A strong jet aloft with a core wind speed of 170+ mph helped drive a fast moving cold front which brought high winds to many locations across the Northern Rockies. Snow above 5500 feet lead to winter storm conditions for high passes and backcountry users (hunting season still in progress).
Every event with a place to put it; 5 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 strong jet aloft with a core wind speed of 170+ mph helped drive a fast moving cold front which brought high winds to many locations across the Northern Rockies. Snow above 5500 feet lead to winter storm conditions for high passes and backcountry users (hunting season still in progress). Lower atmosphere standardized wind anomalies ranged between +3 and +4 for this time of year, indicating a once-in-10-year wind event.
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 17, 1:45 PM PST, 4 hours 10 minutes earlier.
Area Forecast Discussion
National Weather Service Missoula MT
245 PM MST TUE NOV 17 2015
...Damaging winds for portions of the Northern Rockies this
evening and overnight...
...Potential development of snow bands Wednesday morning...
.DISCUSSION...
Damaging wind gusts remain on-track to impact the Northern
Rockies this afternoon through Wednesday morning. Some locations
that are of particular concern will be I-90 Deer Lodge to
Anaconda, the Bitterroot Valley, Highway 12 east of Garrison
Junction to MacDonald Pass, Homestake Pass, and Georgetown Lake
and vicinity, where wind gusts may briefly exceed 70 mph. Winds of
this magnitude will be perilous for high-profile vehicles, damage
to mature trees, significant damage to wooden power poles, and
damage to outdoor items sent airborne. Gust to 60 mph remain
possible for much of the rest of Northern Rockies, particularly
high valleys, mountain ridges, and mountain passes. A strong cold
front moving across the region overnight tonight will further
concentrate winds as wind direction shifts from southwest to
northwest.
Other impacts from this system, will be snow and blowing snow.
Snowfall has already occurred this morning, but is now confined
to the highest elevations with the rising snow levels. However,
snow levels are expected to crash back down to valley floors this
evening as the strong cold front pushes through. Mountain passes,
especially, Marias Pass will see periods of blizzard conditions
this evening when combining the wind and snow. Near zero
visibility and snow covered roads will cause hazardous driving
conditions tonight. Lolo and Lost Trail Passes will also
experience these conditions, though the winds are not expected to
be as strong. Therefore winter weather warnings remain in place
through the night. Valleys will also see a burst of snow overnight
along the front, although accumulations at this time, are expected
to be minimal.
One place to keep an eye on overnight and Wednesday morning, will
be MacDonald and Homestake Passes, as strong winds are forecast
to impact those regions, as well as periods of brief heavy snow.
Advisories/warnings in these areas may need to be revisited.
The potential for snow impacts will continue through the day on
Wednesday. With the rush of the colder airmass behind the front,
and the development of a northwesterly flow, snow banding is a
real possibility. Locations with the highest potential for seeing
snow bands will be the mountains and valleys along and south of
the I-90 Corridor. Expect rapidly changing road/visibility
changes due to the relatively narrow nature of the snow bands.
Some locations could see a few inches of snow, with areas a short
distance away, only relieving a trace of snow. After Wednesday,
expect light widespread snow showers to occur through Friday for
all of the Northern Rockies.
A relatively cold airmass is expected to move over the Northern
Rockies Friday night through Sunday. Models suggest that cold air
will settle into the area valleys and begin a period of daylong
temperature inversions. These inversions are likely to strengthen
through early next week, when high pressure will move overhead.
Freezing fog and low stratus will begin to be a possibility.
Temperature inversions will also have implications concerning air
quality around the region, particularly for prone poor winter air
quality valleys, such as Seeley-Swan, Missoula, Salmon, and low
elevations of Lincoln County.
Long range models suggest that a very broad and very complex
winter storm system will impact the Northern Rockies around the
middle of next week. Currently, there is modest confidence in the
timing and breadth of this system. Potential impacts from this
system include: difficult travel around the region due to snow,
blowing snow, and low visibility, as well as danger to humans and
animals from wind chill below zero. Get ready for winter.
