A lee-side surface trough resided along the Rocky Mountain Front. Strengthening pressure gradient, along with 700mb cross barrier flow, supported warning criteria winds.
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.
A lee-side surface trough resided along the Rocky Mountain Front. Strengthening pressure gradient, along with 700mb cross barrier flow, supported warning criteria winds.
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 11, 11:00 AM MST, 2 hours 15 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 1100 AM MST Tue Dec 11 2018 .SYNOPSIS... Strong winds are expected over the next 36 to 48 hours across much of Southwest and North Central Montana, especially along the Rocky Mountain Front and plains west of the Interstate 15 corridor. Snow is also expected to develop along the Continental Divide and over the mountains and mountain passes of Southwest Montana. Travel could be very difficult to near impossible over Western Glacier County this afternoon and into the day on Wednesday, as strong winds and falling snow lead to blizzard conditions. && .UPDATE... Minor changes to the forecast this morning. Precipitation over the the Northern Rocky Mountain Front looks to pick up later this afternoon but the bulk of heavier snow looks to be more during the evening to overnight hours. Not expecting much in the way of precipitation over much of the Central Montana plains. && .DISCUSSION... Today through Wednesday night...primary forecast concerns are 1) accumulating mountain/mountain pass snow from this afternoon through Wednesday evening; and 2) strong winds from this morning through Wednesday (especially along the Rocky Mountain Front and over the plains of North Central Montana). Monday's fast moving open wave was already beginning to slide into the Northern High Plains as of this morning, with transitory ridging quickly building in over the Northern Rockies, while the next in a series of open waves was still well off of the Pacific Northwest coast. Lee-side surface trough was sharpening along the Rocky Mountain Front this morning, which was leading to a strengthening pressure gradient over this same area. The strengthening pressure gradient along the Rocky Mountain Front has already led to wind gusts of 50 to 60 mph in some locations, which has only helped to build confidence in the current High Wind Warning that is in place from 8am Tuesday through 11am Wednesday. As the pressure gradient strengthens further and H700 cross barrier flow reaches 50 to 70 knots, high winds with gusts to 80 mph along the immediate Rocky Mountain Front and 65 mph over the plains, are expected by late this afternoon/early this evening. A stable layer at/near ridgetops will aide further in momentum transfer to the surface from mountain wave activity. A High Wind Watch has also been issued for the plains of North Central Montana from Wednesday morning through Wednesday evening. Daytime mixing and the passage of the trough axis on Wednesday will aide in the potential for 60 mph wind gust over the plains of North Central Montana, especially in wind prone areas. The increasing H700 flow will also be responsible for transporting abundant Pacific moisture eastward into the Northern Rockies through the day on Wednesday. Orographic lift and increasing ascent from the next fast moving open wave will lead to precipitation development, in the form of snow, along the Continental Divide and over the mountains of Southwest Montana from this afternoon and through most of the day on Wednesday (precipitation has already developed in some areas along the Continental Divide this morning). Models tonight have come in with more QPF, which has led to increases in snowfall amounts along the Continental Divide and over the mountains/mountain pass of Southwest Montana. Snowfall accumulations at Marias Pass of 8-12" are now forecasted, with 1-4" at East Glacier. The combination of falling snow and the strong winds mentioned previously will lead to Blizzard condtions from this afternoon and into the day on Wednesday. Travel could be very difficult to near impossible for those traveling on United States Highway 2 from East Glacier to Marias Pass and United States Highway 89 from Kiowa to Saint Mary. Snowfall accumulations