Isolated strong thunderstorms formed across portions of Richland and Cass counties during the early morning hours of the 29th. These storms produced very large 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.
Isolated strong thunderstorms formed across portions of Richland and Cass counties during the early morning hours of the 29th. These storms produced very large hail. Several hours later a line of thunderstorms approached the New Rockford, North Dakota, area, and began to bow, which is indicative of strong winds. This bowing signature on radar continued as the line of thunderstorms tracked eastward along U. S. Highway 2 toward the Grand Forks (ND) and Oslo (MN) areas, where they gradually weakened.
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 29, 5:50 AM CST, 35 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 650 AM CDT THU AUG 29 2013 .UPDATE... ISSUED AT 650 AM CDT THU AUG 29 2013 SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED FOR THE STRONG BOW MOVING THROUGH THE AREA. THE 2000+J/KG MUCAPE HAVE MOVED NORTHWARD OVER THE PAST SEVERAL HOURS...AS NOSE OF 30 KNOT LOW LEVEL JET (AND ASSOCIATED THUNDERSTORM COMPLEX) HAS MOVED INTO THIS AREA. ANTICIPATE THIS COMPLEX WILL CONTINUE TO MOVE EAST AS LOW LEVEL JET SHIFTS THIS WAY...ALTHOUGH STRENGTH OF THE BOWING SEGMENTS SHOULD WEAKEN AS THE COMPLEX MOVES EAST OF THE VALLEY INTO A MORE STABLE AIRMASS. A BRIEF BREAK IN ACTIVITY IS STILL EXPECTED...THEN MORE THIS AFTERNOON. INCREASED POPS TO NEAR 100% FOR THIS COMPLEX. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 415 AM CDT THU AUG 29 2013 MAIN CONCERN WILL BE SEVERE THUNDERSTORM CHANCES. AT 09Z...THERE IS AN ELEVATED WARM FRONT PROPAGATING NORTHWARD THROUGH THE SOUTHERN FA. MEANWHILE...THERE IS 25-30 KNOT 850MB JET FOCUSED INTO CENTRAL NORTH DAKOTA. THESE FORCING MECHANISMS ARE RESPONSIBLE FOR A COUPLE THUNDER COMPLEXES WHICH WILL AFFECT THE FA THIS MORNING. ALL OF THIS IS OCCURRING AHEAD OF THE MAIN SHORTWAVE ACROSS NE MONTANA. ANTICIPATE SCATTERED ACTIVITY AHEAD OF THE MAIN COMPLEX (POSSIBLY STRONG AT TIMES)...WITH THIS MAIN COMPLEX MOVING THROUGH THE FA THIS MORNING. MESOSCALE ANALYSIS SHOWS MUCAPE AROUND 2000 J/KG ACROSS SOUTHEAST NORTH DAKOTA...WHICH SHOULD MOVE NORTHWARD THROUGH THE NIGHT. THIS COMPLEX WILL INTERACT THE INSTABILITY AS IT MOVES THROUGH DURING THE MORNING...WITH STRONG STORMS POSSIBLE. THERE WILL LIKELY BE A BREAK LATER THIS MORNING INTO THE EARLY AFTERNOON HOURS...WITH REDEVELOPMENT OF STORMS IN THE AFTERNOON AS THE MAIN SHORTWAVE MOVES THROUGH THE NORTHERN PORTION OF THE REGION. MODELS INDICATE A WARM FRONT WILL BE LOCATED FROM VALLEY CITY TO FARGO TO PARK RAPIDS...WITH A SFC- 925MB LOW PROPAGATING ALONG THIS FEATURE. STRONG INSTABILITY AND MODERATE DEEP LAYER SHEAR COMBINED WITH STRONG FORCING SHOULD LEAD TO SEVERE STORMS FROM THE NORTHERN VALLEY INTO NORTHWEST MINNESOTA AS A COLD FRONT MOVES THROUGH. ALSO...STORMS WILL BE POSSIBLE ALONG THE WARM FRONT IF THE CAP CAN BE BROKEN. BEST TORNADO THREAT WOULD BE ALONG THE WARM FRONT...WITH A WIND AND HAIL THREAT AHEAD OF THE SHORTWAVE TO THE NORTH. DID INCLUDE SEVERE MENTION FOR THIS AFTERNOON AND EVENING WITH CONFIDENCE MEDIUM TO HIGH. TEMPERATURES TODAY WILL BE LIMITED TO THE MID-UPPER 80S NORTH OF THE WARM FRONT...BUT AGAIN INTO THE MID 90S ALONG AND SOUTH OF THIS FEATURE. MODELS INDICATE MIXING AND SLIGHTLY DRIER DEWPOINTS SOUTH OF THE FRONT...WHICH WILL PREVENT HEAT ADVISORY CONDITIONS. FRIDAY LOOKS DRY AND SLIGHTLY COOLER WITH MAX TEMPS MID TO UPPER 80S EVERYWHERE. