A vigorous cold front sweeping through the region produced widespread damage across western Montana, but more isolated damage and power outages in north central Idaho.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. 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.
A vigorous cold front sweeping through the region produced widespread damage across western Montana, but more isolated damage and power outages in north central Idaho.
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 Nov 15, 1:47 PM PST, 7 hours 43 minutes earlier.
Area Forecast Discussion
National Weather Service Missoula MT
247 PM MST Mon Nov 15 2021
...DAMAGING WINDS PRESENT ACROSS NORTHERN ROCKIES THIS EVENING
THROUGH TUESDAY MORNING...
.DISCUSSION...
A powerful Pacific jet stream is expected to move over the Northern
Rockies this evening through Tuesday morning, bringing damaging
winds down to the deck. The strong winds will be accompanied by
strong mountain wave activity, where winds off the terrain
concentrate over a limited area for a short duration. High-profile
vehicles will be particularly susceptible to dangerous crosswinds.
Recent saturated ground and wind gusts over 60 mph may damage trees
and infrastructure.
A cold front associated with the powerful Pacific jet stream will
move across the Northern Rockies overnight tonight, concentrating a
burst of snow and rain along the front. There may be a quick dusting
of snow and a brief period low visibility as the front passes
tonight.
By Tuesday afternoon, air aloft is anticipated to cool significantly
and create a potential heavy snow scenario in deep instability.
Portions of west central and southwest Montana will be prime for
snow squalls Tuesday afternoon and evening. Travelers should prepare
for short-duration, powerful bursts of snow that will reduce
visibility and create dangerous road conditions. Snow is anticipated
to drift across the Continental Divide sometime after midnight
(Tuesday into Wednesday) and dwindle throughout the remainder of the
overnight.
High pressure will be present over the Northern Rockies Wednesday
and Thursday, however the nature of the air in-place will not be
supportive to warm conditions. In fact, some valleys may not warm
nearly as much as surrounding terrain (i.e., temperature
inversions), but the magnitude of this valley cold will be somewhat
dependent upon whether or not Tuesday evening snow remains on the
ground in the Tuesday-Wednesday timeframe.
A Pacific storm system is anticipated to disrupt the high pressure
in the Friday through Saturday period, with high-elevation snow and
a wintry mix at lower elevations. The northwest oriented airflow at
the ridgetops on Saturday may be conducive for another round of
banded snow feature, but current weather models provide only limited
clarity on that point.
Aside from a few weak storm system disrupting the status quo, high
pressure appears to be the most prominent weather feature present
across the Northern Rockies in the day 6-14 period. Valley cold
pools may become commonplace across the region, as sun angle
continues to drop.
&&
.AVIATION...Strong winds aloft will eventually mix down to the
surface and translate to widespread west-southwest winds of 20 to
30 knots with gusts up to 50 knots. Timing of strongest winds will
be around and after 16/0000Z through 16/1500Z, with elevated
winds persisting through 17/0000Z. Pilots should also anticipate
low level wind shear at all terminals through roughly 16/1200Z.
Precipitation will begin as rainfall for most locations this
evening with a transition to snow by Tuesday morning. Snow squalls
with isolated wind gusts and periodically low visibility in areas
of heavier bursts of snow will be possible across western
Montana, primarily impacting KMSO and KBTM.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT... High Wind Warning from 7 PM this evening to 8 AM MST Tuesday
Missoula/Bitterroot Valleys.
High Wind Warning until 2 AM MST Tuesday Flathead/Mission
Valleys...Kootenai/Cabinet Region...Lower Clark Fork Region.
High Wind Warning until 8 AM MST Tuesday West Glacier Region.
High Wind Warning from 7 PM this evening to 8 AM MST Tuesday
Bitterroot/Sapphire Mountains...Butte/Blackfoot Region...
Potomac/Seeley Lake Region.
ID...Wind Advisory until midnight PST tonight Northern Clearwater
Mountains...Southern Clearwater Mountains.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
805 PM MST MON NOV 15 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0530 PM NON-TSTM WND GST 6 E LONEPINE 47.70N 114.51W
11/15/2021 M55 MPH LAKE MT MESONET
MESONET STATION MTM57 5.7 E LONEPINE
(MT-MESO).
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
816 PM MST MON NOV 15 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0815 PM NON-TSTM WND DMG 1 SW MISSOULA 46.86N 114.01W
11/15/2021 MISSOULA MT BROADCAST MEDIA
A LARGE TREE WAS BLOWN DOWN ONTO MOUNT
STREET, NEAR BROOKS STREET 1 MILE SOUTH OF
MISSOULA.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
920 PM MST MON NOV 15 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0919 PM NON-TSTM WND DMG CORAM 48.43N 114.04W
11/15/2021 FLATHEAD MT DEPT OF HIGHWAYS
HIGHWAY 2 BLOCKED DUE TO FALLEN TREES IN TWO
SEPARATE LOCATIONS BETWEEN CORAM AND ESSEX.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
921 PM MST MON NOV 15 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0920 PM NON-TSTM WND DMG CONDON 47.52N 113.70W
11/15/2021 MISSOULA MT DEPT OF HIGHWAYS
HIGHWAY 83 BLOCKED NEAR CONDON DUE TO FALLEN
TREES.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
922 PM MST MON NOV 15 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0922 PM NON-TSTM WND DMG 1 NNW TARKIO 47.03N 114.74W
11/15/2021 MINERAL MT DEPT OF HIGHWAYS
MULLAN RD NORTH OF TARKIO IS BLOCKED DUE TO
FALLEN TREES.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
949 PM MST MON NOV 15 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0948 PM NON-TSTM WND DMG NYACK 48.44N 113.81W
11/15/2021 FLATHEAD MT DEPT OF HIGHWAYS
SEVERAL DOWNED TREES ALONG HIGHWAY 2 NEAR
NYACK.
&&The national radar mosaic for the moment the first event began.
1 strong wind. Local standard time, as filed.
A downed tree in the Old Ahsanka Grade area led to 1100 customers losing power, according to Clearwater Power.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2021Every state in 2021This day in weather historyWarnings in Idaho, November 2021
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: 991937.