A thunderstorm that developed over southwest Montana developed a down-burst that affected the Butte area.
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The episode as NWS MSO wrote it up.
A thunderstorm that developed over southwest Montana developed a down-burst that affected the Butte area.
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 Aug 1, 2:43 AM MST, 9 hours 42 minutes earlier.
Area Forecast Discussion National Weather Service Missoula MT 343 AM MDT Thu Aug 1 2019 .DISCUSSION...Little has changed in the overall weather pattern for today, with western Montana and central Idaho remaining under the influence of high pressure with southwest flow aloft. Yet another disturbance in this flow will lead to thunderstorms this afternoon and evening. Moisture today isn't expected to get quite as far north as was seen yesterday, so the main threat for thunderstorms is expected across southwest Montana and Lemhi County (generally south of Stevensville). Thunderstorms will be capable of brief heavy rain and gusty outflow winds. Otherwise, another day of slightly above normal temperatures is anticipated. Highs will run in the low to mid 90s for western Montana valleys and mid 90s to low 100s for lower elevations of north central Idaho. As an upper level trough approaches the region Friday, a dry cold front will move through central Idaho and western Montana. Gusty westerly winds will accompany the front, and when coupled with hot and dry conditions, will increase fire danger over the area. In addition, another round of thunderstorms will develop across Lemhi County eastward into southwest Montana. The combination of quick moving storms and a dry sub-cloud layer will reduce the potential for rainfall to reach the ground. Strong, potentially damaging outflow winds will be a concern with any storms that develop. The hot and dry weather pattern with above normal temperatures, will continue through this weekend, into early next week. Isolated thunderstorms are possible each afternoon, though they will be confined to southwestern Montana and along the Continental Divide. Gusty outflow winds and lightning will be the main concerns from any thunderstorms that do develop. The next chance for more widespread showers and thunderstorms, doesn't appear to occur until the end of next week. && .AVIATION...Thunderstorms will develop once again this afternoon and evening, primarily across southwest Montana and Lemhi County in Idaho. Airfields KBTM and KSMN will likely see thunderstorms in the vicinity between 01/2000z and 02/0100z. Moisture is not expected to make it quite as far north as was seen on Wednesday, so at this time it appears KMSO has a low probability of seeing thunderstorms. Typical threats with thunderstorms are expected, including brief heavy rain, gusty and erratic winds and frequent lightning. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. &&
The Missoula radar (KMSX), 166 km away, was scanning. The volume nearest the first event began at 19:26 UTC.
1 thunderstorm wind. Local standard time, as filed.
The Bert Mooney Airport ASOS reported a peak wind gust of 62 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2019Every state in 2019This day in weather historyWarnings in Montana, August 2019
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: 838250.