Winter Storm and Heavy Snow in Idaho, September 28 to 29, 2019

Name: Winter Storm and Heavy Snow in Idaho, September 28 to 29, 2019
Start: 2019-09-28T14:00
End: 2019-09-29T17:00
Location: Idaho

September 28 to 29, 2019 · NWS MSO · 4 events in 4 counties and zones

An early season snowstorm brought significant snow and gusty winds to the higher terrain and backcountry of central Idaho.

Where it happened

Every event with a place to put it; 4 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 4

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.

What happened

The episode as NWS MSO wrote it up.

An early season snowstorm brought significant snow and gusty winds to the higher terrain and backcountry of central Idaho.

What forecasters said that day

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 28, 12:50 PM PST, 1 hour 10 minutes earlier.

Area forecast discussion, Sep 28, 12:50 PM PST, 1 hour 10 minutes before

Area Forecast Discussion
National Weather Service Missoula MT
250 PM MDT Sat Sep 28 2019

...Snow expected to increase into valleys of west central and
southwest Montana tonight into Sunday morning...

.DISCUSSION...Phase one of the historic early season winter storm
is well underway this afternoon. Numerous wind gusts between 40 to
60 mph have been reported from Missoula northward to the Canadian
border and all along the Continental Divide. The strongest winds
have been focused along the east side of Flathead Lake, where
numerous large trees have come down along Highway 35. Winds are
expected to continue and possibly even increase slightly into this
evening. Up until this point, snow has largely been focused along
the higher terrain of the Continental Divide. Conditions have
begun to deteriorate for mountain passes in these areas, such as
Marias, Homestake and MacDonald Pass. Periods of white out
conditions will occur through the night as howling winds and heavy
snow continue.

Phase two of the storm starts tonight, as snow levels lower
further into most valley locations. Meanwhile, forecast models
indicate a mid level circulation will develop, with a band of
moderate precipitation. This band is expected to move through
central Idaho tonight and then into southwest and west-central
Montana Sunday morning. The chance to see some light snow
accumulations over the Camas Prairie is increasing, though ground
temperatures should keep impacts to roadways fairly minimal. Heavy
wet snow could become an additional stress to vegetation (on top
of continued gusty winds), particularly on Sunday morning across
southwest Montana. Tree and power line damage is possible where
the heavier snow develops. The Missoula and Bitterroot valley is
on the edge of where this heavier precipitation may occur.
The potential for significant damage is still there, so for the
time being, a winter storm watch remains in place.

Northwest Montana valleys will likely not see as much snowfall as
previously anticipated due to the continued gusty northeast winds
into mid day Sunday. The better chance for snowfall in these areas
comes Sunday afternoon and evening, however accumulations for the
most part look pretty limited.

Sunday night into Monday will see conditions improving overall,
though lingering rain and snow showers are anticipated. By Monday
night into Tuesday, clearing skies will allow overnight
temperatures to drop well below freezing. A hard freeze will cause
damage to sensitive vegetation and exposed irrigation equipment.
Well below normal temperatures will continue into at least mid
week.

&&

.AVIATION...Strong winds up to 40 kts have been impacting KGPI
today, and will continue to do so at similar magnitudes through at
least Sunday morning, if not later. Winds at KMSO will continue
to strengthen through the evening hours before leveling off,
maintaining gusts to 30-40 kts through the night. KBTM and KSMN
will see similarly strong winds, but timing is a little trickier.
The strongest winds may not begin until after 29/0600Z. Snow will
become a major player in aviation impacts at all terminals
beginning later tonight, particularly for KMSO after 29/0600Z and
becoming most intense around 29/1100Z through 29/1800Z. KGPI may
be a little delayed, due to a dry slot being observed, and snow
may only begin mid-morning Sunday. Light snow should be expected
at all terminals leading up to these time frames. Heavy impacts
will be limited to after 29/1200Z for all terminals.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Warning from 6 PM this evening to 6 PM MDT Sunday
     Bitterroot/Sapphire Mountains...Butte/Blackfoot Region...
     Potomac/Seeley Lake Region.

     Wind Advisory until 3 AM MDT Sunday Missoula/Bitterroot Valleys.

     Winter Storm Watch from late tonight through Sunday morning
     Missoula/Bitterroot Valleys.

     Winter Storm Warning until 6 PM MDT Sunday Lower Clark Fork
     Region.

     High Wind Warning until 9 AM MDT Sunday Flathead/Mission Valleys.

     Winter Storm Warning until 6 PM MDT Sunday West Glacier Region.

     High Wind Warning until 9 AM MDT Sunday Kootenai/Cabinet Region.

     Winter Weather Advisory from midnight tonight to 6 PM MDT Sunday
     Kootenai/Cabinet Region.

ID...Winter Storm Warning from 6 PM this evening to 6 PM MDT Sunday
     ABOVE 4500 FEET for the Eastern Lemhi County...Western
     Lemhi County.

     Winter Weather Advisory from 8 PM this evening to 11 AM PDT
     Sunday ABOVE 3000 FEET for the Lower Hells Canyon/Salmon
     River Region...Orofino/Grangeville Region.

