This occurred just in Wibaux County, where strong mid-level winds mixed to the surface.
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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 GGW wrote it up.
This occurred just in Wibaux County, where strong mid-level winds mixed to the surface.
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 16, 8:03 AM MST, 42 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 903 AM MDT MON MAY 16 2011 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH WEDNESDAY... UPDATE...SURFACE TROUGH LOCATED NEAR CUT BANK AND BILLINGS AT 15Z WITH TIGHT SURFACE GRADIENT OVER EASTERN MONTANA. STRONG SOUTHEAST WINDS WILL CONTINUE FROM FORT PECK LAKE EAST TODAY. HIGH WIND WARNING FOR WIBAUX COUNTY LOOK REASONABLE AT THIS POINT. ISOLATED SHOWERS EAST OF THE TROUGH BETWEEN HAVRE AND LEWISTOWN MAY AFFECT THE WESTERN ZONES LATER TODAY. WILL MENTION A SLIGHT CHANCE FOR NOW. FORRESTER PREVIOUS SHORT TERM... AS THE AMPLIFIED UPPER RIDGE THAT HAS BROUGHT US DRY CONDITIONS TREKS EAST THE LONG-WAVE UPPER TROUGH CENTERED OVER THE PACNW WILL PUT NORTHEAST MONTANA UNDER THE SOUTHERLY JET OFF THE TROUGH BASE. ASSOCIATED WITH THIS TROUGH WILL BE A FRONTAL BOUNDARY IN PARALLEL WITH THE UPPER LEVEL SOUTHERLY FLOW. THIS WILL LIKELY MOVE OVER NEMONT THIS EVENING. THIS WILL INTRODUCE A PATTERN CHANGE FROM DRY TO WET. TODAY...BY MID MORNING A SURFACE TROUGH WILL EXTENDED FROM THE CANADIAN ROCKIES TO ROUGHLY BILLINGS. THIS TROUGH...ALONG WITH A LARGE SURFACE HIGH AREA TO THE EAST HAVE CREATED A STRONG EAST- WEST GRADIENT ACROSS NEMONT. AS THE TROUGH SLIDES FARTHER EAST TODAY THE WIND WILL DIMINISH FROM THE WEST. THIS SHOULD ALLOW WIND TO DIMINISH BELOW 15-20 KTS ALLOWING THE LWA TO END BY EVENING. 850MB WIND STRENGTH RUNS AT AROUND 50KTS AT 12Z THEN WEAKENS TO 35-40KTS BEFORE MIXING COMES INTO FULL AFFECT. WOULD LIKE TO SEE 50KTS CONTINUE INTO MID-MORNING BEFORE ISSUING A HIGH WIND WARNING FOR VALLEY COUNTY. THE STRONGER WINDS ALOFT MOVE EAST SO UPGRADED WATCH TO WARNING FOR WIBAUX COUNTY. THE STRONG WINDS COMBINED WITH LOW RH VALUES APPROACH RED FLAG CRITERIA. BUT HELD OFF DUE TO THE GREENING UP FROM RECENT RAINS. THE SURFACE TROUGH SHOULD ALLOW INCREASED CLOUDINESS FROM THE WEST DURING THE DAY. MODELS SUGGEST THE FRONTAL BOUNDARY WILL REMAIN TO OUR WEST FOR MOST OF THE DAY. TONIGHT...ALL MODELS MOVE THE FRONT ACROSS NEMONT THIS EVENING WITH SUFFICIENT CONVECTION PARAMETERS TO PRODUCE THUNDER. THE BILLINGS CWA HAS SUFFICIENT INSTABILITY TO POSSIBLY PRODUCE A HAZARDOUS STORM OR TWO...WHICH COULD TRAVEL NORTH INTO OUR AREA. IN THE EVENING THE EASTERN ZONES DEVELOP QUITE STRONG WINDS AT 850MB OF 50 KTS. IF A THUNDERSTORM TAPS INTO THOSE WINDS THEY COULD