Atmospheric conditions combined to allow stronger winds aloft to suddenly reach the ground.
Every event with a place to put it; 2 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.
Atmospheric conditions combined to allow stronger winds aloft to suddenly reach the ground.
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 26, 9:25 AM MST, 1 hour 35 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 1025 AM MDT THU APR 26 2012 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY... TIGHT SURFACE PRESSURE GRADIENTS TO REMAIN ALL DAY BETWEEN THE LOWER PRESSURE OVER W MT...AND A LARGE AND STRONG ARCTIC HIGH...THAT IS CENTER WELL TO OUR N OVER N CANADA. STRONGEST ENHANCED MILK VALLEYS WINDS WILL CONTINUE AROUND GLASGOW..GUSTING TO NEAR 50 MPH. 12 KGGW SOUNDING SHOWING THE STRONG COOLING BELOW 800 MB PAST 24 HOURS. DEPTH OF THE COOLER AIRMASS ABOUT 3K FT OVER GGW. ABOUT A 20F TEMP DIFFERENCE BETWEEN OUR NE AND OUR SW THIS MORNING. WILL LOWER HIGHS IN AREAS THAT ARE STILL ONLY IN THE UPPER 30S AND LOWER 40S AT 9 AM. SATELLITE CHANNELS SHOW PLENTY OF MOISTURE TO WORK WITH AS UPPER FLOW TURNS SW. THERE IS A BIT OF A DRY SLOT THOUGH BETWEEN THE SUBTROPICAL FLOW AND THE PACIFIC BRANCH OF THE FLOW. THIS SHOWING IN OUR SE. THE CONTINUED WARM AIRMASS ALOFT WITH COOLING IN THE LOWER LEVELS IS INCREASING ISENTROPIC LIFT. WITH A COUPLE OF WEAK SHORTWAVES ALSO INDICATED BY MODELS...AND INSTABILITY ALOFT...ISOLATED SHOWERS AND EVEN A THUNDERSTORM POSSIBLE THIS AFTERNOON. MINOR UPDATE TO ADJUST HIGHS AND POPS FOR TODAY. SIMONSEN PREVIOUS SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SATURDAY...TIGHT SURFACE GRADIENT BETWEEN LOW PRESSURE SYSTEM IN WESTERN MONTANA AND HIGH PRESSURE SYSTEM IN MANITOBA WILL BRING STRONG EAST WINDS TO THE FORECAST AREA TODAY. THE GLASGOW AND FORT PECK AREAS WILL SEE THE STRONGEST WINDS WITH THE FUNNELING OF THE MILK AND MISSOURI VALLEYS. WINDS THERE WILL APPROACH HIGH WIND WARNING CRITERIA OF 40 MPH SUSTAINED WITH GUST TO 58 MPH BUT SHOULD STAY BELOW IT. WILL HOLD OFF ON ISSUING A HIGH WIND WARNING FOR NOW. WILL MAINTAIN LAKE WIND ADVISORY THROUGH TONIGHT. UPPER RIDGE MOVES TO THE EAST TODAY TURNING THE FLOW ALOFT TO THE SOUTHWEST AHEAD OF AN UPPER TROUGH AND LOW THAT WILL BE MOVING INLAND ACROSS THE PACIFIC NORTHWEST. THIS WILL BRING INCREASING MOISTURE INTO EASTERN MONTANA AT THE SAME TIME THERE WILL BE ADDITIONAL LOW LEVEL MOISTURE ADVECTING NORTH INTO THE AREA FROM THE GULF OF MEXICO. MAY SEE A FEW INSTABILITY SHOWERS AND THUNDERSTORMS THIS AFTERNOON WITH SOMEWHAT UNSTABLE AIR. THE MOISTURE FROM THE WEST WILL BE OVERRUNNING A FRONTAL BOUNDARY OVER WESTERN MONTANA TODAY. BY SOMETIME TONIGHT...THE ATMOSPHERE WILL BECOME MOIST ENOUGH FOR WIDESPREAD RAIN TO DEVELOP. MODELS STILL DIFFER SOMEWHAT ON HOW QUICKLY RAIN WILL DEVELOP AND THE TIMING OF DRY SLOTS ACROSS EASTERN MONTANA. WILL KEEP RAIN LIKELY IN THE FORECAST FOR NOW. BY FRIDAY MORNING...THE SURFACE LOW AND UPPER LOW BECOME STACKED OVER EASTERN MONTANA. IT IS DURING THE DAY ON FRIDAY INTO FRIDAY NIGHT THAT DEEP MOISTURE AND LIFT COME TOGETHER TO PRODUCE WIDESPREAD RAIN THAT COULD ACCUMULATE TO A HALF INCH TO INCH OF RAIN. OMEGA BLOCKING RIDGE TO THE EAST WILL KEEP THIS LOW IN PLACE THROUGH SATURDAY. SOMEWHAT COLDER AIR FRIDAY NIGHT WILL ALLOW FOR A MIX OF RAIN AND SNOW IN SOME HIGHER ELEVATION AREAS FRIDAY NIGHT INTO SATURDAY MORNING. OTHERWISE...LOOK FOR A COLD RAIN. WHILE THE STACKED LOW REMAINS OVER EASTERN MONTANA ON SATURDAY...THE GULF OF MEXICO MOISTURE CONNECTION GETS CUT OFF FRIDAY NIGHT. THE PRECIP AMOUNTS WILL BE LESS THAN THEY WERE ON FRIDAY WILL MAINTAIN LIKELY POPS IN MOST AREAS FOR SATURDAY. .LONG TERM...SATURDAY NIGHT THROUGH THURSDAY... THE LONG TERM FORECAST STARTS OFF SATURDAY NIGHT WITH A BLOCKING UPPER RIDGE OVER MANITOBA AND THE GREAT LAKES. A LARGE CLOSED VERTICALLY STACKED