High Wind in Montana, December 18 to 19, 2018

Name: High Wind in Montana, December 18 to 19, 2018
Start: 2018-12-18T23:31
End: 2018-12-19T01:45
Location: Montana

December 18 to 19, 2018 · NWS GGW · 1 event in 1 county or zone

Strong winds aloft were able to easily filter down to the surface as the inversion dispersed and a brief disturbance moved through the region.

Where it happened

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.

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Wind
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Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 1

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 GGW wrote it up.

Strong winds aloft were able to easily filter down to the surface as the inversion dispersed and a brief disturbance moved through the region.

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 Glasgow, MT wrote its last area forecast discussion before the first event at Dec 18, 10:47 PM MST, 44 minutes earlier.

Area forecast discussion, Dec 18, 10:47 PM MST, 44 minutes before

Area Forecast Discussion
National Weather Service Glasgow MT
1047 PM MST Tue Dec 18 2018

.DISCUSSION...
Update: Went ahead and upgraded the High Wind Watch to a Warning
as latest model guidance continues to show strong winds mainly
across Southwest Phillips and Petroleum counties. Otherwise, no
major changes to forecast grids. Still expect a slight chance of
showers tonight, with a deeper system affecting the region on
Friday. FGC

Previous discussion:

No significant changes were made with this package.

The High Wind Watch will be left in place as the highest speeds
seen in the forecast grids were at 43 kts (50 mph) over Petroleum
County. Will let the Midnight shift get another look.

Speeds were determined through a mixture of a NBM and MAV guidance
blend.
TFJ

Previous Discussion...
Quasi-zonal flow aloft will keep temperatures above normal for
the remainder of the week.

A shortwave trough and cold front will move through Central and
Eastern Montana tonight. With limited moisture, expect some mid
and high clouds tonight. The main impact of the cold front will be
gusty west winds on Wednesday. 850 mb winds are expected to be
around 50 knots Wednesday morning which means there will be a good
chance of wind gusts reaching 60 mph in SW Phillips County where
west winds tend to funnel around the Little Rockies and possibly
over parts of Petroleum County. Will issue a High Wind Watch for
Wednesday in these areas. Surface high moves in Wednesday Night
and diminishes the winds.

Upper ridge builds into Montana on Thursday with dry weather.
Lingering snow cover and light winds will keep temperatures
somewhat cooler along the Canadian Border.

The next cold front and shortwave trough is expected on Friday.
Models differ on how much moisture and cold air advection is
expected. Gusty west winds should bring good mixing which will
limit the immediate effects of cold air advection at the surface.
Will have a slight chance of light rain and snow on Friday for
now.

Flow aloft turns to the WNW for the weekend allowing colder air to
move in although they will still be around 5 degrees above normal
in most areas.

A weak wave may bring a slight chance of light snow to some areas
on Monday. Otherwise, expect mainly dry weather with slightly
above normal temperatures early next week. Forrester

&&

.AVIATION...

FLIGHT CAT: VFR.

Mid and high clouds will continue to move into the area through
tonight.

WIND: Light and west to southwest tonight. Becoming more
southerly and increasing to 10 to 15 knots this afternoon. Winds
will turn to the west tonight as a cold front moves through the
area and increase to 15 to 25 knots Wednesday morning.

LLWS: LLWS is expected this evening into early Wednesday as a
strong front approaches from the west. Some 30-40kts of shear is
likely across the entire region, including all of the TAF sites.

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 5 AM to 4 PM MST Wednesday for
Petroleum...Southwest Phillips.

&&

weather.gov/glasgow

The radar

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

Open the radar archive at this moment

Event by event

1 high wind. Local standard time, as filed.

High Wind, Little Rocky Mountains

When: December 18, 11:31 PM MST to December 19, 1:45 AM MST
Where: Little Rocky Mountains forecast zone
Measured: 35 kt (40 mph) measured sustained
Reported by: Department of Highways
Coordinates: 48.259, -107.913 (the zone’s center; the record gives no point)

At the Malta South US-191 DOT site, even though the maximum wind gust peaked at only 57 mph multiple times, sustained winds of 40 mph or greater were recorded each hour between 11:31 PM on the 18th and 1:45 AM on the 19th.

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

Every storm in Montana in 2018 Every state in 2018 This day in weather history Warnings in Montana, December 2018

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: 796734.