODELS INDICATE THERE WILL BE AN UPPER CLOSED LOW THAT ROTATES SOUTHWEST WARD ON TOP OF ANOTHER CLOSED LOW OVER THE SOUTHERN PLAINS THAT MOVES EASTWARD. THE UPPER LOW OVER THE NORTHERN PLAINS WILL PUSH A BACK DOOR COLD FRONT INTO EASTERN MONTANA. FRONT WILL HAVE A TOUGH TIME MAKING IT MUCH PAST THE EASTERN MOST ZONES OF THE CWA. MODELS DO DISAGREE ON PLACEMENT OF THE PRECIPITATION BUT MY THOUGHTS ARE THIS THING WILL BE RELATIVELY DRY. GEM KEEPS EASTERN MONTANA DRY WHILE THE GFS AND ECMWF BRING MINIMAL AMOUNTS OF QPF INTO OUR EASTERN ZONES. DECIDED I WOULD LEAVE A SLIGHT CHANCE OF RAIN ACROSS OUR EASTERN ZONES ON SATURDAY FOR NOW. SUNDAY THE UPPER LOW MOVES TO THE SOUTHEAST FLOWING IT CLOSED LOW TWIN BROTHER WHICH IS NOW OVER THE OHIO RIVER VALLEY. SO THE UPPER LEVEL RIDGE WILL ONCE AGAIN DOMINATE THIS TIME PERIOD THROUGH MONDAY AFTERNOON. MONDAY EVENING AND BEYOND...THE LARGE WESTERN CONUS TROUGH ENTRENCHES ITSELF OVER THE WESTERN AND NORTHWESTERN STATES. THIS SCENARIO WILL LIKELY FEED AMPLE MOISTURE AND HIGHER TEMPERATURES OUT AHEAD OF THE LEADING EDGE OF THE TROUGH. MODLES ARE STILL OUT OF PAHSE WITH THE EXACT PLACEMENT OF THE UPPER TROUGH AND QPF. CHANCES FOR INCREASED SHOWERS AND THUNDERSTORMS SEEM POSSIBLE UNDER THIS SOUTHERLY FLOW ALOFT STARTING MONDAY EVENING TROUGH THURSDAY MORNING. EXPECT POSSIBLE THUNDERSTORMS DURING THE AFTERNOON AND EVENING HOURS WITH SHOWERS IN THE OVERNIGHT HOURS. RSMITH && .AVIATION... THE KGGW AND KOLF TERMINALS ARE AT VFR BUT COULD SEE SOME IFR/LIFR CONDITIONS BY MORNING DUE TO PATCHY DENSE FOG DEVELOPMENT. THIS IS A RESULT OF THE LIGHT WINDS...CLEARING SKIES AND ABUNDANT GROUND MOISTURE. THIS WILL RESULT IN MOSTLY LOWER CEILING BUT VISIBILITIES COULD DROP BELOW 2 MILES AT TIMES. THE KSDY AND KGDV TERMINALS ARE FURTHER TO THE EAST AND MAY STAY MVFR/IFR INTO THE MORNING DUE TO LOWER CEILINGS. THE WINDS AT THESE TERMINALS WILL CONTINUE TO GUSTY OUT OF THE NW ABOVE 25 KNOTS. RSMITH && .HYDROLOGY... RAINFALL ENDED ACROSS THE REGION LAST EVENING WITH RUNOFF CONTINUING TO MOVE INTO AREA STREAMS...CREEKS AND RIVERS. GREATEST RESPONSE FROM THE HEAVY RAIN WAS ON THE MUSSELSHELL RIVER AND ITS TRIBUTARY STREAMS...AND THE CREEKS IN SOUTHERN VALLEY COUNTY. RISES ARE OCCURING ON OTHER STREAMS AND CREEKS ALONG WITH MINOR FIELD FLOODING BUT NO SIGNIFICANT PROBLEMS HAVE BEEN REPORTED. && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && WEATHER.GOV/GLASGOW
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GLASGOW MT 346 AM MDT WED MAY 11 2011 MTZ016>027-059>062-121000- CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY- DANIELS-SHERIDAN-WESTERN ROOSEVELT-PETROLEUM-GARFIELD-MCCONE- RICHLAND-DAWSON-PRAIRIE-WIBAUX-NORTHERN PHILLIPS- SOUTHWEST PHILLIPS-NORTHERN VALLEY-EASTERN ROOSEVELT- 346 AM MDT WED MAY 11 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...TODAY AND TONIGHT WIDESPREAD MINOR FLOODING WITH A FEW AREAS OF MORE SIGNIFICANT FLOODING WILL PERSIST TODAY AS RUNOFF FROM RECENT HEAVY RAIN MOVES INTO AREA CREEKS AND STREAMS. SHARP RISES ON THE MAIN STEM RIVERS ARE ALSO EXPECTED OVER THE NEXT FEW DAYS IN RESPONSE TO THE RUNOFF. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
The river gauge at Glasgow rose above flood stage on May 11th, cresting at 28.23 feet on the 12th. The river fell below flood stage on the 15th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2011Every state in 2011This day in weather historyWarnings in Montana, May 2011
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: 309647.