Alert archive / Minnesota / Severe Thunderstorm Warnings in 2026
Severe Thunderstorm Warning 151, NWS Grand Forks, ND
NWS Grand Forks, ND issued this severe thunderstorm warning at Aug 12, 2026, 2:59 AM CDT for Clay County, Minnesota; Cass County, North Dakota. It was in force for 46 min. 3 reports came from inside the area while it was in force.
The area
The outline as issued, with what was reported inside it.
The facts
- Issued
- Aug 12, 2026, 2:59 AM CDT (07:59 UTC)
- Expired
- Aug 12, 2026, 3:45 AM CDT
- In force
- 46 min
- Issued by
- NWS Grand Forks, ND
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
Counties Clay County, MN, Cass County, ND
The radar
The Fargo/Grand Forks radar (KMVX), 79 km from the middle of the area, began a volume at 08:02 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Aug 12, 3:05 AM CDT | TSTM WND GST 60 | Mapleton, ND | Estimated Wind Gust. |
| Aug 12, 3:25 AM CDT | TSTM WND GST 50 | 4 S Fargo, MN | Wind Gust recorded on Personal Weather Station in the Prairie Rose area. |
| Aug 12, 3:28 AM CDT | TSTM WND GST 40 | Moorhead, MN | Wind Gust South Moorhead. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
Did it verify
Verified. The Iowa Environmental Mesonet's Cow matched one storm report to this severe thunderstorm warning; the first came 6 minutes after it went out.
Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.
The nearest sounding before it
Aberdeen, SD (KABR), launched 00:00Z, 8.0 hours before the alert went out and 246 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 2509 J/kg
- Mixed-layer CIN
- -33 J/kg
- Mixed-layer LCL
- 1105 m above ground
- 0-6 km bulk shear
- 53 kt
- 0-1 km storm-relative helicity
- 16 m²/s²
- 0-3 km storm-relative helicity
- -14 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.2
The text
As transmitted.
563 WUUS53 KFGF 120759 SVRFGF MNC027-NDC017-120845- /O.NEW.KFGF.SV.W.0151.260812T0759Z-260812T0845Z/ BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Grand Forks ND 259 AM CDT Wed Aug 12 2026 The National Weather Service in Grand Forks has issued a * Severe Thunderstorm Warning for... Western Clay County in northwestern Minnesota... Eastern Cass County in southeastern North Dakota... * Until 345 AM CDT. * At 259 AM CDT, a severe thunderstorm was located over Mapleton, or 10 miles west of Fargo, moving east at 45 mph. HAZARD...60 mph wind gusts and penny size hail. SOURCE...Radar indicated. IMPACT...Expect damage to roofs, siding, and trees. * Locations impacted include... Fargo, Moorhead, West Fargo, Dilworth, Horace, Mapleton, and Harwood. This includes the following highways... Interstate 29 between mile markers 56 and 78. Interstate 94 in North Dakota between mile markers 335 and 352. Interstate 94 in Minnesota between mile markers 1 and 7. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. && LAT...LON 4674 9715 4706 9715 4705 9664 4674 9662 TIME...MOT...LOC 0759Z 269DEG 40KT 4691 9703 HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...0.75 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...60 MPH $$ Riddle
1 follow-up statement
313 WWUS53 KFGF 120837 SVSFGF Severe Weather Statement National Weather Service Grand Forks ND 337 AM CDT Wed Aug 12 2026 MNC027-NDC017-120847- /O.EXP.KFGF.SV.W.0151.000000T0000Z-260812T0845Z/ Clay MN-Cass ND- 337 AM CDT Wed Aug 12 2026 ...THE SEVERE THUNDERSTORM WARNING FOR WESTERN CLAY AND EASTERN CASS COUNTIES WILL EXPIRE AT 345 AM CDT... The storm which prompted the warning has moved out of the area. Therefore, the warning will be allowed to expire. The warning for central Clay extending east into Becker county remains in effect. && LAT...LON 4674 9715 4706 9715 4705 9664 4674 9662 TIME...MOT...LOC 0837Z 269DEG 40KT 4692 9645 $$ Riddle
What forecasters said that day
The local office's own words before this severe thunderstorm warning went out, 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 this severe thunderstorm warning went out at Aug 11, 11:53 PM CDT, 3 hours 6 minutes earlier. Its key messages:
- Scattered storms overnight and again Wednesday evening will bring strong to severe storms to southeast North Dakota.
