By late in the afternoon of the 31st, a strong thunderstorm formed near Blackduck, Minnesota, and produced very strong winds. Meanwhile, a weak area of surface low pressure over northeast North Dakota combined with a cold front to produce a weak tornado near Crystal.
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.
By late in the afternoon of the 31st, a strong thunderstorm formed near Blackduck, Minnesota, and produced very strong winds. Meanwhile, a weak area of surface low pressure over northeast North Dakota combined with a cold front to produce a weak tornado near Crystal. As the cold front pushed into far southeast North Dakota and west central Minnesota, additional strong thunderstorms fired up, producing more hail and strong wind gusts. As evening approached, an upper level disturbance dropped southeast out of Manitoba, Canada, and helped sustain a few more strong thunderstorms from Pembina toward the Lake of the Woods.
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 31, 12:06 PM CST, 2 hours 18 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 106 PM CDT SAT AUG 31 2013 .UPDATE... ISSUED AT 106 PM CDT SAT AUG 31 2013 THE LATEST OBSERVATIONS ARE SHOWING THE COLD FRONT TO BE SOMEWHERE ALONG A LINE FROM CAVALIER TO VALLEY CITY TO OAKES. FAIRLY EXTENSIVE BATCH OF MID LEVEL CLOUDS ALONG AND BEHIND THE FRONT WITH JUST A FEW SPRINKLES/LIGHT SHOWERS FOR THE MOST PART. MOST OF THE ECHOES ARE SHOWING UP FROM CAVALIER DOWN TOWARD KMBG WHICH FOR THE MOST PART ARE BEHIND THE SFC FRONT POSITION. SPC MESOANALYSIS PAGE SHOWS FAIRLY EXTENSIVE CIN VALUES ACROSS THE FA YET WITH THE MAIN SHORT WAVE WORKING INTO SOUTHWEST MANITOBA NOW. THEREFORE THE UPPER LEVEL FEATURES SO FAR ARE LAGGING THE SFC FEATURES. AS THE CIN IS EXPECTED TO ERODE OVER THE NEXT COUPLE OF HOURS THE FRONT SHOULD BE EAST OF THE VALLEY. BETTER MID AND UPPER LEVEL WINDS ARE EXPECTED TO WORK AROUND THE SOUTHERN PERIPHERY OF THE WAVE BY LATE AFTERNOON WHICH SHOULD BRING BETTER BULK SHEAR VALUES DOWN INTO THE FA. THIS BASIC REASONING WAS ALREADY COVERED IN THE FORECAST SO NO BIG CHANGES MADE. THUS STILL EXPECTING THE TSTMS TO STRENGTHEN BY MID TO LATE AFTERNOON AND TRACK EAST OF THE FA BY EARLY EVENING. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 422 AM CDT SAT AUG 31 2013 BIG ISSUE TODAY WILL BE SEVERE THUNDERSTORM POTENTIAL. GLOBAL OPERATIONAL AND MESOSCALE MODELS ARE IN GOOD OVERALL AGREEMENT AND WILL USE A BLENDED SOLUTION. EARLY THIS MORNING THERE ARE TWO NON-SEVERE CONVECTIVE CLUSTERS ASSOCIATED WITH A PRE-FRONTAL TROUGH. THE STRONGER OF THE TWO IS DRAPED ALONG THE CANADIAN BORDER FROM NORTH OF CAVALIER TO ROSEAU AND THE SECOND IS MOVING ACROSS NORTHEAST SD/SOUTHEAST ND. THIS ACTIVITY WILL WEAKEN AS IT MOVES EASTWARD THROUGH THE REST OF THE MORNING. THERE SHOULD BE A BREAK IN CONVECTION MID-LATE MORNING WITH SOME CLEARING FROM WEST TO EAST. ATTENTION QUICKLY TURNS TO THIS AFTERNOON AND EVENING AS A STRONG CANADIAN SHORT-WAVE AND COLD FRONT DROP ACROSS THE NORTHERN PLAINS. THE COLD FRONT SHOULD BE ALONG A HALLOCK TO GRAND FORKS TO LISBON LINE BY 18 UTC. AHEAD OF THE FRONT...MLCAPE VALUES CLIMB UP TO 2500 J/KG AND WITH THE