     Winter Storm Warning until 5 PM PDT Sunday ABOVE 3000 FEET for
     the Northern Clearwater Mountains...Southern Clearwater
     Mountains.

&&

In the hours before

Local storm report, Sep 28, 10:47 AM PST, 3 hours 13 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
1247 PM MDT SAT SEP 28 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1200 PM     NON-TSTM WND GST 6 N WHITEFISH           48.50N 114.34W
09/28/2019  M51 MPH          FLATHEAD           MT   MESONET

            SUSTAINED 50-51 MPH WINDS OCCURRING AT THE
            SUMMIT OF BIG MOUNTAIN (WHITEFISH MOUNTAIN
            SKI RESORT).

&&

Local storm report, Sep 28, 10:51 AM PST, 3 hours 9 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
1251 PM MDT SAT SEP 28 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1250 PM     NON-TSTM WND DMG 3 SSE WOODS BAY         47.95N 114.03W
09/28/2019                   LAKE               MT   LAW ENFORCEMENT

            UP TO 1000 PEOPLE WITHOUT POWER FOR SEVERAL
            HOURS DUE TO DOWNED POWER LINES FROM WINDS.

&&

Local storm report, Sep 28, 11:06 AM PST, 2 hours 54 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
106 PM MDT SAT SEP 28 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1243 PM     NON-TSTM WND GST LA SALLE                48.31N 114.25W
09/28/2019  M44 MPH          FLATHEAD           MT   ASOS

            KGPI AIRPORT ASOS.

&&

Local storm report, Sep 28, 11:11 AM PST, 2 hours 49 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
111 PM MDT SAT SEP 28 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0105 PM     NON-TSTM WND DMG 6 SW TURAH              46.77N 113.90W
09/28/2019                   MISSOULA           MT   NWS EMPLOYEE

            TREES UPROOTED OR SNAPPED, AS WITNESSED BY
            NWS EMPLOYEE ON THE TRAIL.

&&

Local storm report, Sep 28, 12:53 PM PST, 1 hour 7 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
253 PM MDT SAT SEP 28 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0100 PM     NON-TSTM WND GST 6 N WHITEFISH           48.50N 114.34W
09/28/2019  M55 MPH          FLATHEAD           MT   MESONET

            AT THE SUMMIT OF BIG MOUNTAIN/WHITEFISH
            MOUNTAIN SKI RESORT.

&&

Local storm report, Sep 28, 1:04 PM PST, 56 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
304 PM MDT SAT SEP 28 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0230 PM     NON-TSTM WND GST 3 NNW FINLEY POINT      47.77N 114.09W
09/28/2019  M42 MPH          LAKE               MT   MESONET

&&

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

3 winter storm, 1 heavy snow. Local standard time, as filed.

Winter Storm, Southern Clearwater Mountains

When: September 28, 2:00 PM PST to September 29, 2:00 PM PST
Where: Southern Clearwater Mountains forecast zone
Reported by: SNOTEL
Coordinates: 45.844, -115.467 (the zone’s center; the record gives no point)

General snow amounts of 4 to 9 inches fell above 4000 feet with some locations above 6000 feet, recording over 12 inches of snow. Also, wind gusts to 40 mph were observed on the higher terrain. Difficult travel was experienced by backcountry users with periodic slippery, snow-covered, primary roads such as Highway 12 at Lolo Pass.

Heavy Snow, Northern Clearwater Mountains

When: September 28, 3:00 PM PST to September 29, 2:00 PM PST
Where: Northern Clearwater Mountains forecast zone
Reported by: SNOTEL
Coordinates: 46.674, -115.657 (the zone’s center; the record gives no point)

General snow amounts of 4 to 8 inches fell above 4000 feet with some locations above 6000 feet, experiencing over 12 inches of snow. Difficult travel was experienced by the backcountry users.

Winter Storm, Western Lemhi County

When: September 28, 11:00 PM MST to September 29, 2:00 PM MST
Where: Western Lemhi County forecast zone
Reported by: SNOTEL
Coordinates: 44.943, -113.933 (the zone’s center; the record gives no point)

Snow amounts of 4 to 8 inches were observed above 4000 feet with some locations above 7000 feet, recording over 12 inches of snow. Also, wind gusts to 30 mph were observed on the higher terrain. Backcountry users experienced difficult travel.

Winter Storm, Eastern Lemhi County

When: September 29, 1:00 AM MST to 5:00 PM MST
Where: Eastern Lemhi County forecast zone
Reported by: SNOTEL
Coordinates: 44.943, -113.933 (the zone’s center; the record gives no point)

Snow amounts of 4 to 8 inches were observed above 4000 feet with some locations above 7000 feet, reporting over 12 inches of snow. Also, wind gusts to 35 mph were observed on the higher terrain. Backcountry users experienced difficult travel with periodic slippery, snow-covered, primary roads such as Highway 93 at Lost Trail Pass.

What these are

Winter Storm: A storm that brought snow, sleet or freezing rain at warning levels, usually over several hours or days.
Heavy Snow: Snowfall reaching the local warning threshold without the other hazards of a winter storm.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Idaho in 2019 Every state in 2019 This day in weather history Warnings in Idaho, September 2019

Sources

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: 850542, 850536, 850546, 850555.