Satellite imagery reveals a strong upper level jet. A region of strong flow aloft moves eastward into the region, causing widespread strong winds across much of central MT.
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 TFX wrote it up.
Satellite imagery reveals a strong upper level jet. A region of strong flow aloft moves eastward into the region, causing widespread strong winds across much of central MT. Strong wind gusts develop along the immediate east slopes of the Rocky Mtn front as the initial surge of strong west flow aloft arrives in combination with favorable temperature/wind profiles for Mtn Wave/downslope wind enhancement. Strong west flow aloft overspreads much of north-central MT with gusts peaking during the evening hours. Strongest winds for eastern and southern portions of central MT most likely to occur with the passage of the associated Pacific surface cold front/trough during the evening time frame.
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 Great Falls, MT wrote its last area forecast discussion before the first event at Dec 18, 4:47 AM MST, 1 hour 35 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 447 AM MST Tue Dec 18 2018 .SYNOPSIS... A strong Pacific storm system will move into the northern Rockies and Montana today, bringing strong winds to most of central Montana east of the Continental Divide by this afternoon, spreading into south- central portions of the State on Wednesday. Rain and mountain snow, which may be heavy at times, will develop over areas along and west of the continental divide today while areas of snow develop over adjacent portions of southwest Montana later today and tonight. && .DISCUSSION... Satellite imagery this morning reveals a strong upper level jet and moisture plume moving into WA/OR south of a vigorous/stacked low moving toward the AK panhandle. Little change in the overall impacts expected as this moisture and region of strong flow aloft moves east into the region later today and tonight, bringing widespread strong winds to much of central MT and heavy snow accumulations to areas along the Continental divide with winds and mountain snow decreasing late Wednesday as an upper level ridge rebuilds along the West coast. Strong wind gusts are developing early this morning along the immediate east slopes of the Rocky Mtn front as the initial surge of strong west flow aloft arrives in combination with favorable temperature/wind profiles for Mtn Wave/downslope wind enhancement. Strong west flow aloft will overspread much of north-central MT this afternoon, with gusts peaking this evening. Strongest winds for eastern and southern portions of central MT are most likely to occur with the passage of the associated Pacific surface cold front/trough this evening. Very windy conditions are likely to continue into Wednesday morning for many areas with winds gradually diminishing Wednesday afternoon. Snow will increase across areas along the continental divide west of the Rocky Mtn Front this morning then spread across the higher elevations of SW MT near the ID border this afternoon. Downslope drying will likely keep lower elevations dry through this afternoon but snow showers will become more widespread across SW MT and southern portions of central MT tonight as stability decreases with incoming colder air aloft behind the front. Heaviest snow accumulation and winter weather impacts are expected near MArias pass today and tonight where a winter weather advisory is in place. Several inches of snow accumulation is also possible across the Mtns of SW MT tonight from multiple rounds of snow showers. Hoenisch Wednesday night through Tuesday...The progressive pattern that we have been in for the past or so looks to continue through the early part of next week. The ongoing pattern of shortwave troughs followed by shortwave ridges will continue to shift the weather regimes from wet and windy weather, mild and dry weather. The focus for impactful weather remains on the passage of shortwave troughs Thursday night into Friday, Sunday morning into Monday morning, and again on Tuesday. The initial trough Thursday night into Friday looks to bring another round of gusty winds and mountain snowfall to the area, especially along the Rocky Mountain Front. The next system currently looks weaker in the models with regards to precipitation along the mountains and gusty winds. The final system on Tuesday looks to be the weakest with regards to the winds, but has more precipitation making it over The Divide as there should be less downsloping effect with the weaker cross- barrier flow. However, confidence at this time is lower with regards to the second and third systems from Sunday into Tuesday, due to these scenarios being further out in the forecast period and current discrepancies between the different model runs during this timeframe. -TP && .AVIATION... Updated 1200z. Snow and mountain obscuration will increase this morning along the continental divide as moisture increases while very windy conditions already developing along the immediate east slopes of the Rockies spread east into central MT late this morning and afternoon and continue through this evening. Mountain wave turbulence and low level wind sheer are expected at many central and north-central Montana terminals this afternoon and evening, likely extending into SW MT terminals including KBZN and KEKS tonight. Local MVFR conditions are possible at KBZN and KEKS as well tonight as snow showers move across SW MT. Hoenisch && .PRELIMINARY POINT TEMPS/POPS... GTF 55 36 47 30 / 10 20 0 0 CTB 50 34 44 28 / 10 30 0 0 HLN 47 33 45 25 / 30 60 0 0 BZN 45 28 43 20 / 20 60 10 0 WEY 32 17 31 11 / 80 90 40 0 DLN 41 26 39 18 / 30 50 0 0 HVR 51 35 47 26 / 10 10 10 0 LWT 51 33 43 25 / 0 10 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... High Wind Warning from 11 AM this morning to 5 PM MST Wednesday Broadwater...Cascade...Central and Southern Lewis and Clark... Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton... Fergus...Jefferson...Judith Basin...Liberty...Meagher...Toole. Winter Weather Advisory until 8 AM MST Wednesday above 5000 feet for Northern Rocky Mountain Front...Southern Rocky Mountain Front. High Wind Warning from 5 PM this afternoon to 8 AM MST Wednesday Blaine...Hill. High Wind Warning until 5 PM MST Wednesday Northern Rocky Mountain Front...Southern Rocky Mountain Front. && http://www.weather.gov/greatfalls
5 high wind. Local standard time, as filed.
High wind gust of 65 mph measured at mesonet station mtbrn, two medicine bridge mdt.
High wind gust of 73 mph measured at mesonet 14 W Bynum.
High winds gust of 67 mph reported by the public 3 S Stanford.
High wind gust of 62 mph measured at mesonet station mtsun, sunburst mdt.
High wind gust of 71 mph measured at mesonet station jpkm8, judith peak raws.
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: 797101, 796814, 797100, 797102, 797099.