SYSTEM OVER EASTERN MONTANA. MODELS HAVE BEEN FAIRLY CONSISTENT AND ARE IN AGREEMENT WITH THIS SYSTEM MOVING NORTHEAST INTO SASKATCHEWAN SATURDAY NIGHT INTO SUNDAY. EXPECT MOSTLY RAIN WITH SOME LIGHT SNOW MIXED IN WITH THE RAIN FALLING ACROSS THE WESTERN AND CENTRAL ZONES BY SUNDAY MORNING. LITTLE TO NO ACCUMULATION IS EXPECTED UNLESS YOU LIVE IN NORTHERN VALLEY...DANIELS AND SHERIDAN COUNTIES...WHICH MIGHT BE THE AREAS THAT GETS A LITTLE SNOW ACCUMULATION SUNDAY MORNING. IT WILL REMAIN LESS THEN AN INCH IF ANY SNOW ACCUMULATION HAPPENS. MODELS ARE SHOWING BETWEEN .07 TO .15 HUNDREDTHS OF AN INCH QPF OVER OUR CWA SATURDAY NIGHT THROUGH SUNDAY MORNING. SUNDAY NIGHT INTO MONDAY EXPECT A SLOW DRYING AND WARMING TREND WITH A FEW LINGERING SHOWERS LASTING INTO MONDAY AFTERNOON. TUESDAY THROUGH THURSDAY MORNING ALL MODELS ARE SHOWING ZONAL FLOW WITH WEAK DISTURBANCES MOVING ACROSS EASTERN MONTANA CAUGHT IN THE FLOW. TIMING OF THESE DISTURBANCES IS A BIT DIFFICULT WITH THE BEST CHANCE LOOKING TO BE ON TUESDAY. LEFT A SLIGHT CHANCE OF SHOWERS AND INCLUDED SLIGHT CHANCE OF THUNDERSTORMS TUESDAY AFTERNOON AS THE REGION LOOKS TO BE SLIGHTLY UNSTABLE. RSMITH && .AVIATION... BROKEN VFR CEILINGS EXPECTED THROUGH THE FORECAST PERIOD. THE STRONG SOUTHEAST WINDS WILL CONTINUE INTO FRIDAY WITH TODAY BEING SLIGHTLY STRONGER. RAIN WILL MOVE INTO THE AREA TONIGHT BRINGING MVFR CONDITIONS...IFR CONDITIONS FRIDAY. JAMBA && .GLASGOW WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY UNTIL 6 AM MDT FRIDAY FOR FORT PECK LAKE. && WEATHER.GOV/GLASGOW
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GLASGOW MT 432 AM MDT THU APR 26 2012 MTZ018>020-024>027-059>062-271015- DANIELS-SHERIDAN-WESTERN ROOSEVELT-RICHLAND-DAWSON-PRAIRIE-WIBAUX- NORTHERN PHILLIPS-SOUTHWEST PHILLIPS-NORTHERN VALLEY- EASTERN ROOSEVELT- 432 AM MDT THU APR 26 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...TODAY AND TONIGHT STRONG EAST TO SOUTHEAST WINDS 20 TO 35 MPH WITH GUSTS TO 45 MPH WILL CONTINUE TODAY AND TONIGHT. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY FRIDAY AND FRIDAY NIGHT...A STRONG AND WET STORM SYSTEM WILL IMPACT NORTHEAST MONTANA. WIDESPREAD SIGNIFICANT STEADY RAINFALL IS EXPECTED. SOME LOCATIONS MAY RECEIVE STORM TOTAL AMOUNTS OF UP TO AN INCH OF RAIN. THE RAIN COULD MIX WITH OR TURN TO SNOW OVER NEAR THE CANADIAN BORDER AND HIGHER ELEVATIONS OF THE LITTLE ROCKY MOUNTAINS FRIDAY NIGHT. THE PRECIPITATION WILL LINGER INTO SATURDAY OVER MOST OF THE AREA. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. MTZ016-017-021>023-271015- CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY- PETROLEUM-GARFIELD-MCCONE- 432 AM MDT THU APR 26 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...TODAY AND TONIGHT A LAKE WIND ADVISORY IS IN EFFECT UNTIL 6 AM FRIDAY MORNING FOR EAST WINDS 25 TO 40 MPH WITH GUSTS TO 50 MPH. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY FOR FRIDAY AND FRIDAY NIGHT...A STRONG AND WET STORM SYSTEM WILL IMPACT NORTHEAST MONTANA. WIDESPREAD SIGNIFICANT STEADY RAINFALL IS EXPECTED. SOME LOCATIONS MAY RECEIVE STORM TOTAL AMOUNTS OF UP TO AN INCH OF RAIN. RAIN MAY MIX WITH OR CHANGE TO SNOW NEAR THE CANADIAN BORDER FRIDAY NIGHT. THE PRECIPITATION WILL LINGER INTO SATURDAY IN MOST AREAS. .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.
2 high wind. Local standard time, as filed.
Sustained winds above 40 mph were common across the county throughout the entire day with a peak wind gust of 60 mph recorded at 7:58 PM MDT at the Beaver Hill I-94 DOT site.
Sustained wind speeds near 40 mph were measured throughout the afternoon at the Lindsay Divide MT-200 DOT site.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2012Every state in 2012This day in weather historyWarnings in Montana, April 2012
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: 376254, 376255.