Moist northwest flow spread over cold air trapped in the valleys during the early morning hours. This caused areas of freezing rain to impact the airports at Missoula and Kalispell.
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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 MSO wrote it up.
Moist northwest flow spread over cold air trapped in the valleys during the early morning hours. This caused areas of freezing rain to impact the airports at Missoula and Kalispell.
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 Missoula, MT wrote its last area forecast discussion before the first event at Feb 4, 3:53 AM MST, 6 hours 5 minutes earlier.
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</html>The national radar mosaic for the moment the first event began.
2 winter weather. Local standard time, as filed.
Freezing rain was reported at the Missoula airport.
Freezing rain was reported at Glacier Park International Airport.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2011Every state in 2011This day in weather historyWarnings in Montana, February 2011
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 2026-09-30. Each event’s entry at NCEI: 279745, 279746.