A vertically stacked low pressure system tracked into western North Dakota. Meanwhile, at the surface, an occluded front curved out to the east and south from near Minot to Fargo (ND) to Morris (MN).
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 FGF wrote it up.
A vertically stacked low pressure system tracked into western North Dakota. Meanwhile, at the surface, an occluded front curved out to the east and south from near Minot to Fargo (ND) to Morris (MN). Some afternoon sun over portions of northern South Dakota helped spawn scattered late afternoon and early evening thunderstorms.
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 May 21, 8:31 PM CST, 1 hour 5 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 931 PM CDT SAT MAY 21 2011 .DISCUSSION... MAIN CHANGES FOR THE EVENING UPDATE WERE TO TWEAK POPS FOR ONGOING WEATHER. THE BAND OF RAIN THAT HAS BEEN PERSISTING OVER THE NORTHERN FORECAST AREA THIS EVENING HAS CONTINUED TO LIFT NORTH AND WEST. LOWERED POPS AROUND LAKE OF THE WOODS AS THE BAND HAS MOVED OUT OF THERE...BUT WILL CONTINUE TO GO LIKELY FOR THE DEVILS LAKE BASIN THROUGH THE EVENING BEFORE THE BAND CONTINUES OFF INTO CANADA. THUNDERSTORMS DEVELOPING IN THE CLEARING OVER SD THIS EVENING HAVE MOVED INTO THE SOUTHERN COUNTIES...SO BUMPED UP POPS IN THAT AREA ACCORDINGLY. HOWEVER...INSTABILITY WILL RAPIDLY DIMINISH AS THE SUN SETS AND IT DOES NOT LOOK LIKE WE WILL SEE A LOW LEVEL JET TO SUSTAIN THE CONVECTION. THE STORMS OVER THE SOUTH SHOULD RAPIDLY DIMINISH BEFORE 06Z...LEAVING ONLY A CHANCE FOR SOME LINGERING SHOWERS. && .AVIATION... CONDITIONS HAVE GONE VFR ACROSS ALL LOCATIONS FOR THE TIME BEING. SOME LINGERING THUNDERSTORMS NEAR KFAR WILL DISSIPATE BEFORE 06Z. COULD SEE SOME LIGHT BR DEVELOPING TOWARDS MORNING AT TAF SITES THAT SAW A LOT OF RAIN TODAY...WITH MVFR CONDITIONS MOST LIKELY AT KGFK...KTVF...AND KBJI. THERE COULD BE SOME RECOVERY TOWARDS LATE MORNING...BUT THEN SHOWERS AND EVEN SOME THUNDERSTORMS WILL REDEVELOP ACROSS THE AREA. WILL KEEP JUST A VCSH MENTION FOR NOW. && .PREV DISCUSSION... /ISSUED 229 PM CDT SAT MAY 21 2011/ SHORT TERM... THE MAIN CHALLENGE WILL BE PRECIP CHANCES THROUGH SUNDAY...AND TEMPS. A SLOW MOVING AND POTENT UPPER LEVEL LOW CONTINUES TO SPIN IN THE NORTHERN PLAINS. THE MOST ORGANIZED BAND OF SHOWERS TODAY IS IN THE EAST AND NORTHERN AREAS...WITH CLEARING TRYING TO MOVE INTO NORTHERN SD/SOUTHERN ND. MODELS ARE IN GOOD OVERALL AGREEMENT...WITH NO REAL PREFERENCE TODAY. FOR LATE THIS AFTERNOON AND EVENING...IF CLEARING CAN MOVE INTO SOUTHEAST ND...THEN THUNDERSTORMS MAY DEVELOP. THERE WILL BE ABOUT 1000 J/KG OF SFC BASED CAPE...AND LI/S TO -4C. THERE WILL BE MINIMAL DEEP LAYERED SHEAR THOUGH...BUT COULD BE A FEW PULSE STORMS CAPABLE OF SMALL HAIL AND BRIEF GUSTY WINDS. OTHERWISE...EXPECT MAINLY SHOWERS SLOWLY SHIFTING NORTH AND DISSIPATING THROUGH THE OVERNIGHT. ON SUNDAY...THERE COULD BE A FEW BREAKS OF SUNSHINE DURING THE MORNING AS THE STACKED UPPER LOW DRIFTS INTO THE SOUTHERN FORECASTS AREA. THERE WILL BE CAPES TO AROUND 