Strong wind gusts associated with a mountain wave developed across the MT-200 corridor December 9 into December 10. Winds gusted into the 70s mph in higher criteria zones along the Rocky Mountain Front, and into the upper 50s to lower 60s in lower criteria zones further east (Cascade and Judith Basin Counties).
Every event with a place to put it; 3 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 TFX wrote it up.
Strong wind gusts associated with a mountain wave developed across the MT-200 corridor December 9 into December 10. Winds gusted into the 70s mph in higher criteria zones along the Rocky Mountain Front, and into the upper 50s to lower 60s in lower criteria zones further east (Cascade and Judith Basin Counties).
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 Dec 9, 8:34 PM MST, 1 hour 40 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 834 PM MST Sat Dec 9 2023 .SYNOPSIS... Dry conditions rest of today with our next weather system moving into the western part of the state tonight into tomorrow morning, bringing some light snow to the Rocky Mountain Front and portions of Southwest Montana. Gusty winds tonight through tomorrow morning across portions of North Central Montana. Light snowfall for Sunday night into Monday morning. Seasonably above normal temperatures returns for mid-week. && .UPDATE... No significant changes needed to the overnight and Sunday period of the forecast. Latest probabilistic guidance keeps the chances at 50% or less that winds on the Rocky Mountain Front and adjacent plain will reach High Wind criteria, and observed winds seem to be trending similar to what is in the forecast. Will therefore hold off on a High Wind Warning for those areas, but have issued a Special Weather Statement to highlight the threat that wind gusts will become stronger than they currently are between 9 pm tonight and 6 am Sunday morning. Similar Special Weather Statements were issued for the Cascade and Judith Basin County areas and the Madison River Valley (Ennis and Norris Hill areas), as these areas will also be favored for strong and gusty overnight winds. Only adjustment to the forecast was to add mention of blowing snow in the mountain areas of the Rocky Mountain Front and Central/Southwest Montana. -Coulston && .AVIATION... 440 PM MST Sat Dec 9 2023 (10/00Z TAF Period) A strong westerly flow aloft will keep mountain wave turbulence, periods of low level wind shear, and gusty southwesterly surface winds over North Central, Central, and Southwest Montana through at least 11/00Z. Southerly gusts in excess of 30 kt will be common through the KEKS valley area, with mostly southwest to west winds gusting between 25 and 40 kt over the plains of North Central and Central Montana; gusts will likely exceed 50 kt at times closer to the Rocky Mountain Front. Otherwise, moisture in the flow aloft will bring mostly VFR level mid- and high-level cloudiness to the area through the period with mountain obscuring snow for the mountains of the Rocky Mountain Front, as well as to the mountains of Central and Southwest Montana. It may bring a few snow showers to the plains of North Central Montana, mainly between 03Z and 09Z, which may bring brief periods of MVFR conditions. However, the chance for such conditions will be higher and for a longer period of time in the valleys of Central and Southwest Montana, mainly between 06Z and 18Z. -Coulston Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 440 PM MST Sat Dec 9 2023/ Mostly clear skies across the region this afternoon as high pressure has built in over the state. Winds increase tonight along with our next approaching weather system from the Pacific Northwest that's forecasted to bring light snowfall along the Rocky Mountain Front and mountains across Southwest Montana south of the I-90 corridor. Moisture aloft being transported over the region will help bring some accumulating snowfall to the Little Belt and Big Belt mountains tonight through Monday as temperatures will remain below freezing through this time period. Westerly winds between 850mb and 700mb are forecasted for tonight to be between 55 and 75 knots across the Rocky Mountain Front and spread eastward across the Hi-Plains region. For surface winds, there is high confidence westerly to southwesterly winds can gust between 55 and 70 mph through the overnight hours along the Rocky Mountain