With strong low pressure to the north and strong high pressure to the south, a tight pressure gradient set up across our region, and allowed strong winds aloft to reach down to the surface, mainly near and south of the Missouri River.
Every event with a place to put it; 4 filed by county or forecast zone are drawn at its center, in a lighter ring. 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.
With strong low pressure to the north and strong high pressure to the south, a tight pressure gradient set up across our region, and allowed strong winds aloft to reach down to the surface, mainly near and south of the Missouri River.
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 Nov 13, 2:37 AM MST, 5 hours 7 minutes earlier.
Area Forecast Discussion National Weather Service Glasgow MT 237 AM MST Sat Nov 13 2021 .DISCUSSION... A warm front will move to the east this morning. Some rain and freezing rain is occurring early this morning along and ahead of this front. Have a Winter Weather Advisory in effect until 6 am MST in the northeast where temperatures are currently below freezing. A cold front will quickly follow the warm front this morning. This will bring strong west to NW winds. Wind gusts in the south will be near 60 mph which is enough to issue a High Wind Warning. There will also be some rain showers today with some snow showers north with a shortwave trough moving through with an unstable atmosphere. Will also issue a Lake Wind Advisory for the northern half of Fort Peck Lake that is not in the High Wind Warning. Winds diminish tonight with a high pressure system that quickly moves to the east Sunday morning. A warm front moves through the area during the day on Sunday which will bring the possibility for a mix of rain and snow in the morning and rain in the afternoon and evening. Monday will be a warm day with an upper ridge. The next cold front Monday Night and Tuesday will bring strong west to NW winds that may need another High Wind Warning. There will also be a chance of light rain and light snow. The remainder of the week will be mainly dry with near normal temperatures. && .AVIATION... UPDATED: 0930Z FLIGHT CONDITIONS: Mainly VFR but some brief MVFR conditions are possible early this morning. WINDS/LLWS: Variable 10 knots or less early with LLWS. WNW winds 20 to 30 knots will develop by late morning and continue this afternoon. Gusts 40 to 50 knots will be possible at times this afternoon. WNW winds will diminish to around 10 knots this evening. SYNOPSIS: A warm front will move to the east by 13z with LLWS at times. A cold front will follow by 18z with strong WNW winds. There will be light rain showers at times today with a mix of low and mid level clouds. There will be a period of clear skies in the late afternoon and this evening before mid and high clouds moves in from the west late tonight. && .GLASGOW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 AM MST early this morning for Daniels...Eastern Roosevelt...Northern Valley...Richland... Sheridan...Western Roosevelt. High Wind Warning from 10 AM this morning to 5 PM MST this afternoon for Dawson...Garfield...McCone...Petroleum...Prairie... Southwest Phillips...Wibaux. Lake Wind Advisory from 7 AM this morning to 8 PM MST this evening for Central and Southeast Phillips...Central and Southern Valley. && weather.gov/glasgow
The national radar mosaic for the moment the first event began.
4 high wind. Local standard time, as filed.
At 7:44 AM, a single peak wind gust of 65 mph was measured at the King Coulee RAWS site.
At the Beaver Hill I-94 DOT Site, sustained wind speeds of at least 40 mph were common through the late morning and early afternoon hours. The peak wind gusts of 70 mph were recorded from 11:05 AM to 11:15 AM.
Peak wind gusts of 59 mph were recorded both at the BLM Terry mesonet site at 10:00 AM, and at the Big Sheep Mountain RAWS site site at 10:08 AM.
Between 11:15 AM and 11:45 AM, winds gusted over 58 mph at the BLM Zortman E mesonet site. The peak wind gust at that site was 63 mph and occurred at 11:45 AM.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2021Every state in 2021This day in weather historyWarnings in Montana, November 2021
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: 993350, 993348, 993349, 993351.