The onset of a high impact wind event began on Tuesday January 13th, 2020, when a typical brand of strong winds descended over the normally wind prone Rocky Mountain Front and adjoining areas. Widespread anomalously strong winds then swept through much of Montana on the following day as a vigorous Pacific weather system and its associated 70 to 100 kt 700 mb jet max moved east through the…
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.
The onset of a high impact wind event began on Tuesday January 13th, 2020, when a typical brand of strong winds descended over the normally wind prone Rocky Mountain Front and adjoining areas. Widespread anomalously strong winds then swept through much of Montana on the following day as a vigorous Pacific weather system and its associated 70 to 100 kt 700 mb jet max moved east through the Northern Rockies into the plains. A Pacific cold frontal passage helped transfer these winds to the surface and cold air advection on the sub-sident side of the trough maintained higher winds speeds for much of the day. Great Falls (76 mph), Helena (80 mph), and Havre (78 mph) all set wind wind speed records for the month of January. The winds were not only abnormally strong but they persisted longer than what is normally experienced, with some locations seeing frequent severe wind gusts for six hours or more. The impacts were felt throughout North-central and Southwest Montana and included, road closures due to areas of dense blowing dust, semi trailer roll overs, power outages, property damage, and even a few grass fires.
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 Jan 12, 2:28 PM MST, 1 hour 47 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 228 PM MST Tue Jan 12 2021 .SYNOPSIS... Strong west to southwest winds develop today along the east slopes of the Rockies, with strong and potentially damaging west to southwest winds spreading across the entire region Wednesday. Significant snowfall will accumulate over the higher elevations along the Continental Divide, and above most mountain passes, through Wednesday evening. && .DISCUSSION... There has not been much in the way of changes to the forecast and forecast reasoning for the next 36 to 48 hours. Models continue to indicate a high potential for high winds for Wednesday downwind of a strong atmospheric river event that extends all the way southwest into the central Pacific. The first ripple in this westerly flow is currently producing strong to high winds as expected, especially along the eastern slopes of the Rockies. A ridge-top level temperature inversion is producing a favorable profile for mountain waves, with highest wind gusts so far exceeding 75 mph along the immediate eastern slopes of the Northern Rockies. Radar shows a significant slug of moisture continuing to move to the Continental Divide. However, snow levels have risen above pass level currently so accumulating snows are not expected at or below pass level. A much stronger shortwave trough develops in the westerly flow and produces a higher-impact high wind event across the region on Wednesday. Model reanalyses and ensemble statistics indicate the strength of these winds easily exceed the 90th percentile of a 30-year model climatology. The strongest period of high winds are expected to occur just ahead of, and up to a few hours behind, a cold frontal passage during the daytime hours on Wednesday. Moderate instability associated with steep mid-level lapse rates and some convective potential will enable the strongest mid-level winds to mix down to the surface. There is high confidence in the timing and occurrence of the strong/high winds. These may be the strongest winds of the season, and localized damage should be expected in exposed areas such as some roof or tree damage, power outages, rolled trucks, or blowing dust. In addition to the winds, snow levels will drop quickly behind the passing front. A brief period of intense snow rates are possible for a couple of hours as the front barrels southeast along the Continental Divide of the Northern Rockies, with precipitation rates decreasing thereafter. This brief period of more intense snow with the frontal passage will likely result in the most hazardous impacts to travel, especially for Marias Pass and possibly Roger Pass. Note that the