High Wind in Montana, February 28, 2022

Area Forecast Discussion
National Weather Service Great Falls MT
450 AM MST Mon Feb 28 2022

UPDATED AVIATION SECTION

.SYNOPSIS...

Strong westerly winds through Tuesday will help keep temperatures
well above normal into Wednesday. However, Pacific moisture will
likely bring significant snow accumulations to the higher terrain
on the Rocky Mountain Front. A few showers may fall over the
plains and in the valleys early in the week, but a Pacific weather
system will bring much cooler and more unsettled weather for the
mid to late week period.

&&

.DISCUSSION...

Today through Tuesday... A strong westerly flow aloft with deep
Pacific moisture will continue over the forecast area through this
period. Downsloping westerly winds will keep the bulk of the
precipitation in the mountains along the Continental Divide,
focused mostly on the Rocky Mountain Front. Snow levels will stay
between 5500 feet and 6500 feet through the period, limiting
accumulation to between 2 and 4 inches on Marias Pass; however,
the higher terrain will likely receive between 10 and 20 inches,
making conditions difficult for those venturing into the
backcountry. Weak disturbances moving over the area could bring a
few showers to the plains and southwest valleys, but any
precipitation should remain light.

The more pressing issue for the plains and southwest valleys will
be the wind. The surface pressure gradient will strengthen along
the Rocky Mountain Front and east across central Montana, which
will help translate the winds aloft down to the surface. The
likely periods for strong winds in those areas will be this
afternoon and evening and then again late Tuesday morning into the
afternoon hours. Gusts could range from 70 to 80 mph at times on
the Rocky Mountain Front, and areas across central Montana could
have gusts up to 65 mph. Therefore, will continue the High Wind
Warning as is from noon MST today through 4 pm MST Tuesday.
Another area that could get strong winds is the Ennis valley;
however, confidence is low at this time that High Wind criteria
will be met there. Regardless, the increase in winds in the
southwest valleys has already started to erode the temperature
inversions there, which should help bring milder temperatures.
Overall, temperatures should remain about 10 to 20 degrees above
normal.

Wednesday through Thursday... High pressure ridging will begin
building back into the area Tuesday into Wednesday, which will
help raise snow levels back into the 6000 to 7000 feet range and
help decrease winds. However, a frontal boundary along the
Canadian border will sag south over the plains on Wednesday, which
will provide a good focus for precipitation development. Most of
it will be in the form of light rain, but snow will be more
likely in the mountains, and some snow will mix with rain on the
Hi- Line, as temperatures start to decrease. A deep low pressure
trough will then start to push the high pressure ridge out of the
area Thursday, continuing a good feed of Pacific moisture over a
shallow cold airmass behind the Canadian front. As much of the
area changes over from rain to snow, some areas over the plains
could see a period of icing during the transition. Rain falling on
still frozen ground could cause slick spots, or mixed
precipitation could fall. However, confidence is still low in
either of these situations occurring, so keep an eye out for
further updates.

Thursday Night through next Monday... The low pressure trough
will deepen and settle over the western and central portions of
Canada and the United States, bringing colder and unsettled
weather, as temperatures struggle to get out of the lower 30s
during the daytime. Precipitation will increase and transition to
all snow Thursday night and continue to fall through Friday into
Friday night, before decreasing over the weekend. Expected snow
amounts are still a bit uncertain at this time, but there is a
good chance for at least light measurable snow at lower
elevations, so some winter weather highlights may eventually be
needed.
-Coulston

&&

.AVIATION...
450 AM MST Mon Feb 28 2022 (28/12Z TAF period)

VFR conditions are expected to continue under a strong westerly flow
aloft, but mountain wave turbulence and low level wind shear will be
widespread, possibly with some rotor winds along the Rocky Mountain
Front. Moisture in the flow will also obscure mountains on the Rocky
Mountain Front in clouds and precipitation.

Otherwise, gusty westerly winds will increase over the plains and
into the southwest valleys through 18Z. The strongest winds will be
on the Rocky Mountain Front and adjacent plains, as well as through
the KEKS valley; gusts will mostly be between 40 and 50 kt, but
closer to the Front, gusts could reach 65 kt at times. Winds will
decrease somewhat after 02Z. A few showers may also fall over the
area, but only brief reductions to MVFR conditions are possible.
-Coulston

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  54  39  57  35 /  20  20  10  10
CTB  47  34  50  30 /  30  40  30  10
HLN  54  40  58  36 /  30  30  10  10
BZN  46  32  53  30 /  20  20  10  10
WYS  35  19  41  19 /  10  30  50  20
DLN  49  32  53  33 /  10  30  20  10
HVR  53  38  56  33 /  40  50  20  10
LWT  49  38  54  34 /  30  30  10  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from noon today to 4 PM MST Tuesday Cascade...
Central and Southern Lewis and Clark...Eastern Glacier...Judith
Basin...Northern Rocky Mountain Front...Southern Rocky Mountain
Front.

&&

http://www.weather.gov/greatfalls