A closed low brought heavy snow to higher elevations of southwest Montana with short-term power outages reported.
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The episode as NWS MSO wrote it up.
A closed low brought heavy snow to higher elevations of southwest Montana with short-term power outages reported.
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 May 9, 3:40 AM MST, 5 hours 20 minutes earlier.
Area Forecast Discussion National Weather Service Missoula MT 440 AM MDT MON MAY 9 2016 ...SIGNIFICANTLY COOLER...SNOW DOWN TO 4000 FEET ACROSS NORTHERN ROCKIES THROUGH TUESDAY MORNING... .DISCUSSION... A significantly cool and moist storm system from Canada will continue to move across much of the Northern Rockies today. Snow levels are expected to fall 4000 feet through this evening. Some brief, heavy precipitation along the leading edge of the cold air could present some travel impacts due to snow-covered roads and low visibility. The Glacier Park Region will be most prone to the snowfall today, with the snow threat shifting southward toward the Butte/Blackfoot Region tonight. The evolving weather scenario will be tricky due to the timing of precipitation versus the arrival of cold air, particularly true for Butte/Blackfoot Region. If the snow is delayed for southwest Montana, then it is likely that roadways over Continental Divide passes will be covered by a mix of ice/snow/slush for a time late this evening through Tuesday morning. Even if timing of snowfall is much sooner than tonight, hazardous winter travel over Continental Divide passes remains plausible throughout this afternoon and evening. Thunderstorms will be embedded within shower activity throughout today, with frequent lightning possible. A brief bout of thunderstorms containing small hail are possible along the cold front this afternoon, most likely occurring over the Butte/Blackfoot Region. Also, some gusty northeast winds will develop today, along with the snow, that may limit visibility at times over Marias Pass. The threat of hazardous winter weather conditions lessen by Tuesday afternoon, with warming and drying already underway across much of north central Idaho. Mountain snow and valley rain showers will linger over much of western Montana through sunset Tuesday. Wednesday: Expect a rather pleasant day with seasonable temperatures generally in the 60s across western Montana and 70s in the valleys of north-central Idaho. The only threat for showers will be near the Canadian border later in the day. Thursday: A backdoor Canadian cold front will begin to slowly move westward later in the day. With weak to moderate instability ahead of this feature, showers and thunderstorms will be possible. The biggest threats to the storms will be lightning and gusty winds. Temperatures will generally be several degrees above normal. Friday: The easterly wind gradient will continue across north- central Idaho and western Montana and could pose an issue with gusty winds on area lakes. High temperatures will continue to be pleasant and in the 60s and 70s in western Montana and in the lower 80s across the Camas Prairie in Idaho. Next weekend: An upper level trough will approach the region to bring another chance for showers and thunderstorms. It seems the best chance for shower activity will be over north-central Idaho and southwest Montana, but confidence is low due to model differences. && .AVIATION...Periods of heavy rain showers and gusty northeast winds will spread from north to south across the Northern Rockies during the next 24 hours. A cold storm system out of Canada will have some periods of heavy rain, particularly for KGPI through 10/0000Z. KMSO and KSMN will experience periodic showers from around sunrise through 10/0300Z. There is a possibility of a moderate thunderstorm with small hail passing KBTM between 09/1700Z and 09/1900Z, with periods of moderate snow showers decreasing ceilings and visibility through 10/0600Z. Wind gusts to 30 knots are possible at times for all area terminals, mostly before 10/0300Z. Terrain will be obscured for much of the next 24 hours. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. &&
The national radar mosaic for the moment the first event began.
2 winter weather. Local standard time, as filed.
Gem Mountain, located west of Georgetown Lake, reported 15 inches of heavy snow.
Up to 6 inches of snow fell across the higher terrain of southwest Montana including Georgetown Lake and in the Butte area. Power outages were reported during the evening of May 9th in the Philipsburg area.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2016Every state in 2016This day in weather historyWarnings in Montana, May 2016
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 2026-09-24. Each event’s entry at NCEI: 635818, 635819.