An anomalously strong upper level trough was set up just off the west coast, which resulted in a strong belt of mid level southerly flow across Southwest through North-central Montana. Synoptic winds were already breezy from the south, allowing thunderstorms to easily produce strong wind gusts given inverted-V soundings.
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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 TFX wrote it up.
An anomalously strong upper level trough was set up just off the west coast, which resulted in a strong belt of mid level southerly flow across Southwest through North-central Montana. Synoptic winds were already breezy from the south, allowing thunderstorms to easily produce strong wind gusts given inverted-V soundings. Wind gusts in excess of 80 mph were observed on this day as a line of gusty outflow spread northward over the plains.
A High Wind Warning was also issued for Southwest Montana this day, though no strong synoptic gusts were observed.
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 Great Falls, MT wrote its last area forecast discussion before the first event at Aug 22, 10:31 PM MST, 1 hour 28 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 1131 PM MDT Thu Aug 22 2024 ...Aviation Section Updated... .SYNOPSIS... After a dry and mostly calm day today, winds will be on the increase on Friday as an upper level system pushes into the area. Expect a few thunderstorms to also develop. Looking beyond Friday, a cool and unsettled weather pattern will bring generally below average temperatures along with a few chances for rainfall. && .UPDATE... Current forecast is on track. No updates planned for this evening. There are a few light showers moving northward from Idaho towards Southwest MT, but most of these showers should diminish as they cross over the state line. Otherwise, temperatures look on track. For Friday, there is some concern for the potential fire weather statements, with low humidity and gusty winds over Southwest MT. Midnight shift will take one last look. Otherwise, it will be windy, but wind speeds should remain below warning criteria. Showers/thunderstorms are looking likely by Friday evening as an upper level disturbance moves northward through the CWA. Some storms could be severe, with the main threat being strong winds. The current marginal risk area could be expanded further northward, or even raised a category on later shifts if the HREF pans out. Otherwise, expect a very warm day across the CWA on Friday. Brusda && .AVIATION... 23/06Z TAF Period The initial concern this TAF period will be for widely scattered showers and isolated thunderstorms moving into Southwest Montana from Idaho overnight. Otherwise attention turns to daytime hours Friday, where both deep mixing and scattered afternoon showers and thunderstorms will result in a day of gusty winds. Any areas that see showers Friday afternoon will have the potential to see strong wind gusts (45+ kts). VFR conditions prevail otherwise, with winds slowly diminishing mid to late evening Friday. -AM Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 545 PM MDT Thu Aug 22 2024/ Key Points: -Elevated fire weather conditions expected Friday due to gusty winds and a few thunderstorms across Southwestern Montana -Unsettled weather expected over the next week, leading to a wide variety of weather conditions Short term (through Saturday)... Expect tranquil weather the rest of the day today as weak upper level ridging and high pressure at the surface, save for a low (<10%) chance of a stray shower forming across the higher terrain of Southwestern Montana. Our weather becomes noticeably more active tomorrow as a potent upper level low digs in along the West Coast, especially during the afternoon as an embedded trough axis begins to make its way through Southwestern Montana. Across the southwest, expect winds to increase through the day, with widespread wind gusts of 30-40 mph, and a few locations possibly seeing a few gusts to 50 mph or so. In addition to the winds, this trough axis will also help to kick off a few showers and thunderstorms, which could introduce some additional wind gusts and cause the winds to be erratic for a time. This combination will result in elevated fire weather conditions, making fire starts more likely, and the winds may make any new or existing fires a bit erratic at times. Further north across the plains, expect a breezy day for much of the area, with just a few evening showers and thunderstorms. In the wake of this system on Friday, cooler air will begin to filter into the area Friday night and Saturday, bringing highs from the upper 80s to mid 90s to the mid 70s to mid 80s for highs on Saturday. It will remain breezy, especially along the Rocky Mountain Front, as a lee trough develops, resulting in a tight pressure gradient along the Rocky Mountain Front. A few leftover showers and thunderstorms will develop during the afternoon, though these should remain very isolated on the eastern side of the Continental Divide. Extended (Sunday through next Thursday)... Cooler air will continue to work its way into the area on Sunday in the wake of the trough that will push its way through the area at the end of this week, along with a few isolated to scattered showers, mainly along the Continental Divide in Southwestern Montana. Given the continued push of colder air into the area, some of the higher peaks may see some termination dust (first snowfall) as snow levels fall to around 8000 feet or so. Any accumulations will be light, but they will serve as a reminder that fall is just around the corner. For the rest of the week, a progressive pattern will be in place across the Northwestern US/Southwestern Canada, resulting in variable weather conditions from day to day as we alternate between upper level ridging and upper level troughing. Models are mostly in agreement of the pattern, with just some minor differences in timing of the ridges and troughs. Overall, expect a cool weather pattern with a few chances for rain showers and maybe a thunderstorm. Ludwig && .PRELIMINARY POINT TEMPS/POPS... GTF 52 92 54 80 / 0 20 20 20 CTB 49 88 52 72 / 0 10 40 20 HLN 54 92 54 80 / 0 30 20 40 BZN 52 89 50 83 / 0 50 20 10 WYS 43 74 40 71 / 20 40 20 10 DLN 49 80 45 73 / 0 20 20 20 HVR 58 95 58 83 / 10 30 40 0 LWT 52 90 53 84 / 0 40 20 10 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && http://www.weather.gov/greatfalls
Special Weather Statement
National Weather Service Great Falls MT
1245 AM MDT Fri Aug 23 2024
MTZ325-328>330-230730-
Madison River Valley MT-
Ruby Mountains and Southern Beaverhead Mountains MT-
Gallatin and Madison County Mountains and Centennial Mountains MT-
Beaverhead and Western Madison below 6000ft MT-
1245 AM MDT Fri Aug 23 2024
...STRONG OUTFLOW FROM SHOWERS WILL IMPACT SOUTHERN
MADISON...SOUTHEASTERN BEAVERHEAD AND SOUTHWESTERN GALLATIN COUNTIES
THROUGH 130 AM MDT...