front will traverse the entire region, including Southwest Montana. High winds across southwest Montana will not be as prolonged, but will pack a punch for a few hours with the frontal passage Wednesday afternoon. In some locations, the snow and wind may coincide and produce localized near-whiteout conditions for a brief period. Wind speeds decrease rather quickly Wednesday night as pressure rises behind the passing front, though gusty winds are likely to remain into Thursday from a Havre-to-Lewistown line east, especially in the afternoon hours. Fair weather follows Thursday and Friday with ridging aloft. Gusty winds return to the Rocky Mountain Front Friday afternoon as the ridge begins to flatten and return to a westerly flow aloft. Snow showers are possible Saturday and Sunday with a couple of weak shortwave disturbances crossing the region. Seasonally mild weather continues into next week amid the ongoing west to northwesterly flow aloft. && .AVIATION... 1040 AM MST Tue Jan 11 2021 (12/18Z TAF period) Gusty southwest surface winds will begin to take shape this afternoon across the parts of northcentral MT, with this trend of increasing winds persisting through Wednesday. High level cloud cover is widespread, with mid level clouds developing and thickening through tonight, with mountian becoming obscured as light showers begin to work into the area overnight tonight into Wednesday morning. Otherwise, VFR conditions will prevail through tonight across most TAF sites, but may fall to MVFR ceilings as showers begin to develop along the divide this evening. -TP Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PRELIMINARY POINT TEMPS/POPS... GTF 43 54 26 40 / 10 10 30 0 CTB 40 52 25 38 / 10 20 30 0 HLN 35 52 26 39 / 20 30 20 0 BZN 30 53 18 35 / 30 50 20 0 WYS 18 36 1 23 / 60 70 30 0 DLN 29 49 14 32 / 40 30 10 0 HVR 41 58 26 39 / 10 30 40 0 LWT 37 53 23 34 / 10 20 50 10 && .TFX WATCHES/WARNINGS/ADVISORIES... High Wind Warning from 8 AM to 9 PM MST Wednesday Beaverhead... Broadwater...Central and Southern Lewis and Clark...Gallatin... Jefferson...Madison...Meagher. High Wind Warning from 5 AM to 9 PM MST Wednesday Blaine... Chouteau...Eastern Pondera...Eastern Teton...Fergus...Hill... Liberty...Toole. High Wind Warning from 11 PM this evening to 9 PM MST Wednesday Cascade...Judith Basin. High Wind Warning until 9 PM MST Wednesday Eastern Glacier... Northern Rocky Mountain Front...Southern Rocky Mountain Front. Winter Weather Advisory from 2 AM to 9 PM MST Wednesday Northern Rocky Mountain Front. && http://www.weather.gov/greatfalls
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE GREAT FALLS MT
1221 PM MST TUE JAN 12 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1121 AM NON-TSTM WND GST 8 SE EAST GLACIER PARK 48.36N 113.11W
01/12/2021 M77 MPH GLACIER MT MESONET
MESONET STATION DCRM8 DEEP CREEK RAWS.
1207 PM NON-TSTM WND GST 1 ENE EAST GLACIER PARK 48.45N 113.20W
01/12/2021 M65 MPH GLACIER MT MESONET
MESONET STATION MTBRN TWO MEDICINE BRIDGE
(MT DOT).
1139 AM NON-TSTM WND GST 2 SE BROWNING 48.54N 112.98W
01/12/2021 M58 MPH GLACIER MT MESONET
MESONET STATION MTBWG BROWNING (MT DOT).
1252 AM NON-TSTM WND GST 7 ESE HILGER 47.22N 109.22W
01/12/2021 M56 MPH FERGUS MT MESONET
MESONET STATION JPKM8 JUDITH PEAK RAWS.
1100 AM NON-TSTM WND GST 16 SE GALLATIN GATEWAY 45.44N 110.95W
01/12/2021 M51 MPH GALLATIN MT MESONET
MESONET STATION GNFHY 10.7 W EMIGRANT
(AVALANCHE).
1157 AM NON-TSTM WND GST 4 NNE MCALLISTER 45.50N 111.70W
01/12/2021 M51 MPH MADISON MT MESONET
MESONET STATION MTNOR NORRIS HILL (MT DOT).
0920 PM NON-TSTM WND GST 3 NNE MONARCH 47.14N 110.82W
01/11/2021 M50 MPH CASCADE MT MESONET
MESONET STATION MTMON MONARCH CANYON (MT
DOT).
0650 PM NON-TSTM WND GST KEVIN 48.74N 111.97W
01/11/2021 M50 MPH TOOLE MT MESONET
MESONET STATION DW0975 KEVIN.
1011 AM NON-TSTM WND GST SAINT MARY 48.74N 113.43W
01/12/2021 M50 MPH GLACIER MT MESONET
MESONET STATION SRYM8 SAINT MARY RAWS.
0356 PM NON-TSTM WND GST 3 SW CUT BANK 48.60N 112.37W
01/11/2021 M49 MPH GLACIER MT ASOS
ASOS STATION KCTB CUT BANK AIRPORT.
0958 PM NON-TSTM WND GST 3 WNW RAYNESFORD 47.28N 110.80W
01/11/2021 M48 MPH CASCADE MT AWOS
AWOS STATION K1AM ALPHA.
1115 AM NON-TSTM WND GST 5 NNE CAMERON 45.27N 111.65W
01/12/2021 M47 MPH MADISON MT AWOS
AWOS STATION KEKS ENNIS BIG SKY AWOS.
