The low level jet helped focus persistent rainfall with embedded thunder over southeast North Dakota and west central Minnesota. Numerous reports of heavy rain and flash flooding were received along with isolated hail.
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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 FGF wrote it up.
The low level jet helped focus persistent rainfall with embedded thunder over southeast North Dakota and west central Minnesota. Numerous reports of heavy rain and flash flooding were received along with isolated hail.
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 Grand Forks, ND wrote its last area forecast discussion before the first event at Aug 15, 3:30 AM CST, 5 hours earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 430 AM CDT MON AUG 15 2011 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT. GFS AND ECMWF ARE MORE IN AGREEMENT WITH UPPER LOW OVER WESTERN ONTARIO AT 60 HOURS. THE ECMWF HAS LESS AMPLITUDE AND THE GFS WITH HIGHER AMPLITUDE AND BOTH ARE A BIT FASTER THAN YESTERDAYS RUNS. THE NAM WAS FARTHER NORTH AND BIT SLOWER THAN THE ECMWF AND GFS. WILL USE THE ECMWF AND GFS. UPPER LEVEL RIDGE EXTENDED FROM CENTRAL CANADA INTO TX WILL FLATTEN OVER THE NORTHERN PLAINS AS SHORT WAVES MOVE THROUGH THE FLOW. UPPER LEVEL RIDGE SHIFTS INTO THE DESERT SOUTHWEST THIS PERIOD. 700 AND 850 HPA THETA-E RIDGE EXTEND INTO SOUTHERN SASK AND SOUTHERN ND THIS MORNING. ALSO LOW LEVEL JET EXTENDED INTO EASTERN SD AND SOUTHERN ND. SCATTERED THUNDERSTORMS HAVE BEEN OCCURRING OVER SOUTHWEST ZONES AND STORMS ARE EXPECTED TO DIMINISH LATER THIS MORNING. RAIN CONTINUES TO DEVELOP AND TRAIN OVER PARTS OF RICHLAND COUNTY. RADAR INDICATED BETTER THAN TWO INCHES OF RAIN OVER PARTS OF SOUTHERN RICHLAND COUNTY. WATER VAPOR LOOP INDICATED A SHORT WAVE OVER SOUTHEAST SASK, EASTERN OR, AND ANOTHER OFF THE CA COAST. MAIN UPPER TROUGH WAS OVER BC. EXPECT SHORT WAVES TO MOVE ACROSS SOUTHERN CANADA AND THE NORTHERN PLAINS MON NIGHT. MAIN UPPER TROUGH TO MOVE THROUGH TUE NIGHT. COLD FRONT WILL MOVE ACROSS THE FORECAST AREA TUE AND TUE NIGHT. UPPER LEVEL JET NOSES INTO THE FORECAST AREA BY MON EVENING WITH STORMS MOST LIKELY IN LEFT EXIT REGION OF JET. PRECIPITATION SHOULD MOVE OUT OF THE AREA TUE NIGHT. .LONG TERM...THURSDAY AND FRIDAY. UPPER LEVEL RIDGE REMAINS OVER THE DESERT SOUTHWEST. ZONAL FLOW ACROSS THE NORTHERN PLAINS BECOMES MORE TROUGHLIKE WITH NORTHWEST FLOW DEVELOPING OVER THE CANADIAN HIGH PLAINS THIS PERIOD. TIMING DIFFERENCES REMAINS IN THIS PERIOD. THE GFS IS FASTER WITH A COLD FRONT MOVING THE THE REGION THU/THU NIGHT AND THE ECMWF MOVING THROUGH FRI/FRI NIGHT. NO CHANGE WITH POPS THIS PERIOD. && .AVIATION... VFR CONDITIONS WERE ACROSS THE AREA WITH SOME CIGS OF 4-6 THOUSAND FT OVER THE SOUTHERN RED RIVER VALLEY. WILL CONSIDER MVFR CIGS FOR LATER THIS AFTERNOON OR EVENING. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && HOPPES
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND FORKS ND 700 AM CDT MON AUG 15 2011 MNZ001>009-013>017-022>024-027>032-040-NDZ006>008-014>016-024- 026>030-038-039-049-052>054-161200- WEST POLK-NORMAN-CLAY-KITTSON-ROSEAU-LAKE OF THE WOODS- WEST MARSHALL-EAST MARSHALL-NORTH BELTRAMI-PENNINGTON-RED LAKE- EAST POLK-NORTH CLEARWATER-SOUTH BELTRAMI-MAHNOMEN- SOUTH CLEARWATER-HUBBARD-WEST BECKER-EAST BECKER-WILKIN- WEST OTTER TAIL-EAST OTTER TAIL-WADENA-GRANT-TOWNER-CAVALIER- PEMBINA-BENSON-RAMSEY-EASTERN WALSH-EDDY-NELSON-GRAND FORKS- GRIGGS-STEELE-TRAILL-BARNES-CASS-RANSOM-SARGENT-RICHLAND- WESTERN WALSH- 700 AM CDT MON AUG 15 2011 ...SEVERE WEATHER WILL BE POSSIBLE FOR TODAY AND TUESDAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN NORTH DAKOTA...WEST CENTRAL AND NORTHWEST MINNESOTA. .DAY ONE...TODAY AND TONIGHT A SLIGHT RISK OF SEVERE THUNDERSTORMS WILL BE POSSIBLE ROUGHLY NORTH AND WEST OF A LINE FROM SALOL TO TWIN VALLEY MINNESOTA TO FORT RANSOM NORTH DAKOTA. SOME LARGE HAIL AND DAMAGING WINDS WILL BE POSSIBLE. ALSO LOCALLY HEAVY RAIN WILL BE POSSIBLE. ISOLATED STORMS WILL BE POSSIBLE BY LATE AFTERNOON OR EARLY EVENING. OTHERWISE STORMS WILL OCCUR IN THE WESTERN DAKOTAS AND WILL MOVE INTO THE AREA AFTER SUNSET. AFTERNOON HEATING MAY ISOLATED STORMS THIS AFTERNOON. OTHERWISE AN UPPER LEVEL DISTURBANCE WILL MOVE INTO THE AREA LATER THIS EVENING AND PRODUCE THE THUNDERSTORMS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY A SLIGHT RISK OF SEVERE THUNDERSTORMS WILL BE POSSIBLE ROUGHLY EAST OF A LINE FROM CAVALIER TO JAMESTOWN NORTH DAKOTA. THIS INCLUDES MUCH OF EASTERN NORTH DAKOTA AND NORTHWEST AND WEST CENTRAL MINNESOTA. THUNDERSTORMS WILL BE OCCURRING IN THE MORNING AND WILL MOVE EAST DURING THE DAY. SOME LARGE HAIL AND DAMAGING WINDS CAN BE EXPECTED. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE REQUIRED. HOPPES
The Aberdeen radar (KABR), 126 km away, was scanning. The volume nearest the first event began at 14:32 UTC.
3 flash flood. Local standard time, as filed.
Parts of county road 3 were under water from the heavy rain and flash flooding.
Reports of 4.00 to 6.50 inches of rain were received from Hankinson. This filled ditches and quickly covered some roads and streets in town.
Heavy rain quickly filled ditches and covered several rural roads.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in North Dakota in 2011Every state in 2011This day in weather historyWarnings in North Dakota, August 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: 343754, 343755, 343757.