An upper trough moved into the Western United States, helping to develop an intense surface low pressure system. This low moved into the northern Plains with intense wrap around cold air, wind and snow.
Every event with a place to put it; 10 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.
An upper trough moved into the Western United States, helping to develop an intense surface low pressure system. This low moved into the northern Plains with intense wrap around cold air, wind and snow. The hardest hit areas were zones close to the North Dakota border.
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 Apr 29, 9:43 PM MST, 1 hour 17 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 1043 PM MDT FRI APR 29 2011 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY... EVENING UPDATE... MINOR UPDATE ISSUED FOR TONIGHT WAS FOCUSED ON INCREASING WINDS ENTERING THE REGION BEHIND THE COLD FRONT. A BLIZZARD WARNING CONTINUES TO REMAIN OUT FOR THE EASTERN MOST COUNTIES WHERE A TROWAL WILL WRAP AROUND A LOW PRESSURE CENTER OVER WESTERN NORTHERN DAKOTA AND GENERATE SNOW SHOWERS AND REDUCED VISIBILITIES FROM STRONG WINDS. AS OF 930PM LIGHT CONVECTIVE RAIN SHOWERS ARE CURRENTLY EXITING THE MISSOURI BREAKS AND MOVING SOUTH AS A COLD FRONT PRESSES THROUGH THE REGION OVERNIGHT. BEHIND THIS FRONT CLEARING SKIES AND COLD WINDY CONDITIONS OF 30 TO 35 MPH WITH SOME GUSTS UP TO 45 ARE POSSIBLE... ESPECIALLY ACROSS THE WESTERN PORTION OF THE CWA. GAH PREVIOUS SHORT TERM DISCUSSION... A VERY STRONG STACKED LOW PRESSURE SYSTEM IS GOING TO QUICKLY DEVELOP THIS EVENING OVER FAR WESTERN NORTH DAKOTA. AS IT DOES SO A FULLY DEVELOPED TROUGH OF WARM AIR ALOFT IS GOING TO DEVELOP...DRIVING HEAVY PRECIPITATION ALONG THE BACKSIDE OF THIS SYSTEM OVER FAR EASTERN MONTANA. VERY STRONG WINDS ARE EXPECTED AS THE LOW DEEPENS. THIS COMBINATION OF SNOW AND VERY STRONG WINDS WILL CREATE BLIZZARD CONDITIONS ALONG THE NORTH DAKOTA BORDER...WITH SIGNIFICANT SNOW AND BLOWING SNOW JUST INSIDE THE BORDER. THUS ISSUED BLIZZARD WARNINGS AND WINTER WEATHER ADVISORIES FROM THIS EVENING INTO SATURDAY. A LAKE WIND ADVISORY WAS ALSO ISSUED FOR FORT PECK LAKE GIVEN NOW OPEN WATERS AND STRONG WINDS. WITH ALL THAT SAID...SURFACE TEMPERATURES ARE QUITE WARM THUS DO NOT EXPECT MAJOR ACCUMULATIONS OF SNOW. BUT AS IT WILL BE A HEAVY WET SNOW DO EXPECT SIGNIFICANT HAZARDS FOR POWER POLES...TREES...AND NEWBORN LIVESTOCK. BY MIDDAY SATURDAY EXPECT MOST OF THE SNOWFALL TO HAVE TAPERED OFF...ALTHOUGH WINDS WILL ONGOING. GAVE A BIT OF WIGGLE ROOM ON THE BLIZZARD WARNING EXPIRATION TIME TO ACCOUNT FOR ANY CONTINUING BLOWING SNOW CONCERNS...OR IF THE SYSTEM SLOWS DOWN. SATURDAY EVENING INTO SUNDAY A NORTHWEST FLOW ALOFT WILL BUILD IN BEHIND THE EXITING SYSTEM...WARMING TEMPS. WINDS WILL ALSO DECREASE...HOWEVER WEAK DISTURBANCES IN THIS FLOW WILL KEEP ISOLATED SHOWERS IN THE FORECAST. GILCHRIST .LONG TERM...SUNDAY NIGHT THROUGH FRIDAY... THE EXTENDED FORECAST WILL CONTINUE TO REMAIN UNSETTLED AS IT UNDERGOES A SERIES OF TRANSITIONS. THE FORECAST BEGINS WITH A RIDGE BUILDING OVER THE REGION AND THIS WILL ALLOW TEMPERATURES TO WARM TO NEAR SEASONAL AVERAGES. THE RIDGE WILL SHIFT EAST INTO THE NORTHERN PLAINS AS AN UPPER TROUGH PUSHES SOUTHEAST INTO SOUTHERN BRITISH COLUMBIA AND THE PACIFIC NORTHWEST MONDAY NIGHT AND TUESDAY. THIS FEATURE WILL BRING CHANCES FOR RAIN SHOWERS FOR EASTERN MONTANA. THE CHANCES FOR PRECIPITATION WILL DIMINISH LATE WEDNESDAY AS THIS TROUGH PROPAGATES EASTWARD BY A BUILDING RIDGE OVER THE WEST COAST. TEMPERATURES WILL REBOUND THURSDAY AND FRIDAY AS THE RIDGE MOVES OVERHEARD. THE MODELS BEGIN TO DIFFER TOWARDS THE END OF THE