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 415 AM CDT THU AUG 29 2013 FRIDAY NIGHT-SATURDAY NIGHT...A COUPLE SHORTWAVES WILL MOVE THROUGH THE REGION. THE STRONGEST FEATURE WILL PASS JUST NE OF THE FA...SENDING A STRONG COLD FRONT THROUGH THE REGION SATURDAY AFTERNOON. THUNDERSTORM CHANCES EXIST FRIDAY NIGHT AND AGAIN SATURDAY AFTERNOON. THE STORMS SAT AFTERNOON COULD BE STRONG TO SEVERE...DEPENDING ON ACTUAL TIMING OF THE FRONT AND INSTABILITY PARAMETERS. SUNDAY TO WEDNESDAY...MODELS IN FAIR AGREEMENT WITH THE EXTENDED TIME FRAME AS 500MB FLOW BECOMES NORTHWESTERLY ACROSS THE NORTHERN PLAINS WITH STRONG RIDGE HAVING RETROGRADED BACK OVER THE INTERMOUNTAIN WEST AND SHORT WAVE ENERGY...STRENGTHENING TROUGH...ACROSS THE GREAT LAKES ON SUNDAY. MUCH COOLER AND LESS ACTIVE AS THERMAL PROFILE IN PLACE BY SUNDAY WITH 850MB TEMPS DOWN IN THE SINGLE DIGITS THOUGH SOME LINGERING SHOWERS ARE POSSIBLE IN THE EAST. DRY WEATHER ON MONDAY AND TUESDAY WITH SFC HIGH PRESSURE IN PLACE OVER THE CWFA. BY WEDNESDAY WIDE MODEL SOLNS EXISTS AS GFS BUILDS UPPER RIDGE INTO SOUTHERN CANADA WHERE ECMWF BRINGS ANOTHER POTENT SHORTWAVE AND AUTUMN LIKE AIRMASS INTO THE NORTHERN PLAINS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 650 AM CDT THU AUG 29 2013 STRONG WINDS/IFR CONDITIONS POSSIBLE AT KGFK AND KTVF THIS MORNING AS A STRONG THUNDERSTORM COMPLEX MOVES THROUGH. OTHERWISE...THUNDER CHANCES EXIT BY MID TO LATE MORNING. ADDITIONAL ACTIVITY POSSIBLE THIS AFTERNOON...MOST LIKELY FOR KTVF AND KBJI. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && UPDATE...TG SHORT TERM...TG LONG TERM...TG/JK AVIATION...TG
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND FORKS ND 456 AM CDT THU AUG 29 2013 MNZ001>009-013>017-022>024-027>032-040-NDZ006>008-014>016-024- 026>030-038-039-049-052>054-301200- 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- 456 AM CDT THU AUG 29 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN NORTH DAKOTA...WEST CENTRAL AND NORTHWEST MINNESOTA. .DAY ONE...TODAY AND TONIGHT THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS TODAY. THERE WILL BE TWO ROUNDS OF STORMS. THE FIRST ROUND WILL MOVE THROUGH THE REGION THIS MORNING. THE POTENTIAL EXISTS FOR STRONG WINDS AND LARGE HAIL...ALONG WITH HEAVY RAINFALL THIS MORNING. THE SECOND ROUND OF STORMS WILL DEVELOP THIS AFTERNOON. THE MORE WIDESPREAD ACTIVITY WILL BE ACROSS THE NORTHERN VALLEY INTO NORTHWEST MINNESOTA...WITH MORE ISOLATED TO SCATTERED ACTIVITY TO THE SOUTH. STRONG WINDS...LARGE HAIL...AND A FEW TORNADOS ARE THE MAIN THREATS...ALONG WITH HEAVY RAINFALL. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY THUNDERSTORMS ARE POSSIBLE FRIDAY NIGHT AND AGAIN SATURDAY AFTERNOON. SOME OF THE STORMS MAY BE STRONG TO SEVERE SATURDAY AFTERNOON. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED. TG
