A humid air mass lifted into the area ahead of surface low pressure that was situated over far western North Dakota in the morning into the early afternoon. Two rounds of severe weather developed.
Every event with a place to put it. Tap one for its entry below.
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 humid air mass lifted into the area ahead of surface low pressure that was situated over far western North Dakota in the morning into the early afternoon. Two rounds of severe weather developed. The first round, in the early to mid-afternoon, occurred as an upper level short wave trough passed through the area, with severe thunderstorms developing over the upper James River Valley. Damaging wind gusts were the primary concern with these storms. Later in the afternoon a surface trough affiliated with the surface low served as the focus for thunderstorm development, gradually moving east in the evening. The strongest wind gusts, estimated around 90 mph, occurred in Foster County, while the largest hail was reported to be baseball size and fell in Renville and Morton counties. A tornado also developed in Oliver County but produced no damage, though was visible from far distances, including the Bismarck area, due to the higher base of the thunderstorm.
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 Jul 21, 11:37 AM CST, 1 hour 48 minutes earlier.
Area Forecast Discussion National Weather Service Bismarck ND 1237 PM CDT Fri Jul 21 2017 .UPDATE... Issued at 1236 PM CDT Fri Jul 21 2017 Pops were increased north central ND early this afternoon in response to a convective line that developed - likely associated with an upper level impulse moving east across the northern part of the state today. Latest CAM models still favoring south central ND later this afternoon for severe storm development...so increased pops south central this afternoon/evening when the mid-level cap may break as temps increase. Activity expected to linger in the James Valley through the evening hours. UPDATE Issued at 1013 AM CDT Fri Jul 21 2017 PoPs were increased across northwest and north central ND through the morning with this update in respect to the elevated convection crossing that area in association with a weak impulse translating eastward. MUCAPE up to 1000 J/kg and effective-layer shear values of 40 to 50 kt suggest some potential for severe weather with this elevated convection. Moreover, there is a non-zero chance that the convection will become more surface-based and thus intensify in the next few hours, but recent RAP iterations suggest MLCIN won't weaken sufficiently for that until 19 or 20 UTC. The environment across central and eastern ND this afternoon is still expected to be characterized by MLCAPE of 2500-3000 J/kg and effective shear around 50 kt. Anvil-level flow will also be significant in support of potential supercells with very large hail initially, and a low, but non-zero tornado potential given a discrete supercell moving through this CAPE setting. Upscale growth could occur eventually as cold pools aggregate by late afternoon or evening. CAMs through the 13 UTC HRRR and 12 km NAMNest remain somewhat dispersive with regard to the exact convective evolution, but may be displaying a bit more clustering in advertising initiation occurring close to Bismarck/Mandan in the 21-23 UTC time frame. Again, there's still some uncertainty with how the morning convection will play out in north central ND, but if trends in recent CAMs continue with the next few hourly-update cycles, our confidence in the specifics of timing and evolution may increase by midday. UPDATE Issued at 635 AM CDT Fri Jul 21 2017 Not much change with this forecast update for today, as the severe potential remains unchanged, as well as the uncertainty in the CAMs through the 10 UTC HRRR. Did add PoPs for thunderstorms across northwest North Dakota this morning. This could be a signal for an upper level shortwave across eastern Montana that could yield a round of earlier initiation north central around midday. However, this remains somewhat uncertain. && .SHORT TERM...