High Wind Warning 11, NWS Glasgow, MT

Area Forecast Discussion
National Weather Service Glasgow MT
331 AM MST Sat Dec 19 2020

.DISCUSSION...

A trough of low pressure from the Canadian Rockies is pushing a
tight pressure gradient through the region today. The thickest
cloud cover correlates with the axis of surface low pressure as
well, along with a few virga showers across portions of central
Montana. This seems to be just enough light shower activity to
pull down some stronger winds from aloft, even now during the
overnight and early morning hours for locations such as Havre and
Zortman, where winds have already been gusting in excess of 40
mph recently. Will keep a close eye on it, but I do not expect any
stronger winds to gust through the area today. Widespread 30 to
40 mph winds are more likely. Also, this overnight low pressure
trough is pushing these gusty west and southwest winds in a
chinooking effect across those central Montana locations, where
temperatures are already climbing greater than 40 degrees during
these early morning hours.

Sunday, concerns are increasing for another round of strong and
gusty winds as tight gradient westerly flow from the Canadian
Rockies continues to push through our region. The atmosphere will
allow for some of those gusty winds to reach the surface, as
evidenced by strong model lapse rates in excess of 7 C/km mainly
along and south of US Highway 2 from late Sunday morning through
early Sunday evening. There does not seem to be any regional cold
air advection, but models are starting to pick up on a few
scattered snow or rain showers in the area, which could assist in
pulling those stronger winds from aloft, down to the surface. As
the onset of these expected winds for Sunday are still more than
24 hours away, felt it was best to continue with the High Wind
Watch for now, and let the next shift re-evaluate these threats
and decide if an upgrade to warning is needed. At this time, I
still do not have enough certainty.

As the winds diminish back down below 15 kts on Monday, a weak
ridge of high pressure moves in from the southwest to briefly
clear out skies and keep conditions dry overall.

Monday evening through Wednesday morning, a stronger and colder
low pressure trough from the west will sweep through our region.
For the earlier part of this system, most precipitation will be
confined to central Montana and southern Saskatchewan. Through
the latter part of the system, when the colder northwest winds
take over, better chances for light precipitation will move
through northeast Montana from NW to SE, with little impact, maybe
up to half an inch of new snow through Wednesday morning.

Wednesday evening through Christmas Day, a strong ridge of high
pressure will keep conditions across the region dry and warmer
than average.

&&

.AVIATION...

FLIGHT CONDITIONs:  VFR.

LLWS: Expected at all TAF sites through this afternoon, with 2000
ft. winds over 50 kts possible at times.

WINDS: S-SW 5-15 kts through early this morning. Winds shift later
this morning, and become W 15-25 kts through this afternoon and
evening. Expect gustier winds on Sunday.

SYNOPSIS: A dry weak front moves through the region today.
Temperatures don't really drop behind this front, and its main
impact will be a shift in wind direction and increase in wind
speeds. Winds taper off Saturday night as the atmosphere
decouples, but picks back up Sunday for another round

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
High Wind Watch Sunday afternoon for Central and Southeast
Phillips...Central and Southern Valley...Dawson...Garfield...
McCone...Northern Phillips...Northern Valley...Petroleum...
Prairie...Richland...Western Roosevelt...Wibaux.

High Wind Watch from Sunday morning through Sunday afternoon for
Southwest Phillips.

&&

weather.gov/glasgow