An area of surface low pressure formed over southwest North Dakota, with a frontal boundary extending northeast to near Pembina. With southwest flow aloft, thunderstorms formed over western and north central North Dakota and drifted to the northeast.
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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.
An area of surface low pressure formed over southwest North Dakota, with a frontal boundary extending northeast to near Pembina. With southwest flow aloft, thunderstorms formed over western and north central North Dakota and drifted to the northeast. One thunderstorm strengthened over Towner County and dropped large 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 24, 3:04 AM CST, 1 hour 31 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 404 AM CDT MON AUG 24 2009 .DISCUSSION... PRIMARY FORECAST CHALLENGES INCLUDE PRECIPITATION CHANCES TODAY AND TONIGHT AS WELL AS TEMPERATURES. 00 UTC NAM BETTER INITIALIZED SURFACE LOW POSITION AT 06 UTC ACROSS SOUTHWEST ND WITH THE GFS A BIT TOO FAR EAST. AS SUCH...PREFER THE SLIGHTLY SLOWER NAM SOLUTION FOR TODAY AND TONIGHT/S SYSTEM...BUT DIFFERENCES WITH THE GFS ARE RELATIVELY MINOR. BEYOND 24 HOURS...UTILIZED A MODEL BLEND. 0830 UTC WATER VAPOR LOOP SHOWS UPPER LEVEL RIDGE ACROSS THE NATION/S MID-SECTION WITH AN ILL-DEFINED SHORT WAVE RIDING NORTHEASTWARD ON THE BACKSIDE OF THE RIDGE THROUGH EASTERN MT AND NORTHWEST ND. AT THE SURFACE...LOW PRESSURE IS CENTERED ACROSS SOUTHWEST ND WITH A WARM FRONT STRETCHING FROM NORTHWEST OF BISMARCK TO NEAR MINOT TO PEMBINA AND ALONG THE INTERNATIONAL BORDER. IMPRESSIVE CONVECTIVE CLUSTER HAS DEVELOPED ALONG AND NORTH OF THIS FRONT OVERNIGHT AND IS MOVING EAST-NORTHEASTWARD ACROSS NORTH-CENTRAL ND AT 35 TO 40 KTS. GIVEN CURRENT RADAR TRENDS...DO EXPECT THIS AREA OF SHOWERS AND STORMS TO CLIP THE FAR NORTHWEST PORTION OF THE FORECAST AREA (BENSON/RAMSEY/TOWNER/ CAVALIER COUNTIES) THROUGH 15 UTC. NOT EXPECTING ANY SEVERE WEATHER...BUT BRIEF HEAVY RAIN AND GUSTY WINDS ARE POSSIBLE. FOR THE REST OF THIS MORNING AND AFTERNOON...MODELS ARE IN GOOD AGREEMENT SHOWING THE SURFACE LOW TRACK ACROSS THE NORTHERN RED RIVER VALLEY BY 18 UTC AND INTO SOUTHWEST ONTARIO BY 00 UTC. SURFACE WARM FRONT WILL ALSO MOVE NORTHWARD...KEEPING THE MAJORITY OF THE PRECIPITATION ALONG AND NORTH OF THE INTERNATIONAL BORDER THIS MORNING AS MAJORITY OF FORECAST AREA IS IN THE WARM-SECTOR AND WELL CAPPED GIVEN 700 HPA TEMPERATURES FROM +10 TO +12 C. CHALLENGE THIS AFTERNOON AND EVENING WILL BE TIMING OF THE COLD FRONT ACROSS EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA AS SURFACE LOW LIFTS TO THE NORTHEAST. AHEAD OF THE FRONT 0-6 KM MOST UNSTABLE CAPE IS 1000 TO 1500 J/KG...BUT THIS IS PRIMARILY ABOVE 700 HPA. STRONGEST JET IS WELL TO THE NORTH...BUT BULK SHEAR VALUES FROM 30 TO 40 KTS SEEM REASONABLE WITH SHORT-WAVE MOVING OVERHEAD. AS SUCH...EXPECT SCATTERED SHOWERS AND THUNDERSTORMS ALONG AND EAST OF THE RED RIVER VALLEY THIS AFTERNOON AND EVENING COINCIDENT WITH FRONTAL PASSAGE...WHICH SHOULD PROVIDE ENOUGH LIFT TO HELP BREAK CAP. NOT EXPECTING SEVERE WEATHER AT THIS TIME...BUT SMALL HAIL AND GUSTY WINDS WILL BE POSSIBLE WITH THE STRONGEST STORMS. RAINFALL AMOUNTS SHOULD BE UNDER ONE HALF INCH...BUT LOCALLY HIGHER AMOUNTS ARE POSSIBLE GIVEN VERY MOIST AIRMASS (SURFACE DEW POINT TEMPERATURES IN THE MID TO UPPER 60S). TONIGHT INTO TUESDAY...LOW PRESSURE EXITS THE REGION WITH HIGH PRESSURE BUILDING OVERHEAD. DRY CONDITIONS WILL PREVAIL...BUT TEMPERATURES WILL BE A BIT COOLER...GENERALLY IN THE MID 70S. FOR THE REST OF THE WEEK...EXPECT HIGHS IN THE 70S WITH LOWS IN THE 50S WITH LITTLE TO NO PRECIPITATION THROUGH AT LEAST THURSDAY WITH PRIMARY JET AXIS ACROSS SOUTHERN CANADA AS AN UPPER LEVEL RIDGE RETURNS ACROSS THE INTERMOUNTAIN WEST. && .AVIATION... VFR CONDITIONS HAVE CONTINUED INTO THE EARLY MORNING WITH KDVL AND KGFK DOWN TO AROUND 4K FT OVC. EXPECT CIGS TO LOWER AT THE MN SITES DURING THE DAY. AS A SURFACE LOW MOVES NEWD ACROSS THE FCST AREA TODAY...SE WINDS WILL TURN SWLY AND THEN NWLY IN THE 22Z TO 02Z TIME PERIOD EXCEPT FOR KDVL WILL BE A LITTLE EARLIER AROUND 20Z. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && ROGERS/FRAZIER
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND FORKS ND 627 AM CDT SUN AUG 23 2009 MNZ001>009-013>017-022>024-027>032-040-NDZ006>008-014>016-024- 026>030-038-039-049-052>054-241130- 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 COUNTY-EDDY-NELSON- GRAND FORKS-GRIGGS-STEELE-TRAILL-BARNES-CASS-RANSOM-SARGENT- RICHLAND-WESTERN WALSH COUNTY- 627 AM CDT SUN AUG 23 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN NORTH DAKOTA...WEST CENTRAL AND NORTHWEST MINNESOTA. .DAY ONE...TODAY AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY INTO MONDAY BRINGING A CHANCE FOR SHOWERS AND THUNDERSTORMS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED. MF
The national radar mosaic for the moment the first event began.
1 hail. Local standard time, as filed.
Dime to quarter sized hail damaged mature wheat fields in portions of northern Sorenson Township.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in North Dakota in 2009Every state in 2009This day in weather historyWarnings in North Dakota, August 2009
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: 184826.