Montana, 2019

High Wind in Montana, December 20 to 21, 2019

December 20 to 21, 2019 · NWS TFX · 12 events in 5 counties and zones

Strong westerly flow aloft continues to yield mild and windy conditions across much of the forecast area through Sunday. Occasional light snow, rain, and some mixed precipitation continues for the Northern Rockies through Saturday night, before transitioning to mostly snow thereafter.

The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
12

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 TFX wrote it up.

Strong westerly flow aloft continues to yield mild and windy conditions across much of the forecast area through Sunday. Occasional light snow, rain, and some mixed precipitation continues for the Northern Rockies through Saturday night, before transitioning to mostly snow thereafter. The most impactful weather remains above pass level. Colder air moves in aloft and snow accumulation becomes more efficient. High Wind Warnings for the Rocky Mountain Front and portions of North-central Montana expire at midnight but the windy conditions continue into Saturday. Although, the flow aloft will remain strong, warning criteria winds are not forecast at the surface.

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 Great Falls, MT wrote its last area forecast discussion before the first event at Dec 20, 4:45 AM MST, 2 hours 30 minutes earlier.

Area forecast discussion, Dec 20, 4:45 AM MST, 2 hours 30 minutes before
Area Forecast Discussion
National Weather Service Great Falls MT
445 AM MST Fri Dec 20 2019

Aviation Section Updated.

.SYNOPSIS...

Mild, dry, and windy conditions will prevail along the Rocky
Mountain Front, and across the plains of North-central Montana
through Saturday. Snow will continue over the Northern Rockies
today, generally at elevations above 5000 feet. Cooler
temperatures are expected next week, with periods of light
mountain snowfall.

&&

.DISCUSSION...

Seasonally mild conditions prevail across the forecast area this
morning as a strong atmospheric river continues to transport a
long fetch of Pacific moisture toward the region. Radar and
surface observations reveal rain and snow advancing across
Northwest Montana and pushing up to the Continental Divide. Snow
levels over the Northern Rockies appear to be around 5000 feet
and slowly rising. Snow is accumulating on Marias Pass, where a
Winter Storm Warning remains in effect to address locally
difficult travel over the Marias summit due to snow and blowing
snow. Generally dry conditions prevail elsewhere as the downslope
westerly wind will inhibit precipitation away from the mountains.

The north to south surface pressure gradient remains quite strong
associated with the zonal jet aloft. A further strengthening
surface trough will contribute to a period of strong winds today
along the Rocky Mountain Front and across portions of central
Montana. Additionally, strong southerly winds are expected through
the Madison valley. High wind warnings remain in effect today. Take
actions to secure loose objects around construction zones, and
consider your wind limits if driving a lightweight high profile
vehicle or trailer. The strongest winds are expected through this
afternoon, but breezy conditions will continue on through the
weekend.

A weak shortwave trough moves across Northwest Montana on Monday,
creating a slight chance for light snow over the Northern
Rockies. Forecast model solutions begin to diverge after Monday,
but overall describe an unsettled split westerly flow pattern.
This will maintain generally dry conditions, with near average, to
slightly warmer than average temperatures through next week. A few
periods of mainly mountain snow should be expected through the
week.

&&

.AVIATION...
Updated 445 AM MST Fri Dec 20 2019 (12z/20 TAF period)

Strong winds aloft along with mountain wave activity are expected
through the forecast period for a continuing chance of low level
wind shear and turbulence aloft. Lower elevations east of the
Continental Divide will see breezy to windy conditions along with
variable mid and high level cloudiness. VFR conditions prevail,
except for MVFR ceilings at KWYS.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  50  37  53  35 /   0   0   0   0
CTB  47  33  47  30 /   0   0  10   0
HLN  48  32  50  30 /   0   0   0   0
BZN  45  26  48  27 /   0   0   0   0
WEY  29  16  36  19 /  40  10   0   0
DLN  38  23  41  25 /   0   0   0   0
HVR  46  34  47  30 /  10   0   0   0
LWT  46  35  50  35 /  10   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until midnight MST tonight Cascade...Eastern
Glacier...Eastern Pondera...Eastern Teton...Judith Basin...Toole.

High Wind Warning until midnight MST tonight Southern Rocky
Mountain Front.

High Wind Warning until midnight MST tonight below 5000 feet for
Northern Rocky Mountain Front.

Winter Storm Warning until noon MST Saturday above 5000 feet for
Northern Rocky Mountain Front.

