Strong gradient winds produced a period of high winds during the morning and afternoon hours of the 21st. Sustained wind speeds of 40-45 mph were common, with wind gusts as high as 70 mph.
Every event with a place to put it; 15 filed by county or forecast zone are drawn at its center, in a lighter ring. 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.
Strong gradient winds produced a period of high winds during the morning and afternoon hours of the 21st. Sustained wind speeds of 40-45 mph were common, with wind gusts as high as 70 mph. An old grain bin in Peerless was blown over by the strong winds. There were numerous reports of downed tree branches, and shingles were blown off of some roofs across Valley and Daniels counties. A few of the stronger observed wind reports included:King Coulee RAWS site (Valley County): 64 mphComertown DOT site (Sheridan County): 70 mphSioux Pass DOT site (Richland County): 49 mph sustained
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 21, 7:55 AM MST, 1 hour 35 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 855 AM MDT SAT MAY 21 2005 .SHORT TERM FOR TODAY... WILL UPDATE TO REMOVE PRECIPITATION AS RADAR INDICATING ALL SHOWERS HAVE MOVED EAST. SATELITTE AND OBSERVATIONS SHOW MAINLY CLEAR SKIES IN NORTHEAST MONTANA. WILL KEEP HIGH WIND WARNING GOING AS GRADIENT TIGHTENS. BEST CHANCE IS IN FAR NORTHEAST ZONES WITH 60 KTS SHOWING UP ON THE NAM AT 00Z AT 700 MB. MIXING ALREADY TAKING PLACE THIS MORNING. THE 3 HOUR FORECAST SOUNDING FROM THE RUC...16Z SHOWS MIXING THROUGOUT THE BOUNDARY LAYER AND TAPPING INTO WINDS WELL INTO THE 40 KT RANGE. ALSO LAPSE RATES ON THE NAM ARE AT OR ABOVE 7.5 DEG C PER KM. AS SUNSET APPROACHES THE WINDS WILL SLOWLY DIMINISH. TEMPERATURES IN THE GRIDS LOOK GOOD SO WILL NOT UPDATE THOSE. SAME WITH SKY CONDITION. ADOLPHSON .PREVIOUS DISCUSSION...FOR NORTHEAST MONTANA TODAY THROUGH SUNDAY...AFTER AN ACTIVE EVENING AND EARLY MORNING WITH NUMEROUS WARNINGS (PROBABLY THE MOST SINCE 7/11/04) ATTENTION QUICKLY TURNS TO A HIGH WIND EVENT TODAY. AFTER A VERY ACTIVE 24+ HOUR PERIOD THE WEATHER SETTLES DOWN TONIGHT WITH A NICE LATE SPRING DAY FOR ALL OF NORTHEAST MONTANA SUNDAY. TODAY...SEVERE THREAT HAS COME TO AN END WITHIN THE LAST HOURS ...BUT NOT BEFORE MANY WARNINGS WERE ISSUED LAST EVENING AND EARLY THIS MORNING. SEVERAL REPORTS OF LARGE HAIL AND A REPORT OF DAMAGING WIND GUSTS FROM THE STORMS AS THEY MOVED THROUGH DAWSON...PRAIRIE...AND WIBAUX COUNTIES. I AM SURE THERE WILL BE MORE REPORTS OF SEVERE WEATHER THAT COME IN DURING THE DAY. THE SYSTEM IS NOW DEVELOPING INTO AN MCS ACROSS WESTERN AND CENTRAL NORTH DAKOTA. A STRONG SURFACE LOW HAS MOVED OUT OF NORTHERN WYOMING AND INTO NORTHWEST SOUTH DAKOTA. AN UPPER TROUGH PUSHING THROUGH THE CANADIAN ROCKIES WILL PUSH EAST TODAY AND IS PROGGED BY ALL OF THE OPERATIONAL MODELS TO STRENGTHEN AND DEVELOP INTO A DEEP VERTICALLY STACKED SYSTEM IN SOUTHERN MANITOBA. THE SEVERE WEATHER THREAT QUICKLY SHIFTS GEARS TO A HIGH WIND EVENT TODAY. AT THE SAME TIME THE SURFACE LOW DEEPENS AND LIFTS INTO MANITOBA A PACIFIC HIGH WILL BEGIN TO BUILD INTO THE NORTHERN ROCKIES...WITH ABOUT A 30MB PRESSURE DIFFERENCES BETWEEN THE TWO. THE GFS AND NAM IN MUCH BETTER AGREEMENT THAN LAST NIGHT WITH THE STRONG JET ON THE BACK SIDE OF THE SYSTEM. BOTH MODELS PROG THE STRONGEST WIND BETWEEN 850-700H ACROSS THE NORTHEAST CORNER OF OUR CWA WITH ABOUT 45KTS AT 850H AND 55KTS AT 700H. BUFKIT AND AWIPS MODEL SOUNDINGS SUGGEST STEEP LAPSE RATES IN EXCESS OF 7C/KM AND THE ABILITY TO EASILY MIX DOWN THE STRONGER WIND TO THE SURFACE. IN FACT LOOKS LIKE MUCH OF THE AREA MAY MIX DOWN FROM 600MB OR SO. PLAN TO UPGRADE THE HIGH WIND WATCH TO A WARNING FOR ALL BUT ARE FAR WESTERN ZONES. EXPECT THAT THE WIND PICKS UP TO SUSTAINED SPEEDS OF 35 TO 45 MPH WITH GUSTS TO 60 MPH. MORE MARGINAL