A warm, moist, and unstable airmass contributed to the development of isolated but severe thunderstorms during the early evening hours of July 19. Wind gusts in excess of 50 knots were reported.
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The episode as NWS TFX wrote it up.
A warm, moist, and unstable airmass contributed to the development of isolated but severe thunderstorms during the early evening hours of July 19. Wind gusts in excess of 50 knots were reported.
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 Jul 19, 4:55 PM MST, 4 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 555 PM MDT TUE JUL 19 2016 Updated Aviation Section .DISCUSSION... Tonight through Thursday...The large-scale pattern of a low pressure trof near the West Coast and unsettled southwest flow over Central and Southwest Montana continues. The air mass will be dry this afternoon and evening south of a Helena to Lewistown line and moist to the north. In addition, northeastern portions of the CWA, including Blaine and Fergus counties, will be very unstable late this afternoon and evening. Thunderstorm will be isolated but any development could become severe. The air mass will generally be stable Wednesday although central portions of the CWA will be unstable...Helena to Lewistown with Judith Basin and Fergus counties the most unstable. A disturbance passes across Southwest Montana Wednesday afternoon but the lack of moisture should prevent any convection over southern portions of the region. Another disturbance will move through the flow aloft Thursday but stable conditions should inhibit development. Zelzer Thursday night through Tuesday...A weak upper level disturbance will move across northern Montana early Friday through Friday night. This disturbance will temporary knock down the upper level ridge over the Upper Midwest and allow for scattered thunderstorms to develop over portions of Central and North Central MT. Most of the storms should come to an end by late Friday night. The upper level ridge will then shift to the Southwest US over the weekend and then start to shift northward towards southern MT by early next week. Overall, mostly dry conditions are expected over much of the region from Saturday through Tuesday. With the upper level disturbance moving through Friday, afternoon temperatures will fall back to near normal for both Friday and Saturday and then start to warm a few degrees above normal Sunday through early next week. As of now, the upper level ridge is not expected to build too far north next week, which may allow a few thunderstorms to develop over the area. However, if the upper level ridge does build further northward towards central MT early next week, wide spread afternoon temperatures in the upper 90s to around 100 degrees would become more likely over our region. We will just have to monitor the strength of the ridge and how far it pushes northward early next week, with some adjustments in temperatures possible. Brusda/Coulston && .AVIATION... UPDATED 2355Z. Southwest flow aloft will continue. Isolated showers and thunderstorms will gradually end by 06z with generally clear skies overnight. VFR conditions prevail with MVFR conditions possible in the vicinity of thunderstorms along with gusty erratic winds. && .PRELIMINARY POINT TEMPS/POPS... GTF 55 87 54 90 / 10 10 10 10 CTB 52 82 49 85 / 10 10 10 10 HLN 60 89 58 92 / 10 10 10 10 BZN 54 89 50 93 / 10 10 10 10 WEY 47 80 43 82 / 0 0 0 0 DLN 52 86 50 89 / 10 10 0 10 HVR 57 87 54 89 / 30 10 10 0 LWT 55 84 55 88 / 20 20 10 10 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && weather.gov/greatfalls
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
1200 PM MDT TUE JUL 19 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0730 PM HAIL 3 SE GEYSER 47.24N 110.46W
07/18/2016 E1.00 INCH JUDITH BASIN MT TRAINED SPOTTER
DELAYED REPORT. MAINLY PEA-SIZE WITH A FEW QUARTER-SIZE
HAILSTONES.
&&
KJPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
230 PM MDT TUE JUL 19 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0210 PM TSTM WND DMG 2 NW SHERIDAN 45.48N 112.22W
07/10/2016 MADISON MT PUBLIC
DELAYED REPORT VIA FACEBOOK. THUNDERSTORM WINDS PICKED
UP A CARPORT AND BLEW IT 50 YARDS DAMAGING SEVERAL CARS.
TIME ESTIMATED BASED ON RADAR.
&&
MARTINPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
238 PM MDT TUE JUL 19 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0828 PM TSTM WND GST DENTON 47.32N 109.95W
07/18/2016 M60 MPH FERGUS MT MESONET
DELAYED REPORT.
&&
MARTINPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
246 PM MDT TUE JUL 19 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0828 PM HEAVY RAIN DENTON 47.32N 109.95W
07/18/2016 M1.59 INCH FERGUS MT MESONET
DELAYED REPORT. MEASURED OVER A 34 MINUTE PERIOD.
&&
MARTINPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
247 PM MDT TUE JUL 19 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0907 PM TSTM WND DMG DENTON 47.32N 109.95W
07/18/2016 FERGUS MT TRAINED SPOTTER
DELAYED REPORT. SPOTTER REPORTED SEVERAL TREES DOWN
AROUND TOWN.
&&
MARTINPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
256 PM MDT TUE JUL 19 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0815 PM TSTM WND DMG DENTON 47.32N 109.95W
07/18/2016 FERGUS MT TRAINED SPOTTER
CORRECTION TO PREVIOUS REPORT FOR TIME. SPOTTER
REPORTED SEVERAL TREES DOWN AROUND TOWN.
&&
MARTINThe Great Falls radar (KTFX), 101 km away, was scanning. The volume nearest the first event began at 23:58 UTC.
3 thunderstorm wind. Local standard time, as filed.
A thunderstorm produced a wind gust to 58 mph at East Helena 4NNW.
A thunderstorm produced a wind gust to 70 mph at Geyser 6E.
A thunderstorm produced a wind gust to 78 mph at Havre 26N. Also a gust to 58 mph was reported at the Havre airport.
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, July 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: 637904, 637906, 637908.