(Today and tonight) Issued at 401 AM CDT Fri Jul 21 2017 Severe potential this afternoon and evening central, and near critical fire weather conditions southwest highlight the short term forecast. See the fire weather discussion below for details regarding near critical conditions southwest this afternoon and early evening. Regarding severe convective potential, uncertainty still remains in how the event may evolve as highlighted by run to run inconsistencies across the CAMs through the 07 UTC HRRR. However, the potential for large, destructive hail to 2 inches in diameter or greater, damaging wind gusts to 75 mph, and a tornado or two are possible across most of central North Dakota this afternoon and evening. A cold front approaching the US Highway 83 corridor around 18 UTC with a likely pre-frontal trough, with a weak stationary front across the US Highway 2 corridor will be the surface focal points for initiation. Aloft, a few weak impulses across southeast Montana this morning will propagate into south central North Dakota by midday. A second stronger wave across southern Canada arrives late this afternoon and early evening along the international border. A moist boundary layer characterized by surface dewpoints in the mid to upper 60s, possibly in the 70s across the James River Valley, beneath steep mid level lapse rates yields strong MLCAPE values of 2000-3000 j/kg. Deep layer shear of 30-40kts, locally higher, perpendicular to the cold front/pre- frontal trough favors discrete supercells in a highly unstable environment. Thus, all threats with severe convection are possible as mentioned above. The one limiting factor regarding the tornado potential is weak low level flow and resulting SRH and shear. However, given the strength of instability, relatively low LCLs and likely supercells, a tornado or two is possible. Timing of initiation is uncertain, as a couple rounds of initiation are possible with the various forcing features. However, initiation as early as 18-20 UTC is possible along the pre-frontal trough with the earlier impulses, with a later round of initiation possible with the stronger Canadian wave. A special 18Z sounding will be launched today at Bismarck. .LONG TERM...(Saturday through Thursday) Issued at 401 AM CDT Fri Jul 21 2017 Critical fire weather conditions Saturday highlight the extended forecast. See the fire weather discussion below for details regarding the possibility for critical conditions southwest and south central Saturday. Will continue to monitor the potential for severe convection on Monday as a cold front is favored by the 00 UTC global suites to propagate across North Dakota. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 1236 PM CDT Fri Jul 21 2017 An upper level impulse moving east across northern ND late this morning is expected to continue moving east this afternoon. Latest convective cells have organized into a line near Bottineau/KMOT/New Town. This elevated activity should continue moving east. Otherwise, at noon CDT, a surface low had entered northwestern ND and was located near KISN/Tioga/Stanley area. This low is forecast to reach central ND near KBIS/KMOT by 21z-00z, and near KJMS by around 03z. Dry air and westerly winds west of the front with east/southeast winds and humid air ahead of it is forecast. Thunderstorm initiation along this boundary is expected this afternoon, with best chances near KBIS by around 21z-00z according to the latest high res models. Thunderstorms should increase in coverage late this afternoon into the evening near KMOT/KBIS and into KJMS around 00z-04z. Severe thunderstorms are expected with large hail and damaging winds. Uncertainty regarding exactly where/when convection will initiate, will continue to mention VCTS at KMOT/KBIS/KJMS through 03z, and through 06z at KJMS. && .FIRE WEATHER... Issued at 401 AM CDT Fri Jul 21 2017 Near critical fire weather conditions are possible behind a cold front this afternoon across southwest North Dakota. Relative humidity is expected to fall to 15 to 20 percent with high temperatures in the 90s. The source of uncertainty is forecast wind behind the front at 15 to 20 mph sustained from the west, which at this time may fall short of critical levels and occur during a narrow window. This will closely be monitored. For Saturday, afternoon humidity between 15 and 25 percent, northwest winds sustained at 20 to 25 mph with higher gusts, and temperatures in the 80s are forecast across southwest and south central North Dakota. When combined with dry fuels, critical fire weather conditions are possible. A Fire Weather Watch is in effect. && .BIS WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Saturday afternoon through Saturday evening for NDZ020-031>035-040>046. && UPDATE...JV SHORT TERM...PA LONG TERM...PA AVIATION...JV FIRE WEATHER...PA