&&
.AVIATION...Strong/damaging winds are still expected to impact
all aviation sites this evening and overnight. Snow levels will
be crashing to valley floors this evening once the sunsets and the
cold front pushes through. Lowering ceilings and mountain
obscurations can be expected for the rest of the evening through
tonight. Blizzard conditions can be expected as the cold front
makes it's way from a northwest to southeast direction. The strong
winds and snowfall will lower visibilities for a short period of
time. Strong mountain waves are anticipated behind the front for
northwest Montana, south through the Bitterroot valley. Valleys
could see winds gusts over 50kt for a period of time, with the
mountains seeing 50kt and greater sustained winds. The strongest
winds are expected to be between 0600Z-1200Z.
&&
.AIR STAGNATION...
High pressure over the Northern Rockies this weekend through early
next week will have the potential to create daylong temperature
inversions and stagnant airmasses within valleys across the
region. In particular, Seeley-Swan Valley, Missoula Valley, low
elevations of Lincoln County, and around Salmon Idaho will be most
prone to stagnant air.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Warning until 11 AM MST Wednesday ABOVE 5500 FEET
for the Bitterroot/Sapphire Mountains...Potomac/Seeley Lake
Region.
High Wind Warning from 5 PM this afternoon to 11 AM MST
Wednesday Butte/Blackfoot Region.
High Wind Warning from 5 PM this afternoon to 11 AM MST
Wednesday Flathead/Mission Valleys...Missoula/Bitterroot
Valleys.
High Wind Warning until 11 AM MST Wednesday Lower Clark Fork
Region.
Wind Advisory until 11 AM MST Wednesday Kootenai/Cabinet Region.
Winter Storm Warning until 11 AM MST Wednesday ABOVE 5000 FEET
for the West Glacier Region.
ID...Winter Storm Warning until 11 AM MST /10 AM PST/ Wednesday ABOVE
5500 FEET for the Eastern Lemhi County...Southern
Clearwater Mountains...Western Lemhi County.
High Wind Warning until 10 AM PST Wednesday Lower Hells
Canyon/Salmon River Region...Orofino/Grangeville Region.
Wind Advisory until 10 AM PST Wednesday Northern Clearwater
Mountains.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
628 PM MST TUE NOV 17 2015
...TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
...DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0615 PM NON-TSTM WND GST 1 N GRANGEVILLE 45.94N 116.12W
11/17/2015 M56 MPH IDAHO ID AWOS
AWOS STATION GRANGEVILLE AIRPORT /GIC/
&&
NWS MISSOULA MT
IRIS SYSTEMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
631 PM MST TUE NOV 17 2015
...TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
...DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0630 PM NON-TSTM WND GST BIGFORK 48.06N 114.07W
11/17/2015 M52 MPH FLATHEAD MT TRAINED SPOTTER
POWER HAS BEEN FLICKERING THE LAST 2 HOURS.
HAS SEEN LIGHT FLASHES DOWN THE STREET
POSSIBLY TRANSFORMER ISSUES.
&&
NWS MISSOULA MT
IRIS SYSTEMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
651 PM MST TUE NOV 17 2015
...TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
...DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0646 PM NON-TSTM WND GST 5 NNE FLORENCE 46.69N 114.03W
11/17/2015 M53 MPH MISSOULA MT MESONET
WIND DIRECTION IS DUE SOUTH.
&&
NWS MISSOULA MT
IRIS SYSTEMThe national radar mosaic for the moment the first event began.
3 winter storm, 2 high wind. Local standard time, as filed.
The wind sensor at Idaho County airport recorded sustained wind speeds of 44+ mph, with occasional gusts of 50 to 60 mph. The maximum measured gust was 61 mph at 6:55 pm PST.
A barn, with roof dimensions of approximately 40 by 50 feet, was blown off and traveled 100 to 150 feet to the east-southeast blocking both lanes of McIver Road. Based on the damage, the wind gusts could have been 75 mph.
The Saddle Mountain RAWS at 7900 ft reported 4 inches of snow overnight, with the nearby Deer Mountain RAWS reporting wind gusts of 63 mph during the early morning hours, making for dangerous back-country conditions.
The Savage pass SNOTEL at 6200 ft reported 6 inches of new snow overnight, with heavy snow from 11pm to 1am 11/18. Nearby RAWS sensors showed wind gusts of 40 to 60 mph, making for blizzard-like conditions for anyone in the high terrain.
The Morgan Creek SNOTEL at 7600 ft reported light snow overnight, with nearby winds at Skull Gulch gusting to 56 mph, making for dangerous back-country conditions.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2015Every state in 2015This day in weather historyWarnings in Idaho, November 2015
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: 605736, 605737, 607332, 607330, 607331.