A Pacific cold front swept eastward through north-central Montana during the afternoon and evening of 9 June 2018. This front encountered a warm, relatively-humid, and unstable air mass amidst moderate to strong vertical wind shear.
Every event with a place to put it. 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 TFX wrote it up.
A Pacific cold front swept eastward through north-central Montana during the afternoon and evening of 9 June 2018. This front encountered a warm, relatively-humid, and unstable air mass amidst moderate to strong vertical wind shear. Accordingly, scattered showers and thunderstorms, including supercells, developed. Some of these storms became severe.
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 Jun 9, 2:01 PM MST, 1 hour 29 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 301 PM MDT Sat Jun 9 2018 .SYNOPSIS... A cold front will move through the region tonight, producing showers and thunderstorms. Some storms could be severe early this evening. Much colder temperatures will move into the region by Sunday morning, with snow possible over the higher elevations of Southwest MT and the Rocky Mountain Front. Generally dry conditions are expected over the Plains for Sunday afternoon through Monday, but afternoon highs will be well below normal, generally in the 50s and 60s. && .DISCUSSION... Tonight through Sunday...A strong Pacific cold front is moving into western Montana. This front will move eastward through the region tonight. Expect showers and thunderstorms along the front. Some storms will be severe over portions of Central/North Central MT, mainly before 9 PM this evening. The airmass is more unstable as you go east, but no lift at the moment to trigger any storms in the Lewistown area. That could change later this evening. As colder air moves into the region tonight, the rain will change to snow, mainly for elevations above 6000 feet. A winter weather advisory was issued for the higher elevations for those recreating that might be unprepared for cold/snow. Temperatures will be below normal on Sunday along with gusty west winds. Wind speeds should remain below warning criteria. For Monday through Wednesday, expect a few showers to exit the region on Monday, as temperatures climb back above seasonal normals by Wednesday. Generally dry/quiet conditions expected on Tue into Wed. Wed night through Saturday...Another upper level trof will move through the region, producing a chance for showers/thunderstorms. Some models indicate isolated areas of heavy rainfall on Thursday. Temperatures will cool to near normal by the end of the week. Brusda && .AVIATION... UPDATED 1530Z. VFR conditions early this afternoon will give way to a strong cold frontal passage this evening along with lowering ceilings. Rain/thunderstorms...some severe expected with the frontal passage. Expect rain to change to snow over the mountains. IFR conditions are possible in areas of precipitation. Mountains/passes will become obscured at times after 00z Sun. Brusda && .PRELIMINARY POINT TEMPS/POPS... GTF 48 61 41 61 / 80 70 30 20 CTB 44 58 39 58 / 100 40 30 20 HLN 48 59 39 61 / 90 50 30 20 BZN 45 61 35 59 / 50 70 40 20 WEY 38 54 27 53 / 10 30 30 20 DLN 41 55 32 57 / 70 40 30 20 HVR 52 69 43 64 / 40 30 10 20 LWT 48 64 38 58 / 30 20 10 20 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 3 AM to 10 AM MDT Sunday above 6000 feet for Beaverhead...Central and Southern Lewis and Clark... Gallatin...Jefferson...Madison...Northern Rocky Mountain Front... Southern Rocky Mountain Front. && http://www.weather.gov/greatfalls
Special Weather Statement
National Weather Service Great Falls MT
313 PM MDT SAT JUN 9 2018
MTZ010-044-092130-
Eastern Glacier-Toole-
313 PM MDT SAT JUN 9 2018
...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN GLACIER AND
NORTHWESTERN TOOLE COUNTIES...
At 313 PM MDT, a strong thunderstorm was located 22 miles west of
Sunburst, or 23 miles north of Cut Bank, moving northwest at 40 mph.
Wind gusts of 50 to 55 mph and nickel size hail are possible with
this storm.
