An upper low to the west of the area coupled with a low level jet that brought an unstable airmass from the central plains to produce severe thunderstorms and an isolated tornado.
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.
An upper low to the west of the area coupled with a low level jet that brought an unstable airmass from the central plains to produce severe thunderstorms and an isolated tornado.
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 26, 1:31 PM MST, 6 hours 29 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 231 PM MDT WED MAY 26 2010 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH FRIDAY... AS THE WEAK SHORT WAVE UPPER RIDGE TODAY OVER EASTERN MONTANA GIVES WAY TO THE LARGE SCALE UPPER TROUGH TONIGHT SLOWLY ENCROACHING FROM THE WEST...MULTIPLE PERIODS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THROUGH THE REMAINDER OF THE WEEK. FROM 03Z TONIGHT THROUGH 15Z TOMORROW MORNING...GFS...NAM...AND SREF ALL INDICATE INCREASED CHANCES FOR HIGHER POPS AND QPF AS STORMS MOVE NORTHEAST THROUGH THE AREA...ESPECIALLY ACROSS OUR SOUTHEASTERN AND EASTERN PORTIONS. BUMPED UP POPS AND QPF GRIDS ACCORDINGLY FOR THOSE TIME PERIODS. ANY STRONGER STORMS WHICH MAY BECOME SEVERE LATE TONIGHT ARE EXPECTED TO BE CONFINED TO SOUTHERN AND SOUTHWESTERN PORTIONS OF OUR CWA. AFTER A BRIEF REPRIVE MID DAY THURSDAY...STORMS ARE EXPECTED TO BRING MORE PRECIP TO THE AREA...BEING CONFINED TO MORE NORTHERN PORTIONS THURSDAY EVENING THROUGH EARLY FRIDAY MORNING. SOME OF THE LATE THURSDAY STORMS MAY BECOME SEVERE. ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE LATER ON FRIDAY ALONG OUR NORTHWESTERN HALF CWA. WITH ONLY ONE DAY OF SUNNY SKIES...AND GROUND STILL NEARLY SATURATED...FELT IT WAS BEST TO ISSUE A FLOOD WATCH FOR THE ENTIRE CWA BEGINNING AT 03Z TONIGHT. AS STORMS BECOME MORE ORGANIZED TONIGHT...THE NEXT SHIFT WILL BE BETTER ABLE TO EITHER EXTEND THE WATCH OR POSSIBLY ISSUE MORE FINED TUNED FLOOD WARNINGS IF NECESSARY. BMICKELSON PREVIOUS SHORT TERM DISCUSSION...WEAK HIGH PRESSURE AND UPPER RIDGE MOVES ACROSS EASTERN MONTANA EARLY TODAY FOR DRY AND SUNNY CONDITIONS. THIS WILL ALLOW FOR CONTINUED SMOOTH MOVEMENT OF RUNOFF FROM RECENT HEAVY RAIN THROUGH THE AREA CREEKS AND STREAMS INTO THE RIVERS. THE INFLUENCE OF THE LARGE UPPER LOW OFF THE PACIFIC NORTHWEST WILL BEGIN TO BE FELT BY LATE TODAY AS A SHORTWAVE PUSHES THROUGH THE GREAT BASIN. TIGHTENING GRADIENT DUE TO PRESSURE FALLS OVER WESTERN WYOMING WILL DEVELOP LOW LEVEL JET INTO EASTERN MONTANA TODAY. THIS WILL INCREASE EAST WINDS OVER THE AREA ENOUGH FOR LAKE WIND ADVISORY BY LATE THIS AFTERNOON. AS UPPER LOW PUSHES ONSHORE THE LOW PRESSURE SYSTEM WILL MOVE SLOWLY INTO THE PLAINS THROUGH FRIDAY. THIS WILL KEEP EAST WINDS STRONG OVER THE REGION UNTIL AT LEAST THURSDAY EVENING. SOUTHWEST FLOW ALOFT PULLING WARM AIR NORTHWARD...AND WITH SOUTHEAST LOW LEVEL JET...THE IS ENOUGH SHEAR FOR THUNDERSTORM DEVELOPMENT NORTHEAST OF THE LOW PRESSURE SYSTEM. WHILE SEVERE THUNDERSTORMS ARE POSSIBLE...SOME LIMITING OF INSTABILITY IS BEING INDICATED BY THE MODELS DUE TO LOW LEVEL COLDER AIR EITHER LINGERING OR BEING DRAWN INTO THE SYSTEM FROM THE NORTH. BACKED OFF ON SEVERE WORDING ALTHOUGH SOME POTENTIAL EXISTS STILL FOR MAINLY THE SOUTHEAST ON THURSDAY AFTERNOON AND EVENING. COOLED TEMPERATURES FOR FRIDAY WITH THE EXPECTATION OF SURFACE LOW MOVING INTO NORTH DAKOTA AND MORE LOW LEVEL COLD AIR WRAPPING IN ALONG WITH RAIN AND CLOUDS. EBERT .LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY... SOME