Southwest flow continued to bring Pacific moisture into the area helping trigger afternoon showers and thunderstorms, primarily over higher terrain. Some storms moved out onto the plains and contained gusty, erratic winds and/or brief heavy rain.
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.
Southwest flow continued to bring Pacific moisture into the area helping trigger afternoon showers and thunderstorms, primarily over higher terrain. Some storms moved out onto the plains and contained gusty, erratic winds and/or brief heavy rain. Precipitable water values ranged between 0.75 and 1 inch.
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 Aug 23, 1:41 PM MST, 2 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 241 PM MDT Fri Aug 23 2013 .DISCUSSION... Tonight through Sunday...The region will remain underneath high pressure with a low pressure trof over the Eastern Pacific through Sunday. This will leave the zones underneath unsettled, southwest flow aloft. Isolated to scattered thunderstorms have developed across the southwest zones this afternoon and these will move northeast during the evening. A shortwave will move east of the zones later this evening and thunderstorm activity will diminish. The airmass will become unstable again Saturday afternoon. Strongest instability will be across the southwest zones and northeast across Judith Basin and Fergus counties. Another shortwave will cross the region and scattered showers and thunderstorms will once again develop during the afternoon and evening. The ridge will strengthen Sunday and the airmass will dry but afternoon thunderstorms will again develop. In addition, winds across the southwest zones will strengthen and become gusty ahead of another approaching shortwave. Temperatures through the period will remain well above normals. Zelzer Sunday night through Friday...The pattern changes little during the period. Southwest flow aloft will persist as the area will remain situated between an upper trof over the Eastern Pacific and a strong upper ridge over the central U. S. Monsoonal moisture will continue to be drawn up into southern Montana through the period. Precipitable water values will remain high, generally between three-quarters of an inch to an inch. Isolated thunderstorms will generally develop over the mountains and higher terrain each day with a few moving out over the plains. Thunderstorms may become a bit more widespread on Friday as an upper trof moves to the Pacific Northwest and short wave energy rotates out from the base of the trof and rides into the state embedded within the southwest flow aloft. Temperatures will continue some 8 to 10 degrees above seasonal averages through the period. && .AVIATION... UPDATED 1135Z. Southwest flow aloft will continue. A disturbance aloft will move across northwest Montana this afternoon. Scattered showers and thunderstorms will develop after 17z and continue into early evening. Convective activity should end by 04z. VFR conditions prevail with MVFR conditions possible in the vicinity of showers and/or thunderstorms. && .FIRE WEATHER... An unstable southwesterly flow aloft will prevail over the region for the next few days. As warm/very warm air continues to reside over the region...combined with increasing winds and low humidities...there is the potential for critical fire weather conditions over portions of Southwest MT...especially on Sunday. Any thunderstorm activity over the weekend has the potential to produce strong gusty erratic winds. Looking ahead...afternoon temperatures will generally average 5 to 10 degrees above normal for much of next week. Brusda && .PRELIMINARY POINT TEMPS/POPS... GTF 57 87 56 92 / 20 20 30 20 CTB 56 86 54 89 / 20 10 10 30 HLN 58 87 56 91 / 30 30 40 20 BZN 52 83 48 89 / 30 30 30 20 WEY 40 74 36 79 / 30 50 40 20 DLN 50 81 48 85 / 30 40 40 20 HVR 58 87 57 93 / 30 10 20 20 LWT 54 82 54 89 / 30 20 30 20 && .TFX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING until 3 PM MDT this afternoon Central and Southern Lewis and Clark...Northern Rocky Mountain Front... Southern Rocky Mountain Front. && weather.gov/greatfalls
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GREAT FALLS MT 336 AM MDT FRI AUG 23 2013 MTZ009-014-048-240945- NORTHERN ROCKY MOUNTAIN FRONT- CENTRAL AND SOUTHERN LEWIS AND CLARK- SOUTHERN ROCKY MOUNTAIN FRONT- 336 AM MDT FRI AUG 23 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA. .DAY ONE...TODAY AND TONIGHT A RED FLAG WARNING IS IN EFFECT UNTIL 3 PM MDT TODAY FOR PORTIONS OF THE AREA NEAR THE CONTINENTAL DIVIDE. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY GUSTY WINDS...LOW RELATIVE HUMIDITY...VERY WARM TEMPERATURES AND A CHANCE FOR THUNDERSTORMS MAY INCREASE FIRE WEATHER CONCERNS ON SUNDAY AFTERNOON AND EVENING. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. MTZ008-010>013-015-044>047-049>055-240945- BEAVERHEAD-EASTERN GLACIER-HILL-CASCADE-CHOUTEAU-MADISON-TOOLE- LIBERTY-EASTERN PONDERA-BLAINE-EASTERN TETON-JUDITH BASIN-FERGUS- JEFFERSON-BROADWATER-MEAGHER-GALLATIN- 336 AM MDT FRI AUG 23 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL MONTANA...NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA. .DAY ONE...TODAY AND TONIGHT THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY GUSTY WINDS...LOW RELATIVE HUMIDITY...VERY WARM TEMPERATURES AND A CHANCE FOR THUNDERSTORMS MAY INCREASE FIRE WEATHER CONCERNS ON SUNDAY AFTERNOON AND EVENING. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREAT FALLS MT
121 PM MDT FRI AUG 23 2013
MTZ008-232000-
BEAVERHEAD MT-
121 PM MDT FRI AUG 23 2013
...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL BEAVERHEAD COUNTY UNTIL
200 PM MDT...
AT 115 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 15 MILES NORTHWEST OF LIMA...OR 33 MILES SOUTH OF
DILLON...MOVING NORTHEAST AT 35 MPH.
HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT
DANGEROUS LIGHTNING.
* LOCATIONS IMPACTED INCLUDE...
DELL...
IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.
THE BRIEF HEAVY RAIN MAY ALSO CAUSE RAPID RUNOFF IN STEEP TERRAIN
AREAS...POSSIBLY RESULTING IN FLASH FLOODING. PLEASE USE CAUTION IF
IN SUCH AREAS.
IN ADDITION...THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR
LOCAL RADIO AND TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS...FOR
ADDITIONAL INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL
WEATHER SERVICE.
LAT...LON 4480 11298 4510 11243 4509 11233 4500 11233
4500 11220 4499 11218 4492 11219 4465 11284
TIME...MOT...LOC 1920Z 235DEG 29KT 4478 11280
COULSTONSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREAT FALLS MT 154 PM MDT FRI AUG 23 2013 MTZ008-015-232015- BEAVERHEAD MT-MADISON MT- 154 PM MDT FRI AUG 23 2013 ...SIGNIFICANT WEATHER ADVISORY FOR WESTERN MADISON AND CENTRAL BEAVERHEAD COUNTIES UNTIL 215 PM MDT... AT 145 PM MDT...STORM SPOTTERS REPORTED A STRONG THUNDERSTORM 7 MILES NORTHEAST OF DILLON...MOVING NORTHEAST AT 30 MPH. THE SPOTTER REPORTED THAT A LOT OF PEA SIZED HAIL FELL IN THE TOWN OF DILLON...ENOUGH TO COVER THE GROUND...AS WELL AS GUSTS UP TO 40 MPH. HOWEVER...THERE IS THE POTENTIAL FOR HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 45 MPH WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. RAPID RAINFALL RUNOFF IN STEEP TERRAIN MAY CAUSE WATER TO RUN OVER ROADWAYS FOR A BRIEF PERIOD OF TIME...OR CAUSE BRIEF FLOODING OF LOW LYING AREAS. * LOCATIONS IMPACTED INCLUDE... SHERIDAN... IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A STURDY BUILDING. LAT...LON 4557 11218 4538 11202 4518 11258 4534 11270 TIME...MOT...LOC 1948Z 240DEG 28KT 4530 11253 COULSTON
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
158 PM MDT FRI AUG 23 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0143 PM TSTM WND GST 5 NE DILLON 45.26N 112.55W
08/23/2013 M70 MPH BEAVERHEAD MT ASOS
70 MPH WIND GUST AT THE DILLON AIRPORT.
&&
BRUSDAPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
200 PM MDT FRI AUG 23 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0140 PM TSTM WND DMG DILLON 45.22N 112.63W
08/23/2013 BEAVERHEAD MT PUBLIC
TREE DAMAGE VISIBLE ON THE DILLON WEB CAM...AT THE
DILLON FOOTBALL STADIUM. TIME OF EVENT IS ESTIMATED.
&&
BRUSDAPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
209 PM MDT FRI AUG 23 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0152 PM HAIL 9 ENE DILLON 45.28N 112.48W
08/23/2013 E0.50 INCH BEAVERHEAD MT TRAINED SPOTTER
WINDS ESTIMATED NEAR 50 MPH AND HAIL UP TO A HALF INCH
IN DIAMETER...HAIL DRIFTING UP TO 3 INCHES DEEP NEAR
BUILDINGS.
0152 PM TSTM WND GST 9 ENE DILLON 45.28N 112.48W
08/23/2013 E50 MPH BEAVERHEAD MT TRAINED SPOTTER
WINDS ESTIMATED NEAR 50 MPH AND HAIL UP TO A HALF INCH
IN DIAMETER...HAIL DRIFTING UP TO 3 INCHES DEEP NEAR
BUILDINGS.
&&
BRUSDAPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
234 PM MDT FRI AUG 23 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0155 PM TSTM WND GST 10 NE DILLON 45.33N 112.51W
08/23/2013 M58 MPH BEAVERHEAD MT MESONET
58 MPH WIND GUST AT THE DILLON AGRIMET. TIME OF EVENT
IS ESTIMATED.
&&
BRUSDAThe Missoula radar (KMSX), 228 km away, was scanning. The volume nearest the first event began at 20:45 UTC.
6 thunderstorm wind. Local standard time, as filed.
High winds measuring 61KT (70MPH) were reported at the Dillon Airport.
High winds measuring 50KT (58MPH) were reported at the Dillon Agrimet station.
High winds estimated at 50KT (58MPH) were seen in Bozeman where a tree was blown over hitting a power line.
High winds measuring 55KT (63MPH) were reported 11 miles E of Bozeman at the Bozeman Pass DOT sensor.
High winds measuring 55KT (63MPH) were reported at the Dillon Portable RAWS #2.
High winds measuring 59KT (68MPH) were reported 6 miles SE of Winston at the Canyon Ferry Silos.
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, August 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: 474894, 474895, 474896, 474897, 474898, 474899.