&&

http://www.weather.gov/greatfalls

In the hours before

Local storm report, Dec 20, 2:38 AM MST, 4 hours 37 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
238 AM MST FRI DEC 20 2019

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

0140 AM     NON-TSTM WND GST 1 ENE EAST GLACIER PARK 48.45N 113.20W
12/20/2019  M56 MPH          GLACIER            MT   MESONET

&&

MOLDAN
Local storm report, Dec 20, 3:10 AM MST, 4 hours 5 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
310 AM MST FRI DEC 20 2019

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

0237 AM     NON-TSTM WND GST 2 SSE GEYSER            47.25N 110.48W
12/20/2019  M52 MPH          JUDITH BASIN       MT   MESONET

&&

MOLDAN
Local storm report, Dec 20, 4:41 AM MST, 2 hours 34 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
441 AM MST FRI DEC 20 2019

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

0252 AM     NON-TSTM WND GST 1 ENE EAST GLACIER PARK 48.45N 113.20W
12/20/2019  M59 MPH          GLACIER            MT   MESONET

&&

MOLDAN
Local storm report, Dec 20, 5:35 AM MST, 1 hour 40 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
535 AM MST FRI DEC 20 2019

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

0430 AM     NON-TSTM WND GST 14 W BYNUM              47.98N 112.61W
12/20/2019  M71 MPH          TETON              MT   MESONET

&&

MOLDAN
Local storm report, Dec 20, 5:51 AM MST, 1 hour 24 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
551 AM MST FRI DEC 20 2019

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

0451 AM     NON-TSTM WND GST 2 NW PENDROY            48.07N 112.33W
12/20/2019  M71 MPH          TETON              MT   MESONET

&&

MOLDAN
Local storm report, Dec 20, 5:52 AM MST, 1 hour 23 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
552 AM MST FRI DEC 20 2019

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

0455 AM     NON-TSTM WND GST 2 SE BROWNING           48.54N 112.98W
12/20/2019  M63 MPH          GLACIER            MT   MESONET

&&

MOLDAN

Event by event

12 high wind. Local standard time, as filed.

High Wind, Eastern Teton

When
December 20, 7:15 AM MST
Where
Eastern Teton forecast zone
Measured
69 kt (79 mph) measured gust
Reported by
Mesonet

Mesonet station delmt dellwo (mcscn).

High Wind, Madison

When
December 20, 9:12 AM MST to 10:27 AM MST
Where
Madison forecast zone
Measured
38 kt (44 mph) measured sustained
Reported by
Department of Highways

MT dot station at norris hill recorded an average sustained wind of 44 mph from 9:12 am to 10:27 am.

High Wind, Eastern Glacier

When
December 20, 9:37 AM MST
Where
Eastern Glacier forecast zone
Measured
63 kt (72 mph) measured gust
Reported by
Mesonet

Mesonet station mtbrn two medicine bridge (mt dot).

High Wind, Eastern Glacier

When
December 20, 10:45 AM MST
Where
Eastern Glacier forecast zone
Measured
63 kt (72 mph) measured gust
Reported by
Mesonet

Mesonet station shbm8, spring hill near browning.

High Wind, Toole

When
December 20, 11:44 AM MST
Where
Toole forecast zone
Measured
50 kt (58 mph) measured gust
Reported by
Mesonet

Mesonet station mtswt sweetgrass (mt dot).

High Wind, Eastern Teton

When
December 20, 8:57 PM MST
Where
Eastern Teton forecast zone
Measured
65 kt (75 mph) measured gust
Reported by
Mesonet

Mesonet station mtpnd pendroy (mt dot).

High Wind, Eastern Glacier

When
December 21, 12:37 AM MST
Where
Eastern Glacier forecast zone
Measured
59 kt (68 mph) measured gust
Reported by
Mesonet

Mesonet station mtbrn two medicine bridge (mt dot).

High Wind, Eastern Glacier

When
December 21, 12:13 PM MST
Where
Eastern Glacier forecast zone
Measured
65 kt (75 mph) measured gust
Reported by
Mesonet

Mesonet station mtbwg browning (mt dot).

High Wind, Eastern Teton

When
December 21, 12:45 PM MST
Where
Eastern Teton forecast zone
Measured
55 kt (63 mph) measured gust
Reported by
Mariner

Mesonet station mtm49 6.9 ne choteau (mt-meso).

High Wind, Cascade

When
December 21, 12:54 PM MST
Where
Cascade forecast zone
Measured
50 kt (58 mph) measured gust
Reported by
ASOS

Measured 5 wsw Great Falls.

High Wind, Toole

When
December 21, 3:06 PM MST
Where
Toole forecast zone
Measured
51 kt (59 mph) measured gust
Reported by
Mesonet

Mesonet station mtswt sweetgrass (mt dot).

High Wind, Eastern Teton

When
December 21, 6:09 PM MST
Where
Eastern Teton forecast zone
Measured
58 kt (67 mph) measured gust
Reported by
Mesonet

Gleason raws.

What these are

High Wind
Sustained non-thunderstorm winds of 40 mph or more for an hour, or gusts of 58 mph or more.

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

The same day elsewhere

More

Every storm in Montana in 2019Every state in 2019This day in weather historyWarnings in Montana, December 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: 869954, 869962, 869959, 869960, 869961, 869950, 869965, 869964, 869967, 869970, 869969, 869966.