0730 PM NON-TSTM WND GST SUNBURST 48.88N 111.90W
01/11/2021 M45 MPH TOOLE MT MESONET
MESONET STATION MTSUN SUNBURST (MT DOT).
0730 PM NON-TSTM WND GST 3 SE SUNBURST 48.84N 111.86W
01/11/2021 M45 MPH TOOLE MT MESONET
MESONET STATION FW8513 SUNBURST.
0545 PM NON-TSTM WND GST 8 ESE FORT BENTON 47.79N 110.48W
01/11/2021 M45 MPH CHOUTEAU MT MESONET
MESONET STATION MTM02 10.2 S LOMA (MT-MESO).
0253 PM NON-TSTM WND GST 5 WSW GREAT FALLS 47.47N 111.38W
01/11/2021 M44 MPH CASCADE MT ASOS
ASOS STATION KGTF GREAT FALLS.
1007 PM NON-TSTM WND GST 2 SSE GEYSER 47.25N 110.48W
01/11/2021 M42 MPH JUDITH BASIN MT MESONET
MESONET STATION MTGYS GEYSER (MT DOT).
1159 AM NON-TSTM WND GST 4 NE LIMA 44.69N 112.54W
01/12/2021 M41 MPH BEAVERHEAD MT MESONET
MESONET STATION LMRM8 ANTELOPE RAWS.
0330 PM NON-TSTM WND GST 4 NW COFFEE CREEK 47.39N 110.13W
01/11/2021 M41 MPH FERGUS MT MESONET
MESONET STATION MTM15 3.6 NW COFFEE CREEK
(MT-MESO).
1115 PM NON-TSTM WND GST 20 N RUDYARD 48.85N 110.60W
01/11/2021 M41 MPH HILL MT MESONET
MESONET STATION EW1937 GOLDSTONE.
0800 AM NON-TSTM WND GST FORT BENTON 47.83N 110.66W
01/12/2021 M41 MPH CHOUTEAU MT CO-OP OBSERVER
CO-OP OBSERVER STATION FTBM8 FORT BENTON
COOP.
1144 AM NON-TSTM WND GST 15 WNW WOLF CREEK 47.09N 112.37W
01/12/2021 M40 MPH LEWIS AND CLARK MT MESONET
MESONET STATION MTROG ROGERS PASS (MT DOT).
1115 AM NON-TSTM WND GST 6 SE DUTTON 47.79N 111.60W
01/12/2021 M40 MPH TETON MT MESONET
MESONET STATION DAHMT DAHLMAN.
0858 PM NON-TSTM WND GST 1 ESE MALMSTROM AFB 47.50N 111.17W
01/11/2021 M40 MPH CASCADE MT AWOS
AWOS STATION KGFA MALMSTROM AFB.
0103 PM NON-TSTM WND GST 5 ESE DENTON 47.30N 109.85W
01/11/2021 M40 MPH FERGUS MT MESONET
MESONET STATION MTDEN DENTON (MT DOT).
&&
PEAK WIND GUSTS OF 40+ MPH FROM NOON MST JANUARY 11TH THROUGH NOON MST
JANUARY 12TH.PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
1230 PM MST TUE JAN 12 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1037 AM NON-TSTM WND GST 1 ENE EAST GLACIER PARK 48.45N 113.20W
01/12/2021 M60 MPH GLACIER MT MESONET
MESONET STATION MTBRN TWO MEDICINE BRIDGE
(MT DOT). FIRST OCCURRENCE AT THIS LOCATION
OF HIGH WIND CRITERIA GUST (58+ MPH) AND
SUSTAINED WIND (40+ MPH OVER THE LAST HOUR).
&&
SACPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
1232 PM MST TUE JAN 12 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1124 AM HIGH SUST WINDS 2 SE BROWNING 48.54N 112.98W
01/12/2021 M43 MPH GLACIER MT MESONET
MESONET STATION MTBWG BROWNING (MT DOT).
FIRST OCCURRENCE AT THIS LOCATION OF HIGH
WIND CRITERIA SUSTAINED WIND (40+ MPH OVER
THE LAST HOUR).
&&
SAC42 high wind. Local standard time, as filed.
Dellwo station (14 Bynum) measured a 63 kt (72 mph) non-thunderstorm wind gust.
Station at 4 SSE Ulm measured a 65 kt (75 mph) non-thunderstorm wind gust.
Station MTM02 (8 ESE Fort Benton) measured a 55 kt (63 mph) non-thunderstorm wind gust.
Pony station measured a 56 kt (65 mph) non-thunderstorm wind gust.
