Moderate to strong instability and favorable winds allowed severe thunderstorms to develop and push a severe squall line through portions of northeast Montana.
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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 GGW wrote it up.
Moderate to strong instability and favorable winds allowed severe thunderstorms to develop and push a severe squall line through portions of northeast Montana.
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 Glasgow, MT wrote its last area forecast discussion before the first event at Jun 18, 2:36 PM MST, 3 hours 14 minutes earlier.
Area Forecast Discussion National Weather Service GLASGOW MT 336 PM MDT SAT JUN 18 2016 .SHORT TERM...for northeast Montana...tonight through Mon... Strong shortwave lifting out of the Pacific Northwest this afternoon with convection developing in central Montana. Severe thunderstorm watch has been issued for most of northern Montana for late this afternoon and evening. May need to extend it late tonight for the northeast zones as storms will be later arriving. Convection developing along a cold front that will sweep across the state overnight. Along with the severe thunderstorm potential, strong post frontal winds are also possible with 700mb winds of 40-50 knots. These winds continue through Sunday afternoon so have issued a lake wind advisory for late tonight through Sunday evening. Shortwave trof moves quickly through southern Saskatchewan and Manitoba on Sunday with upper ridge beginning to develop into the northern Rockies. Canadian high pressure slides into the northern plains Sunday night for diminished winds into Monday. Ebert .LONG TERM...Mon night through Sat... General forecast thinking remains roughly the same, with a little bit less confidence as models have now begun to introduce a few rain showers and thunderstorms under the ridge of high pressure. In fact, new model data today brings through a quick low pressure trough to interrupt the ridge Tuesday and Wednesday. I chose to increase PoPs accordingly, following the best model consensus for precip I could find. Thursday and Friday remains in much better confidence for dry and hot conditions under the ridge. After Friday, the normal model discrepancies show up regarding the next storm system from the west. BMickelson Previous long term discussion: The overall pattern aloft over CONUS will be a broad high across the Southwest and ridge axis up through the spine of the Northern Rockies, a trough nudged up against the Northwest Coast, and a larger trough centered across Hudson Bay. The pattern will create a northwest flow for Northeast Montana Monday night. Nemont will initially be located near the boundary between the cool air mass to the northeast and the warm air mass to the southwest. The ridge axis will shift east over the local region allowing the hot air mass to surge north into Montana. Temperatures will quickly rise from the 70s Monday into the 80s Tuesday. A rise to summer temperatures will coincide with the solstice. Wednesday temperatures will rise higher, into the upper 80s. Beyond the middle of the week the forecast become a bit more murky. This uncertainty is based on the location of the western trough. The EC sends it north into BC, while the GFS lingers longer before moving into BC. By the beginning of the weekend the models are out of phase. The effect will be to make it difficult to determine when the associated front moves into Northeast Montana. The fluctuating boundary, along with the instability in place, will likely be able to produce periods of showers with thunder. Templer && .AVIATION... Surface low pressure is now deepening over central Montana and thunderstorms have begun to develop and mature over those higher elevations. Latest model guidance brings these storms through northeast Montana later this afternoon and evening. The Storm Prediction Center continues its Convective Outlook for slight and enhanced chances for severe thunderstorms across portions of the area. When supercell thunderstorms develop, they would mainly threaten KGGW, KOLF and KSDY and locations north with very large hail and very damaging winds. Expect VFR conditions to prevail this afternoon, then lowering ceilings with storms by this evening. Severe thunderstorms with very damaging winds and large hail are possible after 23Z especially for KGGW and KOLF. TAF amendments are likely amid possible temporary VLIFR conditions due to these severe thunderstorms. Winds from the east and southeast today ahead of the front will bring ample warm moist air into the storm environment. A sudden wind shift and cold front from the northwest later this afternoon will be the main focus for storm development. Highly erratic and gusty winds of 40 to 60 mph are expected near the stronger storms. Templer/Mickelson && .GLASGOW WATCHES/WARNINGS/ADVISORIES... Lake Wind Advisory from midnight tonight to 9 PM MDT Sunday For Fort Peck Lake for Central and Southeast Phillips...Central and Southern Valley...Garfield...McCone...Petroleum. && weather.gov/glasgow