At 1244 AM MDT, Doppler radar was tracking showers producing strong
outflow along a line extending from 13 miles west of Lima to 11
miles north of Monida to 17 miles west of Henrys Lake. Movement was
north at 25 mph.
HAZARD...Wind gusts up to 50 mph.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects.
Locations impacted include...
Lima, Monida, Dell, Grant, Bannack Pass, Red Rock Pass, Lakeview,
Clark Canyon, Raynolds Pass, and Snowline.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4445 11300 4473 11311 4508 11311 4512 11227
4509 11137 4472 11144 4470 11149 4466 11147
4461 11153 4454 11147 4456 11171 4451 11182
4456 11187 4452 11211 4457 11229 4453 11236
4445 11239 4449 11260 4448 11278 4436 11284
TIME...MOT...LOC 0644Z 183DEG 21KT 4468 11287 4473 11231 4471 11175
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH
AMThe Pocatello radar (KSFX), 177 km away, was scanning. The volume nearest the first event began at 07:00 UTC.
31 thunderstorm wind. Local standard time, as filed.
RAWS station LMRM8 Antelope measured a 67 mph gust. Time was estimated given RAWS sensors only report once per hour.
Ambient Weather Sensor measured gust.
ASOS station KDLN Dillon Airport measured a strong outflow gust from decaying showers.
RAWS station BRRM8 Brenner measured a severe gust. Time is estimated given RAWS only report once per hour.
Mesonet station MTM16 6.6 miles north of Dell measured a severe gust.
Mesonet station MTM16 6.6 miles north of Dell measured a severe gust.
MDT sensor MTMQM Monida Pass measured a severe gust.
Trained spotter reports a 62 mph gust.
Personal weather sensor measured a 62 mph gust.
Public weather station reported a gust of 58 mph.
MDT sensor MTSBN Sieben Flats measured a severe gust.
Mesonet station EW3831 measured a 61 mph gust.
AWOS sensor K1GM Golf measured a severe gust.
AWOS station K1IM India measured a severe gust.
Ambient Weather Sensor measured gust.
Mesonet station FW1843 measured a severe gust 10 miles WSW of Stockett.
ASOS station KGTF Great Falls Airport measured a sever gust.
Ambient weather sensor measured a severe gust.
MDT sensor MTGYS Geyser measured a severe wind gust.
Mesonet station MTM76 Cascade E MDA measured a severe gust.
Public report of a 59 mph gust. Time estimated using radar.
AWOS station K1BM Bravo measured a severe gust.
The public reported gusts estimated to be 60 mph east of I-15. Debris was lofted in the air.
MDT sensor MTDEN East of Denton measured a severe gust.
Trained spotter reports a partially broken power pole. Time was estimated by radar.
The time and location was estimated. A farmer stated that freshly cut hay was blown by approximately 80 mph winds.
An ambient weather sensor measured this strong gust.
A personal weather station measured a severe gust.
A personal weather station measured this severe gust.
ASOS station KCTB Cut Bank Airport measured a severe caliber gust.
RAWS sensor FBLM8 Fort Belknap measured a severe gust. Time was estimated given RAWS sensors only report one time per hour.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2024Every state in 2024This day in weather historyWarnings in Montana, August 2024
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: 1200642, 1200643, 1200644, 1200646, 1200648, 1200649, 1200650, 1200651, 1200652, 1200653, 1200654, 1200655, 1200656, 1200657, 1200660, 1200661, 1200662, 1200663, 1200664, 1200665, 1200666, 1200667, 1200668, 1200669, 1200670, 1200645, 1200671, 1200672, 1200673, 1200675, 1200676.