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 130 AM CDT THU AUG 29 2013 NDZ049-052-053-290730- RANSOM ND-RICHLAND ND-SARGENT ND- 130 AM CDT THU AUG 29 2013 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN RICHLAND... NORTHEASTERN SARGENT AND SOUTHEASTERN RANSOM COUNTIES UNTIL 230 AM CDT... AT 125 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A THUNDERSTORM 6 MILES EAST OF MILNOR...OR 35 MILES WEST OF WAHPETON... MOVING TO THE NORTHEAST AT 15 MPH. HAIL UP TO THE SIZE OF NICKELS IS EXPECTED WITH THE STORM. THE STORM WILL BE NEAR... DE LAMERE AROUND 135 AM CDT. WYNDMERE AROUND 155 AM CDT. MCLEOD AROUND 205 AM 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 4660 9719 4644 9688 4614 9728 4626 9745 TIME...MOT...LOC 0630Z 216DEG 12KT 4625 9733 TG
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 455 AM CDT THU AUG 29 2013 MNZ002-NDZ030-039-291045- CASS ND-NORMAN MN-TRAILL ND- 455 AM CDT THU AUG 29 2013 ...SIGNIFICANT WEATHER ADVISORY FOR EXTREME NORTHWESTERN NORMAN COUNTY IN NORTHWEST MINNESOTA...AND TRAILL AND NORTHERN CASS COUNTIES IN SOUTHEAST NORTH DAKOTA UNTIL 545 AM CDT... AT 451 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A THUNDERSTORM 14 MILES SOUTHWEST OF HILLSBORO...OR 30 MILES NORTHWEST OF FARGO...MOVING TO THE NORTHEAST AT 20 MPH. HAIL UP TO THE SIZE OF NICKELS IS EXPECTED WITH THE STORM...ALONG WITH FREQUENT LIGHTNING. THE STORM WILL BE NEAR... GRANDIN AROUND 505 AM CDT. BLANCHARD AROUND 510 AM CDT. KELSO AROUND 520 AM CDT. HILLSBORO AROUND 535 AM CDT. FOR MOTORISTS ON INTERSTATE 29...THE STORM WILL BE BETWEEN...MILE MARKER 91 AROUND 505 AM CDT...AND MILE MARKER 115 AROUND 545 AM 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 4762 9727 4750 9685 4710 9706 4724 9744 TIME...MOT...LOC 0955Z 205DEG 17KT 4725 9719 JK
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
508 AM CDT THU AUG 29 2013
NDZ006-014-015-024-291115-
BENSON ND-EDDY ND-RAMSEY ND-TOWNER ND-
508 AM CDT THU AUG 29 2013
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN TOWNER...RAMSEY...EDDY
AND BENSON COUNTIES UNTIL 615 AM CDT...
AT 505 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
THUNDERSTORMS ALONG A LINE EXTENDING FROM 16 MILES NORTHWEST OF LEEDS
TO 14 MILES SOUTHWEST OF NEW ROCKFORD...MOVING TO THE EAST AT 30 MPH.
WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THE STORMS.
THE STORMS WILL BE NEAR...
LEEDS AROUND 515 AM CDT.
BRINSMADE AROUND 525 AM CDT.
NEW ROCKFORD...OBERON AND MINNEWAUKAN AROUND 530 AM CDT.
SHEYENNE AROUND 535 AM 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 4838 9951 4854 9950 4852 9853 4758 9852
4758 9926 4759 9927 4766 9927 4767 9930
4784 9931 4784 9957 4838 9970
TIME...MOT...LOC 1008Z 268DEG 27KT 4849 9959 4757 9936
JKPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
556 AM CDT THU AUG 29 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0530 AM TSTM WND GST NEW ROCKFORD 47.68N 99.14W
08/29/2013 E60 MPH EDDY ND LAW ENFORCEMENT
ESTIMATED AT 60MPH...CAR WAS SHAKING VIOLENTLY
&&
TGRAFENAThe Fargo/Grand Forks radar (KMVX), 80 km away, was scanning. The volume nearest the first event began at 12:24 UTC.
1 thunderstorm wind. Local standard time, as filed.
Several three to five inch diameter tree branches were broken down in a farmyard.
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: 466965.