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GLASGOW MT 337 AM MDT SAT JUN 18 2016 MTZ016>024-059>062-190945- CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY- DANIELS-SHERIDAN-WESTERN ROOSEVELT-PETROLEUM-GARFIELD-MCCONE- RICHLAND-NORTHERN PHILLIPS-SOUTHWEST PHILLIPS-NORTHERN VALLEY- EASTERN ROOSEVELT- 337 AM MDT SAT JUN 18 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS WILL DEVELOP IN THE LATE AFTERNOON OR EARLY EVENING ACROSS THE AREA IN AREAS ALONG AND NORTH OF THE MISSOURI RIVER. THE STORMS WILL CONTINUE FOR MOST OF TONIGHT. SOME SEVERE STORMS WITH LARGE HAIL AND DAMAGING WINDS ARE LIKELY. LOCALLY HEAVY RAIN IS ALSO POSSIBLE. THE BEST CHANCES FOR THUNDERSTORMS WILL BE ALONG THE CANADIAN BORDER. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER TODAY AND TONIGHT IS LOW. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY A COLD FRONT WILL MOVE THROUGH NORTHEAST MONTANA LATE TONIGHT. STRONG WEST WINDS OF 20 TO 30 MPH WITH GUSTS UP TO 45 MPH WILL DEVELOP ACROSS THE AREA SUNDAY MORNING AND CONTINUE THROUGH SUNDAY EVENING BEFORE DIMINISHING. A LAKE WIND ADVISORY IS LIKELY FOR FORT PECK LAKE. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. MTZ025>027-190945- DAWSON-PRAIRIE-WIBAUX- 337 AM MDT SAT JUN 18 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...TODAY AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY A COLD FRONT WILL MOVE THROUGH NORTHEAST MONTANA LATE TONIGHT. STRONG WEST WINDS OF 20 TO 30 MPH WITH GUSTS UP TO 45 MPH WILL DEVELOP ACROSS THE AREA SUNDAY MORNING AND CONTINUE THROUGH SUNDAY EVENING BEFORE DIMINISHING. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Glasgow radar (KGGW), 122 km away, was scanning. The volume nearest the first event began at 00:50 UTC.
22 thunderstorm wind, 18 hail. Local standard time, as filed.
Trained spotter reported tree limbs up to 6 inches in diameter downed by strong winds.
Trained spotter estimated wind gusts up to 60 mph.
Trained spotter reported ping pong ball sized hail.
Trained spotter reported 70 mph wind gusts.
Storm chaser reported quarter sized hail along with damaging winds and zero visibility. Time estimated by radar.
Storm chaser reported 70 mph wind gusts along with large hail and zero visibility. Time estimated by radar.
Public reported hen egg sized hail.
Trained spotter reported tree limbs up to 5 inches in diameter downed by strong winds.
Trained spotter reported a semi-trailer toppled over by strong wind gusts.
A freight train was derailed by high winds. Forty rail cars holding mostly empty containers were blown off the tracks.
Public reported hen egg sized hail.
Trained spotter estimated 80 mph wind gusts.
Trained spotter reported large tree braches, up to 10 inches in diameter, broken off from high winds.
Trained spotter estimated 60 mph wind gusts.
Trained spotter reported golf ball sized hail.
Trained spotter reported some siding was blown off his house from very strong winds.
A 70 mph wind gust was measured by the Saco US-2 DOT site.
Trained spotter reported hen egg sized hail.
Off-duty NWS Employee estimated 60 mph wind gusts based on tree damage in their yard.
Off-duty NWS Employee reported half dollar sized hail.
The Glasgow airport ASOS site measured 61 mph gusts with the passage of a squall line.
Golf ball sized hail was observed at the Glasgow NWS office for up to 5 minutes.
Off-duty NWS employee reported hen egg sized hail.
Public reported 7 power poles blown down along MT Highway 24.
Trained spotter estimated 60 mph wind gusts.
Trained spotter reported golf ball sized hail.
Trained spotter reported golf ball sized hail and 10 broken windows among various buildings. Time estimated from radar.
Trained spotter reported half dollar sized hail.
Trained spotter reported shingles blown off a roof and part of a chimney broken from strong winds.
Trained spotter measured 67 mph wind gusts.
An off-duty NWS employee estimated 75 mph wind gusts.
Public reported ping pong ball sized hail.
Public reported golf ball sized hail.
Public reported near grapefruit sized hail, measuring 3.5 inches in diameter.
The Wolf Point airport ASOS measured a 68 mph wind gust.
Trained spotter reported ping pong ball sized hail.
Trained spotter reported hen egg sized hail.
The McDonalds MT-13 DOT sensor measured a 76 mph wind gust.
Trained spotter reported golf ball sized hail along with winds up to 50 mph.
Public reported, via social media, shingles blown off a roof. Time estimated by radar.
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, June 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: 645877, 645878, 645879, 645880, 645882, 645884, 645883, 645890, 645893, 645892, 645901, 645902, 645903, 645904, 645905, 645906, 645907, 645910, 645909, 645911, 645912, 645913, 645914, 645915, 645916, 645917, 645919, 645920, 645921, 645922, 645923, 645924, 645908, 645925, 645926, 645928, 645929, 645931, 645932, 645933.