Strong, competing weather systems acted to enhance the wind flow between them, directly through central Montana.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
Strong, competing weather systems acted to enhance the wind flow between them, directly through central 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 Glasgow, MT wrote its last area forecast discussion before the first event at Dec 29, 2:29 PM MST, 3 hours 19 minutes earlier.
Area Forecast Discussion National Weather Service Glasgow MT 229 PM MST Sat Dec 29 2018 .DISCUSSION... Afternoon Update: Not too much was changed in terms of the raw grid numbers for the afternoon package today. Generally the forecast remains intact from this morning, and the narrative (including potential hazards) remains as well. The biggest update today will be the issuance of a Wind Chill Watch for Monday morning for areas along and north of the Hi-Line. Expect this Watch to eventually convert to an Advisory, but decided the advanced notice was necessary for the first real potential dangerous cold event of the season. Bigelbach PREVIOUS DISCUSSION: A weak wave in NW flow aloft early this morning could bring a slight chance of light snow to areas along and north of the Missouri River. Upper ridge moves into Montana today with warmer temperatures that will be 5 to 15 degrees above normal. The west will warmer than the east today as temperatures at 2 am are around 20 degrees colder in the east. A surface low moves SE tonight and Sunday morning from Alberta to North Dakota with a upper trough following on Sunday and Sunday Night. A warm front moves through the forecast area this afternoon and evening which could bring a chance of rain and snow. 850 mb winds increase to around 50 knots between late this afternoon and late tonight and then they diminish Sunday morning. A low level inversion will likely limit the ability for the wind to mix to the surface in most areas. However, being a westerly wind, they usually mix to the surface in SW Phillips where the elevations are near 850 mb and the winds get funneled around the Little Rocky Mountains. Will issue a High Wind Warning for that area starting at 2pm this afternoon and going until 6 am Sunday morning as wind gust around 60 mph are likely. A cold front will move south across the forecast area during the day on Sunday with some light rain and snow. Cold air advection will bring falling temperatures during the day in some areas. This will bring much colder temperatures into the region for Sunday Night through Monday Night. With NW winds 15 to 25 mph Sunday Night, wind chills north of the Missouri River will likely reach the Wind Chill Advisory Criteria of 20 below. Some areas will have lows below zero both of those nights as Arctic high pressure moves through the area. The upper trough and high pressure moves to the east on Tuesday and temperatures warm as a warm front moves through the forecast area with a shortwave trough on NW flow aloft. Upper ridge builds into Montana Wednesday and Thursday with well above normal temperatures. Models differ at this point as to whether the next cold front will be Friday or Saturday. Forrester && .AVIATION... LLWS: As the low pressure system approaches, expect strong low- level wind shear across the TAF sites through tomorrow morning. Each site should experience shear of 40-45 kts. Smaller fields to the west, such as Malta, may see 50-55 kts of shear. Expected Flight Category: VFR-IFR Synopsis: Mid and high level VFR clouds today will give way to lower VFR to near MVFR clouds overnight as an approaching low pressure system brings chances for precipitation to the region overnight tonight through much of tomorrow. Visibility and ceilings under active precipitation may fall into MVFR or even close to near IFR range through tomorrow. Winds: Expect southwest winds of 5-15 kts today to shift to the west-northwest and increase over the TAF sites to 10-20 kts tomorrow, with gusts to 25 kts at times. Bigelbach && .GLASGOW WATCHES/WARNINGS/ADVISORIES... Wind Chill Watch from late Sunday night through Monday morning for Central and Southern Valley...Daniels...Eastern Roosevelt... Northern Phillips...Northern Valley...Sheridan...Western Roosevelt. High Wind Warning until 6 AM MST Sunday for Southwest Phillips. && weather.gov/glasgow
The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
At the Malta South US-191 DOT site, sustained winds of 40 to 50 mph were persistent between 11:48 AM and 11:45 PM. Peak wind gusts of 71 mph were recorded between 8:15 PM and 8:19 PM.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2018Every state in 2018This day in weather historyWarnings in Montana, December 2018
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: 796740.