APPROACHING JET-STREAK ALOFT...0 TO 6 KM BULK SHEAR INCREASES TO BETWEEN 40 AND 50 KTS. STRONG DIVERGENCE ALOFT...STEEP MID-LEVEL LAPSE RATES AND PWATS BETWEEN 1.5 AND 2.0 INCHES WILL ALLOW FOR RAPID CONVECTIVE DEVELOPMENT THIS AFTERNOON ALONG AND AHEAD OF THE COLD FRONT. EXPECT INITIATION BETWEEN 2 AND 4 PM MAINLY JUST EAST OF THE RED RIVER ACROSS NORTHWEST AND WEST CENTRAL MN...THEN MOVING EAST INTO CENTRAL MN BY THIS EVENING. THIS MATCHES WELL WITH SPC DAY ONE CONVECTIVE OUTLOOK...WHICH PAINTS A SLIGHT RISK FOR SEVERE THUNDERSTORMS ACROSS SOUTHEAST ND AND INTO ALL OF NORTHWEST AND WEST-CENTRAL MN. LARGE HAIL AND DAMAGING WIND WILL BE THE PRIMARY THREAT...BUT TORNADOES ARE ALSO POSSIBLE. BULK SHEAR IN THE 0 TO 1 KM LAYER INCREASES RAPIDLY LATE THIS AFTERNOON ACROSS THE EASTERN FORECAST AREA UP TO 30 KTS WITH A SIGNIFICANT TORNADO PARAMETER FROM 2 TO 4 IN PLACES. BEST CHANCE FOR TORNADOES WILL BE ALONG AND EAST OF A LINE FROM WASKISH TO DETROIT LAKES TO FERGUS FALLS AND THIS AREA IS HIGHLIGHTED BY A 5 PERCENT RISK IN THE LATEST CONVECTIVE OUTLOOK. WITH IT BEING THE FIRST DAY OF THE LABOR DAY WEEKEND... MANY PEOPLE WILL BE ON AREA LAKES AND THE POTENTIAL IMPACT OF ANY SEVERE WEATHER COULD BE MAGNIFIED. ANYBODY WITH OUTDOOR PLANS TODAY IN THE AREAS HIGHLIGHTED ABOVE SHOULD PAY VERY CLOSE ATTENTION TO THE LATEST CONVECTIVE WATCHES AND WARNINGS. THE LAST OF ANY THUNDERSTORMS SHOULD MOVE EAST OF THE FORECAST AREA BY 9 TO 10 PM THIS EVENING. IN THE WAKE OF TODAY/S COLD FRONTAL PASSAGE WILL BE A MUCH COOLER AND DRIER AIR MASS. 850 HPA TEMPERATURES SUNDAY WILL RANGE FROM +10 TO +12 C...RESULTING IN AFTERNOON HIGHS FROM THE MID 60S ACROSS THE LAKE OF THE WOODS REGION TO THE MID 70S ACROSS SOUTHEAST ND. EXPECT PLENTY OF SUNSHINE WITH A BRISK NORTH WIND. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 422 AM CDT SAT AUG 31 2013 SUNDAY NIGHT INTO MONDAY WILL BE MOSTLY SUNNY/CLEAR AND DRY AS A STRONG SURFACE HIGH PRESSURE SYSTEM MOVES ACROSS THE NORTHERN PLAINS. TEMPERATURES MONDAY MORNING WILL BE IN THE 40S WITH AFTERNOON HIGHS IN THE LOWER TO MID 70S. FOR TUE THROUGH FRI NIGHT...EXPECT A DRY PERIOD THROUGH AT LEAST THU...WITH MODELS IN GOOD AGREEMENT WITH UPPER RIDGING MOVING IN. TEMPS SHOULD WARM ABOVE NORMAL ONCE AGAIN BY MID WEEK...AS 850MB TEMPS CLIMB TO AROUND +20C OR EVEN A BIT HIGHER. THERE COULD BE INCREASING CHANCES FOR CONVECTION BY FRI NIGHT...AS THE UPPER RIDGE BREAKS DOWN. MOST OF THE WEEK WILL BE WARM AND DRY THOUGH. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 106 PM CDT SAT AUG 31 2013 MID DECK ACROSS ERN ND THIS AFTN WILL CONT TO MOVE EAST INTO THE EVENING...IMPACTING ALL TAF SITES. WEAK ECHOES WERE OCCURRING FROM GRAFTON SOUTHWEST TO JAMESTOWN...THOUGH VSBYS WERE NOT RESTRICTED. THE PREFRONTAL TROF SITUATED OVER THE RVR VALLEY WILL SHIFT EAST WITH THE ACTUAL FRONT FURTHER WEST ACROSS CENTRAL ND THIS AFTN. WLY WINDS FROM THE VALLEY WEST WILL TURN NWLY WHILE EAST OF THE VALLEY WINDS WILL TURN NW AFTER 02Z. INCLUDED VCTS ALL SITES EXCEPT KDVL FOR THIS AFTN/EARLY EVENING BEFORE FRONTAL PASSAGE. OTHERWISE NNW WINDS CON OVERNIGHT WITH SCT MID DECK. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && UPDATE...GODON SHORT TERM...ROGERS LONG TERM...ROGERS/DK AVIATION...FRAZIER
