Alert archive / Montana / Winter Weather Advisories in 2021

Winter Weather Advisory 67, NWS Missoula, MT

December 14, 20214 counties in Montana

NWS Missoula, MT issued this winter weather advisory at Dec 14, 2021, 11:38 AM MST for 4 counties in Montana. It was in force for 9 hr.

The area

The counties it named.

The facts

Issued: Dec 14, 2021, 11:38 AM MST (18:38 UTC)
Expired: Dec 14, 2021, 8:33 PM MST
In force: 9 hr
Issued by: NWS Missoula, MT

Counties Granite County, MT, Lake County, MT, Missoula County, MT, Powell County, MT

The radar

The Missoula radar (KMSX), 30 km from the middle of the area, began a volume at 18:37 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 6.6 hours before the alert went out and 232 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1888 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 244 m²/s²
0-3 km storm-relative helicity: 197 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this winter weather advisory went out, 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 this winter weather advisory went out at Dec 14, 4:21 AM MST, 7 hours 17 minutes earlier.

Area forecast discussion, Dec 14, 4:21 AM MST, 7 hours 17 minutes before

Area Forecast Discussion
National Weather Service Missoula MT
421 AM MST Tue Dec 14 2021

...Active Winter Weather pattern through the weekend...

.DISCUSSION...The Idaho County Sheriff posted on Facebook early
this morning that road conditions were poor on Highway 95 with
multiple slide-offs and stalled vehicles due to heavy snow. Snow
will persist this morning only to lessen in intensity by late
morning or early afternoon. In other locations in Montana and also
in Lemhi County, the precipitation has varied from rain, sleet to
snow. The rain in Kalispell will changeover to snow this morning.
A weather spotter call in from Libby to report that 3 inches of
snow has fallen since Monday afternoon. Mixed precipitation is
also possible across west-central Montana and a few locations will
also experience a changeover to snow once the more steady
precipitation shifts eastwards.

Some clearing is expected later tonight and will allow
temperatures across the region to fall into the teens and 20s most
valleys, but single digits in the mountains.

The next weather system arrives Wednesday night into Thursday
with the precipitation type mostly snow across north-central
Idaho and western Montana. The areas that will pick up the most
snow will be the Clearwater Mountains, 5 to 8 inches potentially
for the Elk River and Pierce areas, 3 to 6 inches for both
Lookout and Lolo Passes and Marias Pass. Lower Valleys could pick
up a dusting to 3 inches. Snow showers will persist through Friday
morning. An arctic airmass will shift southeast out of Alberta,
Canada Thursday night into Friday morning. Some of that colder air
could seep westward into the Glacier Park region. The main
impacts of that would be an enhanced potential for snowfall during
that timeframe with some south to east winds through Marias Pass
and Essex.

The 3rd weather system will impact the region Saturday and Sunday.
This trough will be a juicier than the last, so moderate to heavy
mountain snowfall is more likely. This could impact travel
through the mountain passes along the Idaho and Montana border.
There is a 50 percent chance that Lookout Pass could receive at
least 12 inches of snow during this event. Also another impact
will be strong south winds in the Camas Prairie on Saturday.

Looking further down the road into the following week... Latest
indications are that the large blocking high over the northern
Pacific with weather systems dropping southeastward out of Alaska will
continue. Slightly higher confidence is that an active pattern
will continue. This should continue to help the mountains build
snowpack. Lesser confidence with what will happen in the valleys,
maybe a continuance of a roller-coaster ride in terms of up and
down temperatures with varying precipitation types.

&&

.AVIATION...A weather system will bring mixed precipitation across
the region through 15/0300Z then partial clearing is expected.
Variable ceilings and visibility can be expected. SMN may
experience the best chance for snow later this afternoon, possibly
after 14/2000z. A brief break in the precipitation on Wednesday
before another snow-maker moves in by Thursday.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory until 5 PM MST this afternoon
     Butte/Blackfoot Region.

     Winter Weather Advisory until 11 AM MST this morning
     Bitterroot/Sapphire Mountains.

     Winter Weather Advisory until 11 AM MST this morning
     Missoula/Bitterroot Valleys.