BE BROUGHT TO THE SURFACE FOR LOCALLY HIGH WINDS. INCREASED POPS AND QPF FOR THIS EVENING AND TONIGHT...MAINLY IN THE CENTRAL ZONES. TUESDAY THROUGH WEDNESDAY...THE SHORT TERM MODELS DIFFER SOMEWHAT ON THE BOUNDARY POSITION. BUT WHEREVER THE BOUNDARY IS WILL SEE SOME HEAVIER RAIN. WITH THE ENTIRE TROUGH SLOWLY SHIFTING EAST IT IS LIKELY THE AREA OF HEAVIER RAIN WILL IN OUR EASTERN ZONES TUESDAY MORNING. THE SURFACE TROUGH WILL TAP INTO SOME OF THE GULF MOISTURE AND SEND IT NORTH ADDING TO THE PACIFIC MOISTURE...UPPING THE QPF FOR WEDNESDAY. THE TUESDAY AFTERNOON CONVECTIVE PARAMETERS LOOK SIMILAR TO MONDAY...BUT WEDNESDAY COULD BE MUCH MORE ACTIVE...ESPECIALLY IN THE SOUTHWEST ZONES. SCT .LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY... EXTENDED PERIOD FEATURES UPPER LOW CURRENTLY MOVING ACROSS THE WEST COAST...PUSHING THROUGH THE GREAT BASIN AND INTO THE CENTRAL PLAINS. THIS WILL BRING UNSETTLED CONDITIONS OF WETTER AND A LITTLE COOLER WEATHER INTO NEXT WEEKEND. MODELS IN REASONABLY GOOD AGREEMENT BRINGING THE LOW ACROSS THE CENTRAL ROCKIES WEDNESDAY NIGHT THROUGH FRIDAY. ECMWF BEGINS TO DIVERGE FROM THE MODEL CONSENSUS BY THE END OF THE WEEK...BY HAVING THE LOW RETROGRADE SOMEWHAT TO THE NORTHWEST. REGARDLESS STACKED CLOSED LOW WILL PULL PLENTY OF MOISTURE NORTH...FROM THE PACIFIC AND FROM THE GULF...AND ROTATE IT INTO MONTANA FOR SOME POTENTIALLY MODERATE TO HEAVY QPF THURSDAY INTO FRIDAY. GREATER UNCERTAINTY AMONG MODELS OVER THE WEEKEND. UPPER LOW WEAKENS AS IT MOVES INTO THE CENTRAL PLAINS AND ANOTHER TROF DEVELOPS ALONG THE WEST COAST. CLIMO POPS AND TEMPERATURES LOOK GOOD FOR THIS PERIOD DUE TO LOW MODEL CONFIDENCE. EBERT && .AVIATION... VFR. STRONG WINDS WILL BE OF SOME CONCERN INTO THE EVENING. SOUTHEASTERLY WINDS AT 20 TO 35 KTS AND GUSTING UP TO 50 KTS WILL BE SPREADING EAST THROUGH THIS MORNING. LOW LEVEL WIND SHEAR WILL BE AN ISSUE EARLY...UNTIL THE WINDS FULLY MIX. THE STRONGER WINDS MAY LINGER ALONG THE NORTH DAKOTA BORDER OVERNIGHT. RAE && .HYDROLOGY... AREA RIVERS...CREEKS...AND STREAMS WILL CONTINUE TO FALL OVER THE NEXT FEW DAYS THANKS TO DRY WEATHER. A FLOOD ADVISORY EXPIRED THIS MORNING FOR THE MUSSELSHELL RIVER ON THE PETROLEUM/GARFIELD COUNTY LINE. THE MUSSELSHELL RIVER DROPPED BELOW FLOOD STAGE THIS MORNING. CONFIDENCE IS GROWING IN ANOTHER WET PACIFIC STORM SYSTEM IMPACTING NORTHEAST MONTANA TUESDAY INTO FRIDAY. SIGNIFICANT RAINFALL IS POSSIBLE WITH THIS SYSTEM...THEREFORE ADDITIONAL RISES ON AREA CREEKS...STREAMS AND RIVERS WILL BE POSSIBLE. PLEASE CONTINUE TO MONITOR THE LATEST FORECASTS FOR DETAILS. && .GLASGOW WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY UNTIL 6 PM MDT THIS EVENING FOR FORT PECK LAKE. HIGH WIND WARNING UNTIL 9 PM MDT THIS EVENING FOR WIBAUX. && WEATHER.GOV/GLASGOW
