On November 7th, deep troughing over the western US kept Montana in an area of large scale ascent and upper level divergence, allowing H700 mb and surface low pressure systems to deepen over Eastern Idaho and move northeastward through Eastern Montana and the Dakotas. This is a favorable track to bring cold temperatures, gusty winds, and sufficient moisture for accumulating snow to…
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.
On November 7th, deep troughing over the western US kept Montana in an area of large scale ascent and upper level divergence, allowing H700 mb and surface low pressure systems to deepen over Eastern Idaho and move northeastward through Eastern Montana and the Dakotas. This is a favorable track to bring cold temperatures, gusty winds, and sufficient moisture for accumulating snow to Central/North-central Montana. The snowfall was enhanced by northerly upslope flow over the plains onto the higher terrain in addition to the moisture wrapping around the northwest side of the low pressure system. Snow and gusty northerly winds initially developed over the Northern Rocky Mountain Front early Saturday November 7th, before expanding south and eastward through the remainder of the region Saturday night into Sunday. At the height of the storm, winds gusted into the 40 to 60 mph range, resulting in blizzard conditions over much of Central and North-central Montana.
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 Nov 7, 5:16 PM MST, 1 hour 58 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 516 PM MST Sat Nov 7 2020 ...Aviation Section Update... ...Major Winter Storm to Impact North-Central and Central Montana Tonight Through Sunday with Blizzard Conditions Expected Across Portions of North-Central Montana... .SYNOPSIS... A major winter storm will move into the area tonight with rain and snow changing to snow for most areas this evening and all areas by Sunday morning. Snow may be heavy at times with strengthening north to northwest creating significant blowing and drifting snow late tonight through Sunday over the plains before snow and winds diminish Sunday night. && .DISCUSSION... Little change from previous forecasts with regard to snow amounts and wind/visibility impacts expected with the storm tonight through Sunday. Upper level low lifting out of the Great Basin will merge with upper troughing and much colder air moving south from western Canada tonight to create a significant winter storm across the region. The resulting mid level circulation developing in ID/SW MT this evening tracks east to eastern MT by Sunday morning and onward to SK/MB Sunday night. Snow associated with the Canadian trough and colder airmass moving south along the Rockies will spread southward this evening while an initial disturbances ejecting out of the Great Basin system spreads widespread showers northward, evolving into an area of widespread precipitation this evening as flow aloft turns SE then easterly ahead of the mid-level circulation developing over ID. The cold air surging southward, initially along the east slopes of the Rockies, will trigger the change from rain to snow for western portions of north-central and central MT early this evening with the colder air and change to snow spreading south and eastward overnight. Areas from Bozeman to Lewistown and Havre may not see the change-over to snow until after midnight tonight with areas east of Lewistown changing to snow early Sunday morning. Snow intensity peaks Sunday morning for most areas but continues into the afternoon. Light snow lingers into Sunday evening across north-central MT before ending late Sunday night. Total snow accumulation forecasts have changed little with greatest amounts expected across much of north-central MT and lesser amounts across southwest MT. Gusty N to NW winds will spread south and east across the area tonight and across most of north-central and SW MT by Sunday morning. Strongest winds with gusts as high as 40-50 mph are likely across western portions of north-central MT late tonight through Sunday morning where a Blizzard Warning remains in effect. Gusts in the 35 to 45 mph rage are likely further east across the remaining counties in north-central MT later Sunday morning through the afternoon with these winds reaching eastern portions of north-central MT late Sunday morning through the afternoon and the Blizzard warning has been expanded to include Judith Basin, Fergus and Blaine counties. Significant impacts are expected in the areas under Winter Storm and Blizzard warnings from the combination of wind and snow, peaking Sunday morning