     Winter Weather Advisory until 11 AM MST this morning Lower Clark
     Fork Region.

     Winter Weather Advisory until 11 AM MST this morning
     Flathead/Mission Valleys.

     Winter Weather Advisory until 11 AM MST this morning West
     Glacier Region.

     Winter Weather Advisory until 11 AM MST this morning
     Kootenai/Cabinet Region.

     Winter Weather Advisory until 11 AM MST this morning
     Potomac/Seeley Lake Region.

ID...Winter Weather Advisory until 11 AM MST this morning Eastern
     Lemhi County...Western Lemhi County.

     Winter Weather Advisory until 10 AM PST this morning Northern
     Clearwater Mountains...Southern Clearwater Mountains.

     Winter Weather Advisory until 10 AM PST this morning Lower Hells
     Canyon/Salmon River Region...Orofino/Grangeville Region.

&&

In the hours before

Local storm report, Dec 14, 8:02 AM MST, 3 hours 36 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
802 AM MST TUE DEC 14 2021

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

0801 AM     SNOW             NINEMILE                47.02N 114.41W
12/14/2021  E5.0 INCH        MISSOULA           MT   PUBLIC

&&

RNL

Local storm report, Dec 14, 8:10 AM MST, 3 hours 28 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
810 AM MST TUE DEC 14 2021

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

0809 AM     HEAVY SNOW       GRANGEVILLE             45.93N 116.12W
12/14/2021  M11.0 INCH       IDAHO              ID   PUBLIC

            SOCIAL MEDIA POST WITH A PICTURE OF A RULER
            STUCK IN THE SNOW.

&&

RNL

Local storm report, Dec 14, 8:46 AM MST, 2 hours 52 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
846 AM MST TUE DEC 14 2021

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

0845 AM     SNOW             KOOSKIA                 46.15N 115.98W
12/14/2021  E2.0 INCH        IDAHO              ID   PUBLIC

            2 INCHES IN TOWN, ABOUT 4 INCHES ESTIMATED
            AT 2,400 FT OUTSIDE OF TOWN. FACEBOOK
            COMMENT.

&&

RNL

Local storm report, Dec 14, 8:53 AM MST, 2 hours 45 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
853 AM MST TUE DEC 14 2021

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

0853 AM     SNOW             YAAK                    48.83N 115.71W
12/14/2021  M3.2 INCH        LINCOLN            MT   COCORAHS

&&

RNL

Local storm report, Dec 14, 9:22 AM MST, 2 hours 16 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
922 AM MST TUE DEC 14 2021

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

0921 AM     HEAVY SNOW       GRANGEVILLE             45.93N 116.12W
12/14/2021  M11.8 INCH       IDAHO              ID   PUBLIC

            SECOND REPORT FROM GRANGEVILLE ON SOCIAL
            MEDIA WITH A PICTURE OF A RULER IN THE SNOW.

&&

RNL

Local storm report, Dec 14, 11:16 AM MST, 22 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
1116 AM MST TUE DEC 14 2021

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

1115 AM     HEAVY SNOW       1 ESE COTTONWOOD        46.05N 116.33W
12/14/2021  M8.0 INCH        IDAHO              ID   PUBLIC

            SOCIAL MEDIA POST WITH PICTURE OF RULER IN
            THE SNOW AT 8 INCHES.

&&

RNL

The office that day

Everything else NWS Missoula, MT issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 14, 7:40 AM MST	Winter Storm Warning	MSO	Deer Lodge, Granite, Powell, Silver Bow	14 hr
Dec 14, 2:55 PM MST	Special Weather Statement	MSO	Silver Bow	65 min
Dec 14, 4:05 PM MST	Special Weather Statement	MSO	Lake	55 min
Dec 14, 4:36 PM MST	Winter Weather Advisory	MSO	Flathead, Lake, Sanders	4 hr
Dec 14, 4:47 PM MST	Winter Weather Advisory	MSO	Missoula, Ravalli	4 hr

Nearby

Winter Weather Advisories in Montana, 2021 Every winter weather advisory in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.