The Cut Bank Airport measured a 63 kt (72 mph) non-thunderstorm wind gust.
MDT Norris Hill station measured a 56 kt (65 mph) non-thunderstorm wind gust.
Station at 5 SSE Stockett measured a 72 kt (83 mph) non-thunderstorm wind gust.
West Butte station (16 WNW Whitlash) measured a 62 kt (71 mph) non-thunderstorm wind gust.
MDT Two Medicine Bridge station measured a 71 kt (82 mph) non-thunderstorm wind gust.
MDT Browning station (2 SE Browning) measured a 65 kt (75 mph) non-thunderstorm wind gust.
MDT Pendroy station (2 NW Pendroy) measured a 64 kt (74 mph) non-thunderstorm wind gust.
Trained spotter at 10 S Chinook measured a 60 kt (69 mph) non-thunderstorm wind gust.
The Dillon Airport measured a 58 kt (67 mph) non-thunderstorm wind gust.
MDT Big Hole Pass station measured a 53 kt (61 mph) non-thunderstorm wind gust.
Station at 1 SSW Minton measured a 52 kt (60 mph) non-thunderstorm wind gust.
MDT Elk Park Station (11 SW Basin) measured a 55 kt (63 mph) non-thunderstorm wind gust.
MDT Inverness station measured a 68 kt (78 mph) non-thunderstorm wind gust.
Station EW5772 (10 S Cut Bank) measured a 62 kt (71 mph) non-thunderstorm wind gust.
May station (10 N Joplin) measured a 67 kt (77 mph) non-thunderstorm wind gust.
Estimated 66 kt (76 mph) non-thunderstorm wind gust reported at 18 SW Augusta.
Station EW1937 Goldstone (20 N Rudyard) measured a 70 kt (81 mph) non-thunderstorm wind gust.
Station at 8 ENE Fairfield measured a 56 kt (65 mph) non-thunderstorm wind gust.
MDT Loma station (1 N Loma) measured a 57 kt (66 mph) non-thunderstorm wind gust.
Station DW4821 Chester (14 NNW Joplin) measured a 70 kt (80 mph) non-thunderstorm wind gust.
Big Rock station (1 SSW Shelby) measured a 59 kt (68 mph) non-thunderstorm wind gust.
MTM05 station (6 NW Ledger) measured a 58 kt (67 mph) non-thunderstorm wind gust.
Great Falls Airport measured a 66 kt (76 mph) non-thunderstorm wind gust.
The Cut Bank airport measured a 65 kt (75 mph) non-thunderstorm wind gust.
MDT station MTSBN (8 SSW Wolf Creek) measured a 62 kt (71 mph) non-thunderstorm wind gust.
Ginger RAWS station (3 WNW Townsend) measured a 63 kt (72 mph) non-thunderstorm wind gust.
MDT Denton station (5 ESE Denton) measured a 65 kt (75 mph) non-thunderstorm wind gust.
The Helena Airport measured a 70 kt (80 mph) non-thunderstorm wind gust.
White Sulphur Springs station K7S6 measured a 68 kt (78 mph) non-thunderstorm wind gust.
Ranch BB station (12 SE Boulder) measured a 64 kt (74 mph) non-thunderstorm wind gust.
MDT Geyser station measured a 68 kt (78 mph) non-thunderstorm wind gust.
Station FBLM8 (13 S Fort Belknap) measured a 62 kt (71 mph) non-thunderstorm wind gust.
Checkerboard station measured a 59 kt (68 mph) non-thunderstorm wind gust.
Estimated non-thunderstorm wind gust of 76 kt (87 mph) reported at 2 E Utica.
Dellwo station (14 W Bynum) measured a 65 kt (76 mph) non-thunderstorm wind gust.
The Bozeman Airport KBZN measured a 52 kt (60 mph) non-thunderstorm wind gust.
Station K1CM measured a 63 kt (72 mph) non-thunderstorm wind gust.
Trained spotter at 2 WSW Moore measured a 82 kt (94 mph) non-thunderstorm wind gust.
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, January 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: 929450, 929104, 929107, 929476, 929446, 929475, 929105, 929479, 929441, 929442, 929451, 928881, 928878, 928879, 929102, 929457, 929455, 929444, 929473, 929469, 929456, 929452, 929108, 929474, 929480, 929454, 929106, 929447, 929470, 929103, 929109, 929471, 929477, 929459, 929462, 928880, 929478, 929464, 929453, 929112, and more.