This storm will remain over mainly rural areas of northeastern
Eastern Glacier and northwestern Toole Counties.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
LAT...LON 4894 11213 4888 11247 4899 11258 4900 11256
4900 11218
TIME...MOT...LOC 2113Z 155DEG 35KT 4897 11239
KJSpecial Weather Statement National Weather Service Great Falls MT 321 PM MDT SAT JUN 9 2018 MTZ009-010-092145- Northern Rocky Mountain Front MT-Eastern Glacier MT- 321 PM MDT SAT JUN 9 2018 ...SIGNIFICANT WEATHER ADVISORY FOR EASTERN GLACIER COUNTY UNTIL 345 PM MDT... At 320 PM MDT, Doppler radar was tracking a strong thunderstorm 8 miles east of South Browning, or 24 miles west of Cut Bank, moving north at 50 mph. Half inch hail and wind gusts up to 50 mph will be possible with this storm. Locations impacted include... Browning, North Browning and South Browning. PRECAUTIONARY/PREPAREDNESS ACTIONS... Frequent cloud to ground lightning is occurring with this storm. Lightning can strike 10 miles away from a thunderstorm. Seek a safe shelter inside a building or vehicle. && A Severe Thunderstorm Watch remains in effect until 900 PM MDT for north central Montana. LAT...LON 4900 11246 4832 11263 4832 11299 4900 11323 TIME...MOT...LOC 2120Z 166DEG 41KT 4851 11283 KJ
Special Weather Statement National Weather Service Great Falls MT 331 PM MDT SAT JUN 9 2018 MTZ048-092145- Southern Rocky Mountain Front- 331 PM MDT SAT JUN 9 2018 ...A STRONG THUNDERSTORM WILL AFFECT NORTH CENTRAL LEWIS AND CLARK AND SOUTHWESTERN TETON COUNTIES... At 331 PM MDT, a strong thunderstorm was located 17 miles northwest of Augusta, or 20 miles west of Choteau, moving northeast at 35 mph. Wind gusts up to 50 mph and half inch hail are possible with this storm. Locations impacted include... Pishkun Reservoir. Frequent cloud to ground lightning is occurring with this storm. Lightning can strike 10 miles away from a thunderstorm. Seek a safe shelter inside a building or vehicle. LAT...LON 4759 11253 4768 11276 4797 11261 4784 11225 TIME...MOT...LOC 2131Z 208DEG 32KT 4771 11260 Coulston
Special Weather Statement National Weather Service Great Falls MT 358 PM MDT SAT JUN 9 2018 MTZ009-046-048-092230- Southern Rocky Mountain Front-Northern Rocky Mountain Front-Eastern Pondera- 358 PM MDT SAT JUN 9 2018 ...A STRONG THUNDERSTORM WILL AFFECT CENTRAL PONDERA AND NORTH CENTRAL TETON COUNTIES... At 357 PM MDT, a strong thunderstorm was located 14 miles southwest of Valier, or 22 miles west of Conrad, moving northeast at 40 mph. Wind gusts up to 50 mph and pea size hail are possible with this storm. Locations impacted include... Valier, Pendroy and Dupuyer. This includes the following highways... Interstate 15 between mile markers 345 and 348. Highway 89 between mile markers 59 and 79. Frequent cloud to ground lightning is occurring with this storm. Lightning can strike 10 miles away from a thunderstorm. Seek a safe shelter inside a building or vehicle. This storm may intensify, so be certain to monitor local radio stations and available television stations for additional information and possible warnings from the National Weather Service. LAT...LON 4828 11188 4798 11240 4813 11266 4849 11225 TIME...MOT...LOC 2157Z 221DEG 33KT 4813 11244 Coulston
Special Weather Statement National Weather Service Great Falls MT 409 PM MDT SAT JUN 9 2018 MTZ010-044-092230- Eastern Glacier-Toole- 409 PM MDT SAT JUN 9 2018 ...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NORTHEASTERN GLACIER AND NORTHWESTERN TOOLE COUNTIES... At 409 PM MDT, radar indicated strong thunderstorms were located along a line extending from 23 miles northwest of Cut Bank to near Kevin. Movement was northeast at 50 mph. Wind gusts up to 50 mph, brief heavy rain, and pea size hail are possible with these storms. Locations impacted include... Sunburst, Kevin, Sweet Grass, Oilmont and Santa Rita. This includes Interstate 15 between mile markers 378 and 397. Frequent cloud to ground lightning is occurring with this storm. Lightning can strike 10 miles away from a thunderstorm. Seek a safe shelter inside a building or vehicle. LAT...LON 4900 11151 4865 11195 4885 11278 4900 11268 TIME...MOT...LOC 2209Z 214DEG 43KT 4894 11259 4881 11196 Coulston
Special Weather Statement
National Weather Service Great Falls MT
429 PM MDT SAT JUN 9 2018
MTZ044-092245-
Toole MT-
429 PM MDT SAT JUN 9 2018
...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN TOOLE COUNTY UNTIL
445 PM MDT...
At 429 PM MDT, Doppler radar was tracking a strong thunderstorm 7
miles west of Sunburst, or 21 miles northeast of Cut Bank, moving
northeast at 35 mph.
Half inch hail and wind gusts up to 50 mph will be possible with this
storm.
Locations impacted include...
Sweet Grass.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
&&
A Severe Thunderstorm Watch remains in effect until 900 PM MDT for
north central Montana.
LAT...LON 4900 11181 4888 11195 4891 11211 4894 11216
4900 11215
TIME...MOT...LOC 2229Z 205DEG 32KT 4890 11207
KJThe Great Falls radar (KTFX), 172 km away, was scanning. The volume nearest the first event began at 22:31 UTC.
1 thunderstorm wind, 1 hail. Local standard time, as filed.
MT DOT sensor 6-miles NNW of Sunburst reported 62-mph peak gust from thunderstorm.
Spotter reported ping pong ball-size hail 2-miles NW of Benchland.
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, June 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: 750848, 750849.