Thunderstorms developed over parts of central North Dakota into the James River Valley as a cold front pushed through the region. A storm over the upper James River Valley became severe, with estimated wind gusts around 65 mph in Foster 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.
Thunderstorms developed over parts of central North Dakota into the James River Valley as a cold front pushed through the region. A storm over the upper James River Valley became severe, with estimated wind gusts around 65 mph in Foster County.
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 Sep 2, 6:23 PM CST, 22 minutes earlier.
Area Forecast Discussion National Weather Service Bismarck ND 723 PM CDT Wed Sep 2 2020 .UPDATE... Issued at 709 PM CDT Wed Sep 2 2020 Cold front moving across the state is causing for areas of strong winds and critical fire danger. Some sites are seeing gusts 60 MPH or higher, with sustained winds near or over 40 MPH. A few of these winds gusts have been enhanced by shallow convection although they are all generally along the synoptic cold front. Have decided to issue a High Wind Warning for passage of this front for a brief period of strong winds this evening. Strongest winds will again come along this front and any weak convective showers. For the stronger convective storms will continue to monitor for more short lived convective wind gusts and issue any needed severe thunderstorm warnings. Either way wind gusts near 70 MPH are possible this evening. && .SHORT TERM...(This evening through Thursday night) Issued at 314 PM CDT Wed Sep 2 2020 Strong winds and critical fire weather conditions through this evening remain the primary message of our forecast. As of 20 UTC, a surface warm front is approaching the James River valley, with deep mixing and increasing low- and midlevel winds in its wake within the warm sector of an approaching Alberta clipper. Critical fire weather conditions are ongoing in western and parts of central ND, and RAP-based Fosberg index values support high- end values of 60 to 70 in southwestern ND through late afternoon with wind gusts of 50 mph and minimum RH values around 15 percent. This is a serious situation and reflects a higher-end Red Flag Warning. A strong cold frontal passage is still expected beginning late this afternoon in northwest ND and through the remainder of the area this evening. Upstream pressure 3-hour pressure rises on the order of 6-8 mb are forecast to intensify further with recent RAP and HRRR cycles forecasting a rather impressive 10 mb/3 hour area of pressure rises moving through western and south central ND in the 23 to 03 UTC time frame. Upstream, observed post-frontal gusts have mainly peaked in the 45 kt range, though a few spots within north central and northeastern MT have touched the 50 kt speed, and recent Glasgow radar imagery reveals 70 kt winds within 3000 to 5000 ft AGL. The 17 UTC HRRR cycle was higher with peak winds in the post-frontal mixed layer than its prior cycles, but the 18 UTC HRRR arrived a bit lower, supporting peak winds at the top of the boundary layer mainly in the 42 to 47 kt range this evening. Thus, after much consideration we are holding with a Wind Advisory instead of upgrading to a High Wind Warning, though we gave it very serious consideration and later observational trends could still necessitate such an adjustment. Elsewhere, we added the rest of east central ND to a Wind Advisory, and kept that eastern section from Rolla down to Jamestown and Ellendale valid until 09 UTC in collaboration with NWS Grand Forks. Otherwise, weak instability associated with the frontal passage may still drive convection and downdraft-enhanced winds, especially in central ND where CAMs are most aggressive with the coverage of convection. Given sufficient lightning, we may need to issue Severe Thunderstorm Warnings to handle this higher-order wind potential that would be less widespread outside of the newly issued High Wind Warning. On Thursday, mixed-layer winds will remain sufficient for breezy to windy conditions in residual cyclonic flow behind the exiting shortwave trough. Forecast soundings suggest mean boundary layer winds on the order of 20-25 kt in central ND, and closer to 20 kt in western ND. Highs will be cooler, in the mid 60s to lower 70s F, and it appears the stronger winds will not overlap with the lowest humidity, the latter of which will be in western ND. The winds may begin to relax by afternoon in the west, too, when a surface ridge axis begins to approach the region. That ridge is forecast to cross the area Thursday night, likely creating a favorable scenario for radiational cooling, so we relied on the cooler, MOS-based guidance for lows in that period since it often verifies well in those scenarios. We're thus calling for lows in the 40 to 45 F range over the entire area Thursday night. .LONG TERM...