Isolated showers and a few weak thunderstorms developed in cyclonic flow to the north of a low pressure system centered over central South Dakota. A short lived landspout tornado developed south of Zap in Mercer County.
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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.
Isolated showers and a few weak thunderstorms developed in cyclonic flow to the north of a low pressure system centered over central South Dakota. A short lived landspout tornado developed south of Zap in Mercer County. The tornado touched down in an open field and impacted no structures. There was no damage to evaluate. By National Weather Service policy the tornado is rated EF-U (Unknown).
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 30, 11:25 AM CST, 1 hour 27 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Bismarck ND 1225 PM CDT Sat Aug 30 2025 .KEY MESSAGES... - Cooler temperatures in the 70s expected across the south today, with 80s lingering in the north. - Near seasonable high temperatures in the mid 70s to mid 80s return Sunday through Labor Day, with lows generally in the 50s. Cooler temperatures possible during the middle of next week. - Isolated to scattered showers and thunderstorms possible through Sunday, mainly south, shifting to the east on Labor Day. The probability for severe weather is very low. && .UPDATE... Issued at 1225 PM CDT Sat Aug 30 2025 All fog previously found across western and central North Dakota has lifted at the time of this mid day update. Another round of fog is possible tonight through early Sunday morning most areas south of Highway 200. Otherwise, scattered showers continue over southwest and portions of south central North Dakota. With the ongoing destabilization of the atmosphere this afternoon, a few isolated thunderstorms have started to develop over south central North Dakota. These storms will continue to be possible through the early evening. Have made some slight adjustments to the PoPs and Sky grids by blending in the latest models, but otherwise the forecast remains on track. UPDATE Issued at 945 AM CDT Sat Aug 30 2025 Fog across much of western and central North Dakota has begun to lift at the time of this late morning update, though visibilities around 1 mile or less still lingers over a portion of south central North Dakota. Visibilities are anticipated to rapidly improve over the next hour or two. Otherwise, scattered showers continue to circulate over an upper level low languishing over South Dakota this morning, mainly found to the south of Interstate 94 in southwestern and south central North Dakota. No major adjustments to the forecast were performed at this time, as it remain broadly on track. UPDATE Issued at 648 AM CDT Sat Aug 30 2025 Fog starting to be reported across much of North Dakota early this morning. Some sites are report visibility as low as a quarter mile. Webcams still showing the more dense fog to be isolated to scattered. Given this coverage uncertainty have issued an SPS to account for this fog this morning. Motorists should still drive with caution as areas with fog could see a quarter mile or less through the mid morning hours. Similar setup is found tonight, thus placed at least patchy fog mention in the forecast for tonight into Sunday morning. Otherwise upper low continues to bring some shower activity in the south. Made minor PoP adjustments to account for these ongoing showers. SPC has broad general risk for thunderstorms later today into this evening. Made some slight pop adjustment to include slight chances for thunderstorms further north today, yet still south of Highway 2. && .DISCUSSION... Issued at 425 AM CDT Sat Aug 30 2025 Weak surface flow combined with high RH could bring widespread fog this morning. Highest confidence would be for areas south of Highway 2, although much of the state could see at least patchy fog. Confidence and coverage is not quite high enough for an advisory at this time, although will continue to monitor observations for any potential fog product. Upper low will continue to slowly move across the region today. This will continue to bring chances for showers and thunderstorms to the southern half of the state today. North of this will see enough instability this afternoon for a few isolated thunderstorms, although confidence in thunderstorm chances decreases closer to the international border given a surface high in Canada. With a lack of shear, the severe weather threat is low today. Any thunderstorm that does develop could be slow moving and perhaps produce some heavy rain. Cold air funnels were also observed yesterday closer to the upper low in South Dakota. This could happen again today across the region given similar conditions. High temperatures will be cooler in the south and generally in the 70s, while remain warm and in the 80s across the north. Upper low continues to linger across the areas tonight, and could linger at least some shower chances in the southwest and south central. Humidity values will again be high, while light winds are also forecast. Fog could return, although cloudy skies may limit this potential. Look for lows tonight mainly in the 50s. Upper low looks to push south on Sunday, although lingering moisture and weak instability could still provide a few showers in southern and western portions. South wind will warm temperatures slightly and back into the mid 70s to mid 80s. Fog may then return again Sunday night into Monday morning, although a steady south wind along with some cloud cover may limit this. Shower activity looks to