Front. Latest NBM 4.1 Probabilistic data has a 75% probability of winds gusting above 55 mph for along the Rocky Mountain Front through tomorrow morning. Elsewhere, winds have potential to gust between 30 mph and 50 mph. A winter weather advisory has been issued this afternoon for tonight through tomorrow evening for Northwest Beaverhead County and Madison County Mountains and Centennial Mountains. Snowfall amounts for these locations have remained consistent over the last few forecast periods and latest hi-resolution model guidance has given support for accumulating snowfall to occur during this time frame. For mountain passes across these locations can see between 2" and 6" beginning tonight through tomorrow evening. Mountain peaks may see higher snowfall amounts. A quick moving upper level shortwave will move from North- Central Montana southward across Central and Southwest Montana for Sunday night into Monday morning. Light snowfall is forecasted across the region with snowfall amounts between a trace to a half inch, making the morning commute on Monday potentially slippery as surface air temperatures are forecasted to be below freezing. Temperatures on Monday will be near seasonal averages (in the 30s) as the shortwave trough brings some cooler air to the region. After this shortwave moves through, dry conditions returns as upper level ridging builds back into the state. Temperatures after Monday become seasonably above average with highs in the 40s to 50s on Wednesday and Thursday. Webb && .PRELIMINARY POINT TEMPS/POPS... GTF 31 47 30 36 / 20 10 20 40 CTB 25 41 26 32 / 10 0 10 30 HLN 27 46 30 39 / 20 20 20 60 BZN 20 41 25 39 / 20 40 30 40 WYS 4 24 16 31 / 60 80 60 50 DLN 18 38 23 36 / 30 40 20 30 HVR 24 44 24 36 / 10 0 10 20 LWT 19 47 27 36 / 20 10 10 30 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from midnight tonight to 5 PM MST Sunday for Gallatin and Madison County Mountains and Centennial Mountains-Northwest Beaverhead County. && http://www.weather.gov/greatfalls
Special Weather Statement National Weather Service Great Falls MT 804 PM MST Sat Dec 9 2023 MTZ301-302-307-308-100530- East Glacier Park Region-Northern High Plains- Southern Rocky Mountain Front-Southern High Plains- Including the cities of East Glacier Park, Kiowa, Babb, Saint Mary, Marias Pass, Logan Pass, Browning, Heart Butte, Dupuyer, Rogers Pass, Bynum, Choteau, and Pendroy 804 PM MST Sat Dec 9 2023 ...Strong and Gusty Winds through Tonight... Southwest winds will continue to strengthen through the evening hours tonight along the Rocky Mountain, becoming strong and gusty with frequent gusts to between 55 and 70 mph. The period strongest winds is generally expected to occur between 9 PM MST this evening and 3 AM MST on Sunday, but strong winds can still be expected outside of this timeframe. Travelers should be prepared for strong cross winds, especially if operating a high profile vehicle. Know your vehicles limits. Moldan MTZ312-313-100530- Cascade County below 5000ft-Judith Basin County and Judith Gap- Including the cities of Great Falls, Raynesford, Geyser, Stanford, Windham, Benchland, Hobson, and Moccasin 804 PM MST Sat Dec 9 2023 ...Strong and Gusty Winds through Tonight... Southwest winds will continue to strengthen through the evening hours tonight along the Montana Highway 200 corridor, becoming strong and gusty with frequent gusts to between 40 and 50 mph. The period strongest winds is generally expected to occur between midnight and 6 AM MST on Sunday, but strong winds can still be expected outside of this timeframe. Travelers should be prepared for strong cross winds, especially if operating a high profile vehicle. Know your vehicles limits. Moldan MTZ303-100530- Eastern Glacier, Western Toole, and Central Pondera- Including the cities of Cut Bank, Ethridge, and Santa Rita 804 PM MST Sat Dec 9 2023 ...Strong and Gusty Winds through Tonight... Southwest winds will continue to strengthen through the evening hours tonight over the plains of Glacier, Toole, and Pondera Counties, becoming strong and gusty with frequent gusts to between 40 and 50 mph, especially in the Cut Bank Area. The period strongest winds is generally expected to occur between midnight and 6 AM MST on Sunday, but strong winds can still be expected outside of this timeframe. Travelers should be prepared for strong cross winds, especially if operating a