High Wind in Montana, November 14 to 16, 2021

Area Forecast Discussion
National Weather Service Great Falls MT
510 AM MST Sun Nov 14 2021

...Update to aviation and removed the Winter Weather Advisory...

.SYNOPSIS...

Strong winds are expected across the area today, especially across
the plains of North-Central Montana, as a strong weather system
moves through the area. Wind gusts will be strongest along the
Rocky Mountain Front, where wind gusts in excess of 80 mph are
possible, with wind gusts over 60 mph expected across most of the
plains. Winds will weaken a bit on Sunday night and Monday
morning, but will return Monday afternoon as a strong cold front
pushes into the area.

&&

.DISCUSSION...

Current radar and satellite data this morning show clouds and
areas of light rain associated with an upper level warm front
(which appears to be very well defined for these parts) pushing
through the area this morning, along with some upslope rain and
snow showers along the Rocky Mountain Front. While things are
mainly quiet at this early hour, things will likely change quite a
bit after sunrise as thermal mixing begins to tap into stronger
winds a few thousand feet above the surface.

While we await the morning weather balloon data, model soundings
(a way to represent conditions through the atmosphere at a given
point) suggest that strong winds in excess of 60 mph are likely
already around 4000 feet above the surface across the plains, and
should continue to increase further through the day today. These
winds will readily mix their way down to the surface as the lower
levels of the atmosphere begin to mix this morning, which will
result in strong wind gusts for most places across the plains
today, with many areas seeing wind gusts over 60 mph, and some
areas along the Rocky Mountain Front seeing wind gusts well over
80 mph. These winds are expected to produce areas of significant
impacts, with the potential for power outages and blowing dust,
along with very difficult driving conditions, especially for
high-profile vehicles. The existing High Wind Watch was largely
left untouched, though Toole, Choteau, and Meagher Counties have
been added as portions of these counties are expected to see wind
gusts over 60 mph this afternoon. The High Wind Watch that was in
effect for the remainder of the plains has been scaled back a bit
for the remaining counties, and now goes into effect tomorrow
evening (more on that below).

Winds will remain quite strong through the evening and overnight,
though a slight reprieve is possible as thermal mixing relaxes a
bit. However, any overnight reprieve that we receive will be
short lived, as winds will quickly increase again after sunrise as
mixing resumes. In addition to the winds on Monday, it will be
quite warm for this time of year, with high temperatures in the
mid 60s for most of the area. This warm, downsloping air will also
be quite dry, which may result in a few areas of very elevated to
nearly critical fire weather conditions. However, this warmth
will not last long, as the final piece of this long lived wind
event will approach Monday evening in the form of a strong cold
front. As this cold front pushes through the area Monday night,
expect one final push of strong, gusty winds, with most areas
across the North-Central Plains seeing a decent chance at 60 mph
winds again. Behind the front, winds will gradually die down as a
much cooler and more seasonable air mass settles into the area.

Beyond this cooldown, things quickly become much less certain.
some of the global weather models suggest that upper level ridging
will build back into the region, though there is quite a bit of
disagreement as to the strength and staying power this ridge will
have. Regardless, expect temperatures to moderate slightly for the
remainder of the week, with limited chances for precipitation for
most of the area through Friday.
Ludwig

&&

.AVIATION...
500 PM MST Sun Nov 14 2021 (14/12Z TAF period)

Upper level warm front will continue to bring areas of light rain
showers to portions of the North-Central Plains and Continental
Divide through this morning. In addition, strong winds a few
thousand feet above the surface will quickly mix to the surface,
especially across the plains, this morning, resulting in strong wind
gusts and areas of blowing dust today. These strong winds will also
lead to mountain waves and turbulence, especially across SW MT and
near the Rocky Mountain Front. Ludwig

KWYS TAF will not be issued until airport operations resume next
spring.

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.

&&

.FIRE WEATHER...

A high wind event is expected to overspread the area today,
bringing widespread wind gusts over 60 mph across the plains from
today through Tuesday afternoon, with minimal chances for
precipitation. In addition, warm, dry air will arrive on Monday,
with high temperatures across the region reaching the low to mid
60s with RH values near or slightly above 20%. Fire weather
Watches/Warnings have not been issued as of this discussion, but
may be needed in future forecast updates.
Ludwig

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  62  49  65  31 /  20  10   0  20
CTB  57  45  57  26 /  20  20  20  50
HLN  63  45  66  33 /  10   0   0  30
BZN  63  40  64  32 /  20   0   0  20
WYS  42  29  45  28 /  30   0   0  30
DLN  59  37  60  31 /  10   0   0  30
HVR  60  43  63  28 /  80  20  10  20
LWT  60  45  64  29 /  70  10   0  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Watch from Monday evening through Tuesday morning
Blaine...Fergus...Hill...Liberty.

High Wind Warning from noon today to noon MST Tuesday Cascade...
Central and Southern Lewis and Clark...Chouteau...Eastern
Glacier...Eastern Pondera...Eastern Teton...Judith Basin...
Meagher...Northern Rocky Mountain Front...Southern Rocky
Mountain Front...Toole.

&&

http://www.weather.gov/greatfalls