IN PHILLIPS AND PETROLEUM COUNTIES WHERE I SUSPECT THE WIND WILL FALL JUST SHY OF WARNING CRITERIA...BUT WILL NEED TO KEEP A CLOSE EYE ON THINGS. LINGERING RAIN IN THE NORTHEAST CORNER WILL QUICKLY EXIT THE AREA EARLY THIS MORNING...AND THEN THE BEST CHANCE OF SHOWER DURING THE AFTERNOON WILL BE ACROSS OUR NORTHEAST ZONES CLOSEST TO THE DEVELOPING UPPER LOW. STRONG DOWNSLOPE AND SUBSIDENCE SHOULD HELP TO CLEAR OUT MUCH OF THE CWA WITH THE SKY TURNING M/SUNNY BY MID-MORNING ACROSS MOST OF THE AREA. TEMPERATURES WILL BE COOLER TODAY...BUT WITH A MILD START...GOOD MIXING...AND STRONG LATE MAY SUNSHINE TEMPERATURES WILL REBOUND TO 65-70 DEGREES ACROSS MOST OF THE CWA. TONIGHT...STACKED SYSTEM IN MANITOBA DRIFTS SLOWLY EAST/SOUTHEAST WITH SOME MID AND UPPER LEVEL RIDGING DEVELOPING ACROSS MONTANA BETWEEN THE DEPARTING LOW AND ANOTHER STRONG SYSTEM OFF THE BRITISH COLUMBIA COAST. AT THE SURFACE THE RIDGE IN THE NORTHERN ROCKIES SETTLES INTO MONTANA. THE WIND SHOULD QUICKLY DIMINISH AT SUNSET ACROSS MOST OF THE CWA AS THE ATMOSPHERE DECOUPLES AND WILL ALLOW THE WARNING TO EXPIRE AT 03Z. ACROSS OUR EASTERN MOST ZONES ALONG THE NORTH DAKOTA BORDER...CLOSEST TO THE JET...THE WIND SHOULD QUICKLY DIMINISH...BUT MAY REMAIN IN THE 20 TO 30 MPH RANGE WITH SOME HIGHER GUSTS FOR AN HOUR OR TWO PAST SUNSET. SUNDAY...FINALLY A QUIET WEATHER DAY THE UPPER RIDGE SHARPENS AND CRESTS ACROSS EASTERN MONTANA. THE SURFACE RIDGE WEAKENS AND SLIDES INTO THE HIGH PLAINS. THE NEXT STRONG 100+ KT JET PUNCHES INTO THE PACIFIC NORTHWEST AROUND A CLOSED LOW ALONG THE BRITISH COLUMBIA COAST. MAY START TO SEE AN INCREASE IN HIGH CLOUDS...MAINLY ACROSS OUR WESTERN ZONES DURING THE AFTERNOON. AFTER A COOL START...TEMPERATURES SHOULD REBOUND INTO THE L/M 70S ACROSS MOST OF THE CWA DURING THE AFTERNOON. CB .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY... MODELS REMAIN IN FAIR AGREEMENT AND ARE MUCH MORE CONSISTENT WITH UPPER LOW EVOLUTION MIDWEEK. THUS ONLY MINOR CHANGES WILL BE MADE TO THE FORECAST. SUNDAY NIGHT AND MONDAY...NEXT SHORTWAVE LIFTS FROM PACIFIC NORTHWEST INTO CENTRAL CANADA DURING THIS TIME FRAME. GFS CONTINUES TO GENERATE PRECIP ALONG WEAK COLD FRONT IN EASTERN MONTANA OVERNIGHT AND INTO THE MORNING. NAM IS FURTHER NORTH WITH THIS SHORTWAVE AND THUS DRIER AND SLOWER WITH THE WAVE. WILL CONTINUE WITH THE WETTER GFS SOLUTION BUT KEEP POPS LOW. MONDAY NIGHT THROUGH SATURDAY...GFS IS NOW WEAKER WITH THE UPPER LOW DEVELOPING OVER CENTRAL CANADA AND SURFACE LOW STRENGTHENS OVER SOUTHERN MANITOBA. THIS MAY BE TOO FAR EAST TO GENERATE MUCH PRECIP OVER NORTHEAST MONTANA DURING THIS PERIOD ALTHOUGH COOL CYCLONIC FLOW WILL LEAD TO THE POSSIBILITY OF AFTERNOON INSTABILITY SHOWERS. WILL KEEP TEMPERATURES ON THE HIGH SIDE OF THE ENSEMBLE GUIDANCE AS LONGER DAYS LEND THEMSELVES TO DEEP MIXED LAYER. EBERT && .GLASGOW WATCHES/WARNINGS/ADVISORIES...HIGH WIND WARNING FOR MTZ017>020-MTZ022>027-MTZ061-062 UNTIL 9 PM THIS EVENING. && WEATHER.GOV/GLASGOW
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GLASGOW MT 607 AM MDT SAT MAY 21 2005 MTZ016>027-059>062-221215- 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- 607 AM MDT SAT MAY 21 2005 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...TODAY AND TONIGHT A HIGH WIND WARNING IS IN EFFECT FOR MUCH OF NORTHEAST MONTANA TODAY. REFER TO GTFNPWGGW OR WWUS75 KGGW FOR MORE INFORMATION. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY NO HAZARDOUS WEATHER 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.
15 high wind. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2005Every state in 2005This day in weather historyWarnings in Montana, May 2005
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: 5453936, 5453933, 5453940, 5453934, 5453935, 5453942, 5453937, 5453941, 5453938, 5453939, 5453947, 5453943, 5453944, 5453945, 5453946.