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND FORKS ND 444 AM CDT SAT AUG 31 2013 MNZ001>009-013>017-022>024-027>032-040-NDZ006>008-014>016-024- 026>030-038-039-049-052>054-010945- 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- 444 AM CDT SAT AUG 31 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN NORTH DAKOTA...WEST CENTRAL AND NORTHWEST MINNESOTA. .DAY ONE...TODAY AND TONIGHT SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EVENING MAINLY ALONG AND EAST OF THE RED RIVER VALLEY AS A STRONG COLD FRONT MOVES ACROSS THE REGION. THE PRIMARY THREATS WILL BE LARGE HAIL AND DAMAGING WIND...BUT TORNADOES ARE ALSO POSSIBLE ALONG AND EAST OF A LINE FROM WASKISH TO DETROIT LAKES TO FERGUS FALLS. PEOPLE WITH OUTDOOR PLANS SHOULD PAY CLOSE ATTENTION TO THE LATEST WATCHES AND WARNINGS AND BE PREPARED TO TAKE ACTION IF NECESSARY. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NECESSARY THIS AFTERNOON AND EVENING FOR AREAS ALONG AND EAST OF THE RED RIVER VALLEY. ROGERS
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 141 PM CDT SAT AUG 31 2013 MNZ002-022-311900- MAHNOMEN MN-NORMAN MN- 141 PM CDT SAT AUG 31 2013 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL NORMAN AND EXTREME WESTERN MAHNOMEN COUNTIES UNTIL 200 PM CDT... AT 136 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A THUNDERSTORM NEAR ADA...OR 36 MILES NORTHEAST OF FARGO...MOVING TO THE EAST AT 45 MPH. WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THE STORM. THE STORM WILL BE NEAR... TWIN VALLEY...GARY AND FLAMING AROUND 150 PM CDT. WAUKON...RANUM AND FAITH AROUND 155 PM CDT. BE PREPARED TO TAKE SHELTER IF THE STORMS INTENSIFY AND BECOME SEVERE...OR A WARNING IS ISSUED BY THE NATIONAL WEATHER SERVICE. LAT...LON 4748 9606 4726 9607 4724 9656 4742 9659 TIME...MOT...LOC 1841Z 262DEG 41KT 4735 9640 MF
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 153 PM CDT SAT AUG 31 2013 MNZ002-003-NDZ039-311915- CASS ND-CLAY MN-NORMAN MN- 153 PM CDT SAT AUG 31 2013 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN CLAY AND SOUTHERN NORMAN COUNTIES IN NORTHWEST MINNESOTA...AND EASTERN CASS COUNTY IN SOUTHEAST NORTH DAKOTA UNTIL 215 PM CDT... AT 150 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A THUNDERSTORM 6 MILES NORTHEAST OF HARWOOD...OR 12 MILES NORTH OF FARGO...MOVING TO THE EAST AT 40 MPH. HAIL UP TO ONE-HALF INCH IN DIAMETER IS EXPECTED WITH THE STORM. THE STORM WILL BE NEAR... FELTON AROUND 210 PM CDT. BE PREPARED TO TAKE SHELTER IF THE STORMS INTENSIFY AND BECOME SEVERE...OR A WARNING IS ISSUED BY THE NATIONAL WEATHER SERVICE. LAT...LON 4718 9644 4698 9641 4696 9691 4714 9693 TIME...MOT...LOC 1853Z 264DEG 36KT 4706 9679 MF
