A fast moving shortwave trough and attendant surface cold front moved through the region on Sunday May 31st. Strong southwest to west winds developed along and behind the front as it swept through the area.
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 fast moving shortwave trough and attendant surface cold front moved through the region on Sunday May 31st. Strong southwest to west winds developed along and behind the front as it swept through the area. Some convection was observed ahead of the front but most of the wind gusts were classified as non thunderstorm.
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 May 31, 8:21 AM MST, 1 hour 10 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 921 AM MDT Sun May 31 2020 .UPDATE... A few strong thunderstorms are crossing the Continental Divide north of Lincoln up to Glacier National Park. Radar velocity and surface observations are consistent with short-term model guidance showing a rapid increase in strong southwest winds associated with a pending frontal passage. Strong pressure rises following the frontal passage will help force strong west to southwest winds across western portions of North-central Montana. The forecast winds were updated to better match observed trends and the latest model guidance. These updates prompted a High Wind warning for areas north and west of Great Falls, as there is higher confidence that sustained winds will reach 40 mph later this morning into the early afternoon. Wind speeds were also increased over southwest Montana to match observations. Overall, today's weather will be characterized by rapidly increasing winds, with mild/warm temperatures and falling humidity behind the front. && .SYNOPSIS... Some lingering showers continue to track from south to north across southwest and central Montana through this morning. A cold front will then bring windy but drier conditions for much of the day on Sunday with continued above normal temperatures. For Monday, another round of showers over the southwest and central Montana is expected during the afternoon and evening hours. && .AVIATION... Updated 450 AM MDT Sun May 31 2020 (31/12z TAF issuance) VFR conditions are generally expected to continue for at least the next 24 hours, though strong southerly to southwesterly winds just off the surface will contribute to strong low-level wind shear. With even minimal surface heating in the morning, these winds will reach the surface and result in widespread windy conditions across the region through this afternoon, with winds diminishing through the evening. NOTE: Amendments not scheduled for Ennis (KEKS) due to ongoing runway closure. && .PREV DISCUSSION... /ISSUED 450 AM MDT Sun May 31 2020/ Lingering showers will continue to track across southwest and central Montana this morning, bringing some periods of light rain to the area. Strong west to southwesterly winds are expected to develop today across the region, as a disturbance passes through the area and strong subsidence builds over southwest and northcentral Montana. Strongest winds are expected along the Rocky Mountain Front, where wind gusts could approach 50-60 mph late this morning through this afternoon. A second disturbance crossing late in the afternoon and evening may have just enough moisture to support the development of a few thunderstorms over central Montana and eastern parts of north-central Montana. An isolated severe storm cannot be ruled out if thunderstorms can develop, mainly east of a Chinook-Lewistown line. A broad and weak high pressure ridge with an anticyclonic westerly flow aloft will then move over the northern CONUS Monday and Tuesday. This will continue the breezy westerly winds and chances of showers and thunderstorms with temperatures around 10 degrees above normal. However, a broad low pressure trough will then bring a more cyclonic westerly to southwesterly flow aloft for Wednesday through next Saturday. Although this will likely not impact temperatures significantly (still looking at temperatures around 10 degrees above normal), the greater impact will be an increase in the chance for showers and thunderstorms across much of north-central and southwest Montana. && .PRELIMINARY POINT TEMPS/POPS... GTF 81 46 76 48 / 20 0 10 20 CTB 75 45 71 44 / 90 0 0 10 HLN 81 48 78 48 / 0 0 10 30 BZN 82 46 81 49 / 0 0 20 30 WYS 70 41 75 43 / 10 0 0 20 DLN 77 46 78 48 / 0 0 30 10 HVR 90 48 78 50 / 10 0 0 20 LWT 82 48 74 48 / 10 0 20 50 && .TFX WATCHES/WARNINGS/ADVISORIES... High Wind Warning until 6 PM MDT this evening Eastern Glacier... Eastern Pondera...Eastern Teton...Liberty...Northern Rocky Mountain Front...Southern Rocky Mountain Front...Toole. && http://www.weather.gov/greatfalls
Special Weather Statement
National Weather Service Great Falls MT
848 AM MDT Sun May 31 2020
MTZ009-010-311530-
Northern Rocky Mountain Front MT-Eastern Glacier MT-
848 AM MDT Sun May 31 2020
...SIGNIFICANT WEATHER ADVISORY FOR WESTERN GLACIER COUNTY UNTIL 930
AM MDT...
At 846 AM MDT, Doppler radar was tracking a line of strong
thunderstorms approaching Glacier National Park from the
southwest. Movement was northeast at 50 mph.
Pea size hail and wind gusts of 50 to 55 mph will be possible with
these storms.
Locations impacted include...
Kiowa, East Glacier Park Village, Many Glacier, Babb, Marias Pass,
Goat Haunt, Saint Mary, Logan Pass and Starr School.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall is also occurring with these storms, and may lead
to localized flooding.
&&
LAT...LON 4899 11285 4831 11335 4834 11339 4837 11334
4842 11335 4842 11340 4846 11348 4855 11347
4862 11375 4873 11371 4878 11377 4884 11378
4885 11391 4882 11395 4889 11406 4891 11401
4900 11406
TIME...MOT...LOC 1446Z 213DEG 44KT 4903 11434 4831 11324
RCGSpecial Weather Statement National Weather Service Great Falls MT 931 AM MDT Sun May 31 2020 MTZ014-048-311600- Southern Rocky Mountain Front MT- Central and Southern Lewis and Clark MT- 931 AM MDT Sun May 31 2020 ...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL LEWIS AND CLARK AND SOUTH CENTRAL TETON COUNTIES UNTIL 1000 AM MDT... At 929 AM MDT, Doppler radar was tracking strong thunderstorms southwest of Augusta. Movement was northeast at 50 mph. Wind gusts of 50 to 55 mph will be possible with these storms. Locations impacted include... Augusta, Pishkun Reservoir and Nilan Reservoir. LAT...LON 4777 11243 4752 11205 4732 11249 4744 11278 TIME...MOT...LOC 1529Z 224DEG 45KT 4746 11272 4733 11245 RCG
5 high wind. Local standard time, as filed.
Cut Bank ASOS reported a 57 kt (66 mph) wind gust that was classified as non thunderstorm. Light rain was occurring at the time but thunderstorms were distant.
MDT station at Norris Hill reported a non thunderstorm wind gust of 52 kt (60 mph).
MDT station at 4 NNW SunBurst reported a 52 kt (60 mph) non thunderstorm wind gust.
MDT station at 2 E Inverness reported a 54 kt (62 mph) non thunderstorm wind gust.
The Cut Bank ASOS reported a 54 kt (62 mph) non thunderstorm wind gust.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2020Every state in 2020This day in weather historyWarnings in Montana, May 2020
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: 889464, 889466, 889469, 889470, 889471.