An elevated thunderstorm developed over the city of Great Falls just after midnight on the 18th of August. It quickly became severe by dropping large hail across the city.
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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.
An elevated thunderstorm developed over the city of Great Falls just after midnight on the 18th of August. It quickly became severe by dropping large hail across the city. Numerous reports of damaged vehicles were reported along with some damage to structures.
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 Aug 17, 10:59 PM MST, 33 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 1159 PM MDT WED AUG 17 2016 Aviation Section Updated .UPDATE... Upper level low over N-central Canada with trough extending SW towards the Nrn Rockies this evening with additional embedded shortwave and upper level jet energy upstream in central AB and NE BC. To the south, elevated subtropical moisture is pushing into SW MT ahead of a shortwave spinning over SE ID. Showers and a few thunderstorms will continue to diminish in coverage over SW MT this evening with dry low level air leading to little precipitation but locally gusty winds. To the north, An axis of elevated instability and pooled low level moisture in upslope flow continues to exist behind the frontal boundary across N-central MT. Thunderstorms thus far have been confined to areas along the Rocky Mtn Front/Glacier Park region with this activity decreasing in intensity. However, with additional incoming upper level support we may continue to see isolated to scattered showers and thunderstorms across n-central MT tonight. Hoenisch && .AVIATION... UPDATED 0559Z. Scattered showers/thunderstorms will affect the region through 21z on Thu. Then an area of steady rain will move southward from Canada into North Central MT after 23z Thu and continue to affect Central MT through 06z Fri. Expect ceilings to gradually lower through the period with IFR conditions developing. Some LIFR conditions are possible near mountains with mountains becoming obscured through the period. Brusda && .PREV DISCUSSION... /ISSUED 555 PM MDT WED AUG 17 2016/ Tonight through Friday...The initial surface front has moved through central Montana as it continues its journey south. Winds have generally shifted to the north. Moisture associated with the upper trof moving across southern Canada is approaching the international boundary. The airmass across northern Montana remains unstable and isolated thunderstorms are possible late this afternoon into evening. Additionally, satellite imagery indicates moisture is also moving into southern Montana and isolated convective activity is also possible there this evening. A stronger push of cooler air will cross the Canadian border and push south into central Montana after midnight tonight. North winds behind this secondary front will be breezy at times. Showers and isolated thunderstorms will develop behind the front and become widespread across the area Thursday as the trof moves through. Enough cooler air will accompany the front to lower snow levels to around 7000 feet allowing for light snow to fall on the higher peaks of Glacier National Park and over King's Hill. Showers will continue Friday morning but precipitation will decrease from the north and west by afternoon. Temperatures will remain well below seasonal averages through the period. Friday night through Wednesday...The main upper level low from earlier in the week will be pulling away from the region by Friday night...with a northwesterly flow aloft resulting in its wake through Saturday. An upper level ridge will then start to rebuild over the region from Sunday through Tuesday, resulting in warmer air moving back into the region. Additionally, mostly dry conditions are expected across the area during this time. By Wednesday, both the GFS/EC hint at another upper level trof and Canadian cold front to move southward into North Central MT. I have put in some low pops from late Tuesday night through Wednesday, but mainly over North Central MT. In terms of temperatures, expect rebounding temperatures on Saturday, with above normal temperatures from Sun through Tue. By Wednesday, cooler temperatures start to move back into the region with the passage of the upper level trof. Brusda/Coulston && .PRELIMINARY POINT TEMPS/POPS... GTF 55 63 43 69 / 30 90 90 40 CTB 53 59 44 70 / 50 80 80 30 HLN 60 68 50 70 / 20 90 80 50 BZN 58 74 48 69 / 20 70 70 60 WEY 48 72 38 60 / 30 40 50 30 DLN 56 76 47 69 / 20 50 50 40 HVR 57 65 49 71 / 30 80 80 30 LWT 55 65 45 66 / 10 80 90 70 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && weather.gov/greatfalls
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREAT FALLS MT
915 PM MDT WED AUG 17 2016
MTZ009-180415-
NORTHERN ROCKY MOUNTAIN FRONT MT-
915 PM MDT WED AUG 17 2016
...SIGNIFICANT WEATHER ADVISORY FOR WESTERN GLACIER COUNTY UNTIL 1015
PM MDT...
AT 911 PM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 20
MILES NORTHWEST OF KIOWA...OR 5 MILES NORTHWEST OF
SAINT MARY...MOVING SOUTHEAST AT 20 MPH.
DIME SIZE HAIL AND WINDS IN EXCESS OF 30 MPH WILL BE POSSIBLE WITH
THIS STORM IN ADDITION TO VERY HEAVY RAINFALL AND FREQUENT LIGHTNING.
LOCATIONS IMPACTED INCLUDE...
KIOWA...BABB...STARR SCHOOL...LOGAN PASS...
SAINT MARY AND MANY GLACIER.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
HEAVY RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD TO
LOCALIZED FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.
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.
PERSONS IN CAMPGROUNDS SHOULD CONSIDER SEEKING STURDY SHELTER UNTIL
THIS STORM PASSES.
&&
LAT...LON 4863 11297 4841 11340 4846 11348 4856 11348
4859 11354 4858 11361 4860 11364 4859 11369
4862 11376 4869 11374 4870 11371 4877 11375
4894 11350
TIME...MOT...LOC 0311Z 309DEG 17KT 4877 11354
HOENISCHSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREAT FALLS MT 1202 AM MDT THU AUG 18 2016 MTZ012-048-049-180645- SOUTHERN ROCKY MOUNTAIN FRONT MT-CASCADE MT-EASTERN TETON MT- 1202 AM MDT THU AUG 18 2016 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN CASCADE... SOUTHEASTERN TETON AND CENTRAL LEWIS AND CLARK COUNTIES UNTIL 1245 AM MDT... AT 1201 AM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 13 MILES SOUTHWEST OF FORT SHAW...OR 18 MILES NORTHWEST OF CASCADE... MOVING EAST AT 10 MPH. ANOTHER STORM WAS LOCATED 10 MILES WEST OF SIMMS, ALSO MOVING EAST AT 10 MPH. DIME TO NICKEL SIZE HAIL AND WIND GUSTS UP TO 40 MPH WILL BE POSSIBLE WITH THESE STORMS. LOCATIONS IMPACTED INCLUDE... FORT SHAW...FORT SHAW...SUN RIVER AND SIMMS. LAT...LON 4736 11211 4753 11211 4757 11172 4730 11172 TIME...MOT...LOC 0601Z 291DEG 8KT 4739 11204 KJ
The Great Falls radar (KTFX), 9 km away, was scanning. The volume nearest the first event began at 06:30 UTC.
2 hail. Local standard time, as filed.
A thunderstorm dropped 1.5 inch diameter hail at Great Falls. Also, 1 inch and 1.25 inch hail was reported at Great Falls and at Tracy 4NE. Numerous reports of damaged vehicles were received by law enforcement and some damage to structures was reported.
A thunderstorm dropped 1 inch diameter hail at Belt 10WNW and at Belt 7NW.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2016Every state in 2016This day in weather historyWarnings in Montana, August 2016
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: 643893, 643894.