(Thursday night through Wednesday) Issued at 314 PM CDT Wed Sep 2 2020 A warming trend is expected through Saturday, but then confidence remains high in a shift to a colder weather pattern by early next week, albeit with uncertainty in timing of the transition. Global ensemble guidance is closely clustered in simulating rising heights aloft Friday and Saturday with corresponding low- and mid- level warm air advection beneath broad northwest flow aloft. This is reflected in NBM-based temperature forecasts which have highs in the 75 to 85 F range Friday area-wide, and around 90 F in the southwest on Saturday. Low-level southerly flow may increase on Saturday, potentially leading to elevated fire weather concerns. Thereafter, middle- and upper-level ridging in the southwest U.S. is forecast to retrograde and amplify off the west coast, though ensemble guidance varies with the degree and position of the 500 mb height anomalies. GEFS-based guidance has remained the most progressive with corresponding downstream troughing across the central U.S., and in particular with the lead shortwave which is expected to herald that pattern change. Ensemble-based cluster analysis has offered some support for a slower scenario over the last 24 hours, and indeed the spread in NBM membership for highs on Sunday -- the most likely period of pattern transition -- has increased significantly over western and central ND. The mean of the NBM has shifted warmer with highs on Sunday with the forecast highs now in the 70s F, though the simple, one standard deviation of NBM membership ranges from the mid 60s to lower 90s F Sunday. Thereafter, guidance agrees that a cold front will have arrived by Labor Day, though the westward extent and amplitude of the middle and upper-level troughing is uncertain, with the 12 UTC ECMWF the most aggressive, cutting off a 500 mb by midweek. That particular model core does have a tendency to be overly aggressive with cut- off lows, but this exemplifies the uncertainty. Regardless, CIPS analogs, which are driven by the GEFS, support a high confidence in well below normal temperatures and high probabilities of the first widespread frost of the season Monday night and Tuesday night. NBM-based guidance similarly supports that, as well as a period of increased precipitation chances centered on Labor Day as the initial upper-level trough develops across the region. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 709 PM CDT Wed Sep 2 2020 Strong winds along a cold front will be found through this evening with many sites seeing gusts over 50 knots. Showers along this front could also bring brief MVFR conditions through this evening. Showers and wind then diminish after 05z_Thursday (tonight) with perhaps some lingering low to mid level clouds producing MVFR conditions. By Thursday morning widespread VFR conditions look to return. Winds may be breezy at times in the afternoon, although not as high as recent days. && .FIRE WEATHER... Issued at 314 PM CDT Wed Sep 2 2020 Critical fire weather conditions will continue over western and most of central ND through this evening. We have maintained the Red Flag Warning, with emphasis not only on a serious combination of low humidity, strong winds, and temperatures near 90 degrees, especially southwest, but also on a cold frontal passage in the late afternoon and evening. That front will cause winds to shift to the northwest with gusts up to 55 mph widespread across the area. Conditions will improve by late evening as humidity starts to recover and increase. && .BIS WATCHES/WARNINGS/ADVISORIES... High Wind Warning until midnight CDT /11 PM MDT/ tonight for NDZ019>023-033>036-040>047-050. Red Flag Warning until 10 PM CDT /9 PM MDT/ this evening for NDZ001>003-009>011-017>022-031>036-040>047-050. Wind Advisory until midnight CDT /11 PM MDT/ tonight for NDZ001>004-009>012-017-018-031-032. Wind Advisory until 4 AM CDT Thursday for NDZ005-013-025-037-048- 051. && UPDATE...Anglin SHORT TERM...CJS LONG TERM...CJS AVIATION...Anglin
