Northwesterly flow aloft persisted over North-Central Montana during the late morning of February 15th through morning of the 16th. Within this flow, a disturbance at 700 mb traversed North-Central Montana during late evening of the 15th and early morning of the 16th.
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.
Northwesterly flow aloft persisted over North-Central Montana during the late morning of February 15th through morning of the 16th. Within this flow, a disturbance at 700 mb traversed North-Central Montana during late evening of the 15th and early morning of the 16th. This disturbance caused the 700 mb flow to become more westerly and strengthen across the Rocky Mountain Front. In response, a surface trough east of the Rocky Mountain Front strengthened. This caused the surface pressure gradient to tighten, which in turn allowed westerly winds to intensify along the Rocky Mountain Front. These strong winds, combined with a loose snow pack, led to a blizzard along the Northern Rocky Mountain Front.
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 Feb 15, 7:55 PM MST, 45 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 755 PM MST Thu Feb 15 2018 .SYNOPSIS... Winds will begin to increase along the Rocky Mountain Front this evening, overspreading the remainder of the plains overnight. Strong winds along the northern Rocky Mountain Front will result in blowing and drifting snow with blizzard conditions along and west of highway 89. Drifting snow will impact the rest north central Montana as winds increase. Temperatures will slowly rise into the teens though the night in the plains. Lows will fall into the single digits and teens over the valleys. && .EVENING UPDATE... Latest surface analysis and observations indicate the stronger winds remain confined right along the Rocky Mtn Front at this hour. With time, though, we still expect a tightening pressure gradient to allow stronger winds to develop further out over the plains. Until that time, though, mostly clear skies and a good snowpack are allowing temps to fall faster than originally forecast in several areas, especially Cut Bank to Great Falls to Lewistown. For this evening, then, the main change was to lower temps this evening before the increasing wind allows rising temps the remainder of the night. Along the Rocky Mtn Front, winds have been a bit slower to increase and webcams in the area suggest significant blowing/drifting of snow has yet to begin. However, an increasing trend has been noted in wind gusts in this area and more widespread blowing/drifting should begin shortly. For now, we will leave the Blizzard Warning as is, but will closely monitor conditions through the night to determine if any changes are needed. Elsewhere, the Winter Weather Advisory for snow and blowing snow still looks good. The greatest impacts from blowing/drifting snow will likely be where the heaviest fresh snow fell yesterday/last night. Of note, blowing/drifting may hold off until a bit later overnight or even until Friday morning. Even so, we'll keep the current start times as is. MARTIN && .AVIATION... Updated 2350Z. System that brought snowfall to the region earlier today has moved out of Montana leaving mostly clear skies and VFR conditions. However, the next system will begin to send mid- and high-level clouds over the forecast area this evening with cloud heights lowering after 12Z as areas of light snow and mountain obscurations develop from west to east. Also, westerly surface winds will increase overnight producing areas of blowing and drifting snow along with low level wind shear and turbulence aloft. mpj && .PREV DISCUSSION... /ISSUED 450 PM MST Thu Feb 15 2018/ An active weather pattern will continue across the region though the weekend resulting in several periods of impactful weather. Tonight though Friday night... The cold airmass will begin to retreat to the east tonight as a trough of low pressure forms along the lee side of the northern Rockies. This will result in increasing winds starting over the Rocky Mountain Front this evening and spreading east into the plains through the overnight hours. These winds will result in widespread blowing and drifting snow over north central Montana with blizzard conditions along and west highway 89 from the Heart Butte area up to Browning and Babb. Across the remainder of north central Montana restricted visibilities are possible but the biggest impacts will be from snow drifting across roadways. A cold front will sweep though the area Friday evening with winds shifting north and gradually decreasing. Heavy snow will impact the higher elevations of the Rocky Mountain Front with several inches of snowfall expected. Over the plains and valleys a brief band of moderate to heavy snow will be possible with the passage of the cold front resulting in quick snow accumulations of 1 or 2 inches. Saturday though Sunday morning... Pacific moisture will begin to overrun the cold airmass resulting in the development of moderate to heavy snow over north central Montana on Saturday afternoon. An arctic cold front will push south into the area Saturday night bringing additional moderate to heavy snowfall. Heavy snow accumulations approaching a foot are possible in a band over north central Montana. Models solutions diverge with the placement of the heaviest snowfall. Took a blended approach to the snow totals, which is heavily based on the National Blend model output. Forecast snowfall totals will likely change as the event nears. Sunday afternoon though Monday... Widespread light snow is likely but the main impacts will be from dangerously cold wind chills falling into the 20s and 30s below zero over north central Montana. Southwest Montana will likely remain warmer until Sunday night when the arctic airmass works its way southward. Monday night though Thursday... After a very cold start to the day on Tuesday temperatures will slowly moderate though the week but remain below average for most locations. A few periods of light snow will be possibly though the late week. Langlieb && .PRELIMINARY POINT TEMPS/POPS... GTF -6 35 11 28 / 10 60 80 70 CTB 1 32 5 19 / 10 60 80 70 HLN 9 32 16 33 / 0 50 70 70 BZN 6 29 15 34 / 0 60 90 60 WEY 8 26 12 28 / 20 90 80 70 DLN 13 29 18 37 / 10 40 50 40 HVR -3 30 5 18 / 0 50 30 50 LWT 0 29 10 28 / 0 60 80 60 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 11 PM this evening to 5 AM MST Saturday Blaine...Chouteau...Fergus...Hill...Liberty. Winter Weather Advisory until 5 AM MST Saturday Cascade...Judith Basin...Meagher. Blizzard Warning until 6 AM MST Friday Northern Rocky Mountain Front. Winter Weather Advisory until 5 AM MST Saturday Central and Southern Lewis and Clark...Eastern Glacier...Eastern Pondera... Eastern Teton...Southern Rocky Mountain Front...Toole. Winter Weather Advisory from 6 AM Friday to 5 AM MST Saturday Northern Rocky Mountain Front. && http://www.weather.gov/greatfalls
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
317 PM MST THU FEB 15 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0317 PM SNOW 1 N HELENA 46.61N 112.02W
02/15/2018 E2.3 INCH LEWIS AND CLARK MT PUBLIC
&&
JAA1 blizzard. Local standard time, as filed.
Montana DOT reported severe driving conditions on US-2 from East Glacier to Browning and along US-89 from Two Medicine Creek to Browning. These severe driving conditions stemmed from significant blowing and drifting snow.
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, February 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: 735868.