500 J/KG IN THE NORTH AND NEAR 1500 J/KG IN THE SOUTH. THIS WILL MEAN LIKELY THUNDERSTORM CHANCES BY AFTERNOON. THIS WILL HINGE LARGELY ON INSOLATION...BUT WITH LOW CONVECTIVE TEMPS IN THE UPPER 60S TO AROUND 70...EXPECT THUNDERSTORMS NEAR THE UPPER LOW. BY MONDAY...CLEARING AND DRYING WILL MOVE FROM NORTH TO SOUTH. EXPECT THINGS TO SLOWLY CLEAR THROUGH THE DAY WITH THE BEST THREAT FOR MAINLY MORNING SHOWERS IN THE SOUTH AND EAST. ON TUE...EXPECT DRY WEATHER WITH NW FLOW ALOFT AND A WEAK PRESSURE GRADIENT. TEMPS SHOULD BE NEAR TO SLIGHTLY BELOW NORMAL. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY GFS/ECMWF IN REASONABLE AGREEMENT THROUGH NEXT WEEK...BOTH SHOWING A WEAK UPPER RIDGE BUILDING ACROSS THE HIGH PLAINS WEDNESDAY AND INTO THE NORTHERN PLAINS BY THURSDAY. WITH UPPER LEVEL DYNAMIC FORCING WELL TO THE NORTH AND SOUTH AND SURFACE HIGH PRESSURE...FORECAST AREA SHOULD REMAIN DRY THROUGH THURSDAY WITH HIGHS IN THE UPPER 60S TO NEAR 70 DEGREES. SHORT-WAVE ENERGY EJECTS EASTWARD FROM EASTERN PACIFIC TROUGH THURSDAY NIGHT INTO FRIDAY BRINGING WITH IT THE THREAT THUNDERSTORMS. LATEST GFS IS STRONGER AND A BIT QUICKER WHEN COMPARED TO THE ECMWF...SO WILL KEEP POPS IN THE CHANCE CATEGORY FOR NOW. TEMPERATURES APPEAR TO GRADUALLY WARM INTO NEXT WEEKEND...BUT HIGHS SHOULD ONLY REACH INTO THE LOWER 70S. HYDROLOGY... MINOR FLOODING CONTINUES ON SIX POINTS IN THE HSA. RIVER LEVELS CONTINUE TO RECEDE AND GRAND FORKS HAS FALLEN BELOW FLOOD STAGE. RAINFALL THIS WEEKEND MAY CAUSE A FEW MINOR RISES ON SOME POINTS...BUT OVERALL MINIMAL IMPACTS ARE EXPECTED. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && JR
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND FORKS ND 700 AM CDT SAT MAY 21 2011 MNZ001>009-013>017-022>024-027>032-040-NDZ006>008-014>016-024- 026>030-038-039-049-052>054-221200- 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 SAT MAY 21 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN NORTH DAKOTA...WEST CENTRAL AND NORTHWEST MINNESOTA. .DAY ONE...TODAY AND TONIGHT BANDS OF RAIN WILL ROTATE NORTH AND WEST ACROSS THE AREA. CLEARING IS FORECAST TO MOVE INTO THE SOUTHERN RED RIVER VALLEY THIS AFTERNOON. HOWEVER AFTERNOON AND EVENING INSTABILITY SHOWERS CAN BE EXPECTED. NEARLY A HALF TO THREE QUARTERS OF AN INCH OF RAIN IS EXPECTED OVER NORTHEAST NORTH DAKOTA AND NORTHWEST MINNESOTA. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY SHOWERS AND AN ISOLATED THUNDERSTORM WILL MOVE THROUGH SUNDAY. THUNDERSTORMS WOULD BE MOST LIKELY IN THE LATE AFTERNOON AND EARLY EVENING. THE STORMS ARE NOT EXPECTED TO BE SEVERE. ADDITIONAL LIGHT SHOWERS ARE EXPECTED MONDAY. AN ADDITIONAL QUARTER TO HALF AN INCH OF RAIN IS EXPECTED SUNDAY AND MONDAY MAINLY OVER THE NORTHERN RED RIVER VALLEY. THE TOPSOIL HAS DRIED OUT IN MOST AREAS AND SHOULD BE ABLE TO TAKE THIS RAIN. THERE COULD BE A SMALL RISE ON SOME RIVERS IN AREAS THAT DO GET THE HEAVIER AMOUNTS. BUT OVERALL RIVERS WILL CONTINUE TO RECEDE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED. HOPPES