CHANGES WERE MADE TO SATURDAY NIGHT AND THE SUNDAY PERIOD AS MODELS ARE COMING INTO AGREEMENT WITH COLD UPPER LOW PASSING THROUGH THE AREA. TEMPERATURES WERE LOWERED ACCORDINGLY AND PRECIPITATION COULD MIX WITH SNOW IN SPOTS LATE SATURDAY NIGHT AND/OR SUNDAY. REST OF FORECAST LOOKED GOOD. JAMBA PREVIOUS DISCUSSION... FRIDAY NIGHT TROUGH MONDAY...A LARGE UPPER LEVEL TROF OVER THE WESTERN US CONTINUES DIGGING ALL THE WAY INTO THE GREAT BASIN. AT THE SAME TIME A LARGE AMPLIFIED UPPER LEVEL RIDGE REMAINS OVER THE CENTRAL PART OF THE NATION. SHORTWAVE ENERGY WILL ROUND THE BASE OF THE UPPER TROF AND EJECT AN UPPER LOW NORTHWARD FROM THE GREAT BASIN FRIDAY NIGHT AND INTO SOUTHERN ALBERTA BY SATURDAY AFTERNOON. A 700MB LOW WILL PUSH UP INTO EASTERN MONTANA AND OVER SOUTHERN SASKATCHEWAN DURING THE SAME TIME FRAME. GOOD CAPE VALUES ACROSS NORTHEAST MONTANA FRIDAY NIGHT INTO SATURDAY MORNING SHOULD HELP SUSTAIN THUNDERSTORMS. THE THUNDERSTORMS WILL BECOME JUST RAIN SHOWERS ON SATURDAY AND THE SHOWERS ACTIVITY WILL REMAIN LIKELY ACROSS NEMONT INTO SATURDAY EVENING. IT WILL BECOME MORE OF A CHANCE OF CONTINUED SHOWERS INTO SUNDAY AFTERNOON AND MONDAY. ALSO THE INSTABILITY STAYS EAST OF MONTANA OVER EASTERN NORTH DAKOTA SO TOOK OUT THE MENTION OF THUNDERSTORMS BOTH SUNDAY AFTERNOON AND SUNDAY EVENING AND ON MONDAY AS WELL. ALSO DROPPED THE DAYTIME HIGHS DOWN IN THE LOWER TO MID 50S BOTH SATURDAY AND SUNDAY AS THE CORE OF THE UPPER 500 MB LOW HEADS EASTWARD ACROSS SOUTHERN SASKATCHEWAN. THE ECMWF IS A LITTLE WARMER WITH 850 MB TEMPERATURES THAN THE GFS FOR SUNDAY AFTERNOON SO USED A BLEND OF THE TWO MODELS FOR HIGHS ON SUNDAY. UPPER FLOW BECOMES ZONAL ON MONDAY AND TUESDAY WITH A WEAK RIDGE TRYING TO BUILD IN BY WEDNESDAY. THE GFS IS INDICATING WEAK DISTURBANCES PASSING OVER HEAD ON TUESDAY WITH SOME INSTABILITY ACROSS SOUTHERN AND CENTRAL MONTANA. WENT AHEAD AND LEFT THE THUNDERSTORMS IN THE FORECAST FOR TUESDAY AFTERNOON AND EVENING. DRIED THINGS OUT SOME FOR WEDNESDAY AND WEDNESDAY NIGHT ACROSS THE REGION. RSMITH && .AVIATION... VFR CONDITIONS WILL DROP INTO THE MVFR RANGE LATER TONIGHT AS SHOWERS AND THUNDERSTORMS MOVE NORTHEAST. THERE COULD BE BRIEF PERIODS OF IFR CONDITIONS WITH THE HEAVIEST PRECIPITATION AND/OR FOG ESPECIALLY IN THE GLENDIVE AND SIDNEY AREAS. A MVFR CEILING MAY HANG AROUND THE AREA THURSDAY. JAMBA && .HYDROLOGY... AN ESFGGW AND A FFAGGW PRODUCTS ARE BEING ISSUED TO COVER THE TWO DIFFERENT TYPES FLOOD SITUATIONS FOR THE AREA. THE ESFGGW IS A HYDROLOGIC OUTLOOK HIGHLIGHTING THE FLOOD POTENTIAL ON THE MILK RIVER NEAR GLASGOW. THE FLOOD THREAT LOOKS LOWER THAN YESTERDAY AS IT IS EXPECTED TO CREST ABOUT A FOOT BELOW FLOOD STAGE ON THE 29TH. THE FLASH FLOOD WATCH WILL BE HIGHLIGHTING THE POTENTIAL FOR FLASH FLOODING ASSOCIATED WITH THUNDERSTORMS LATE THIS EVENING AND LATE TONIGHT. JAMBA && .GLASGOW WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH FROM 9 PM MDT THIS EVENING THROUGH LATE THURSDAY NIGHT FOR 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. LAKE WIND ADVISORY UNTIL 9 PM MDT THURSDAY FOR FORT PECK LAKE. && WEATHER.GOV/GLASGOW
