Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 270243
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
843 PM MDT Mon Oct 26 2020

.UPDATE...
Main update this evening was to increase cloud cover over much of
the area overnight. The northwest flow aloft will continue to move
mid- and high-level cloudiness over the area. These clouds should
start to move out of the area later tonight through Tuesday
morning as the flow becomes more anticyclonic and moves the clouds
east out of the area.

Otherwise, breezy and gusty westerly winds continue over the
plains, which will likely prevent temperatures there from falling
much more (3 to 5 degrees west, 5 to 8 degrees east) through
midnight; the winds start increasing around and after midnight,
which will help warm temperatures overnight. The current
temperature and wind forecast appears to generally be on track.
Coulston

&&

.SYNOPSIS...

Strong and gusty winds will continue to cause areas of drifting
snow tonight through Tuesday across North-central Montana. Mostly
dry and warmer weather, accompanied by continued breezy to windy
conditions, will prevail from mid- week into early next week.

&&

.AVIATION...
630 PM MDT Mon Oct 26 2020 (27/00Z TAF period)

VFR conditions will continue through at least the next 24 hours
as scattered to broken mid and high level cloudiness moves over
North Central and Southwest Montana. The primary concern will be
the winds. The strong winds aloft will cause widespread
turbulence, as well as low level wind shear at the North Central
and Central Montana terminals (KCTB KHVR KLWT KGTF KHLN). Gusty
winds will gradually translate down to the surface over the
plains through 12Z and continuing through the period. The
strongest winds will likely occur on the Rocky Mountain Front and
adjacent plains. Coulston

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

&&

.PREV DISCUSSION...
/ISSUED 630 PM MDT Mon Oct 26 2020/

Increasing west winds are helping to push temperatures back to
near 30 degrees across North-central Montana this afternoon.
Drifting snow is occurring in some areas, but so far has not
resulted in significant reductions in visibility. The winter
weather advisory for blowing snow will remain in effect.

Surface pressure analyses indicate a strong 1039mb high
positioned over western Montana, coupled with falling pressure
east of the Continental Divide. The resulting, and increasing
pressure gradient is driving stronger winds along the Rocky
Mountain Front. The gradient and mid-level winds increase further
late tonight into Tuesday as a shortwave clipper system moves
through central Alberta. Confidence is moderate to high that
locations close to the northern Rocky Mountain Front will
experience a period of potentially impactful winds are likely to
occur Tuesday. The surface snow pack appears to have been mostly
scoured out, and with warmer temperatures, drifting and blowing
snow may be present but not expected to produce widespread
impacts. A high wind warning is now posted for this area.

Expect another very cold night in the Southwest MT valleys, but
then temperatures begin to gradually trend warmer.

Longer term forecast solutions continue to indicate a trend
toward seasonally mild and dry conditions. There may be some
periods of high winds late in the week under a strong westerly
flow aloft.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  20  42  28  45 /   0   0   0   0
CTB  21  40  26  41 /   0   0   0   0
HLN  16  44  27  49 /   0   0   0   0
BZN   6  41  18  48 /   0   0   0   0
WYS  -5  39   9  45 /   0   0   0   0
DLN  12  44  23  52 /   0   0   0   0
HVR  18  41  23  41 /   0   0   0   0
LWT  17  45  29  47 /   0   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon MDT Tuesday Cascade...Eastern
Glacier...Eastern Pondera...Eastern Teton...Judith Basin...Toole.

High Wind Warning from midnight tonight to midnight MDT Tuesday
night Eastern Glacier...Northern Rocky Mountain Front...Southern
Rocky Mountain Front.

Winter Weather Advisory until noon MDT Tuesday Central and
Southern Lewis and Clark...Northern Rocky Mountain Front...
Southern Rocky Mountain Front.

&&

$$

http://www.weather.gov/greatfalls


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