A large dew point depression of 40 to 50 degrees provided good evaporative cooling potential, allowing for the acceleration of thunderstorm downdrafts. These stronger downdrafts translated into severe outflow flow winds.
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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.
A large dew point depression of 40 to 50 degrees provided good evaporative cooling potential, allowing for the acceleration of thunderstorm downdrafts. These stronger downdrafts translated into severe outflow flow winds.
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 Jul 13, 1:36 PM MST, 54 minutes earlier.
Area Forecast Discussion National Weather Service Missoula MT 236 PM MDT Wed Jul 13 2022 .DISCUSSION...Showers and thunderstorms have been active across the Northern Rockies since this morning. This trend is expected to continue through the afternoon with the main threats being lightning and gusty outflows. We have received a couple reports of storms being wet as well, so a brief heavy downpour or small hail cannot be ruled out. Late this afternoon, thunderstorm threat will shift into Lemhi county, Idaho and southwest Montana. These areas have the potential to see outflow winds of 35 to 40 mph, with a 5 percent chance of up to 60 to 70 mph. Above normal heat will persist into Thursday and Friday, with high temperatures averaging 5-10 degrees above normal. One change will be a relatively dry airmass working into our area from north to south beginning this evening. There are still questions in the models on how far south the dry air will spread by Friday, which makes the convection forecast difficult. Expect summertime thunderstorms to pop up each day, with Lemhi County and southwest Montana having the highest chance to experience one. On Friday, the models are depicting an open wave moving through the Northern Rockies, however there is little confidence on the exact position. If the GFS (Global Forecast System) is correct, then southwest Montana will experience increased convective activity Friday afternoon. This weekend will be hot and dry! Please exercise caution while recreating or working outside, taking frequent breaks and staying hydrated when possible. Overnight temperatures will be slow to cool off as well, so be sure to check on the most vulnerable in your community. && .AVIATION...Widespread light showers and isolated thunderstorms will continue to develop over Idaho and slowly move to the east- northeast across western Montana through the evening. Terminals with the highest probability for thunderstorms, will be KBTM, where the strongest thunderstorms are expected to be. The timing for thunderstorm activity, will be from 13/2000Z to 14/0000Z this evening. Gusty winds up to 40kts with frequent lightning will be the primary threats. Brief heavy rain may also lower visibility for short periods of time. While the chances for convection is much lower, vicinity thunder is possible for KMSO and KGPI during the same time as above. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. &&
Special Weather Statement
National Weather Service Missoula MT
202 PM MDT Wed Jul 13 2022
MTZ007-132030-
Butte/Blackfoot Region MT-
202 PM MDT Wed Jul 13 2022
...A strong thunderstorm will impact portions of southeastern Silver
Bow County through 230 PM MDT...
At 202 PM MDT, Doppler radar was tracking a strong thunderstorm 10
miles east of Divide, or 14 miles south of Butte, moving northeast at
25 mph.
HAZARD...Winds in excess of 40 mph.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects.
Locations impacted include...
Butte, Janney and Newcomb.
This includes Interstate 90 between mile markers 227 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 4574 11235 4574 11246 4576 11249 4576 11250
4574 11252 4571 11252 4569 11255 4577 11269
4602 11244 4593 11244 4589 11240 4585 11243
4579 11228
TIME...MOT...LOC 2002Z 221DEG 23KT 4577 11253
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPHSpecial Weather Statement
National Weather Service Missoula MT
210 PM MDT Wed Jul 13 2022
MTZ007-132045-
Butte/Blackfoot Region MT-
210 PM MDT Wed Jul 13 2022
...A strong thunderstorm will impact portions of north central Deer
Lodge, southeastern Granite and southern Powell Counties through 245
PM MDT...
At 209 PM MDT, Doppler radar was tracking a strong thunderstorm 8
miles west of West Valley, or 11 miles west of Anaconda, moving
northeast at 25 mph.
HAZARD...Winds in excess of 40 mph.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects.
Locations impacted include...
Anaconda, West Valley, Lost Creek and Georgetown.
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 4599 11317 4611 11337 4636 11314 4619 11286
TIME...MOT...LOC 2009Z 221DEG 23KT 4612 11320
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPHSpecial Weather Statement
National Weather Service Missoula MT
249 PM MDT Wed Jul 13 2022
IDZ009-010-132130-
Eastern Lemhi County ID-Western Lemhi County ID-
249 PM MDT Wed Jul 13 2022
...A strong thunderstorm will impact portions of central Lemhi County
through 330 PM MDT...
At 249 PM MDT, Doppler radar was tracking a strong thunderstorm near
Salmon, moving north at 25 mph.
HAZARD...Winds in excess of 40 mph.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects.
Locations impacted include...
Salmon and Carmen.
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 4503 11407 4531 11401 4526 11369 4525 11367
4499 11382
TIME...MOT...LOC 2049Z 193DEG 20KT 4509 11393
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPHSpecial Weather Statement
National Weather Service Missoula MT
324 PM MDT Wed Jul 13 2022
IDZ009-010-132145-
Eastern Lemhi County ID-Western Lemhi County ID-
324 PM MDT Wed Jul 13 2022
...A strong thunderstorm will impact portions of north central Lemhi
County through 345 PM MDT...
At 324 PM MDT, the public reported a strong thunderstorm 9 miles
southeast of North Fork, or 9 miles north of Salmon, moving northeast
at 45 mph.
HAZARD...Wind gusts of 50 to 55 mph.
SOURCE...Public.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects.
Locations impacted include...
Salmon, North Fork, Gibbonsville and Carmen.
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 4523 11411 4561 11391 4556 11381 4552 11383
4552 11377 4548 11376 4545 11378 4543 11376
4541 11377 4539 11373 4533 11374 4529 11368
4525 11369 4523 11365 4510 11380
TIME...MOT...LOC 2124Z 215DEG 38KT 4531 11385
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPHThe Missoula radar (KMSX), 209 km away, was scanning. The volume nearest the first event began at 21:29 UTC.
1 thunderstorm wind. Local standard time, as filed.
A RAWS station above the city of Salmon recorded a wind gust to 66 mph. There was extensive damage within Salmon, mainly centered on the southern side of the city. Damage included damage to roofs, RVs blown over, and high school bleachers blown over.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2022Every state in 2022This day in weather historyWarnings in Idaho, July 2022
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: 1044846.