A low pressure system off the southern Oregon coast Thursday moved slightly inland Friday remaining nearly stationary after that. Several disturbances in the flow affected portions of Central and Southwest Montana.
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 low pressure system off the southern Oregon coast Thursday moved slightly inland Friday remaining nearly stationary after that. Several disturbances in the flow affected portions of Central and Southwest Montana. Strong lift over northwest portions of Central Montana during the evening, combined with a fairly unstable airmass and strong wind shear, aided in development of thunderstorms that included a threat of gusty winds, small hail, and brief heavy rain.
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 Sep 5, 3:07 PM MST, 6 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 407 PM MDT Thu Sep 5 2013 .UPDATE... New thunderstorm watch just issued for Beaverhead and Madison Counties, valid until 11 pm tonight. Strong to possibly severe storms may develop in east-central Idaho and move north into the affected counties this evening. Strong outflow winds, large hail, and locally heavy rainfall will be possible with these storms. Area of thunderstorms currently located from central Glacier County southeast to Judith Gap will continue to move north over next few hours, with good chance for additional storm development from Lewistown to Chester. These storms are not expected to be severe but will produce gusty winds of 40-50 mph and locally heavy rainfall. Waranauskas && .AVIATION... UPDATED 1800Z. Moist and unstable south-southwest flow aloft will continue over the region through Friday. showers and thunderstorms already tracking north through areas along/west of the continental divide will become more numerous with additional development occurring farther east this afternoon...likely to impact most SW and north-central MT terminals with the exception of KHVR. Main impact from thunderstorm activity will be wind gusts to 40kts and brief heavy rain, creating localized MVFR conditions. Small hail also a possibility in stronger cells later this afternoon...mainly along and adjacent to the Continental Divide. Hoenisch && .PREV DISCUSSION... /ISSUED 249 PM MDT Thu Sep 5 2013/ Tonight through Saturday...An upper low off the southern Oregon coast early Thursday afternoon will move into Washington Friday and continue nearly stationary through Saturday. Several weather disturbances will affect the forecast area in the southwest flow aloft ahead of the low. One weather disturbance over southern Idaho early Thursday afternoon will move northeast and be over northcentral Montana by late Thursday evening. There still will be a threat of gusty winds, small hail, and brief heavy rain with the associated thunderstorms. Another weather disturbance is expected to move northeast through western portions of the forecast area Friday afternoon/evening. Again there will be a threat of gusty winds, small hail, and brief heavy rain with the thunderstorms associated with the disturbance. Models indicate fairly strong lift over northwest portions of the forecast area during the evening so this combined with a fairly unstable airmass and fairly strong wind shear will lead to a threat of severe thunderstorms and will include this mention in the forecast. For late Friday night and Saturday there are differences amongst the models with their forecasts of weather disturbances. Will hold onto isolated to scattered showers and thunderstorms with more numerous showers/thunderstorms over the Rocky Mountain Front. Cooler air will move into the northwest plains Friday and then spread southeast Saturday. Guidance