A disturbance moving across the region was able to produce enough instability to produce showers and thunderstorms across portions of northeast Montana, a couple of which produced gusty winds and severe hail.
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 GGW wrote it up.
A disturbance moving across the region was able to produce enough instability to produce showers and thunderstorms across portions of northeast Montana, a couple of which produced gusty winds and severe hail.
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 Glasgow, MT wrote its last area forecast discussion before the first event at Aug 1, 1:39 PM MST, 5 hours 34 minutes earlier.
Area Forecast Discussion National Weather Service Glasgow MT 239 PM MDT Tue Aug 1 2017 .SHORT TERM...for northeast Montana...tonight through Thu... The stage is basically set for the most significant actual cold front and associated widespread storm system that northeast Montana has seen for the last several weeks. Obviously, this will not put an end to the current drought, but it is expected to bring some much needed relief to the area in terms of temperature, humidity, and possible rainfall. Overall, precipitation model data has fallen into a fairly good consensus showing thunderstorms beginning later this afternoon and rain showers lingering after the cold front through Wednesday. Just over half an inch of rain is possible over the far NE corner of the state, while around a tenth of an inch is expected around the Missouri Breaks. One of the wild cards would be the strength and intensity of an severe thunderstorms tonight, moving through our Petroleum and Garfield Counties. SPC has their slight risk area just to the south of those counties, but some near-short term model data seem to suggest that some damaging wind gusts from storm outflows could impact those areas. Wanted to err on the side of caution and included mention of this in the forecast grids for that time frame. After midnight tonight those threat should be well SE away from our CWA. Overnight tonight into early Wednesday morning, the main push of the cold front will be evident with the arrival of a steady north wind. Given gusty east winds ahead of the front now, gusty and erratic winds from possible thunderstorms, and possible gusty winds with and behind the cold front, felt it was best to issue a Lake Wind Advisory to cover those chances. Wednesday afternoon, storms begin to clear from west to east, with very comfortable temperatures for mid-week. BMickelson .LONG TERM...Thu night through Tue... The inherited long range forecast remains in excellent standing depicting prevailing northwest flow aloft ahead of an upper ridge built up along the Pacific shore. This will mean lower heights for eastern Montana and a lowering trend in temperatures. In fact, consensus model blends continue to produce readings that are seasonable, if even a little bit below average. Precipitation changes will depend on shortwaves embedded in the flow, and with the ridge further upstream, the track may be closer to the forecast area in recent weeks. The first wave will approach sometime Friday or Friday night with an isolated chance for showers. With the trough axis directly through northeast Montana for Saturday, chances for precipitation may increase, especially near the MT/ND border. Yet another shortwave with a cold front may approach Monday night or Tuesday with additional shower chances and continued seasonable temperatures. Maliawco Previous Long Term Discussion... Northwest flow aloft will prevail Thursday Night and Friday. A shortwave trough on Friday will bring a cold front south across the area. Some of the northern zones could see a slight chance of showers with this system. Another shortwave trough moves through NE Montana on Saturday with a chance of showers and thunderstorms mainly in the northeast. Temperatures will be cooler than normal. Shortwave ridge in the NW flow aloft will allow for dry weather on Sunday. Flow aloft turns more WNW on Monday allowing some warmer air from the west to move into the forecast area. Models are pointing toward an upper trough with a cold front on Tuesday that could bring a chance of showers into the forecast area. Forrester && .AVIATION... VFR conditions will prevail most of the time today and tonight. East winds will prevail today at 10 to 15 knots. A cold front dropping south this evening will bring scattered showers and thunderstorms to the area. Areas of MVFR ceilings and vicinity thunderstorms are possible late tonight as low clouds move into the area. Winds will back to a more northerly direction overnight with speeds around 10 knots. BMickelson && .FIRE WEATHER... Fire weather concerns are expected to ease beginning late tonight with the arrival of a bonafide cold front thanks to a low pressure trough from Saskatchewan. Ahead of the cold front tonight, marginally severe thunderstorms will be a concern south of the Missouri Breaks. Gusty and erratic winds will be possible. Any fire start this evening could easily spread. Most of the rainfall is expect in the NE corner of the state while lesser amounts will be near the Missouri Breaks. The cooler air will continue through Wednesday. Rain showers will end by Wednesday evening. BMickelson && .GLASGOW WATCHES/WARNINGS/ADVISORIES... Lake Wind Advisory until 10 AM MDT Wednesday For Fort Peck Lake for Central and Southeast Phillips...Central and Southern Valley...Garfield...McCone...Petroleum. && weather.gov/glasgow
Hazardous Weather Outlook National Weather Service Glasgow MT 230 PM MDT Tue Aug 1 2017 MTZ016-017-023-025>027-060-021000- Central and Southeast Phillips-Central and Southern Valley-McCone- Dawson-Prairie-Wibaux-Southwest Phillips- 230 PM MDT Tue Aug 1 2017 This Hazardous Weather Outlook is for portions of northeast Montana. * Potential Impacts: Strong Thunderstorms. * Timing: Later this afternoon through tonight, generally near and south of the Missouri River. * Hail: Less than 1 inch in diameter. * Wind: Gusts up to 50 mph. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Hazardous Weather Outlook is issued when hazardous weather could impact the region within the next week. Be sure to stay tuned for future updates as locations, timing, and impacts could change. Begin preparations to mitigate any impacts that could result from the hazardous weather. && MTZ021-022-021000- Petroleum-Garfield- 230 PM MDT Tue Aug 1 2017 This Hazardous Weather Outlook is for portions of northeast Montana. * Potential Impacts: Severe Thunderstorms. * Timing: Later this afternoon through tonight. * Hail: 1 inch in diameter. * Wind: Gusts to around 60 mph. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Hazardous Weather Outlook is issued when hazardous weather could impact the region within the next week. Be sure to stay tuned for future updates as locations, timing, and impacts could change. Begin preparations to mitigate any impacts that could result from the hazardous weather. &&
Special Weather Statement
National Weather Service Glasgow MT
650 PM MDT TUE AUG 1 2017
MTZ021-020145-
Petroleum MT-
650 PM MDT TUE AUG 1 2017
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN PETROLEUM COUNTY
UNTIL 745 PM MDT...
At 650 PM MDT, Doppler radar was tracking a strong thunderstorm 11
miles south of Grass Range, or 23 miles southwest of Winnett, moving
east at 25 mph.
Nickel size hail and winds in excess of 40 mph will be possible with
this storm.
Locations impacted include...
Winnett, Flatwillow and Tiegen.
LAT...LON 4684 10863 4684 10861 4705 10861 4709 10828
4675 10827 4675 10863
TIME...MOT...LOC 0050Z 261DEG 20KT 4685 10880
TemplerThe Billings radar (KBLX), 129 km away, was scanning. The volume nearest the first event began at 02:11 UTC.
2 hail. Local standard time, as filed.
The hail was accompanied by little rain or wind. The length of the event is based on the spotter report and corroborated by radar.
Hail the size of nickels and quarters fell from a thunderstorm with no rain accompanying it. Enough hail had fallen that it was piling up.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2017Every state in 2017This day in weather historyWarnings in Montana, August 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: 704878, 704879.