Winter Weather Advisory 2, NWS Great Falls, MT

Area Forecast Discussion
National Weather Service Great Falls MT
306 PM MST Sun Jan 3 2021

.SYNOPSIS...

Very strong and gusty west winds and mountain snow will diminish
through the evening hours. Lower elevation rain/snow showers
moving through the eastern portions of Central and North-central
Montana will tapper off once the front exits the region late this
afternoon. Quieter weather is expected for Monday but more wind
and mountain snow if forecast Monday night into Tuesday.

&&

.DISCUSSION...

Remainder of this afternoon through Monday afternoon...A strong
Pacific Front swept through the region and brought wind gusts
close to 70 mph along with rain and snow showers as it passed.
This front is now moving through the eastern portions of the CWA
as of this writing and should clear our area by late this
afternoon. The High Wind Warnings for for the Rocky Mountain
front, Tool, and East Glacier Counties were canceled early as the
wind threat has passes for these locations. The remaining wind
products were allowed to continue but further eastward trimming of
the warned area is likely later this afternoon as the high wind
threat moves east with the cold front. Snow has diminished in the
Marias Pass are but will keep the winter Weather Advisory going
here due to visible blowing snow on local MDT road cameras. Aside
from a brief drop in temperature, there is not much in the way of
cold air in the wake of this front. Tonight's lows will still be
slightly cooler than last night but still well above average.
There will be a brief period transient ridging on Monday for
quieter conditions overnight through early Monday afternoon. RCG

Monday evening through next Sunday...The next disturbance arrives
by late Monday afternoon, brining another round of gusty winds
and mostly mountain precipitation. Winds with this system do not
appear to be strong enough for High Highlights at this time but
Winter Weather Advisories will be considered in the near future
for the East Glacier area and possible the Centennial and Henry's
Lake Mountain in far Southwestern MT. At least a few snow showers
will be possible over lower elevations late Monday night into
early Tuesday as colder northwesterly flow moves through the
region. Another transient ridge brings mostly dry conditions
Tuesday evening into Wednesday, followed by another weather system
Thursday and Thursday night, then shortwave ridging on Friday.
This pattern will continue into next weekend, although diagnostic
model solutions become "messy and indeterminate" so timing of
shortwaves is currently considered low confidence. Will continue
to use the National Blend of Models (NBM) for the Saturday and
Sunday time frame. RCG/mpj

&&

.AVIATION..
1047 AM MST Sun Jan 3 2021 (03/18Z TAF period)

Low level wind shear, mountain wave turbulence, and strong surface
winds continue to be the primary concerns for this TAF period,
especially for Central/North-central areas. Surface wind gusts of 45
to 60 knots are expected over the plains terminals through early
this evening. Winds will be lighter over the southwest but there
will be a westerly wind shift this afternoon with a Cold frontal
passage, when gusts could approach and possibly exceed 35 kts for a
short period. Abundant Pacific moisture in strong westerly flow
aloft will continue to bring periods of mountain snow to the
Continental Divide and adjacent mountains through this evening. A
few rain/snow showers can't be ruled out for other areas this
afternoon, with the best chances at KCTB, KEKS, KHVR. Conditions
should improve markedly after 04/03Z with winds diminishing and
skies becoming partly to mostly clear for widespread VFR conditions
but low level wind shear will likely continue into the overnight
hours due to lingering strong northwesterly flow aloft. RCG/mpj

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  29  49  34  45 /   0   0  10  10
CTB  26  43  30  39 /   0   0  10  10
HLN  23  44  30  42 /   0   0  30  10
BZN  19  44  27  40 /   0  10  50  20
WYS  16  32  17  28 /  30  50  90  60
DLN  19  41  24  35 /   0  20  50  10
HVR  25  46  31  43 /   0   0  10  10
LWT  23  47  30  40 /   0   0  20  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 5 PM MST this afternoon Cascade...
Central and Southern Lewis and Clark...Chouteau...Eastern
Pondera...Eastern Teton...Judith Basin...Liberty.

High Wind Warning until 7 PM MST this evening Blaine...Fergus...
Hill...Meagher.

Winter Weather Advisory until 5 PM MST this afternoon Northern
Rocky Mountain Front.

&&

http://www.weather.gov/greatfalls