of to 3-6 inches at Big Hole Pass and 6-9 inches at Chief Joseph Pass has also led to a further westward expansion of the Winter Weather Advisory into Beaverhead County. Snowfall accumulations of 4-8" are now forecasted for elevations above 6000 feet in Madison and Gallatin Counties, which will lead to difficult travel conditions, especially in areas of blowing snow. - Moldan Thursday through Tuesday...This period will continue the progressive weather pattern, but the passing disturbances will mainly bring precipitation to the mountains and winds to the plains. A high pressure ridge will build over the western United States Thursday into Thursday night with a low pressure trough lingering over northern Canada. The resulting strong and moist westerly flow aloft will bring snow and blowing snow to the mountains, but lower elevations will remain dry. Strong southwest winds will persist over the plains through this time, especially along the Rocky Mountain Front, where potential wind gusts in excess of 70 mph at times could warrant high wind highlights. Winds will decrease somewhat on Friday, as the low pressure trough moves east of the area and the high pressure ridge continues to build north into the area. This should also keep temperatures 10 to 15 degrees above normal, so have gone about 5 to 10 degrees warmer than consensus guidance. A fast- moving low pressure trough from the Pacific Ocean will move through the area Friday night into early Saturday, which will continue breezy winds over the plains, bring a quick shot of light snow to the mountains, and cool temperatures a bit closer to normal. Another high pressure ridge will move over the area Saturday afternoon through Sunday, keeping the area dry with slightly above normal temperatures. A weak shortwave trough will then move over the area Monday into Tuesday, bringing another chance for snow to the mountains, but continuing the mild temperatures elsewhere. - Coulston && .AVIATION... Updated 1800Z. VFR conditions expected throughout the most of the TAF period, but ceilings will begin to lower from the west after 00Z as the next upper level disturbance approaches the Northern Rockies. There will be a chance for some scattered snow over Southwest Montana after 12Z. Mountain obscuration is likely across Southwest Montana and along the Continental Divide for much of the TAF period. Westerly winds will increase substantially over the plains of North Central Montana with mountain wave turbulence immediately downwind of the Continental Divide. Low level wind shear will be a concern. && .PRELIMINARY POINT TEMPS/POPS... GTF 45 34 42 26 / 10 10 20 0 CTB 42 31 39 24 / 10 10 20 0 HLN 43 28 42 20 / 10 10 10 0 BZN 36 25 40 13 / 10 20 30 0 WEY 22 14 25 -1 / 30 100 100 0 DLN 35 22 33 8 / 10 30 30 0 HVR 40 32 42 22 / 0 30 50 0 LWT 40 30 38 22 / 0 10 40 10 && .TFX WATCHES/WARNINGS/ADVISORIES... High Wind Watch from Wednesday morning through Wednesday afternoon Blaine...Cascade...Chouteau...Eastern Pondera... Eastern Teton...Fergus...Hill...Judith Basin...Liberty...Toole. Winter Weather Advisory from 8 PM this evening to 5 PM MST Wednesday Beaverhead. Winter Weather Advisory from 11 PM this evening to 5 PM MST Wednesday Gallatin...Madison. High Wind Warning from 8 AM this morning to 11 AM MST Wednesday Eastern Glacier...Northern Rocky Mountain Front...Southern Rocky Mountain Front. Blizzard Warning from 2 PM this afternoon to 11 AM MST Wednesday Northern Rocky Mountain Front. && http://www.weather.gov/greatfalls
7 high wind. Local standard time, as filed.
MDT Road Report @mdtroadreport.|Overturned trailer on US-2 just east of Browning at milepost 223.0 roadreport.mdt.mt.gov.|1:15pm 11 Dec 2018 MDT Road Report.
MDT Road Report @mdtroadreport.|Overturned semi in ditch on US-89 near Spring Hill on US-89 S at milepost 107.0 roadreport.mdt.mt.gov 2:00pm 11 Dec 2018 MDT Road Report.
Wind gust of 71 MPH measured at mesonet station mtbwg Browning.
Wind gust 67 mph mesonet 18 SW Augusta.
Wind gust 61 mph measured at mesonet 2 SW Cameron.
Wind Gust 58 mph measured at mesonet 2 E Black Eagle.
Wind gust of 58 mph measured at mesonet 7 ESE Hilger.
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: 796725, 796737, 790772, 797089, 797090, 797088, 797091.