Heavy snow showers associated with a slow moving front impacted travel on Interstate 90 at Lookout Pass and briefly caused moderate impact to Missoula, Seeley Lake and portions of southwest Montana.
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The episode as NWS MSO wrote it up.
Heavy snow showers associated with a slow moving front impacted travel on Interstate 90 at Lookout Pass and briefly caused moderate impact to Missoula, Seeley Lake and portions of southwest Montana.
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 Mar 4, 2:47 PM MST, 4 hours 43 minutes earlier.
Area Forecast Discussion
National Weather Service Missoula MT
247 PM MST Sat Mar 4 2017
.DISCUSSION...Valley rain and mountain snow showers are passing
through the region this afternoon as a trough takes hold of north
central Idaho and western Montana. A shortwave is forecast to pass
this evening that has the potential to bring moderate to heavy
snow showers north of Highway 12 in Idaho and between Missoula and
Lookout Pass. These showers may also extend into the Mission and
Flathead valleys with a mix of rain and snow this evening changing
to snow tonight. Additional shortwaves are planned to pass
tonight and snow levels will continue a lowering trend. The cold
front is on track to pass during Sunday, and as with most cold
fronts this time of year that reach the Georgetown Lake/Deerlodge/Butte
area, intense snow is possible during the afternoon. Winter
Weather Advisories have been issued to define the snow for this
afternoon and through Sunday morning. The lowering snow levels and
passing cold front on Sunday may lead to additional winter
weather highlights. Overall the next 36 hours will see variable
snow levels and quickly changing conditions for north central
Idaho and western Montana.
On Monday, cooler air will allow snow levels to drop well below
valley floors and another round of snow is expected over mountain
passes such as Lookout, Lolo, Marias and Lost Trail. These passes
could see an additional 3 to 7 inches of snow Monday through
Monday night. Valleys will see scattered snow showers off and on
throughout the day Monday and we could see anywhere from a trace
of snow to 4 inches of snow.
Starting Tuesday afternoon, a stronger surge of moisture will
bring more mountain snow with periods of heavy snow possible
Tuesday night into Wednesday. By Wednesday night, a strong jet
will approach the Northern Rockies and will bring some tropical
moisture to the area. Warm, moist air will lead to rising snow
levels on Thursday and heavy rain will be possible for valleys
across central Idaho and northwest Montana. Many valleys in these
areas still have significant amount of snow on the ground and when
combined with the tropical moisture, this could lead to overland
flooding in the valleys Wednesday and Thursday.
&&
.AVIATION...A broad upper trough is taking over the region and
north central Idaho and western Montana are under the active
southwesterly jet portion of the weather system. Low elevation
rain showers and mountain snow are keeping terrain obscured with
periodic reductions to visibility. Latest radar trends are
showing stronger convective showers that are driving snow levels
down with moderate to heavy snow. High resolution model guidance
show the convective showers to move through north central Idaho
and west central/northwest Montana in multiple waves this
afternoon through tonight. These showers will drive snow levels
down to most valley floors and heavy showers will produce moderate
to heavy snow with very low visibility.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Warning until noon MST Sunday Lower Clark Fork
Region.
Winter Weather Advisory until 10 AM MST Sunday Flathead/Mission
Valleys.
Winter Weather Advisory until 6 PM MST Sunday West Glacier
Region.
Winter Weather Advisory until noon MST Sunday
Bitterroot/Sapphire Mountains.
ID...Winter Weather Advisory until 11 AM PST Sunday Northern
Clearwater Mountains.
&&The national radar mosaic for the moment the first event began.
3 winter weather, 1 heavy snow. Local standard time, as filed.
An intense band of snow brought heavy snow to Lookout Pass for several hours during the evening of the 4th which caused the Montana Department of Transportation to issue severe driving conditions.
Heavy snow showers with two inch per hour rates brought low visibility and a short period of slick roads. An NWS Missoula employee reported zero visibility with snow-covered roads during the event. Anywhere from 3 to 7 inches of snow fell with this band, but due to the fact that it occurred during a relatively quiet period on a Sunday morning, the impact was mostly moderate.
A Greenough spotter reported that one inch of snow had fallen in only 30 minutes and it was still snowing. Seeley Lake received two inches during this event.
Web cams revealed periods of heavy snow with the slow moving front from Ovando south to Butte. The Bert Mooney Airport reported moderate to heavy snow between 7 and 735 pm MST on the 5th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2017Every state in 2017This day in weather historyWarnings in Montana, March 2017
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: 678324, 678325, 678326, 678329.