Hazardous Weather Outlook National Weather Service Bismarck ND 1234 PM CDT Fri Jul 21 2017 NDZ003>005-011>013-019>023-025-034>037-042-045>048-050-051-221745- Renville-Bottineau-Rolette-Ward-McHenry-Pierce-Mercer-Oliver- McLean-Sheridan-Wells-Foster-Morton-Burleigh-Kidder-Stutsman- Grant-Sioux-Emmons-Logan-La Moure-McIntosh-Dickey- 1234 PM CDT Fri Jul 21 2017 /1134 AM MDT Fri Jul 21 2017/ This Hazardous Weather Outlook is for portions of north central North Dakota, south central North Dakota, and southeast North Dakota. .DAY ONE...This Afternoon and Tonight Scattered severe thunderstorms are expected this afternoon and evening across central North Dakota, generally along and east of US Highway 83. Large, destructive hail to 2 inches in diameter or greater, damaging winds to 75 mph, and a tornado or two are possible. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Critical fire weather conditions are possible Saturday across south central North Dakota. A Fire Weather Watch is in effect. There is chance of thunderstorms Monday night through Wednesday. .SPOTTER INFORMATION STATEMENT... Spotter activation is likely this afternoon and evening across central North Dakota. Please report severe weather to the National Weather Service in Bismarck at 701-223-4582. NDZ001-002-009-010-017-018-031>033-040-041-043-044-221745- Divide-Burke-Williams-Mountrail-McKenzie-Dunn-Golden Valley- Billings-Stark-Slope-Hettinger-Bowman-Adams- 1234 PM CDT Fri Jul 21 2017 /1134 AM MDT Fri Jul 21 2017/ This Hazardous Weather Outlook is for portions of northwest North Dakota and southwest North Dakota. .DAY ONE...This Afternoon and Tonight Near critical fire weather conditions are possible across southwest North Dakota this afternoon and early evening. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Critical fire weather conditions are possible Saturday across southwest and south central North Dakota. A Fire Weather Watch is in effect. There is chance of thunderstorms Monday night through Wednesday. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed. CJS/PA
Special Weather Statement
National Weather Service Bismarck ND
134 PM CDT FRI JUL 21 2017
NDZ022-023-211900-
Wells ND-Sheridan ND-
134 PM CDT FRI JUL 21 2017
...A STRONG THUNDERSTORM WILL AFFECT WESTERN WELLS AND SHERIDAN
COUNTIES UNTIL 200 PM CDT...
At 133 PM CDT, Doppler radar was tracking a strong thunderstorm 11
miles northeast of Mcclusky, moving southeast at 40 mph.
Penny size hail and wind gusts to 40 mph will be possible with this
storm.
Locations impacted include...
Mcclusky, Goodrich, Manfred, Denhoff, Sheyenne Lake and Hoffer Lake.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
LAT...LON 4733 10005 4733 10039 4750 10066 4770 10049
4778 10025 4773 9969
TIME...MOT...LOC 1833Z 313DEG 34KT 4763 10031
EDWARDSThe Bismarck radar (KBIS), 104 km away, was scanning. The volume nearest the first event began at 19:23 UTC.
25 hail, 8 thunderstorm wind, 1 tornado, 1 funnel cloud. Local standard time, as filed.
Several large branches were blown down in Chaseley.
Measured wind gusts to 74 mph combined with quarter size hail to cause widespread damage in the Juanita area. One foot diameter trees were broken down. Wind driven hail caused damage to windows, vehicles, and siding. A grain truck was knocked over, and a door was torn off a quonset hut. Crops were damaged, with some corn flattened. Other reports of wind included estimates as high as 85 mph.
Multiple power lines and trees were down. A tractor-trailer truck was blown over.
There were numerous reports of this tornado over a rural area of eastern Oliver County. It was visible from Bismarck and Mandan. No damage occurred and so the tornado was rated EF0.
Thunderstorm wind gusts were estimated by the public.
Large hail fell over a broad swath of the city of Mandan, with the largest hail reported near the baseball field on 3rd Street SW.
A brief funnel cloud was reported.
Some large branches broke down in Hazelton.
Many tree branches were broken down.
Tree branches were broken down.
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, July 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: 715250, 715251, 715255, 715257, 715258, 715259, 715260, 715263, 715265, 715266, 715267, 715268, 715269, 715270, 715271, 715272, 715275, 715276, 715277, 715279, 715281, 715283, 715285, 715287, 715288, 715289, 715291, 715292, 715293, 715294, 715295, 715298, 715301, 715303, 715304.