During the early evening of September 1st, a line of thunderstorms formed between Stump Lake, in Nelson County, and Pembina, in Cavalier County. However, one cell on the far southern end of the line quickly became the strongest storm, and it would hold together as the storm tracked to the south-southeast, through Griggs, Steele, and Cass counties, before weakening.
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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.
During the early evening of September 1st, a line of thunderstorms formed between Stump Lake, in Nelson County, and Pembina, in Cavalier County. However, one cell on the far southern end of the line quickly became the strongest storm, and it would hold together as the storm tracked to the south-southeast, through Griggs, Steele, and Cass counties, before weakening. This cell produced several weak tornadoes, funnel clouds, and 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 Sep 1, 2:33 PM CST, 1 hour 57 minutes earlier.
Area Forecast Discussion National Weather Service Grand Forks ND 333 PM CDT Fri Sep 1 2017 .SHORT TERM...(This evening through Saturday) Issued at 317 PM CDT Fri Sep 1 2017 Main cold front/NW Wind shif t approaching Langdon and Devils Lake at 2030 UTC. A band of shower/tstorms tried to form ahead of it west of DVL past noon, but as it moves east it is encountering less favorable airmass and are pretty weak. Low clouds holding in the Red River valley ahead of the cold front and preventing much heating ahead of the front. Thus forsee chance for development of storms lowering and risk of severe storm while not zero is lessening. Will hold onto pops thru the evening mainly east of the Red River. .LONG TERM...(Saturday night through Friday) Issued at 317 PM CDT Fri Sep 1 2017 NW wind on Saturday but with sunshine, temperatures will rebound back into the mid 70s to low 80s. Very warm day on Sunday as winds turn southwest ahead of a cold front which will enter the northern RRV late aftn and move south Sunday evening. Some areas of E ND will see 90. Limited moisture with front itself means a general dry frontal passage. Mid level moisture behind the front dropping southeast thru the area Labor Day will bring clouds and a few showers. Cooler temps as well. Tuesday will see a shortwave trof trof exiting northern Minnesota with lingering showers across northcentral MN through the morning and a cool northerly near surface wind flow behind a departing cold front. Surface high pressure steadily marches across the area from late Tuesday into Wednesday... with north winds turning light and variable on Wednesday and temperatures starting to recover back into the 70s. During this period... the H5 ridge axis remains firmly locked over the western intermountain region with a moderate northwest H5 flow aloft over the Northern Plains. For the late week period... the H5 ridge axis starts to lean into the Northern Plains a bit, with northwest flow weakening and warming occurring at layers aloft. Late Thursday should see a southerly return flow near the surface as surface low pressure deepens in the western dakotas. Overall dry conditions are expected to persist with temperature arcing near to slightly above seasonal normals for Thursday and Friday. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 107 PM CDT Fri Sep 1 2017 MVFR and ocnl IFR cigs RRV and eastward thru nw/wc MN in south- southeastly gusty winds ahd of front. Clearing of these low clouds eastward very problematic and uncertain until the front passes. Overall improving from west to east tonight and VFR thur Saturday as winds turn northwest. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && SHORT TERM...Riddle LONG TERM...Riddle/Gust AVIATION...Riddle
Hazardous Weather Outlook National Weather Service Grand Forks ND 419 AM CDT Fri Sep 1 2017 MNZ001>005-007-008-013>015-029-NDZ006>008-014>016-024-026>030-038- 039-049-052>054-021200- West Polk-Norman-Clay-Kittson-Roseau-West Marshall-East Marshall- Pennington-Red Lake-East Polk-Wilkin-Towner-Cavalier-Pembina- Benson-Ramsey-Eastern Walsh County-Eddy-Nelson-Grand Forks-Griggs- Steele-Traill-Barnes-Cass-Ransom-Sargent-Richland- Western Walsh County- 419 AM CDT Fri Sep 1 2017 This hazardous weather outlook is for portions of eastern North Dakota, west central and northwest Minnesota. .DAY ONE...Today and Tonight Isolated severe thunderstorms are possible late this afternoon into the evening across eastern North Dakota and adjacent portions of Minnesota. Expected impacts will be hail greater than one inch, damaging wind gusts up to 60 mph, and possibly a tornado or two. .DAYS TWO THROUGH SEVEN...Saturday through Thursday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is possible this afternoon and evening. MNZ006-009-016-017-022>024-027-028-030>032-040-021200- Lake Of The Woods-North Beltrami-North Clearwater-South Beltrami- Mahnomen-South Clearwater-Hubbard-West Becker-East Becker- West Otter Tail-East Otter Tail-Wadena-Grant- 419 AM CDT Fri Sep 1 2017 This hazardous weather outlook is for portions of eastern North Dakota, west central and northwest Minnesota. .DAY ONE...Today and Tonight Showers along with isolated thunder possible today. A few stronger storms are possible. .DAYS TWO THROUGH SEVEN...Saturday through Thursday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated.
The Fargo/Grand Forks radar (KMVX), 93 km away, was scanning. The volume nearest the first event began at 22:30 UTC.
4 hail, 4 thunderstorm wind, 3 tornado, 2 funnel cloud. Local standard time, as filed.
A brief tornado touchdown with water swirl was noted over the north end of Stump Lake. As the tornado lifted, the funnel continued to track to the east. Peak winds were estimated at 70 mph.
This tornado touched down just east of Stump Lake and tracked to the east. Photos showed a persistent rope tornado with intermittent dust swirls. Peak winds were estimated at 80 mph.
Heavy rain was reported with a few dime to quarter sized hail.
A few half dollar sized hailstones fell just north of highway 15, in northwest Lee Township.
Occasional nickel to ping pong ball sized hail fell in very heavy rain across southeast Lenora Township.
A funnel cloud was observed just west of the Steele County line in far southeast Romness Township.
This tornado tracked intermittently for about two miles across a portion of the Sheyenne River Valley. Large tree branches were broken down in various shelterbelts and groves along the path, mainly along the valley edge. Peak winds were estimated at 75 mph.
Large hail fell with very heavy rain. Some of the hailstones were the size of golf balls.
Several four to eight inch diameter tree branches were snapped in a farmstead shelterbelt near county road 25, north of highway 200, in west central Greenview Township.
Strong wind gusts were associated with the rear flank shelf cloud. Some dime to nickel sized hail fell as well.
Large tree branches were blown down around the town of Hope. One poplar tree was snapped at the golf course.
A persistent wall cloud with a brief funnel cloud were observed. The wall cloud was nearly rain wrapped.
A few large tree branches were blown down in shelterbelts. Corn and bean fields were flattened in spots across northwest Rochester and northeast Ellsbury townships.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in North Dakota in 2017Every state in 2017This day in weather historyThe tornado archive for North Dakota, 2017Warnings in North Dakota, September 2017
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: 712452, 712453, 712454, 712455, 712456, 712457, 712458, 712459, 712460, 712461, 712463, 712464, 712465.