An upper level trough moved across western Montana producing strong 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.
An upper level trough moved across western Montana producing strong 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 Sep 10, 10:00 AM MST, 7 hours 31 minutes earlier.
Area Forecast Discussion
National Weather Service Missoula MT
1100 AM MDT Mon Sep 10 2012
NOTE: This is the routine afternoon MSO Discussion issued early to
address concerns in the short term.
...Strong cold front winds will cause **critical fire weather as
well as public impacts** today into this evening across north-
central Idaho and western Montana...
...Clearing skies and calm winds should setup favorable conditions
for **freezing temperatures** in western Montana valleys Wednesday and
Thursday mornings...
...Smoke will clear somewhat Tuesday before filling in again for
west-central Montana and north-central Idaho Wednesday through
the end of the week...
.DISCUSSION...A cold, yet relatively dry upper level trough will
be passing through the Northern Rockies Region today and
tonight. This trough system will pack a windy punch throughout the
area. Several wind impacts are highlighted in today's forecast. 1)
Red Flag Warning are in effect for all of north-central Idaho,
west-central and southwest Montana. 2) A Lake Wind Advisory has
been issued for Flathead Lake in northwest Montana, and 3) A Wind
Advisory has been issued for the Missoula and Bitterroot Valleys.
Moisture associated with the system will be quite limited with the
bulk of the cloud cover and chances of precipitation confined to the
mountains of northwest Montana.
Winds will be decreasing this evening, then continue to diminish
overnight tonight as the surface pressure gradient relaxes and
shallow surface-based inversion develop. Higher elevations will
likely experience continued breezy condition overnight with only
modest humidity recoveries in Idaho and southwest Montana.
Tuesday/Wednesday...The upper level flow will be northwesterly
during this period. However, by Wednesday an upper ridge will be
build into northern Idaho from the west. Dry, cool conditions will
prevail during this periods. Clear skies and calm winds at night,
favor strong radiational cooling and strengthening of surface-based
inversions. Widespread freezing temperatures can be expected in the
valleys of western Montana by Wednesday morning prompting the
issuance of a Freeze warning. These stronger valley inversions
will trap smoke from area wildfires with very little mixing
anticipated to help air quality. /msj
Thursday will see another very cold start to the day. High
pressure moving in will mean stronger valley inversions and
smoked-in areas like the Bitterroot and Idaho canyons will
struggle to warm up in the afternoon. Smoke will continue for the
rest of the week awaiting more wind and a possible air mass change
coming this weekend with a Canadian cold front. Potential exists
with this weekend's front to strengthen into more of a closed low
pressure circulation due to building eastern Pacific high pressure
ridge and buckling jet stream. /ss
&&
.AVIATION...A cold front will moving through later today. Smoke
that is obscuring central ID and west central MT terrain will thin
somewhat with increasing wind scouring and mixing. Westerly
surface gusts approaching 35kts are possible until around 02z this
evening before diminishing. Stratocumulus cloud deck over NW MT
nearer the cold air aloft will also decrease late tonight. /ss
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...RED FLAG WARNING until Midnight MDT tonight Bitterroot/Sapphire
Mountains...Butte/Blackfoot Region.
RED FLAG WARNING until Midnight MDT tonight Flathead/Mission
Valleys...Kootenai/Cabinet Region...Lower Clark Fork
Region...Missoula/Bitterroot Valleys...Potomac/Seeley Lake
Region...West Glacier Region.
FREEZE WARNING from 3 AM to 9 AM MDT Wednesday Flathead/Mission
Valleys...Lower Clark Fork Region...Missoula/Bitterroot
Valleys.
WIND ADVISORY until 7 PM MDT this evening Missoula/Bitterroot
Valleys.
LAKE WIND ADVISORY until 8 PM MDT this evening For Flathead Lake.
WIND ADVISORY until Midnight MDT tonight ABOVE 6000 FEET FOR THE
West Glacier Region.
ID...RED FLAG WARNING until 9 PM MDT this evening Eastern Lemhi
County...Western Lemhi County.
RED FLAG WARNING until 11 PM PDT this evening Lower Hells
Canyon/Salmon River Region...Northern Clearwater
Mountains...Orofino/Grangeville Region...Southern
Clearwater Mountains.
&&The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
A wind gust of 85 mph was recorded at Logan Pass, elevation 6775 feet.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2012Every state in 2012This day in weather historyWarnings in Montana, September 2012
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: 412879.