An organized upper level wave triggered thunderstorms that brought damaging hail to Silver Bow 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 MSO wrote it up.
An organized upper level wave triggered thunderstorms that brought damaging hail to Silver Bow 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 Missoula, MT wrote its last area forecast discussion before the first event at Jul 10, 2:40 AM MST, 10 hours 27 minutes earlier.
Area Forecast Discussion National Weather Service Missoula MT 340 AM MDT Mon Jul 10 2017 .DISCUSSION...A weak disturbance moving through this morning has led to a few showers and isolated thunderstorms across southwest Montana and the Bitterroot mountains. The storms are fairly weak, but a few of the storms are producing lightning and light to moderate rainfall. For this afternoon, an approaching shortwave trough will lead to the development of thunderstorms mainly across southwest Montana, Lemhi county of Idaho, parts of west-central Montana, and in northwest Montana near Glacier Park. A few moderate to strong storms will be possible in southwest Montana near Butte with the main threats being strong gusty winds, brief heavy rain and hail. A weak cool front pushing through this afternoon will also bring breezy westerly winds of 10-20 mph with locally higher gusts to valleys across western Montana and central Idaho. A short break from the hot temperatures is expected behind the front on Tuesday. High temperatures will be near normal on Tuesday with highs in the low to mid 80s for many valleys across western Montana and central Idaho. By Wednesday into the coming weekend, a building hot ridge pattern will return and reintroduce southwest flow. As a result, temperatures will once again climb well above normal into the 90s and low 100s for several days. Extended model guidance shows inconsistencies on how long this heatwave will persist past the weekend, however. In addition to hot temperatures, a series of waves will introduce isolated shower/thunderstorm activity for Lemhi County and southwest Montana each afternoon and evening. && .AVIATION... A few isolated showers/thunderstorms will continue for southwest Montana in the vicinity of KBTM this morning. Hi-res model guidance suggests the coverage of storm activity will increase throughout mid day and afternoon, especially after 10/2000Z. This activity will likely impact KSMN, KBTM, and northwest Montana in the vicinity of KGPI. However, there is less certainty for the storm activity over west-central Montana and KMSO. The main thunderstorm threats will be gusty winds, lightning, small hail, and brief heavy rainfall. Otherwise, expect occasional breezy afternoon westerly wind gusts. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. &&
Special Weather Statement
National Weather Service Missoula MT
129 PM MDT MON JUL 10 2017
MTZ007-102015-
Butte/Blackfoot Region MT-
129 PM MDT MON JUL 10 2017
...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL SILVER BOW COUNTY UNTIL
215 PM MDT...
At 129 PM MDT, Doppler radar was tracking a strong thunderstorm near
Divide, or 15 miles south of Butte, moving northeast at 40 mph.
Nickel size hail and winds in excess of 40 mph will be possible with
this storm.
This strong thunderstorm will be near...
Butte and Walkerville around 155 PM MDT.
Other locations impacted by this storm include Janney and Newcomb.
LAT...LON 4575 11248 4576 11250 4575 11252 4572 11252
4567 11259 4578 11280 4612 11251 4610 11247
4605 11248 4602 11244 4593 11244 4589 11240
4585 11243 4583 11239
TIME...MOT...LOC 1929Z 216DEG 33KT 4579 11263The Missoula radar (KMSX), 196 km away, was scanning. The volume nearest the first event began at 20:07 UTC.
3 hail. Local standard time, as filed.
A person from the public reported nickel to quarter size hail along Highway 41 on Twitter.
A resident on Z Bar T Road estimated hail smaller than golf balls but larger than quarters which caused tree branches to break and dented a camper.
Nickel to quarter size hail fell causing Aspen tree leaves to tear off and destroyed a bird feeder.
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, 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: 705219, 705220, 705221.