- Multiple rain chances with a 50% chance for a cumulative half inch through early next week for most areas across the region.
Area forecast discussion, Aug 11, 11:53 PM CDT, 3 hours 6 minutes before
Area Forecast Discussion National Weather Service Grand Forks ND 1153 PM CDT Tue Aug 11 2026 .KEY MESSAGES... - Scattered storms overnight and again Wednesday evening will bring strong to severe storms to southeast North Dakota. - Multiple rain chances with a 50% chance for a cumulative half inch through early next week for most areas across the region. && .UPDATE... Issued at 1154 PM CDT Tue Aug 11 2026 Strong to severe thunderstorms continue to slowly move east across central North Dakota tonight. Storms will gradually weaken as the night progresses, however, isolated severe storms could bring impacts into portions of eastern North Dakota after midnight. The primary hazard will be large hail. UPDATE Issued at 634 PM CDT Tue Aug 11 2026 Severe thunderstorm watch will be in effect for Barnes, Ransom, and Sargent County through 1 AM CDT. && .DISCUSSION... Issued at 237 PM CDT Tue Aug 11 2026 ...Synopsis... Currently a very elongated ridge exists across the southern CONUS with zonal to WNW mid level flow in the northern CONUS. As we progress through the week, ridging over the four corners into Texas panhandle will amplify. At the same time PNW troughing begins to turn flow more zonal over us as the ridge gets pushed east. By Thursday SW flow looks to dominate the western CONUS bringing pacific moisture over the Rockies with embedded shortwaves. Certainly still differences remaining among clusters but the potential for a wet late week/weekend continues to increase. Current guidance is now favoring western areas (eastern North Dakota) over eastern areas (northwest Minnesota) with a 60% chance for over half an inch in the next seven days vs only 40% chance out east. As much of this rain looks to be more convective and thunderstorm driven vs a slow soaking rain totals will likley vary greatly over short distances. - Severe threat today This morning MUCAPE of 1000-2000 j/kg atop a nearly stationary surface boundary led to the formation of a lone supercell that tracked from north of Jamestown towards Fort Ransom dropping up to baseball sized hail along the way. Overall this was mostly a surprise and not in the forecast given the skinny CAPE, however the very favorable straight hodos and eff shear of around 50kts at least helped explain it a little. Looking ahead to this evening CAMS largely maintain the instability across the area but fail to convect despite an overall capable environment should a forcing mechanism exist. The chance for a storm this evening is likely less than 10% but if one goes, something similar to this morning is certainly possible. By the overnight there is higher confidence in storms forming west of Bismarck and moving east reaching the James/Sheyenne river valleys around 4-5am. Storms still look to be elevated and a primary hail threat, but cant 100% rule out damaging winds. This threat would persist into the mid morning hours mainly for southeast North Dakota and perhaps west central Minnesota is storms made it that far east. - Severe threat Wednesday A more pronounced shortwave will roll across the Dakotas Wednesday evening bringing forcing for widespread convection. thunderstorms may occasionally have large hail and gusty winds but overall this looks to be more of a general thunderstorm/widespread rain event for eastern North Dakota. Amounts will generally will be a quarter to half inch but isolated totals in excess of 1" are possible. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 1154 PM CDT Tue Aug 11 2026 VFR conditions prevail through the period at all TAF sites. Still monitoring for the possibility of thunderstorm activity during the early morning hours Wednesday, however, confidence in coverage remains quite low at this time. The most likely timing for potential storms would be 07Z through around 10Z, and would primarily be in the vicinity of KFAR. Winds are expected to remain light and variable overnight before increasing slightly heading into Wednesday morning. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && UPDATE...Lynch DISCUSSION...TT AVIATION...Lynch