Hazardous Weather Outlook National Weather Service Bismarck ND 637 PM CDT Wed Sep 2 2020 NDZ001>003-009>011-017>022-031>036-040>047-050-032345- Divide-Burke-Renville-Williams-Mountrail-Ward-McKenzie-Dunn- Mercer-Oliver-McLean-Sheridan-Golden Valley-Billings-Stark-Morton- Burleigh-Kidder-Slope-Hettinger-Grant-Bowman-Adams-Sioux-Emmons- Logan-McIntosh- 637 PM CDT Wed Sep 2 2020 /537 PM MDT Wed Sep 2 2020/ This Hazardous Weather Outlook is for portions of north central North Dakota, northwest North Dakota, south central North Dakota, southeast North Dakota, and southwest North Dakota. .DAY ONE...Tonight A Red Flag Warning and Wind Advisory are in effect this afternoon and evening for strong, shifting winds and low humidity. See weather.gov/bis for details. There is a chance of thunderstorms late this afternoon and evening. Widespread severe weather is not expected, but strong wind gusts are possible with any storms. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed. NDZ004-005-012-013-023-025-037-048-051-032345- Bottineau-Rolette-McHenry-Pierce-Wells-Foster-Stutsman-La Moure- Dickey- 637 PM CDT Wed Sep 2 2020 This Hazardous Weather Outlook is for portions of north central North Dakota, south central North Dakota, and southeast North Dakota. .DAY ONE...Tonight A Wind Advisory is in effect. See weather.gov/bis for details. There is a chance of thunderstorms late this afternoon and evening. Widespread severe weather is not expected, but strong wind gusts are possible with any storms. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BISMARCK ND
654 PM CDT WED SEP 2 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0644 PM NON-TSTM WND GST 5 S DICKINSON 46.80N 102.80W
09/02/2020 M59 MPH STARK ND ASOS
ASOS STATION KDIK DICKINSON AIRPORT.
&&
ZHPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BISMARCK ND
657 PM CDT WED SEP 2 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0505 PM NON-TSTM WND GST 4 SW CHARLSON 48.02N 102.94W
09/02/2020 M63 MPH MCKENZIE ND MESONET
MESONET STATION 324070 4 WSW CHARLSON
(NDAWN).
&&
ZHPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BISMARCK ND
709 PM CDT WED SEP 2 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0655 PM NON-TSTM WND GST 3 W BUFFALO SPRINGS 46.17N 103.30W
09/02/2020 M62 MPH BOWMAN ND AWOS
AWOS STATION KBWW BOWMAN AIRPORT.
&&
ZHPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BISMARCK ND
739 PM CDT WED SEP 2 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0700 PM NON-TSTM WND GST 1 ENE LINCOLN 46.77N 100.68W
09/02/2020 M59 MPH BURLEIGH ND PUBLIC
MEASURED FROM A HOME WEATHER STATION.
&&
ZHPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BISMARCK ND
742 PM CDT WED SEP 2 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0739 PM NON-TSTM WND DMG WILTON 47.16N 100.78W
09/02/2020 MCLEAN ND FIRE DEPT/RESCUE
PICTURES RELAYED VIA DISPATCH OF A LARGE
COMMERCIAL/INDUSTRIAL BUILDING DESTROYED.
TIME ESTIMATED FROM FRONTAL PASSAGE ON RADAR
.
&&
ZHPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BISMARCK ND
745 PM CDT WED SEP 2 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0704 PM NON-TSTM WND DMG WILTON 47.16N 100.78W
09/02/2020 MCLEAN ND FIRE DEPT/RESCUE
CORRECTS TIME OF PREVIOUS REPORT: NON-TSTM
WND DMG REPORT FROM WILTON. PICTURES RELAYED
VIA DISPATCH OF A LARGE
COMMERCIAL/INDUSTRIAL BUILDING DESTROYED.
TIME ESTIMATED FROM FRONTAL PASSAGE ON RADAR
.
&&
ZHThe Fargo/Grand Forks radar (KMVX), 136 km away, was scanning. The volume nearest the first event began at 00:47 UTC.
2 thunderstorm wind. Local standard time, as filed.
Patio furniture blew about 50 yards away from the original location and was damaged.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in North Dakota in 2020Every state in 2020This day in weather historyWarnings in North Dakota, September 2020
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: 913436, 913437.