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GLASGOW MT 343 AM MDT MON MAY 16 2011 MTZ016-017-021>023-059>061-171100- CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY- PETROLEUM-GARFIELD-MCCONE-NORTHERN PHILLIPS-SOUTHWEST PHILLIPS- NORTHERN VALLEY- 343 AM MDT MON MAY 16 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...TODAY AND TONIGHT STRONG SOUTHEAST WINDS 25 TO 35 MPH WITH GUSTS TO 55 MPH WILL AFFECT THE AREA TODAY. A LAKE WIND ADVISORY IS IN EFFECT FOR FORT PECK LAKE THROUGH 6 PM WITH WINDS DIMINISHING DURING THE EVENING. A FLOOD ADVISORY REMAINS IN EFFECT FOR THE MUSSELSHELL RIVER ON THE PETROLEUM/GARFIELD COUNTY LINE. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY CONFIDENCE IS GROWING IN ANOTHER WET PACIFIC STORM SYSTEM IMPACTING NORTHEAST MONTANA TUESDAY INTO FRIDAY. SIGNIFICANT RAINFALL IS POSSIBLE WITH THIS SYSTEM...THEREFORE ADDITIONAL RISES ON AREA CREEKS...STREAMS AND RIVERS WILL BE POSSIBLE. PLEASE CONTINUE TO MONITOR THE LATEST FORECASTS FOR DETAILS. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. MTZ018>020-024>026-062-171100- DANIELS-SHERIDAN-WESTERN ROOSEVELT-RICHLAND-DAWSON-PRAIRIE- EASTERN ROOSEVELT- 343 AM MDT MON MAY 16 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...TODAY AND TONIGHT STRONG SOUTHEAST WINDS 25 TO 35 MPH WITH GUSTS TO 55 MPH WILL AFFECT THE AREA TODAY. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY CONFIDENCE IS GROWING IN ANOTHER WET PACIFIC STORM SYSTEM IMPACTING NORTHEAST MONTANA TUESDAY INTO FRIDAY. SIGNIFICANT RAINFALL IS POSSIBLE WITH THIS SYSTEM...THEREFORE ADDITIONAL RISES ON AREA CREEKS...STREAMS AND RIVERS WILL BE POSSIBLE. PLEASE CONTINUE TO MONITOR THE LATEST FORECASTS FOR DETAILS. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. MTZ027-171100- WIBAUX- 343 AM MDT MON MAY 16 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...TODAY AND TONIGHT A HIGH WIND WARNING IS IN EFFECT FOR WIBAUX COUNTY TODAY FROM 9 AM TO 9 PM FOR WIND UP TO 40 MPH WITH GUSTS TO 60 MPH. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY CONFIDENCE IS GROWING IN ANOTHER WET PACIFIC STORM SYSTEM IMPACTING NORTHEAST MONTANA TUESDAY INTO FRIDAY. SIGNIFICANT RAINFALL IS POSSIBLE WITH THIS SYSTEM...THEREFORE ADDITIONAL RISES ON AREA CREEKS...STREAMS AND RIVERS WILL BE POSSIBLE. PLEASE CONTINUE TO MONITOR THE LATEST FORECASTS FOR DETAILS. .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 high wind. Local standard time, as filed.
The Beaver Hill DOT sensor reported several hours of sustained winds over 40 mph with gusts over 55 mph. No damage was reported.
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: 307543.