but continuing through much of the day. Travel will be particularly difficult in areas under the Blizzard warning, where blowing snow and very low visibility impacts Sunday morning may transition to greater impacts from blocked roadways and drifting snow Sunday afternoon as snow intensity diminishes. Snow and winds decrease Sunday night as the storm system lifts out into central Canada. Most areas will see steady temperatures in the teens and lower 20s Sunday with wind chill values as low as the teens below zero by late Sunday afternoon. Temperatures fall to the single digits and teens above zero Sunday night and potentially colder in some areas near the Canadian border where some clearing is possible by Monday morning. Tuesday through next Saturday...A broad low pressure trough will develop over much of North America during this time, which will keep temperatures below normal. Weak shortwave troughs will pass over Montana during this time, bringing periods of gusty winds and generally light precipitation, and minor temperature fluctuations. At this point, there is a chance for strong winds Friday and next Saturday, but will continue to monitor the situation for now, as confidence in the forecast is somewhat low that far out. Coulston && .AVIATION... 516 PM MST Sat Nov 7 2020 (08/00Z TAF period) A major winter storm causes widespread aviation impacts throughout this TAF period. Expect LIFR conditions to occur due to low visibility and low ceiling at all airfields. Blizzard conditions are forecast across north-central and central Montana. During periods of gusty winds, expect reduced visibility in snow and blowing snow. In areas of light winds, visibility will be reduced in snow and fog. Low level wind shear is included in the following TAFs: KCTB, KHLN and KWYS. Expect all associated turbulence. Widespread mountain obscuration is forecast. Aircraft icing is to be expected. - Fogleman Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PRELIMINARY POINT TEMPS/POPS... GTF 16 22 10 27 / 100 100 90 10 CTB 14 19 3 25 / 100 100 80 0 HLN 17 24 9 27 / 90 100 70 10 BZN 20 28 5 23 / 90 90 40 10 WYS 22 30 3 23 / 100 80 20 0 DLN 17 25 2 23 / 80 100 30 0 HVR 19 28 8 23 / 100 100 100 30 LWT 18 25 8 26 / 90 100 60 30 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from 8 PM this evening to 5 AM MST Monday Broadwater...Central and Southern Lewis and Clark...Jefferson... Meagher. Blizzard Warning until 5 AM MST Monday Eastern Glacier...Eastern Pondera...Eastern Teton...Liberty...Northern Rocky Mountain Front...Southern Rocky Mountain Front...Toole. Winter Weather Advisory from 11 PM this evening to 5 AM MST Monday Beaverhead...Gallatin...Madison. Blizzard Warning from 11 PM this evening to 8 AM MST Monday Blaine...Fergus...Judith Basin. Blizzard Warning from 8 PM this evening to 8 AM MST Monday Cascade...Chouteau...Hill. && http://www.weather.gov/greatfalls
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
623 PM MST SAT NOV 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0609 PM HIGH SUST WINDS 2 SE BROWNING 48.54N 112.98W
11/07/2020 M30 MPH GLACIER MT MESONET
MESONET STATION MTBWG BROWNING (MT DOT).
GUST 43 MPH.
&&
JAFPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
624 PM MST SAT NOV 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0600 PM HIGH SUST WINDS 10 S CUT BANK 48.49N 112.37W
11/07/2020 M31 MPH GLACIER MT MESONET
MESONET STATION EW5772 CUT BANK. GUST 42
MPH.
&&
JAFPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
625 PM MST SAT NOV 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0600 PM HIGH SUST WINDS 10 S CUT BANK 48.49N 112.37W
11/07/2020 M31 MPH GLACIER MT MESONET
MESONET STATION EW5772 CUT BANK. GUST 39
MPH.
&&
JAFPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
626 PM MST SAT NOV 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0559 PM HIGH SUST WINDS 8 SSW WOLF CREEK 46.89N 112.11W
11/07/2020 M31 MPH LEWIS AND CLARK MT MESONET
MESONET STATION 301005 SIEBEN. GUST 42 MPH.
&&
JAFPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
636 PM MST SAT NOV 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0627 PM HEAVY SNOW 5 WSW GREAT FALLS 47.47N 111.38W
11/07/2020 M0.3 INCH CASCADE MT ASOS
ASOS STATION KGTF GREAT FALLS. WIND
34021G28MPH.
&&
JAFPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
702 PM MST SAT NOV 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0655 PM SNOW 7 SSE ULM 47.33N 111.48W
11/07/2020 M2.0 INCH CASCADE MT TRAINED SPOTTER
SPOTTER REPORTS 2 INCHES OF SNOW IN ABOUT AN
HOUR SINCE IT JUST STARTED SNOWING.
&&
FMK17 blizzard, 7 winter storm. Local standard time, as filed.
