A pair of severe thunderstorms following in line passed through Divide County producing hail up to the size of golf balls. Significant crop damage was reported to the north-northwest of Appam.
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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 BIS wrote it up.
A pair of severe thunderstorms following in line passed through Divide County producing hail up to the size of golf balls. Significant crop damage was reported to the north-northwest of Appam.
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 Bismarck, ND wrote its last area forecast discussion before the first event at Aug 17, 6:38 PM CST, 2 hours 12 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Bismarck ND 738 PM CDT Sun Aug 17 2025 .KEY MESSAGES... - Isolated to scattered showers and thunderstorms in the east through this evening, then isolated thunderstorms possible across the west through tonight. The threat for severe weather is low. - Areas of fog are likely to develop across central and eastern North Dakota tonight into Monday morning. - Isolated thunderstorms possible on Monday. A strong to severe storm is possible across south central North Dakota, with the main hazards being hail to the size of ping pong ball and wind gusts to 60 mph. - Warmer and drier weather expected through mid week. Some moderate heat impacts are possible. && .UPDATE... Issued at 738 PM CDT Sun Aug 17 2025 Monitoring two separate areas of convection early this evening. One is a batch of mostly showers with infrequent lightning along the James River Valley. This activity is tied to a slow moving 700 mb trough that is forecast to drift into the Red River Valley later this evening. It is located along the eastern edge of a pool of 2000 J/kg, but both SBCIN and MLCIN are present, and effective bulk shear is analyzed to be no greater than 25 kts. However, radar estimates that 3 to 5 inches of rain has fallen in northeast Stutsman County in the past couple of hours as an area of heavier rain persisted in that location. The second area is a line of isolated showers and thunderstorms that is slowly drifting into northwest North Dakota. A couple storms became strong at times prior to entering the state, but intensity has quickly waned on this side of the border. Current trends suggest that the chance for a stronger storm in western North Dakota remains very low. && .DISCUSSION... Issued at 352 PM CDT Sun Aug 17 2025 Upper level wave will push eastward and out of the state tonight. Weak instability close to this wave could bring some shower and thunderstorm activity across the east through this evening. Being displaced from the wave combined with a lack of shear, severe weather is not expected. Some CAMs have isolated thunderstorm activity in the west overnight tonight along an axis of instability. The lift for this looks limited, thus just put in slight chances. If a storm can develop, modest shear could bring a strong storm although the chance for severe weather looks low. Winds will become calm tonight and with lingering high dewpoints will bring RH values near 100%. This could bring patchy to areas of fog to much of the CWA tonight into Monday morning. Lows tonight will generally be in the mid 50s to mid 60s. The axis of instability moves over central ND on Monday. A weak warm front also looks to set up Monday warming temperatures back into the 80s for most areas with light winds also expected. Either weak disturbances in the westerly flow aloft or this frontal boundary at the surface could bring isolated thunderstorms in the axis of high cape. Either one of these disturbances would provide weak lift, thus the confidence in thunderstorm formation is low. The potential is there for an isolated severe storm if one can develop. SPC currently has a Marginal Risk (level 1 of 5) in south central portions. CAPE is high yet shear is modest. Storm mode would be multi cluster to perhaps supercell. Thus the main hazards would be ping pong ball size hail and 60 mph winds. Monday night, thunderstorm activity will diminish and another night of light winds and high RH values could return patchy to areas of fog. Given the similar setup to tonight have added fog mention in for Monday night into Tuesday morning as well. A broad ridge aloft then looks to settle in over the state Tuesday. This will bring further warming temperatures in the 80s to perhaps 90s in the west. Heat Risk could even reach the moderate level in some western areas. Even with some afternoon instability, ridge aloft should cap any chances for thunderstorms Tuesday. After a mild and dry night Tuesday night, further warming and generally dry conditions will be expected on Wednesday. Widespread mid 80s to mid 90s are forecast, with perhaps some upper 90s in the west. This could bring more widespread moderate to perhaps isolated major Heat Risk across the CWA. Breezy southerly winds may also be found, as well as some lower RH in the west. Fuels are likely too green for any fire danger across the area. Surface low and perhaps a cold front could return shower and thunderstorm chances Wednesday night into Thursday morning. Thunderstorm activity could then linger into Thursday with some cooler temperatures possible in the north behind the mentioned front. Depending on timing of this front there could be at least some isolated severe weather chances as well. Late next week into next weekend looks mainly dry and cool as northwest flow is forecast to remain across the area. Cooler highs in the 70s with lows in the 40s and 50s are forecast. Perhaps some breezy northwest winds may also be found in this pattern next weekend. These temps and winds are dependent on how this northwest flow pattern sets up, although NBM temperatures spreads are currently small indicating higher confidence in this pattern change. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 738 PM CDT Sun Aug 17 2025 Isolated showers and thunderstorms are possible this evening across western North Dakota, as well as near KJMS and surrounding areas. Additional showers and perhaps a few thunderstorms could develop or move into western North Dakota later tonight, but the probability at any given location is very low. MVFR ceilings prevail from north central to southeast North Dakota early this evening. The low ceilings are expected to expand across all of central North Dakota and lower to IFR/LIFR levels through tonight. Fog/mist underneath the low clouds could also reduce visibility to IFR levels. Conditions are expected to improve to VFR by Monday afternoon, with VFR prevailing across western North Dakota through the forecast period. Winds will remain light and variable. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && UPDATE...Hollan DISCUSSION...Anglin AVIATION...Hollan
Hazardous Weather Outlook National Weather Service Bismarck ND 748 PM CDT Sun Aug 17 2025 NDZ037-048-051-190100- Stutsman-La Moure-Dickey- 748 PM CDT Sun Aug 17 2025 This Hazardous Weather Outlook is for portions of southeast North Dakota. .DAY ONE...Tonight Isolated thunderstorms are possible this evening. Severe weather is not expected, but storms could produce locally heavy rain. .DAYS TWO THROUGH SEVEN...Monday through Saturday An isolated severe thunderstorm is possible Monday afternoon and evening. Expected hazards are hail to the size of ping pong balls and wind gusts to 60 mph. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed. NDZ001-002-009-010-017>019-021-031-032-040-043-190100- Divide-Burke-Williams-Mountrail-McKenzie-Dunn-Mercer-McLean- Golden Valley-Billings-Slope-Bowman- 748 PM CDT Sun Aug 17 2025 /648 PM MDT Sun Aug 17 2025/ This Hazardous Weather Outlook is for portions of northwest North Dakota, south central North Dakota, and southwest North Dakota. .DAY ONE...Tonight Isolated thunderstorms are possible this evening through tonight. Severe weather is not expected. .DAYS TWO THROUGH SEVEN...Monday through Saturday The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed. NDZ020-034>036-042-045>047-050-190100- Oliver-Morton-Burleigh-Kidder-Grant-Sioux-Emmons-Logan-McIntosh- 748 PM CDT Sun Aug 17 2025 /648 PM MDT Sun Aug 17 2025/ This Hazardous Weather Outlook is for portions of south central North Dakota and southeast North Dakota. .DAY ONE...Tonight The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Monday through Saturday An isolated severe thunderstorm is possible Monday afternoon and evening. Expected hazards are hail to the size of ping pong balls and wind gusts to 60 mph. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed. NDZ033-041-044-190100- Stark-Hettinger-Adams- 648 PM MDT Sun Aug 17 2025 This Hazardous Weather Outlook is for portions of southwest North Dakota. .DAY ONE...Tonight Isolated thunderstorms are possible this evening through tonight. Severe weather is not expected. .DAYS TWO THROUGH SEVEN...Monday through Saturday An isolated severe thunderstorm is possible Monday afternoon and evening. Expected hazards are hail to the size of ping pong balls and wind gusts to 60 mph. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed. NDZ003>005-011>013-022-023-025-190100- Renville-Bottineau-Rolette-Ward-McHenry-Pierce-Sheridan-Wells- Foster- 748 PM CDT Sun Aug 17 2025 This Hazardous Weather Outlook is for portions of north central North Dakota, south central North Dakota, and southeast North Dakota. .DAY ONE...Tonight The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Monday through Saturday The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed. Hollan
Special Weather Statement
National Weather Service Bismarck ND
805 PM CDT Sun Aug 17 2025
NDZ001-180145-
Divide ND-
805 PM CDT Sun Aug 17 2025
...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN DIVIDE COUNTY
THROUGH 845 PM CDT...
At 805 PM CDT, Doppler radar was tracking a strong thunderstorm 10
miles north of Westby, or 30 miles northeast of Plentywood, moving
east at 15 mph.
HAZARD...Wind gusts up to 50 mph and nickel 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...
Fortuna and Alkabo.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
&&
LAT...LON 4900 10370 4890 10372 4881 10387 4889 10405
4900 10405
TIME...MOT...LOC 0105Z 282DEG 12KT 4901 10399
MAX HAIL SIZE...0.88 IN
MAX WIND GUST...50 MPH
ADAMSpecial Weather Statement
National Weather Service Bismarck ND
859 PM CDT Sun Aug 17 2025
NDZ001-009-180230-
Divide ND-Williams ND-
859 PM CDT Sun Aug 17 2025
...STRONG THUNDERSTORMS WILL IMPACT NORTHWESTERN WILLIAMS AND WESTERN
DIVIDE COUNTIES THROUGH 930 PM CDT...
At 859 PM CDT, Doppler radar was tracking a cluster of strong
thunderstorms along a line extending from 11 miles northeast of
Fortuna to near Hanks City to 5 miles southwest of Grenora. Movement
was east at 10 mph.
HAZARD...Wind gusts up to 40 mph and nickel 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...
Grenora, Westby, Fortuna, Alkabo, Writing Rock State Historical Site,
Hanks City, Zahl, and Hanks.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with these storms and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
&&
LAT...LON 4900 10375 4893 10343 4872 10346 4850 10368
4859 10405 4889 10405 4900 10395
TIME...MOT...LOC 0159Z 274DEG 9KT 4900 10355 4862 10377 4858 10404
MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH
ADAMThe Minot AFB radar (KMBX), 205 km away, was scanning. The volume nearest the first event began at 02:48 UTC.
1 hail. Local standard time, as filed.
Crops were severely damaged, including an entire canola field which was totaled.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in North Dakota in 2025Every state in 2025This day in weather historyWarnings in North Dakota, August 2025
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: 1289725.