With moisture flowing in from the west and a strong cold front descending from the north, a significant winter storm brought accumulating snow to many northeast Montana locations. The higher snowfall amounts for this region were located in the higher elevations of central Montana and along and near US Highway 2.
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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 GGW wrote it up.
With moisture flowing in from the west and a strong cold front descending from the north, a significant winter storm brought accumulating snow to many northeast Montana locations. The higher snowfall amounts for this region were located in the higher elevations of central Montana and along and near US Highway 2.
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 Glasgow, MT wrote its last area forecast discussion before the first event at Dec 18, 7:43 PM MST, 8 hours 17 minutes earlier.
Area Forecast Discussion National Weather Service Glasgow MT 743 PM MST Mon Dec 18 2017 .DISCUSSION... 730PM UPDATE: Changes to the forecast focused on PoPs. Looking over confidence in the upcoming event. As multiple parameters are coming into agreement the chance for hundredth PoP has ramped up from 70 percent to nearly 100 percent for many areas Tuesday overnight. Therefore, have also upgraded the winter weather advisory for northern Phillips county to Winter Storm Warning. GAH Afternoon Update (3pm MST): Focus of the update was to the system coming tomorrow through Wednesday. Snow totals have been updated to match closer to WPC guidance. With continued increasing totals without decreases in the interim, and run-to-run consistency increasing the confidence of the impacts for this system, the Winter Storm Watch has been upgraded to a Warning around the Little Rockies and Hwy-191, and an Advisory for much of the rest of the region outside of Prairie and Wibaux Counties, where accumulations do not look to be as significant, and where some rain may also preclude some accumulation by pre-wetting the ground. Temperatures continue to be adjusted downwards in the near term to account for the expected snowpack, but temperatures near the end of the period have been brought up some from the past couple of forecast packages, as some guidance have been starting to resolve a return to warmer weather, thus decreasing confidence in such deep cold. Bigelbach Morning Update (9am MST): No significant changes to the forecast for the morning package. Minor tweaks to temperature and wind grids comprised the main areas of updating this morning. Bigelbach PREVIOUS DISCUSSION: A shift in the overall pattern is expected to lead to accumulating snow by midweek, followed by much colder temperatures. A split upper trof is currently moving across the western CONUS, with the northern portion heading across the northern Plains states toward the Great Lakes, and the southern portion in the form of a nearly entirely cutoff low over the Sonoran desert region of the US and Mexico. A surface boundary has set up over northern Montana, bringing cloudy skies and a mixture of rain and snow showers this morning. These will continue off and on throughout the day as this trof slowly moves south and east through the region, and some locations across far northeast Montana may see between half an inch to an inch of snow. Just behind this, a low pressure system will push into the area from the northwest, allowing cold air to push into Montana from the north. This system will bring snow to the region beginning as early as Tuesday afternoon, which will persist into Thursday morning. Currently, the highest snowfall amounts are anticipated to be across the higher terrain of the Little Rockies. Areas of northeast Montana north of the Missouri River should also see higher snowfall amounts due to the surface boundary expected to set up as cold air tries to push down from the north side of this storm. Current forecast snow amounts look to be 5 to 8 inches over the Little Rockies, and 3 to 5 inches over the rest of the area north of the Missouri, with generally 2 inches or less south. As these totals are anticipated from Tuesday morning through Wednesday afternoon, a Winter Storm Watch has been issued for this time period. Winds may also be somewhat breezy as this front passes through, and we will keep an eye on that as the storm approaches to determine how significant impacts from that will be. Cold air will drop significantly as the system clears out from the area, and with fresh snow cover, temperatures will drop to near or below zero Wednesday night. Cold northwest flow will keep temperatures cold, and there is increasing model consensus regarding the probability of an upper level low diving down in the Great Basin region from the Pacific Northwest on Thursday. So have a chance of snow south of the Missouri for Thursday night into Friday as this system passes, although current thinking is that the precipitation will remain to our south and over the Rockies with this storm. Beyond this, model guidance diverges, although at this time it looks like northeast Montana will remain cold under a generally unstable northwest flow regime through Christmas. Hickford && .AVIATION... WINTER WEATHER ADVISORY: Expect delays and accumulating snow on runways from 00Z-00Z Wed to Thurs. FLIGHT CAT: VFR-IFR SYNOPSIS: Showers from earlier this evening have clear out of the TAF sites overnight with VFR ceilings. However, by Tuesday afternoon snow will begin to move into the terminals from west to east. Ceilings will drop to MVFR overnight, and where snow starts IFR visibilities will slowly set in and likely last through Wednesday afternoon and evening. KGDV seems to be just far enough south that it may remain out on the early snow and IFR until into Wednesday afternoon. WIND: West at 10 kts tonight. Flipping to the east and increasing to 10-20 kts Tuesday afternoon. GAH && .GLASGOW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 5 PM Tuesday to 5 PM MST Wednesday for Central and Southern Valley...Daniels...Dawson...Eastern Roosevelt...Garfield...McCone...Northern Valley...Richland... Sheridan...Western Roosevelt. Winter Storm Warning from 11 AM Tuesday to 5 PM MST Wednesday for Central and Southeast Phillips...Northern Phillips... Southwest Phillips. Winter Weather Advisory from 11 AM Tuesday to 5 PM MST Wednesday for Petroleum. && weather.gov/glasgow
The national radar mosaic for the moment the first event began.
2 winter storm. Local standard time, as filed.
A trained spotter located 6 miles west southwest of Chapman reported 8 to 10 inches of snow, primarily falling overnight on the 19th and into the 20th.
A trained spotter at the Buckhorn general store in Zortman reported 14 inches of snow, beginning at approximately 8:00 the morning of the 19th and ending at 2:00 PM the afternoon of the 20th.
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, December 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: 727978, 727968.