diminish somewhat Sunday night, with lows in the 50s remaining. Labor Day, a weak short wave looks to move across the state and return chances for showers and thunderstorm, mainly in central and eastern portions. With continues warm temperatures in the mid 70s to mid 80s, instability may be slightly increased. This wave could also bring some increased, yet still low, shear. Thus an isolated stronger storm is possible Monday, although the chance for severe weather remains low. Shower and thunderstorm chances may linger through the night Monday night, mainly in the north and east. Look for lows to continue in the 50s. Cold front still forecast to come through sometime Tuesday. Current timing has this front moving through Tuesday morning, bringing some showers and thunderstorm chances. If this front delays to later in the day then perhaps an isolated stronger storm is possible. Breezy northerly winds may be found behind this front on Tuesday, with temperatures also cooling into the 60s and 70s. Tuesday night could see some lingering showers and thunderstorms in the south. Colder overnight lows in the upper 30s to upper 40s are forecast. A post frontal day then sets up for Wednesday with cooler temperatures in the 60s. A steady northerly wind may also be found, although the breezier winds are forecast for eastern North Dakota. Surface high moving in should limit precipitation chances on Wednesday. Cool overnight lows in the 40s, with perhaps some 30s are then possible through the end of the work week. Building ridge to our west with a broad surface high in the region should also limit the chances for precipitation through the end of next week. Temperature spreads remain large for late next week, although generally show a warming trend. NBM currently has forecast highs warming back into the 70s. If the large western ridge moves further inland these temperatures could be warmer. Lower humidity values could also be found during the day with this more dry pattern. Winds could stay northwest through the end of the week, although strong winds are currently not expected given low ECMWF EFI values. && .AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 1225 PM CDT Sat Aug 30 2025 VFR ceilings and visibility is found at all terminals to begin the 18Z TAF period. Scattered showers and a few thunderstorms are possible through the afternoon and early overnight period, with the highest confidence in the southwest. Have included a PROB30 -TSRA group at KDIK with this update. Early tonight through Sunday morning, ample near surface moisture and calm winds could allow for fog development across southern North Dakota. Have added visibility reductions at KBIS and KJMS with this update. There is less confidence in visibility reductions at KDIK at due to prevailing mid level cloud cover overnight, thus have opted to not include any mentions of such in the TAF at this time. Light south to southwesterly winds this afternoon will generally diminish, becoming very light and variable across the south through late Sunday morning. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && UPDATE...Adam DISCUSSION...Anglin AVIATION...Adam
Hazardous Weather Outlook National Weather Service Bismarck ND 1205 PM CDT Sat Aug 30 2025 NDZ001>005-009>013-311715- Divide-Burke-Renville-Bottineau-Rolette-Williams-Mountrail-Ward- McHenry-Pierce- 1205 PM CDT Sat Aug 30 2025 This Hazardous Weather Outlook is for portions of north central North Dakota and northwest North Dakota. .DAY ONE...This Afternoon and Tonight The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Sunday through Friday The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed. NDZ017>023-025-031>037-040>048-050-051-311715- McKenzie-Dunn-Mercer-Oliver-McLean-Sheridan-Wells-Foster- Golden Valley-Billings-Stark-Morton-Burleigh-Kidder-Stutsman- Slope-Hettinger-Grant-Bowman-Adams-Sioux-Emmons-Logan-La Moure- McIntosh-Dickey- 1205 PM CDT Sat Aug 30 2025 /1105 AM MDT Sat Aug 30 2025/ This Hazardous Weather Outlook is for portions of northwest North Dakota, south central North Dakota, southeast North Dakota, and southwest North Dakota. .DAY ONE...This Afternoon and Tonight Isolated thunderstorms are possible today through this evening. The chance of severe weather is low. .DAYS TWO THROUGH SEVEN...Sunday through Friday The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
Special Weather Statement National Weather Service Bismarck ND 900 AM CDT Sat Aug 30 2025 NDZ021-022-035-301600- McLean-Sheridan-Burleigh- Including the cities of Garrison, Washburn, Underwood, Wilton, Turtle Lake, Mcclusky, Goodrich, and Bismarck 900 AM CDT Sat Aug 30 2025 ...PATCHY DENSE FOG ACROSS PORTIONS OF CENTRAL NORTH DAKOTA THIS MORNING... Patchy dense fog will reduce the visibility to one quarter mile or less in parts of central North Dakota this morning. Motorists should be prepared for rapidly changing visibilities, and should use extra caution traveling. Use low beam headlights and be extra cautious at intersections and railroad crossings. The fog is expected to dissipate by the mid to late morning.
The Bismarck radar (KBIS), 97 km away, was scanning. The volume nearest the first event began at 18:52 UTC.
1 tornado. Local standard time, as filed.
The tornado touched down in an open field south of Zap and impacted no structures. There was no damage to evaluate. By National Weather Service policy the tornado is rated EF-U (Unknown).
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 historyThe tornado archive for North Dakota, 2025Warnings 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: 1291497.