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 750 PM CDT SAT MAY 21 2011 NDZ049-052-220145- RANSOM ND-SARGENT ND- 750 PM CDT SAT MAY 21 2011 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL SARGENT AND SOUTHERN RANSOM COUNTIES UNTIL 845 PM CDT... AT 745 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A THUNDERSTORM 5 MILES WEST OF FORMAN...OR 23 MILES NORTH OF BRITTON... MOVING TO THE NORTH AT 15 MPH. HAIL UP TO THE SIZE OF NICKELS IS EXPECTED WITH THE STORM...ALONG WITH HEAVY RAIN. THE STORM WILL BE NEAR... GWINNER AND STIRUM AROUND 815 PM CDT. IF SEVERE WEATHER IS OBSERVED CONTACT YOUR LOCAL LAW ENFORCEMENT AND ASK THEM TO RELAY YOUR INFORMATION TO THE NATIONAL WEATHER SERVICE. TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. RITTERLING
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
811 PM CDT SAT MAY 21 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0800 PM HAIL MCLEOD 46.39N 97.30W
05/21/2011 E0.50 INCH RANSOM ND CO-OP OBSERVER
&&
WBARRETTPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
812 PM CDT SAT MAY 21 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0800 PM HAIL GWINNER 46.22N 97.66W
05/21/2011 E0.25 INCH SARGENT ND PUBLIC
&&
WBARRETTPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
852 PM CDT SAT MAY 21 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0845 PM HAIL RUTLAND 46.05N 97.51W
05/21/2011 E1.00 INCH SARGENT ND FIRE DEPT/RESCUE
SEVERAL QUARTERS EMBEDDED WITHIN A GREATER VOLUME OF PEA
SIZE HAIL.
&&
WBARRETTPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
916 PM CDT SAT MAY 21 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0900 PM HAIL 4 N CAYUGA 46.13N 97.38W
05/21/2011 E0.50 INCH SARGENT ND PUBLIC
GROUND WHITE WITH SMALL HAIL LESS THAN A DIME IN SIZE.
0900 PM FLOOD 4 N CAYUGA 46.13N 97.38W
05/21/2011 SARGENT ND PUBLIC
FIELDS ARE FLOODED WITH WATER.
&&
JRSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 923 PM CDT SAT MAY 21 2011 MNZ040-220300- GRANT MN- 923 PM CDT SAT MAY 21 2011 ...SIGNIFICANT WEATHER ADVISORY FOR EASTERN GRANT COUNTY UNTIL 1000 PM CDT... AT 920 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A THUNDERSTORM NEAR HOFFMAN...OR 20 MILES WEST OF ALEXANDRIA...MOVING TO THE NORTHEAST AT 30 MPH. HAIL UP TO ONE-HALF INCH IN DIAMETER IS EXPECTED WITH THE STORM. THE STORM WILL BE NEAR... RURAL EASTERN GRANT COUNTY THROUGH 1000 PM CDT BE PREPARED TO TAKE SHELTER IF THE STORMS INTENSIFY AND BECOME SEVERE...OR A WARNING IS ISSUED BY THE NATIONAL WEATHER SERVICE. WJB
The Fargo/Grand Forks radar (KMVX), 198 km away, was scanning. The volume nearest the first event began at 03:36 UTC.
2 hail. Local standard time, as filed.
Dime to quarter sized hail fell along with heavy rains and strong winds. Some small branches were broken down and lawn chairs were blown around in a farm yard.
Pea to penny sized hail was reported.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2011Every state in 2011This day in weather historyWarnings in Minnesota, May 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: 317922, 293556.