Falling snow and winds gusting from 35 to 45 mph bring blizzard conditions to the Chouteau Airport. Severe driving conditions reported at 850 pm lst along highway 287 from MP 46 to 64.
Snow and winds gusting at 35 mph brought blizzard conditions to the Fairfield area. Snow accumulation was estimated to be 8 inches and drifts were about 2 feet. Times estimated with those at the Chouteau Airport. Severe driving conditions reported at 750 pm lst on I15 from Dutton to Pondera County line.
MDT Deep Creek station reports moderate to heavy snow and wind gusts up to 55 mph.
Sustained winds up to 41 mph combined with falling snow for blizzard conditions at 5 E Conrad. Severe driving conditions reported on I15 from Brady to Conrad at 915 pm lst.
Severe driving conditions reported on highway 12 from MacDonald Pass to Helena due to snow and winds. Relayed by twitter.
Sustained winds up to 45 mph with gusts up to 53 mph combined with falling snow for blizzard conditions at 6 NNW Sunburst. Neighboring Eastern Glacier and Pondera Counties were reporting severe driving conditions.
Sustained winds up to 43 mph with gusts up to 53 mph combined with falling snow for blizzard conditions at 2 SE Browning.
Heavy snow and wind gusts of 30 to 40 mph lead to blizzard conditions at 5 SW Carter. Visibility was about a tenth of a mile. Severe driving conditions were reported on highway 87 from Carter to Fort Benton at 645 am lst via twitter.
Wind and snow bring winter storm conditions to Northwestern Madison County. Winds gusted up to 55 mph and visibility dropped to a quarter mile at times in Twin bridges. Severe driving conditions were reported by MDT.
Sustained winds up to 42 mph combined with falling snow for blizzard conditions at 2 WNW Moccasin.
Blizzard conditions occurred at 5 WSW Great Falls with visibility down to a quarter mile and winds generally above 35 mph. Snow drifts up to 2 feet were also reported. Severe driving conditions were later reported throughout Cascade County between 12 and 7 am lst.
Sustained winds up to 43 mph with gusts as high as 54 mph combined with falling snow for blizzard conditions at 2 NWs Pendroy.
Severe driving conditions reported on I15 from Lincoln interchange to Sieben interchange. Relayed via twitter.
Highway 200 was closed from Eddies Corner to Lewistown due to blizzard conditions. Message relayed via MDT twitter.
Severe driving conditions reported via twitter on US 12 MM 55 to 77 due to snow and winds.
Highway 191 closed from Garneill to Eddies Corner due to blizzard conditions. Portions of this highway run through both Judith Basin and Fergus Counties. Message relayed via MDT twitter.
Severe driving conditions reported on I15 form Dearborn to Hardy Creek due to snow and wind. Message relayed via MDT twitter.
Snow and winds gusting up to 50 mph combined for blizzard conditions at Inverness. Severe driving conditions were reported on highway 2 form the Liberty County line to Hingham at 720 am lst via twitter.
The Cut Bank Airport observed sustained winds above 35 mph with gusts up to 50 mph, which combined with falling snow for blizzard conditions. Severe driving conditions reported on State route 213 from Cut Bank to the Canadian border at 9 am lst. Message relayed by MDT twitter.
A trained spotter reported 30 to 55 mph winds, visibility less than a quarter mile for blizzard conditions at Joplin. Close to one foot of snow fell and wind chills were near - 15 degrees F. Severe driving conditions were reported on highway 2 from Chester to the Hill County line at 720 am lst via twitter.
Snow with winds gusting up to 37 mph brought blizzard conditions to the Lewistown Airport.
Snowfall total of 6 inches was reported at Clancy.
State route 464 (Duck Lake Rd) closed from Browning to St. Marys due to blizzard conditions. Message was relayed by MDT twitter.
Snow and winds gusting up to 45 mph brought blizzard conditions to 13 S Fort Belknap.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2020Every state in 2020This day in weather historyWarnings in Montana, November 2020
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: 924614, 924615, 924808, 924597, 924806, 924598, 924603, 924613, 925008, 924604, 924606, 924605, 924805, 924788, 924804, 924789, 924803, 924802, 924607, 924608, 924647, 925009, 924801, 924616.