Anomalous atmospheric moisture combined with slow moving thunderstorms caused copious amounts of rain and in some places flooding.
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 MSO wrote it up.
Anomalous atmospheric moisture combined with slow moving thunderstorms caused copious amounts of rain and in some places flooding.
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 Missoula, MT wrote its last area forecast discussion before the first event at Jun 6, 12:26 PM MST, 5 hours 4 minutes earlier.
Area Forecast Discussion National Weather Service Missoula MT 126 PM MDT Tue Jun 6 2023 .DISCUSSION...A well-formed closed low pressure circulation over central California is continuing to send moisture north into the Northern Rockies. This feature is part of a much larger puzzle that includes a high amplitude ridge over the central U.S. and another low spinning over the East Coast. The California low will remain in place over the next few days with the help of the other atmospheric features over the U.S., sending smaller scale disturbances north and eastward towards Idaho and Montana. In the short term... this afternoon and Wednesday... clear skies in the morning with some deep instability and available moisture will be capable of fueling afternoon showers and thunderstorms throughout north-central Idaho and southwest Montana. Lack of strong steering winds and appreciable shear will result in storms producing mostly heavy rain and small hail, with little in the way of damaging hail or strong outflow winds. An increase in moisture on Wednesday will allow afternoon storm activity to spread further north. A more significant rain event will begin on Thursday. A mid levels low will setup over northwest Wyoming, pushing additional Gulf moisture into the Northern Rockies from the east. Precipitable water amounts will jump to about 200-250 percent of normal. Lift will be provided by the mid levels circulation and enhanced by terrain. The heaviest rainfall will be along and south of I-90 over western Montana and into north-central Idaho. Areas north of I-90 along the Continental Divide will also see periods of heavy rain on Thursday. The mid levels circulation will migrate to the northwest on Friday, bringing the focus of heavier precipitation north and west. Expect chances for heavy rain to increase across all of northwest Montana north of I-90, as well as Clearwater and Idaho Counties. Visitors to Glacier Park should be prepared for wet weather Thursday afternoon through Saturday morning. && .AVIATION...Scattered showers and a few thunderstorms will be in the vicinity of KBTM and KSMN through 07/0300z. Brief heavy rain may occur with storms. A lesser chance of showers or a thunderstorm will be in the vicinity of KMSO. Skies will clear overnight and Wednesday morning with another potential for scattered showers and thunderstorms redevelop in the vicinity of all terminals. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. &&
Special Weather Statement
National Weather Service Missoula MT
411 PM MDT Tue Jun 6 2023
MTZ007-062300-
Butte/Blackfoot Region MT-
411 PM MDT Tue Jun 6 2023
...A strong thunderstorm will impact portions of eastern Deer Lodge
and central Silver Bow Counties through 500 PM MDT...
At 411 PM MDT, trained weather spotters reported a strong
thunderstorm near Butte, moving north at 5 mph.
HAZARD...Winds in excess of 40 mph and half-inch size hail.
SOURCE...Trained weather spotters.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Butte, Silver Bow, Walkerville, Nissler, Ramsay, Janney and Newcomb.
This includes Interstate 90 between mile markers 211 and 231.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
&&
LAT...LON 4588 11242 4582 11266 4603 11285 4612 11251
4610 11248 4606 11247 4605 11248 4604 11246
TIME...MOT...LOC 2211Z 157DEG 6KT 4592 11259
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPHSpecial Weather Statement
National Weather Service Missoula MT
512 PM MDT Tue Jun 6 2023
MTZ007-070000-
Butte/Blackfoot Region MT-
512 PM MDT Tue Jun 6 2023
...A strong thunderstorm will impact portions of southeastern Silver
Bow County through 600 PM MDT...
At 512 PM MDT, Doppler radar was tracking a strong thunderstorm near
Divide, or 13 miles southwest of Butte, moving east at 15 mph.
HAZARD...Wind gusts up to 50 mph and penny size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
This storm will remain over mainly rural areas of southeastern Silver
Bow County.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
&&
LAT...LON 4574 11246 4576 11249 4576 11250 4574 11252
4571 11252 4568 11256 4571 11274 4589 11272
4590 11241 4589 11240 4585 11243 4579 11227
4575 11228
TIME...MOT...LOC 2312Z 275DEG 12KT 4580 11263
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPHSpecial Weather Statement
National Weather Service Missoula MT
517 PM MDT Tue Jun 6 2023
MTZ007-070000-
Butte/Blackfoot Region MT-
517 PM MDT Tue Jun 6 2023
...A strong thunderstorm will impact portions of north central Deer
Lodge, southeastern Granite and south central Powell Counties through
600 PM MDT...
At 517 PM MDT, Doppler radar was tracking a strong thunderstorm 8
miles west of West Valley, or 10 miles west of Anaconda, moving
northeast at 15 mph.
HAZARD...Winds in excess of 40 mph and penny size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Anaconda, West Valley, Lost Creek and Georgetown.
This includes Interstate 90 between mile markers 198 and 199.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
&&
LAT...LON 4603 11316 4617 11333 4642 11300 4621 11275
TIME...MOT...LOC 2317Z 233DEG 14KT 4613 11319
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPHThe Missoula radar (KMSX), 170 km away, was scanning. The volume nearest the first event began at 00:28 UTC.
1 flash flood, 1 heavy rain, 1 debris flow. Local standard time, as filed.
The Bert Mooney Airport recorded 1.65 inches of rain in an hour. The 911 dispatch reported manholes being blown from deep water rushing down the streets, a motorhome was pushed into a ditch, and there were multiple reports of water in people's homes.
Fields were flooded east of Victor near the Home Acres Road area. The radar estimated rainfall showed 2.60 inches fell in only 1.5 hours.
A layer of mud was found caked over the Drummond Frontage Road the day after the rainfall which depicted that a debris flow had occurred.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2023Every state in 2023This day in weather historyWarnings in Montana, June 2023
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: 1101167, 1101171, 1101173.