A slow-moving low pressure system was accompanied by unusually-high amounts of moisture, periods of steady of heavy rain, and some thunderstorms over north-central Montana during May 25th through the early morning of the 28th. In addition, relatively-high snow levels allowed rain to fall on lingering snowpack along the Rocky Mountain Front, where easterly upslope flow enhanced rainfall totals.
Every event with a place to put it. Tap one for its entry below.
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 slow-moving low pressure system was accompanied by unusually-high amounts of moisture, periods of steady of heavy rain, and some thunderstorms over north-central Montana during May 25th through the early morning of the 28th. In addition, relatively-high snow levels allowed rain to fall on lingering snowpack along the Rocky Mountain Front, where easterly upslope flow enhanced rainfall totals. Portions of the Rocky Mountain Front received as much as around 3 to 6 inches of total rainfall. Runoff from snowmelt and significant rainfall led to flooding along some rivers and overland flooding. The worst flooding was focused in the Augusta area, along the Sun River, and along Badger Creek in the Browning area.
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 26, 8:47 AM MST, 13 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 947 AM MDT Sun May 26 2019 .SYNOPSIS... Periods of rain are expected across the region today through Monday. The heaviest precipitation will fall over the Rocky Mountain Front today, then across the south on Monday. Drier and warmer conditions are expected from Tuesday through Thursday. && .UPDATE... Only change to the morning forecast was to change the flood watch to a flood warning. See Hydro section below. Otherwise, current forecast is on track. Rain, heavy at times continues to push northwestward through North Central MT. Showers/thunderstorms should become more widespread over Central/Southwest MT this afternoon. Temperatures look on track for today, with the warmest temperatures in the Havre and Bozeman areas. Brusda && .AVIATION... Updated 530 AM MDT Sun May 26 2019 (12Z TAFs) Scattered rain showers will continue to track north across the region today, with the heaviest activity to the west of the KGTF/KCTB terminals. Temporary MVFR conditions in showers will become more widespread in low ceilings and rain. IFR conditions will possible at times, especially west of KGTF and KCTB. && .HYDROLOGY... The flood watch has been changed to a flood warning. The Dearborn River could rise to just below moderate flood stage. Other rivers over the western portions of North Central MT could also go above flood stage, such as the Teton, Badger and Two Medicine Rivers. Widespread rainfall of 1 to 2 inches has been reported along the front range of the Rockies already, with a few isolated 3 inch reports. An additional 1 to 2 inches of rain is possible today and tonight. That amount of rainfall could cause impacts on rural, and possibly some cities, especially along/west of Interstate 15. Thus a flood warning is in effect for this region until further notice. Brusda && .PREV DISCUSSION... /ISSUED 530 AM MDT Sun May 26 2019/ The anticipated heavy rain event for the Northern Rocky Mountain Front is developing as expected based on continuity in forecasts. A diffluent flow aloft is positioned over a stalled surface front, with a moist low-level easterly upslope flow all combining to produce the observed rainfall. The suite of short-term model guidance captured the overall patterns of heavier rain through the evening, so confidence remains high that total rain amounts in this area will reach 1 to 3 inches, with locally up to 4 inches possible. For southwest Montana, scattered showers with a few embedded thunderstorms are expected this afternoon, also capable of producing moderate to heavy rain. Areas of rain shift further south on Monday afternoon as the closed upper low moves across the interior west. Dry air filtering in from the north will bring precipitation to an end over North- central MT by Monday afternoon. Rain ends for most of our forecast area early Tuesday as an upper level ridge builds over the Pacific Northwest. PN Tuesday through Sunday...Ridge of high pressure will generally diminish any lingering showers on Tuesday, although a large upper level disturbance may bring a few showers to the southwest as it moves eastward into the plains. Tuesday night through Wednesday then sees warming temperatures and mainly dry conditions, with only a few mountain thunderstorms possible. Dry conditions could bring some lowering RH especially on Wednesday. This may bring some increased fire danger, especially to the Hi-Line. A weak trough and cold front then push across the region for Thursday and Friday. This combined with instability from warming temperatures could bring some scattered shower and thunderstorm activity. Shear is fairly low, so any thunderstorms that do develop will be generally slow moving and capable of producing some periods of moderate to heavy rain. The weak waves to end the work week suppresses the high pressure ridge enough to allow a more broad scale trough to enter into the area for the weekend. The result could be another weekend of scattered shower and thunderstorm activity. With modest instability and weak flow aloft, more moderate to heavy rain is possible. This active pattern with periods of heavy rain may then continue into the next week. This may need to be monitored for potential flooding concerns. Temperatures are expected to warm to near or slightly above normal by mid week. These near normal temps may even stick around during the active periods late in the week into the weekend. Anglin && .PRELIMINARY POINT TEMPS/POPS... GTF 56 45 56 42 / 90 80 60 20 CTB 52 41 62 38 / 100 80 30 0 HLN 61 47 58 44 / 100 80 70 40 BZN 65 44 59 42 / 90 90 70 50 WEY 61 34 56 35 / 80 60 90 50 DLN 62 43 57 42 / 70 60 70 30 HVR 64 42 66 40 / 50 40 10 0 LWT 57 43 51 39 / 60 80 70 40 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && http://www.weather.gov/greatfalls
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
651 AM MDT SUN MAY 26 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0530 AM NON-TSTM WND GST 3 NNW JOPLIN 48.59N 110.79W
05/26/2019 M51 MPH LIBERTY MT MESONET
MESONET STATION EW9056 JOPLIN.
&&
BRUSDAThe national radar mosaic for the moment the first event began.
7 flood. Local standard time, as filed.
Law enforcement reported a portion of Teton Canyon Road had been washed-out by flooding along the North Fork of the Teton River. Exact duration of flooding unknown.
MT DOT reported floodwater on US-2, 3-miles west of East Glacier. Exact duration of flooding unknown.
Lewis and Clark County Emergency Manager reported floodwater over roads in Augusta. In addition, at 3:15 PM MST, MT DOT reported US-287 was closed from Augusta to 1/2-mile south of Augusta due to floodwater across the roadway. Exact duration of flooding unknown.
Fergus County Sheriff reported flooding near Utica. Exact duration of flooding unknown.
MT DOT reported floodwater across MT-200 just east of the town of Sun River. In addition, NWS employees documented additional flooding along the Sun River, in and near the town of Sun River, on May 28th. Exact duration of flooding unknown.
Meagher County Sheriff closed US-12 between Martinsdale and Two Dot Highway because of floodwater across the roadway. Floodwater was up to 4-feet deep. Exact duration of flooding unknown.
Emergency manager shared video of flooded wheat field adjacent to the Teton River. Estimated time of the event. Exact duration of flooding unknown.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2019Every state in 2019This day in weather historyWarnings in Montana, May 2019
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: 818918, 818916, 818917, 818919, 818926, 818921, 818932.