On Friday, October 23, Montana was in the crosshairs for a strong early winter snow storm set to begin later that afternoon afternoon and continue through Saturday evening. A strong upper level disturbance positioned over southeast Alaska would continue to move south-southeastward during the day, reaching the Pacific Northwest/British Columbia border by late in the afternoon. This feature would then approach western Montana overnight in conjunction with a strong surface cold front that would sweep southward out of Alberta into north central portions of the state. Widespread snow (heavy at times), blowing snow, and very cold wind chills were anticipated overnight and through the day on Saturday. Snow gradually tapered off Saturday night into early Sunday morning as the core of the upper level trough continued moving southward. Models were in excellent agreement on the details of this storm with very good run-to-run consistency so confidence was very high that impacts will be extensive and widespread. It appeared that the east slopes of the Rocky Mountains and much of central Montana would see upwards of 8 to 12 inches of snow accumulation, and some models even suggested that up to 18 inches of snow was not out of the question. The Winter Storm Warning remained in effect for this region, and was later upgraded to a Blizzard Warning for areas along the Rocky Mountain Front. Lesser amounts of snow were expected along eastern portions of the Hi-Line and in southwest Montana, so these areas were under a Winter Weather Advisory. Finally, a surface high pressure system would be centered over central and western Montana Sunday morning. This resulted in low temperatures on Sunday falling to near or below zero with many record temperatures expected to be set across the entire forecast area.

Winter Weather in SOUTHERN ROCKY MOUNTAIN FRONT, MONTANA
From 23-OCT-20 12:30:00 to 24-OCT-20 17:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Co-op observer reports 6.5 of snow in Choteau.

Heavy Snow in GALLATIN, MONTANA
From 23-OCT-20 20:00:00 to 24-OCT-20 09:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter reports 13 inches new snow overnight. still snowing.

Winter Weather in SOUTHERN ROCKY MOUNTAIN FRONT, MONTANA
From 23-OCT-20 12:30:00 to 24-OCT-20 17:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Co-op observer reports 6.5 of snow in Choteau.

Heavy Snow in MEAGHER, MONTANA
From 23-OCT-20 13:00:00 to 24-OCT-20 10:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Reported via facebook, likely 12+ inches, and still coming down.

High Wind in BEAVERHEAD, MONTANA
From 24-OCT-20 01:05:00 to 24-OCT-20 01:05:00 (MST-7)
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet station hrkm8 harkness raws.

Winter Weather in MADISON, MONTANA
From 23-OCT-20 12:00:00 to 24-OCT-20 09:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reports 1-2 of new snow, visibility under 1/2 mi at times in blowing snow. 1 WSW of Virginia City.

Heavy Snow in BROADWATER, MONTANA
From 23-OCT-20 11:00:00 to 24-OCT-20 07:20:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Social media estimate of 12-14in near canyon ferry.

Heavy Snow in JEFFERSON, MONTANA
From 23-OCT-20 11:00:00 to 24-OCT-20 09:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Co-op observer reports 20 of new snow and till snowing at time of observation.

Heavy Snow in JEFFERSON, MONTANA
From 23-OCT-20 11:00:00 to 24-OCT-20 14:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public reports 18 of heavy snow near Montana City via Twitter.

Heavy Snow in SOUTHERN LEWIS AND CLARK, MONTANA
From 23-OCT-20 11:00:00 to 24-OCT-20 16:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reports 25 of snow from Friday to Saturday.

Heavy Snow in SOUTHERN LEWIS AND CLARK, MONTANA
From 23-OCT-20 11:00:00 to 24-OCT-20 15:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reports 21.5 of snow 7 miles north of Helena.

Heavy Snow in NORTH ROCKY MOUNTAIN FRONT, MONTANA
From 23-OCT-20 11:00:00 to 24-OCT-20 16:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Social Media report of 13 of snow in Dupuyer.

Heavy Snow in GALLATIN, MONTANA
From 23-OCT-20 12:00:00 to 24-OCT-20 03:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reports 12 of snow. Storm total.

Heavy Snow in CHOUTEAU, MONTANA
From 23-OCT-20 12:00:00 to 24-OCT-20 07:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Social media. estimated over 1 ft with snow still falling.

Heavy Snow in EASTERN TETON, MONTANA
From 23-OCT-20 12:30:00 to 24-OCT-20 15:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Storm total snowfall of 9 inches.

Heavy Snow in MEAGHER, MONTANA
From 23-OCT-20 13:30:00 to 24-OCT-20 06:53:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Social media report of 9.5in snow in Martinsdale.

Winter Weather in MADISON, MONTANA
From 23-OCT-20 19:00:00 to 24-OCT-20 04:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reports 3 of new snow overnight.

Heavy Snow in JUDITH BASIN, MONTANA
From 23-OCT-20 14:00:00 to 24-OCT-20 09:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reports 8 of snow. Storm total SWE was 0.55.

Winter Weather in EASTERN PONDERA, MONTANA
From 23-OCT-20 12:30:00 to 24-OCT-20 08:20:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter best guess is 6in. blowing/drifting; some bare spots, some drifts to 2ft.

Heavy Snow in CASCADE, MONTANA
From 23-OCT-20 17:00:00 to 24-OCT-20 17:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Measured 10.5 at the National Weather Service Great Falls, MT office.

Winter Weather in EASTERN TETON, MONTANA
From 23-OCT-20 12:30:00 to 24-OCT-20 06:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snow totals 6 as of 7:30 MDT. Visibility under 1/2 mile, drifts are 8 in.

Heavy Snow in BROADWATER, MONTANA
From 23-OCT-20 18:00:00 to 24-OCT-20 11:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter estimated about 18 inches of new snow since 5 pm friday.