Diffluent, unstable southwest flow aloft ahead of an upper low moving across southern Canada, resulted in late afternoon and evening thunderstorms over portions of North Central Montana. Some storms became severe with large hail and damaging winds.
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The episode as NWS TFX wrote it up.
Diffluent, unstable southwest flow aloft ahead of an upper low moving across southern Canada, resulted in late afternoon and evening thunderstorms over portions of North Central Montana. Some storms became severe with large hail and damaging 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 Jun 10, 1:22 PM MST, 1 hour 13 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 222 PM MDT FRI JUN 10 2016 .DISCUSSION... THIS AFTERNOON THROUGH SUNDAY EVENING... Latest analysis shows circulation center and axis of Pacific upper-level trof has reached the WA/OR coast and is expected to make somewhat slow but steady progress eastward overnight. Moist southwest flow aloft along the leading edge of the trof combined with easterly surface winds bringing low-level moisture have set the stage for another round of thunderstorms this aftn/eve across central MT. Most parameters (CAPE, 0-6km wind shear, lifted index etc.) are well within the range for strong to severe storms, but will have to break the shallow low-level inversion that was still evident on the special balloon sounding we did at midday. We still expect that break to occur, but it may be later this aftn or early eve. Additional support for severe weather will come from the arrival of stronger jet stream winds (100-115 mph) now through this evening. Morning forecast models did shift the jet's core (115-125mph) to the west side of the Divide from earlier runs, so jet's contribution in our area may be reduced, but should be sufficient to help boost some storm development. Models continue to indicate slow approach of a surface cold front from the Pacific system, LCL not making it east of the Rocky Mtn Front until mid-late evening as cold air push behind it is not particularly strong. That may help storms persist a bit longer in our region as unstable conditions persist ahead of the front. Most convective activity will dissipate across the central counties by midnight, but scattered showers and a few storms will linger along the Hiline through the overnight hours. Southwest flow aloft continues on Sat as the trof axis moves to the ID Panhandle, so most locations will see another round of showers and some thunderstorms Sat aftn. With less instability behind the front, best chances for severe storms move to eastern MT tomorrow, and we'll see more of the short-lived, pulse-type storms with only marginal threat for gusty outflow winds and small hail. The trof axis finally reaches our area on Sun, bringing mostly dry conditions. Forecast on track for cooler temps through the weekend with highs in the upper 60s to low 70s on Sat/Sun. Waranauskas SUNDAY NIGHT THROUGH FRIDAY...A somewhat dry and breezy westerly flow aloft will move into the forecast area Sunday night into Monday. The resulting downsloping winds will keep North Central Montana dry through this period, but a disturbance will keep a chance of showers and thunderstorms over Southwest Montana. A low pressure center will then move out of the Gulf of Alaska and south along the Pacific Coast Tuesday through Wednesday. The resulting moist and unstable southwest flow aloft over Montana will bring a good chance of showers and thunderstorms to the forecast area during this time. Temperatures may cool enough to cause minor snow accumulation above mountain pass level, but significant impacts are unlikely. A high pressure ridge will then amplify over the central United States, which will shift the flow a bit farther west and focus the bulk of the showers/storms more so over Western Montana for Thursday into Friday. Temperatures will not fluctuate much during the period. Slightly above normal temperatures will fall to slightly below normal through Wednesday, but they will warm back above normal by Friday as the high pressure ridge builds into the area. Coulston && .AVIATION... UPDATED 1810Z. A Pacific cold front and upper level disturbance will move through the region late this afternoon/overnight. Expect widespread shower/thunderstorms to develop mainly north of I90. Some storms will produce strong winds/large hail. The storms griddle exit the Havre region by 10z Saturday. Expect VFR conditions across the region generally after 12z Sat. Brusda && .PRELIMINARY POINT TEMPS/POPS... GTF 54 67 44 71 / 30 30 20 10 CTB 51 65 40 66 / 70 20 10 0 HLN 58 67 47 72 / 30 40 30 10 BZN 53 69 44 71 / 20 40 30 20 WEY 48 61 39 61 / 10 40 30 20 DLN 53 66 43 69 / 20 50 30 10 HVR 55 72 47 72 / 60 40 20 0 LWT 54 67 46 70 / 30 40 40 10 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && weather.gov/greatfalls
PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE GREAT FALLS MT
1206 PM MDT FRI JUN 10 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0200 PM HAIL 8 S HAVRE 48.43N 109.68W
06/09/2016 E1.50 INCH HILL MT PUBLIC
ESTIMATED QUARTER TO ABOUT PING PONG SIZE HAIL...NEAR
BEAVER CREEK PARK.
&&
CORRECTED EVENT...REMARKS
BRUSDASPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREAT FALLS MT 303 PM MDT FRI JUN 10 2016 MTZ012-013-050-102145- CASCADE MT-JUDITH BASIN MT-CHOUTEAU MT- 303 PM MDT FRI JUN 10 2016 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL CHOUTEAU... NORTHEASTERN CASCADE AND NORTHERN JUDITH BASIN COUNTIES UNTIL 345 PM MDT... AT 303 PM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR BELT...OR 12 MILES SOUTHEAST OF GREAT FALLS...MOVING EAST AT 55 MPH. HALF INCH HAIL AND WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE WITH THIS STORM. LOCATIONS IMPACTED INCLUDE... BELT...HIGHWOOD...TRACY...SAND COULEE...SHONKIN...STOCKETT... CENTERVILLE AND ARMINGTON. 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 4731 11121 4744 11129 4778 11040 4747 11019 TIME...MOT...LOC 2103Z 248DEG 47KT 4741 11106 MARTIN
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
324 PM MDT FRI JUN 10 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0308 PM HAIL STOCKETT 47.36N 111.16W
06/10/2016 E1.00 INCH CASCADE MT AMATEUR RADIO
&&
MLSThe Great Falls radar (KTFX), 55 km away, was scanning. The volume nearest the first event began at 21:34 UTC.
6 hail, 3 thunderstorm wind. Local standard time, as filed.
A severe thunderstorm dropped 1.75 inch diameter hail at Highwood 10SE and 2 inch diameter hail at Highwood 8S. Small tree limbs were reported down.
A thunderstorm dropped 1 inch diameter hail at Geraldine.
A thunderstorm dropped 1 inch diameter hail at Monarch.
A thunderstorm dropped 2 inch diameter hail at Square Butte 1SW. Also, 1.75 inch diameter hail was reported at Winifred 12W and 2 inch diameter hail at Winifred 10W.
A thunderstorm dropped 1.25 inch diameter hail at Coffee Creek 6N. Also, 1.75 inch diameter hail was reported at Stanford 2NNE and a thunderstorm wind gust to 62 mph was reported at Denton 7NE.
Thunderstorm winds toppled two power poles.
A thunderstorm produced a wind gust to 64 mph at Roy 2E.
A thunderstorm dropped 1.75 inch diameter hail at Roy 10NE and 2 inch diameter hail at Roy 15NE.
A thunderstorm wind gust to 60 mph was reported at Denton 5ESE. Also, a thunderstorm gust to 63 mph was reported at Denton 7NE, a gust to 64 mph was reported at Suffolk 3WSW, and a gust to 62 mph was reported at Roy 2E. The Roy area was particularly hard hit by thunderstorms. Numerous power poles in the area were snapped off by the wind, large trees were downed, and sheet metal was reported to be blowing across Highway 191. Hail up to an inch in diameter was also reported at some locations.
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: 635732, 635733, 635735, 635734, 635736, 635737, 635738, 635739, 635740.