The region was in the ascent side of an approaching trough, which in combination with a developing surface low, resulted in widespread snow and heavy snow across much of the region.

Heavy Snow in NORTHWEST BEAVERHEAD COUNTY, MONTANA
From 12-APR-23 22:00:00 to 13-APR-23 12:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Multiple snotels measured snow reaching winter storm warning criteria, including Lemhi Ridge, Darkhorse Lake, and Slagamelt Lakes. The highest accumulation was at the Darkhorse Lake Snotel, which estimated 9 inches new snow in 24 hours.

Heavy Snow in CASCADE COUNTY BELOW 5000FT, MONTANA
From 12-APR-23 21:00:00 to 13-APR-23 21:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

NWS Great Falls measured 10.6 inches storm total snow ending 6 PM MDT 4/13; 7.6 of which fell by noon MDT 4/13. An additional public report was received that stated 8 inches new snow fell near Tiger Butte in 24 hours.

Heavy Snow in JUDITH BASIN COUNTY AND JUDITH GAP, MONTANA
From 12-APR-23 21:00:00 to 13-APR-23 13:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Multiple public reports were received detailing winter storm warning snow amounts. Most reports were in the Geyser to Raynesford areas along MT-200, with the peak report coming out of Raynesford (12 inches Storm total).

Heavy Snow in MADISON RIVER VALLEY, MONTANA
From 12-APR-23 21:00:00 to 13-APR-23 18:00:00 (MST-7)
Reported by: COOP Observer

COOP Observer at Norris Madison had an overnight snowfall total of 7 inches.

Heavy Snow in RUBY MOUNTAINS AND SOUTHERN BEAVERHEAD MOUNTAINS, MONTANA
From 12-APR-23 21:00:00 to 13-APR-23 13:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Two Snotel sites, JL Meadow, and Beagle SPrings, estimated snow that meets winter storm criteria. JL Meadow estimated 9 inches event total, while Beagle Spring estimated 8 inches in 12 hours.

Heavy Snow in FERGUS COUNTY BELOW 4500FT, MONTANA
From 13-APR-23 04:00:00 to 13-APR-23 22:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A report was received on Facebook of 8 inches storm total snow ending 11PM MDT 4/13.

Heavy Snow in BIG BELT, BRIDGER AND CASTLE MOUNTAINS, MONTANA
From 12-APR-23 14:00:00 to 13-APR-23 16:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Three snotels estimated storm total snow that exceeds winter storm warning criteria. The sites are Boulder Mountain (11 inches storm total), Sacajawea (8 inches), and Brackett Creek (9 inches).

Heavy Snow in GALLATIN AND MADISON COUNTY MOUNTAINS AND CENTENNIAL MOUNTAINS, MONTANA
From 12-APR-23 21:00:00 to 13-APR-23 16:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Many snotel sites estimated storm total snow that exceeds winter storm warning criteria. These sites include (Storm Total) Shower Falls (10 inches), Madison Plateau (7 inches), Black Bear (9 inches), Clover Meadow (8 inches), Lower Twin (9 inches), and Albro Lake (7 inches).

Heavy Snow in SOUTHERN ROCKY MOUNTAIN FRONT, MONTANA
From 12-APR-23 19:00:00 to 13-APR-23 15:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Snotel Dupuyer Creek estimated 10 inches storm total snow, with 7 inches falling over 12 hours.

Heavy Snow in UPPER BLACKFOOT AND MACDONALD PASS, MONTANA
From 12-APR-23 17:00:00 to 13-APR-23 18:00:00 (MST-7)
Reported by: SNOTEL

Several SNOTEL sites estimated snowfall amounts of seven inches over an 18 hour period.

Heavy Snow in ELKHORN AND BOULDER MOUNTAINS, MONTANA
From 12-APR-23 17:00:00 to 13-APR-23 17:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Multiple snotels estimated storm total snow in excess of winter storm warning criteria. These include (Storm Total): Frohner Meadow (14 inches), Tizer Basin (14 inches), and Rocker Peak (13 inches). An additional trained spotter report was received stating 8 inches storm total snow 1 mile SE of Montana City.

Heavy Snow in LITTLE BELT AND HIGHWOOD MOUNTAINS, MONTANA
From 12-APR-23 19:00:00 to 13-APR-23 08:51:00 (MST-7)
Reported by: COOP Observer

The COOP observer located about seven miles south of Shonkin had an event total snow amount of 17 inches. In addition, automate SNOTEL equipment at Onion Park estimated 7 inches new snow in 12 hours ending 8AM MDT 4/13. An additional public report of 11 inches storm total snow was received from 8 miles NNW of Monarch.

Heavy Snow in BEARS PAW MOUNTAINS AND SOUTHERN BLAINE, MONTANA
From 13-APR-23 06:00:00 to 13-APR-23 21:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Blaine county DES reported up to 8 inches event total snow near Clear Creek ending 10 PM MDT 4/13.

Heavy Snow in BEAVERHEAD AND WESTERN MADISON BELOW 6000FT, MONTANA
From 12-APR-23 13:45:00 to 13-APR-23 13:45:00 (MST-7)
Reported by: COOP Observer

The COOP observer located in Virginia City reported an event total snow amount of 12.4 inches. A trained spotter 8 miles south of Dillon reported 8 inches new snow in 24 hours ending at 245 PM MDT 4/13. An additional public report was received in Dillon that reported 6 inches of storm total snow at the time of report (1223 PM MDT 4/13).