Hazardous weather outlook, Aug 11, 2:52 PM CDT, 12 hours 7 minutes before
Hazardous Weather Outlook National Weather Service Grand Forks ND 252 PM CDT Tue Aug 11 2026 MNZ001-002-004>009-013>017-022>024-NDZ006>008-014>016-024-026>030- 054-122000- West Polk-Norman-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- Towner-Cavalier-Pembina-Benson-Ramsey-Eastern Walsh-Eddy-Nelson- Grand Forks-Griggs-Steele-Traill-Western Walsh- 252 PM CDT Tue Aug 11 2026 This hazardous weather outlook is for portions of eastern North Dakota, west central and northwest Minnesota. .DAY ONE...This Afternoon and Tonight The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Wednesday through Monday The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation may be required today. MNZ003-027>032-040-NDZ038-039-049-052-053-122000- Clay-West Becker-East Becker-Wilkin-West Otter Tail- East Otter Tail-Wadena-Grant-Barnes-Cass-Ransom-Sargent-Richland- 252 PM CDT Tue Aug 11 2026 This hazardous weather outlook is for portions of eastern North Dakota and west central Minnesota. .DAY ONE...This Afternoon and Tonight Isolated to scattered thunderstorms this afternoon and evening may bring hail over 1 inch and damaging winds over 60 mph. .DAYS TWO THROUGH SEVEN...Wednesday through Monday The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated today.
In the hours before
Special weather statement, Aug 12, 1:23 AM CDT, 1 hour 36 minutes before
Special Weather Statement
National Weather Service Grand Forks ND
123 AM CDT Wed Aug 12 2026
NDZ038-120715-
Barnes ND-
123 AM CDT Wed Aug 12 2026
...A STRONG THUNDERSTORM WILL IMPACT CENTRAL BARNES COUNTY THROUGH
215 AM CDT...
At 122 AM CDT, Doppler radar was tracking a strong thunderstorm near
Spiritwood moving east at 30 mph.
HAZARD...Wind gusts up to 40 mph and penny size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Valley City, Sanborn, Rogers, Eckelson, Urbana, and Bald Hill Dam.
This includes Interstate 94 in North Dakota between mile markers 272
and 296.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4708 9791 4676 9791 4676 9844 4698 9844
4698 9847 4707 9847
TIME...MOT...LOC 0622Z 271DEG 24KT 4692 9856
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH
RiddleSpecial weather statement, Aug 12, 2:16 AM CDT, 43 minutes before
Special Weather Statement
National Weather Service Grand Forks ND
216 AM CDT Wed Aug 12 2026
MNZ003-NDZ038-039-120815-
Clay MN-Barnes ND-Cass ND-
216 AM CDT Wed Aug 12 2026
...A STRONG THUNDERSTORM WILL IMPACT WESTERN CLAY...CASS AND
EASTERN BARNES COUNTIES THROUGH 315 AM CDT...
At 215 AM CDT, Doppler radar was tracking a strong thunderstorm over
Oriska, or 12 miles east of Valley City, moving east at 45 mph.
HAZARD...Wind gusts up to 50 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Fargo, Moorhead, West Fargo, Dilworth, Horace, Casselton, and
Mapleton.
This includes the following highways...
Interstate 29 between mile markers 50 and 82.
Interstate 94 in North Dakota between mile markers 302 and 352.
Interstate 94 in Minnesota between mile markers 1 and 7.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4666 9779 4712 9783 4711 9664 4665 9662
TIME...MOT...LOC 0715Z 269DEG 39KT 4693 9775
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH
RiddleThe office that day
Everything else NWS Grand Forks, ND issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 12, 3:25 AM CDT | Severe Thunderstorm Warning | FGF | Becker, Clay, Otter Tail | 32 min |
| Aug 12, 1:23 AM CDT | Special Weather Statement | FGF | Barnes | 52 min |
| Aug 12, 2:16 AM CDT | Special Weather Statement | FGF | Cass | 59 min |
Nearby
Severe Thunderstorm Warnings in Minnesota, 2026Severe Thunderstorm Warnings in North Dakota, 2026Every severe thunderstorm warning in 2026
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.