Blizzard in Little Belt and Highwood Mountains, Montana

MT DOT sensor at Monarch Canyon showed visibility at or below one-quarter mile for at least 7 hours (Power failed at that point). US-89 was closed from Armington Junction to White Sulphur Springs early morning May 8. The Onion Park Snotel estimated 28 inches new snow with rates of 2 inches per hour. Elsewhere, the Porphyry Peak RAWS reported sustained winds averaging 25 mph, with gusts into the 50's mph before the sensor failed at 1005 PM MDT May 7. A widespread power outage affected much of the zone through Wednesday morning. End time is estimated given lack of observations after late evening of the 7th. The Monarch Fire Department reported 48 inches storm total snow by noon Wednesday the 8th. They reported numerous trees down, trees were on houses, roadways, and in Belt Creek. Other snowfall estimates from snotels in the zone: 29 inches at Stringer Creek over 24 hours, 21 inches at Deadman Creek over 24 hours, and 16 inches of new snow at Spur Park over 24 hours. Around $114,000 in damages were done to utilities.

A closed upper level low lifted northeast across eastern Montana on May 6th through the 9th. This low merged with a shortwave streaming from the Pacific Northwest. This storm system brought strong winds across Central and North Central Montana with the highest wind gust measured near Whitlash where a mesonet station measured an 87 mph gust. Widespread wind gusts of 55 and 75 mph were measured. Most damage was limited to trees being uprooted and power outages, but an exterior barrier of a high school roof was torn off by the wind in Shelby. Additionally, ample precipitation was observed with this system. Precipitation was mostly rain at lower elevations and fell as heavy snow in the mountains. Blizzard conditions were observed in the Little Belts, where multiple feet of snow was observed.