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 311 PM CDT SAT AUG 31 2013 MNZ009-017-312100- NORTH BELTRAMI MN-SOUTH BELTRAMI MN- 311 PM CDT SAT AUG 31 2013 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL BELTRAMI COUNTY UNTIL 400 PM CDT... AT 308 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A THUNDERSTORM 11 MILES WEST OF BLACKDUCK...OR 17 MILES NORTH OF BEMIDJI...MOVING TO THE EAST AT 35 MPH. THOSE ON THE OPEN WATERS OF LOWER RED LAKE SHOULD SEEK SHELTER. HAIL UP TO NICKEL SIZE IS EXPECTED WITH THE STORM. THE STORM WILL BE NEAR... HINES AROUND 320 PM CDT. BLACKDUCK AROUND 325 PM CDT. SHOOKS AND FUNKLEY AROUND 335 PM CDT. BE PREPARED TO TAKE SHELTER IF THE STORMS INTENSIFY AND BECOME SEVERE...OR A WARNING IS ISSUED BY THE NATIONAL WEATHER SERVICE. LAT...LON 4764 9507 4798 9512 4791 9441 4761 9441 TIME...MOT...LOC 2011Z 271DEG 32KT 4772 9475 DTR
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
316 PM CDT SAT AUG 31 2013
MNZ022>024-027-028-312100-
EAST BECKER MN-HUBBARD MN-MAHNOMEN MN-SOUTH CLEARWATER MN-WEST BECKER
MN-
316 PM CDT SAT AUG 31 2013
...SIGNIFICANT WEATHER ADVISORY FOR EXTREME SOUTHERN CLEARWATER...
NORTHEASTERN BECKER...EXTREME SOUTHERN MAHNOMEN AND WESTERN HUBBARD
COUNTIES UNTIL 400 PM CDT...
AT 313 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
THUNDERSTORM 21 MILES NORTHEAST OF DETROIT LAKES...NEAR WHITE
EARTH...MOVING TO THE EAST AT 35 MPH.
HAIL UP TO ONE-HALF INCH IN DIAMETER IS EXPECTED WITH THE STORM.
THE STORM WILL BE NEAR...
BAD MEDICINE LAKE AROUND 330 PM CDT.
TWO INLETS AROUND 345 PM CDT.
BE PREPARED TO TAKE SHELTER IF THE STORMS INTENSIFY AND BECOME
SEVERE...OR A WARNING IS ISSUED BY THE NATIONAL WEATHER SERVICE.
LAT...LON 4700 9584 4716 9589 4715 9555 4717 9554
4716 9513 4710 9509 4698 9510
TIME...MOT...LOC 2016Z 272DEG 32KT 4708 9559
DTRThe Fargo/Grand Forks radar (KMVX), 205 km away, was scanning. The volume nearest the first event began at 20:22 UTC.
15 thunderstorm wind, 7 hail. Local standard time, as filed.
Very strong winds and pea sized hail were reported on the north shore of Blackduck Lake.
Shingles were blown off of multiple structures and a steeple was blown off a church.
A few trees were blown down with pea size hail.
The winds were measured by a MNDOT RWIS sensor along Interstate 94.
The hail fell along the south side of Hungry Man Lake.
The winds were measured by the Fergus Falls airport AWOS.
Forty to fifty mile an hour winds accompanied the hail.
Several three to four inch diameter tree branches were blown down.
The strong winds were measured at the Prairie Wetland Center.
Trees were blown down and twisted off. Several small sheds or fish houses were blown over and at least one heavily damaged between Wall Lake and Bass Lake.
A few trees were blown down.
The winds were measured by a MNDOT RWIS site located along highway 171.
The winds were measured by a MNDOT RWIS site along highway 11.
Several four to six inch diameter tree limbs were snapped.
A tree was blown down at a campground along the Canadian border.
The hail fell at the Tamarac Resort on Round Lake.
Several three to five inch diameter branches were snapped.
Trees were blown down at Arnesens Rocky Point Resort.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2013Every state in 2013This day in weather historyWarnings in Minnesota, August 2013
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: 466971, 466972, 466973, 466974, 466975, 466976, 466977, 466978, 466979, 466980, 466981, 466982, 466983, 466984, 466985, 466991, 466986, 466987, 466988, 466992, 466989, 466990.