Winter Storm in West Glacier Region, Montana

Intense overrunning mechanisms led to high snowfall rates, with Hungry Horse receiving 8 inches of snow in only 7 hours. At the Essex MDT sensor, the primary Arctic cold front passed between 0700MST and 0800MST producing gusty winds and snowfall. A secondary Arctic surge between by 2200MST on the 17th caused temperatures to drop to 6 degrees Fahrenheit, with wind gusts up to 33 mph creating wind chills as low as 15 degrees Fahrenheit below zero. Nearby, the Summit station recorded approximately 2 inches of snow in less than one hour between 1400MST and 1500MST on the 17th.

A record-breaking winter storm impacted western Montana as a very cold trough, originating from Siberia, transitioned southeast into the region. This system coincided with an Arctic air mass pushing west toward the Continental Divide. A powerful surface low of 981 millibars broke all-time February sea level pressure records across the Northern Rockies, including a record 985.2 mb at Missoula (previous record 985.5 mb in 1963). The negatively tilted nature of the trough resulted in prolonged heavy snowfall on the morning of the 17th, particularly across northwest Montana. By February 18th, shortwaves embedded in the cyclonic flow produced convective snow showers and squalls overrunning the Arctic boundary in place. This brought isolated flash-freeze and high impact travel to the evening commute.