high profile vehicle. Know your vehicles limits. Moldan MTZ325-100530- Madison River Valley- Including the cities of Cameron, Ennis, Jeffers, McAllister, and Norris 804 PM MST Sat Dec 9 2023 ...Strong and Gusty Winds through Tonight... Southerly winds will remain strong and gusty through the overnight hours tonight in the Madison Valley, with frequent gusts of between 40 and 50 mph expected. The period strongest winds is generally expected to occur between midnight and 6 AM MST on Sunday, but strong winds can still be expected outside of this timeframe. Travelers should be prepared for strong cross winds, especially if operating a high profile vehicle. Know your vehicles limits. Moldan
Special Weather Statement National Weather Service Great Falls MT 808 PM MST Sat Dec 9 2023 MTZ301-302-307-308-100530- East Glacier Park Region-Northern High Plains- Southern Rocky Mountain Front-Southern High Plains- Including the cities of East Glacier Park, Kiowa, Babb, Saint Mary, Marias Pass, Logan Pass, Browning, Heart Butte, Dupuyer, Rogers Pass, Bynum, Choteau, and Pendroy 808 PM MST Sat Dec 9 2023 ...Strong and Gusty Winds through Tonight... Southwest winds will continue to strengthen through the evening hours tonight along the Rocky Mountain Front, becoming strong and gusty with frequent gusts to between 55 and 70 mph. The period strongest winds is generally expected to occur between 9 PM MST this evening and 3 AM MST on Sunday, but strong winds can still be expected outside of this timeframe. Travelers should be prepared for strong cross winds, especially if operating a high profile vehicle. Know your vehicles limits. Moldan MTZ312-313-100530- Cascade County below 5000ft-Judith Basin County and Judith Gap- Including the cities of Great Falls, Raynesford, Geyser, Stanford, Windham, Benchland, Hobson, and Moccasin 808 PM MST Sat Dec 9 2023 ...Strong and Gusty Winds through Tonight... Southwest winds will continue to strengthen through the evening hours tonight along the Montana Highway 200 corridor, becoming strong and gusty with frequent gusts to between 40 and 50 mph. The period strongest winds is generally expected to occur between midnight and 6 AM MST on Sunday, but strong winds can still be expected outside of this timeframe. Travelers should be prepared for strong cross winds, especially if operating a high profile vehicle. Know your vehicles limits. Moldan MTZ303-100530- Eastern Glacier, Western Toole, and Central Pondera- Including the cities of Cut Bank, Ethridge, and Santa Rita 808 PM MST Sat Dec 9 2023 ...Strong and Gusty Winds through Tonight... Southwest winds will continue to strengthen through the evening hours tonight over the plains of Glacier, Toole, and Pondera Counties, becoming strong and gusty with frequent gusts to between 40 and 50 mph, especially in the Cut Bank Area. The period strongest winds is generally expected to occur between midnight and 6 AM MST on Sunday, but strong winds can still be expected outside of this timeframe. Travelers should be prepared for strong cross winds, especially if operating a high profile vehicle. Know your vehicles limits. Moldan MTZ325-100530- Madison River Valley- Including the cities of Cameron, Ennis, Jeffers, McAllister, and Norris 808 PM MST Sat Dec 9 2023 ...Strong and Gusty Winds through Tonight... Southerly winds will remain strong and gusty through the overnight hours tonight in the Madison Valley, with frequent gusts of between 40 and 50 mph expected. The period strongest winds is generally expected to occur between midnight and 6 AM MST on Sunday, but strong winds can still be expected outside of this timeframe. Travelers should be prepared for strong cross winds, especially if operating a high profile vehicle. Know your vehicles limits. Moldan
The national radar mosaic for the moment the first event began.
3 high wind. Local standard time, as filed.
ASOS station KGTF Great Falls measured a single gust to 58 mph.
An Ambient Weather Sensor 4 miles wsw of Geyser measured two gusts in excess of 60 mph, including a peak gust of 67 mph.
NWS employee found a 3 to 6 inch diameter branch broken in Great Falls associated with the passing mountain wave.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2023Every state in 2023This day in weather historyWarnings in Montana, December 2023
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: 1144798, 1144800, 1144799.