suggests low level cooler air over the western plains and drier air over western portions of southwest Montana could lead to a stable airmass so will remove the mention of thunderstorms on Saturday in these areas. Blank Saturday Night through Thursday...Medium range models continue to slow the progression of the upper level trough through the forecast area. However, the existing forecast continues to appear favorable, showing moist southwest flow ahead of the trough with scattered to numerous showers and thunderstorms expected over a wide portion of my forecast area. This pattern continues until the system finally moves east of the region on Tuesday. An upper level ridge rebuilds over the Intermountain West for the remainder of the forecast period allowing temperatures to rebound back to about 15 degrees above seasonal averages with little or no precipitation expected. mpj && .PRELIMINARY POINT TEMPS/POPS... GTF 57 89 54 78 / 40 40 70 30 CTB 55 77 51 72 / 40 30 80 30 HLN 57 88 56 80 / 30 30 40 30 BZN 51 89 49 83 / 20 20 20 40 WEY 42 77 40 76 / 20 20 20 30 DLN 50 84 48 80 / 20 20 10 30 HVR 60 92 58 78 / 30 10 60 40 LWT 56 90 54 78 / 30 30 40 40 && .TFX WATCHES/WARNINGS/ADVISORIES... SEVERE THUNDERSTORM WATCH until 11 PM MDT this evening Beaverhead...Madison. && SHORT TERM...WARANAUSKAS LONG TERM...HOENISCH AVIATION...HOENISCH weather.gov/greatfalls
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GREAT FALLS MT 516 AM MDT THU SEP 5 2013 MTZ009>014-044>051-061215- NORTHERN ROCKY MOUNTAIN FRONT-EASTERN GLACIER-HILL-CASCADE- CHOUTEAU-CENTRAL AND SOUTHERN LEWIS AND CLARK-TOOLE-LIBERTY- EASTERN PONDERA-BLAINE-SOUTHERN ROCKY MOUNTAIN FRONT- EASTERN TETON-JUDITH BASIN-FERGUS- 516 AM MDT THU SEP 5 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL MONTANA...NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA. .DAY ONE...TODAY AND TONIGHT AN APPROACHING PACIFIC WEATHER SYSTEM WILL BRING INCREASING CHANCES OF THUNDERSTORMS LATE THIS AFTERNOON AND EVENING. SOME STORMS WILL BE STRONG WITH LOCALLY HEAVY RAINFALL...GUSTY OUTFLOW WINDS AND SMALL HAIL. THERE IS ALSO A THREAT OF SEVERE STORMS PRODUCING LARGE HAIL ON THURSDAY AFTERNOON AND EVENING ACROSS THE ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY AFTERNOON AND EVENING THUNDERSTORMS ARE EXPECTED TO REDEVELOP ON FRIDAY AND SATURDAY...THEN SPREAD EASTWARD ACROSS CENTRAL MONTANA. SOME STORMS WILL BE STRONG IN THE AFTERNOON WITH LOCALLY HEAVY RAINFALL... GUSTY OUTFLOW WINDS AND SMALL HAIL. .SPOTTER INFORMATION STATEMENT... REPORTS OF SEVERE WEATHER OR FLASH FLOODING WOULD BE GREATLY APPRECIATED. MTZ008-015-052>055-061215- BEAVERHEAD-MADISON-JEFFERSON-BROADWATER-MEAGHER-GALLATIN- 516 AM MDT THU SEP 5 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST MONTANA. .DAY ONE...TODAY AND TONIGHT AN APPROACHING PACIFIC WEATHER SYSTEM WILL BRING INCREASING CHANCES OF THUNDERSTORMS. SOME STORMS WILL BE STRONG WITH LOCALLY HEAVY RAINFALL...GUSTY OUTFLOW WINDS AND SMALL HAIL. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... REPORTS OF SEVERE WEATHER OR FLASH FLOODING WOULD BE GREATLY APPRECIATED.
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREAT FALLS MT
211 PM MDT THU SEP 5 2013
MTZ014-052100-
CENTRAL AND SOUTHERN LEWIS AND CLARK MT-
211 PM MDT THU SEP 5 2013
...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL LEWIS AND CLARK COUNTY
UNTIL 300 PM MDT...
AT 200 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 20 MILES SOUTHEAST OF LINCOLN...MOVING NORTH
AT 30 MPH.
WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH
HEAVY RAIN AND FREQUENT LIGHTNING.
* LOCATIONS IMPACTED INCLUDE...CANYON CREEK...MARYSVILLE AND
LOCATIONS MAINLY WEST OF INTERSTATE 15 IN THE SIEBEN FLATS AREA.