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GLASGOW MT 409 PM MDT WED MAY 26 2010 MTZ016>027-059>062-272215- 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- 409 PM MDT WED MAY 26 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...THIS AFTERNOON AND TONIGHT AS THE NEXT LOW PRESSURE SYSTEM DEVELOPS OVER SOUTHWEST MONTANA...EAST WIND SPEEDS OF 25 TO 30 MPH AND A FEW GUSTS UP TO 40 MPH WILL CONTINUE THROUGH THE OVERNIGHT HOURS TONIGHT. A LAKE WIND ADVISORY IS IN EFFECT FOR FORT PECK LAKE THROUGH TONIGHT. ALTHOUGH WATER LEVELS ON AREA STREAMS HAVE SUBSIDED SLIGHTLY THANKS TO A WARMER AND DRIER DAY TODAY...SHOWERS AND THUNDERSTORMS WILL RETURN LATER TONIGHT. ALONG WITH HIGH WINDS AND HAIL...THE EXACT TRACKS AND TIMING OF THE STRONGER STORMS MAY RAISE ADDITIONAL FLASH FLOODING CONCERNS...ESPECIALLY ACROSS THE SOUTHERN HALF OF THE FORECAST AREA. A FLASH FLOOD WATCH IS IN EFFECT BEGINNING AT 9 PM TONIGHT FOR ALL OF NORTHEAST MONTANA. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY AS THE LARGE WESTERN U.S. LOW PRESSURE SYSTEM CONTINUES TO DEVELOP AND MOVE SLOWLY EASTWARD...EAST WINDS WILL REMAIN STRONG ENOUGH ACROSS FORT PECK LAKE TO CONTINUE THE LAKE WIND ADVISORY THROUGH THURSDAY NIGHT. THE FLASH FLOOD WATCH WILL CONTINUE THROUGH THE EARLY MORNING HOURS ON FRIDAY DUE TO REPEATED PERIODS OF RAINFALL EXPECTED FOR NORTHEAST MONTANA. STRONGER THUNDERSTORMS WILL BE POSSIBLE THURSDAY AFTERNOON AND EVENING ALONG AND NEAR A FRONTAL BOUNDARY STRETCHING ACROSS NORTHEAST MONTANA...WITH THE MAIN THREATS BEING LARGE HAIL AND DAMAGING WINDS...POSSIBLY EVEN AN ISOLATED TORNADO. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Glasgow radar (KGGW), 178 km away, was scanning. The volume nearest the first event began at 03:01 UTC.
9 hail, 3 flash flood, 1 heavy rain, 1 tornado. Local standard time, as filed.
CoCoRahs observer reported 1.12 inches of rainfall overnight. This brought the monthly total so far for him to 5.42 inches.
Two sets of storm chasers reported a rope tornado that touched down sometime between 854 and 859 pm MDT. There were some conflicts between reports on timing and exact location. One report had the tornado on the ground for 15 seconds.
A resident reported hail about the size of quarters.
At 2000 MST eleven miles south-southwest of Brockway tennis ball size hail (2.5 inch diameter) was reported for 5 minutes. Smaller reports of hail included: 0.75 inch stones at 2010 MST 14 miles west of Circle; 0.75 inch stones at 2035 MST 10 miles south of Circle; and 0.75 inch stones at 2053 MST 7 miles ESE Circle.
Trained spotter 3 miles west of Weldon reported 1.75 inch hail; a member of the public reported 1.0 inch hail 3 miles southwest of Weldon.
Spotter reported penny size hail.
Heavy rain during the evening brought the failure of a local dam. The dam's name was 7-Tree and the gash or hole made was 50-60 feet wide by 40-50 feet deep.
Spotter reported water over Highway 24 at North Rock Creek turnoff. Adjacent fields were covered with two to three feet of water.
Official reported areas of Kiwanis Park (Downstream Recreation Area) were under water. Water was also reported to be over Highway 24 near the Duck Creek Road.
A member of the public reported 1.75 inches 12 miles northwest of Lindsay at 2114 MST. Smaller hail of 1.0 inch stones was reported 15 miles east of Circle at 2110 MST.
Quarter sized hail piled up to a foot on Highway 59.
Spotter reported quarter size hail.
Trained Spotter and Coop Observer reported quarter-size hail.
Resident reported one inch hail.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2010Every state in 2010This day in weather historyThe tornado archive for Montana, 2010Warnings in Montana, May 2010
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: 223083, 222828, 224277, 224278, 224279, 234284, 238580, 238581, 238582, 224283, 224292, 234285, 224293, 224294.