FORECAST. HOWEVER...THEY DO INDICATE THAT ANOTHER UPPER LEVEL TROUGH WILL SWING THROUGH THE PACIFIC NORTHWEST INTO MONTANA BRINGING ANOTHER ROUND OF PRECIPITATION. AES && .AVIATION... THE SPRING STORM CONTINUES TO INCREASE IN STRENGTH AS THE SURFACE LOW AND UPPER LOW STACK UP. THIS EVENING THE LOW CENTER WILL MOVE INTO NORTH DAKOTA. PRECIPITATION WILL WRAP AROUND THE LOW AND APPROACH THE LOCAL TAF SITES FROM THE NORTH. IN ADDITION NORTHERLY WINDS WILL CONTINUE STRONG TONIGHT...ESPECIALLY AT THE EASTERN TAF SITES. CLOUD COVER WILL INCREASE AND LOWER THIS EVENING WHICH WILL LEAD TO MVFR CEILINGS. RAIN AND SNOW SHOWERS THAT HAVE DEVELOPED THIS AFTERNOON ARE EXPECTED TO CONTINUE OVERNIGHT. KGGW AND KOLF WILL HAVE GUSTY NORTHWEST WINDS 15 TO 25 MPH FOR MOST OF THE FORECAST PERIOD...KSDY AND KGDV WILL SEE WINDS INCREASING AFTER MIDNIGHT TO SPEEDS UP TO 40MPH. PERIODS OF MVFR AND IFR VISIBILITY ARE POSSIBLE OVERNIGHT AND EARLY SATURDAY MORNING. FLIGHT CATEGORIES ARE EXPECTED TO IMPROVE BY LATE SATURDAY MORNING AS WINDS AND CHANCES FOR PRECIPITATION DIMINISH. AES/SCT && .HYDROLOGY... THE MILK RIVER CONTINUES ITS VERY SLOW DECLINE FROM TAMPICO TO NASHUA. THE RIVER AT TAMPICO IS BELOW FLOOD STAGE. THE RIVER AT GLASGOW AND NASHUA ARE AT MINOR FLOOD STAGE AND GRADUALLY FALLING. THIS TREND SHOULD CONTINUE FOR AT LEAST THE NEXT WEEK. HOWEVER...A SIGNIFICANT AMOUNT OF SNOW CONTINUES TO BE ON THE GROUND IN THE CYPRESS HILLS REGION OF SOUTHWEST SASKATCHEWAN AND SOUTHEAST ALBERTA. WHEN THIS SNOW MELTS IT WILL FLOW DOWN FRENCHMAN CREEK...ENTERING THE MILK RIVER NEAR SACO SOMETIME IN MAY. ALTHOUGH THE EXACT TIMING OF THE MELT IS UNCERTAIN...WHEN THIS SNOWMELT OCCURS ANOTHER RISE ON THE MILK RIVER WILL LIKELY ACCOMPANY IT. THE MAGNITUDE AND TIMING OF THIS NEXT RISE IS UNCERTAIN AT THIS TIME. && .GLASGOW WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY UNTIL 8 PM MDT SATURDAY FOR FORT PECK LAKE. WINTER WEATHER ADVISORY UNTIL NOON MDT SATURDAY FOR DANIELS... WESTERN ROOSEVELT...MCCONE...PRAIRIE. BLIZZARD WARNING UNTIL 2 PM MDT SATURDAY FOR SHERIDAN... RICHLAND...DAWSON...WIBAUX...EASTERN ROOSEVELT. && WEATHER.GOV/GLASGOW
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GLASGOW MT 326 PM MDT FRI APR 29 2011 MTZ016-017-021-022-301200- CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY- PETROLEUM-GARFIELD- 326 PM MDT FRI APR 29 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...THIS AFTERNOON AND TONIGHT A FLOOD WARNING CONTINUES FOR THE MILK RIVER. A SPRING STORM WILL BRING RAIN TODAY AND RAIN CHANGING TO SNOW TONIGHT. SNOW ACCUMULATION OF AROUND AN INCH IS POSSIBLE TONIGHT AND SATURDAY. THERE IS ALSO THE POTENTIAL FOR STRONG NORTHERLY WINDS THIS AFTERNOON AND TONIGHT. A LAKE WIND ADVISORY IS IN EFFECT FOR FORT PECK LAKE. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY STRONG NORTHWEST WINDS WILL CONTINUE THROUGH THE DAY SATURDAY. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. MTZ059>061-301200- NORTHERN PHILLIPS-SOUTHWEST PHILLIPS-NORTHERN VALLEY- 326 PM MDT FRI APR 29 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...THIS AFTERNOON AND TONIGHT A SPRING STORM WILL BRING RAIN CHANGING TO SNOW TONIGHT. SNOW ACCUMULATION OF AROUND AN INCH OR SO IS POSSIBLE TONIGHT AND SATURDAY. STRONG NORTHWESTERLY WINDS WILL ACCOMPANY THE STORM TONIGHT INTO SATURDAY. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY 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. MTZ018>020-023>027-062-301200- DANIELS-SHERIDAN-WESTERN ROOSEVELT-MCCONE-RICHLAND-DAWSON-PRAIRIE- WIBAUX-EASTERN ROOSEVELT- 326 PM MDT FRI APR 29 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...THIS AFTERNOON AND TONIGHT A VERY STRONG SPRING STORM SYSTEM WILL BRING ACCUMULATING SNOWFALL AND STRONG NORTHWEST WINDS TO THE AREA THIS EVENING INTO SATURDAY. A BLIZZARD WARNING IS IN EFFECT FOR SHERIDAN...EASTERN ROOSEVELT...RICHLAND...DAWSON...AND WIBAUX COUNTIES. A WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW IS IN EFFECT FOR DANIELS...WESTERN ROOSEVELT...MCCONE...AND PRAIRIE COUNTIES. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY THE STORM SYSTEM WILL EXIT THE REGION BY SATURDAY EVENING...ALLOWING WINDS TO SUBSIDE. .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.
5 high wind, 5 blizzard. Local standard time, as filed.
At 0200 MST, Rockglen Saskatchewan reported several hours with winds sustained over 30 mph and frequent gusts over 45 mph. A Ham Radio operator/weather spotter had sustained winds in the 40s with gusts over 50 mph a few times from 0200 to 1400 MST.
McDonald's DOT sensor had sustained winds from 45 to 65 mph. The Wolf Point ASOS only reported winds between 35 to 50 mph.
Plentywood reported sustained winds between 35 and 50 mph with a gust to 61 mph while the Crosby, ND RAWS reported a gust to 78 mph. Whiteout conditions were reported by Law Enforcement on Highway 5. Electricity was lost in Wesby with winds estimated to peak at 80 mph. This created drifts to 6 feet deep, uprooted a 300 foot tall pine tree (with a 15 to 20 inch diameter trunk) and rotated a stop sign.
Poplar RAWS reported sustained winds of 40 mph while the DOT sensor at the state line reported a gust to 75 mph before power was lost at 0430 MST April 30th. Visibility of only 10 feet and drifts of 3 to 4 feet helped cause vehicles from Bainville to the North Dakota state line get stuck or slide off of U.S. Highway 2. County Emergency Manager reported that the wind and snow combined knocked out power to an estimated 1500 customers in Eastern Roosevelt and Sheridan Counties. Also on April 30th, a box car from a freight train grabbed low hanging power lines and power poles and dragged them along, ripping up fences.
Beaver Hill RAWS reported winds sustained above 40 mph with a gust to 64 mph. Blizzard conditions were reported by the Emergency Manager with trucks sliding off of I-94 and stuck in ditches on Highway 7 along with plows. 4 to 5 foot drifts were common. 12 inches of new snow were reported near Carlyle.
At 1244 MST, King Coulee RAWS reported a measured wind gust of 58 mph, At 1506 MST, Nashua reported sustained winds over 45 mph with sustained winds over 40 mph since 1155 MST.
The Glendive AWOS reported several hours of sustained winds above 40 mph through 1600 MST with a gust to 67 mph. Lindsay Divide had similar winds with a gust to 59 mph. A small amount of snow fell too with the most being reported (2) at 2 miles west of Bloomfield. Blizzard conditions were reported over most of the county. Power was lost at 0235 MST in the Lindsay area.
The Hillside DOT sensor had sustained winds of over 40 mph with peak gusts near 60 mph. The Jordan ASOS had sustained winds over 40 mph with frequent gusts over 50 mph.
Winds at Fallon were sustained over 35 mph with a peak gust of 67 mph. A gust to 61 mph were reported at Big Sheep RAWS.
Winds were sustained at 35 to 45 mph with gusts to 60 mph for several hours. A peak gust of 75 mph was reported at the Sioux Pass DOT station. Snow amounts ranged from 2 to 8 inches, which contributed to the blizzard conditions. Power lines and trees were knocked down by the heavy/wet snow and damaging winds.
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, April 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: 289972, 305786, 305834, 305884, 307054, 305776, 307044, 305789, 305804, 305891.