LAT...LON 4720 11258 4719 11222 4665 11229 4665 11242
4669 11243 4669 11252 4670 11254 4682 11254
4683 11256
TIME...MOT...LOC 2009Z 181DEG 26KT 4674 11242
BRUSDASPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREAT FALLS MT 321 PM MDT THU SEP 5 2013 MTZ012>014-048>050-052230- CASCADE-CHOUTEAU-CENTRAL AND SOUTHERN LEWIS AND CLARK- SOUTHERN ROCKY MOUNTAIN FRONT-EASTERN TETON-JUDITH BASIN- INCLUDING THE CITIES OF...GREAT FALLS...BIG SANDY...FORT BENTON... HELENA...LINCOLN...CHOTEAU...FAIRFIELD...STANFORD 321 PM MDT THU SEP 5 2013 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL MONTANA UNTIL 430 PM MDT... AT 315 PM...AN AREA OF SHOWERS AND THUNDERSTORMS CONTINUES TO MOVE NORTHWARD AT 25 MPH THROUGH MUCH OF CENTRAL MONTANA. THESE THUNDERSTORMS HAVE HAD A HISTORY OF PRODUCING WIND GUSTS BETWEEN 35 AND 45 MPH...WITH ISOLATED WIND GUSTS AROUND 50 MPH. ADDITIONALLY...BRIEF HEAVY RAINFALL IS POSSIBLE WITH SOME OF THE STRONGER STORMS. SOME LOCATIONS NEAR THE PATH OF THE STRONGER STORMS ARE AUGUSTA...SIMMS...AREAS EAST OF FORT BENTON AND GEYSER.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
332 PM MDT THU SEP 05 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0224 PM TSTM WND GST 6 SE WINSTON 46.41N 111.58W
09/05/2013 M49 MPH BROADWATER MT MESONET
49 MPH THUNDERSTORM WIND GUST.
&&
BRUSDAThe Great Falls radar (KTFX), 2 km away, was scanning. The volume nearest the first event began at 22:11 UTC.
14 thunderstorm wind, 12 hail, 4 heavy rain. Local standard time, as filed.
Strong winds estimated at 50KT (58MPH) snapped a tree 8-10 inches in diameter.
High winds measuring 54KT (62MPH) reported at the Great Falls Airport ASOS.
High winds measuring 52KT (60MPH).
High winds measuring 57KT (66MPH) reported at the Whitehall RAWS.
High winds measuring 52KT (60MPH).
High winds measuring 52KT (60MPH).
Strong winds estimated 50KT (58MPH) causing vehicle rollover on Interstate 90, mobile home damage, and numerous reports of roof and power line damage.
High winds estimated 52KT (60MPH).
High winds measuring 69KT (79MPH) tipped a pivot over.
High winds estimated at 52KT (60MPH) along with heavy rainfall.
Heavy rain measuring 3.20 inches in 24 hours. An 8X12 wood framed greenhouse was also blown over.
Hail measuring 1.00 inches (quarter sized) was reported in the Dearborn, MT area.
Hail measuring 1.75 inches (golf ball sized) and rainfall of .45 inches was reported by Sieben Livestock. Damage to siding of a residential building was also reported.
High winds measuring 60KT (69MPH) at Millegan.
Hail measuring 1.00 inches (quarter sized), along with brief heavy rain, was reported.
Rain measuring 2.10 inches in 40 minutes reported.
Hail measuring 1.00 inches (quarter sized) and brief heavy rain were reported.
High winds estimated 61KT (70MPH) in the Armington Junction area.
High winds estimated 52KT (60MPH).
Rain measuring 0.82 inches in 25 minutes.
High winds estimated 52KT (60MPH) with tree branches reported down.
Hail measuring 1.00 inches (quarter sized) was reported covering the ground. Brief heavy rain was also reported.
Hail measuring 1.75 inches (golf ball sized) was reported, along with damage to homes and vehicles, 20 mi S of Cascade, MT. Storm lasted about 15 minutes.
Hail measuring 1.50 inches (ping pong ball sized) and heavy rain were reported.
Hail measuring 1.00 inches (quarter sized) was reported near Neihart, MT.
Hail measuring 1.00 inches (quarter sized) was reported 5 mi SSE of Ulm, MT.
Hail measuring 1.75 inches (golf ball sized) and 35MPH winds were reported 4 mi ESE of Stockett, MT.
Hail measuring up to 2.00 inches (lime sized) was reported in Stockett, MT via a KRTV Facebook report.
Hail measuring 1.50 inches (ping pong ball sized) was reported 5 mi ESE of Stockett, MT.
Heavy rain measuring 0.95 in one hour during the morning with 0.60 more across a couple afternoon hours.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2013Every state in 2013This day in weather historyWarnings in Montana, September 2013
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: 475729, 475732, 475733, 475736, 475734, 475735, 475731, 475739, 475738, 475737, 475728, 475713, 475715, 475742, 475716, 475725, 475718, 475740, 475741, 475726, 475744, 475719, 476302, 475721, 475722, 476307, 476309, 476310, 476311, 476312.