Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 201036

Area Forecast Discussion
National Weather Service Great Falls MT
336 AM MST Sat Jan 20 2018


High pressure over the Great Basin and a low pressure trough in
Alberta will combine for breezy to windy conditions over North
Central Montana through the weekend. Mostly dry conditions and
seasonable temperatures are expected at lower elevations. However,
the mountains near Glacier National Park will see periods of high
mountain snow today through Sunday.



Today through Monday...Montana will remain beneath a shortwave
ridge aloft this weekend while energy associated with a broad
upper trough moves through the southwestern USA. Downslope
pressure gradients along the Rocky Mountain Front will cause
breezy to windy conditions to prevail across North Central
Montana and temperatures will remain near seasonable averages.
Additionally, mostly dry conditions will prevail at lower
elevations through the weekend. The only exception to this will be
the higher mountains in and around Glacier National Park where
periods of snow can be anticipated today through Sunday.
Conditions are expected to change Sunday night into Monday as a
progressive westerly flow aloft brings shortwave energy through
the region. Widespread mountain snows will develop along the
Continental Divide and there will be an increasing chance for
precipitation for much of Southwest Montana. At this time, it
appears that snow amounts will remain generally light and I do not
anticipate the need for any winter weather highlights. mpj

Monday night through Saturday...Shortwave energy moves east of the
forecast area Monday night into Tuesday with precipitation
decreasing over the region. Medium range models are in good
agreement that a progressive flow aloft will move a broad upper
level ridge over the state Tuesday evening through Wednesday
morning for mostly dry conditions at lower elevations and slightly
warmer temperatures. However, the prevailing westerly flow aloft
will continue to bring a chance for light mountain snows along the
Continental Divide. By Wednesday evening a broad upper level
trough moves inland across the western USA, with the bulk of
associated energy and precipitation remaining mainly south of
Montana. Despite this, Montana is still expected to see a general
cool down in temperatures with unsettled conditions associated
with the upper trough bringing a chance for snow showers off and
on from Wednesday night through Saturday. mpj


Updated 0600Z.

Precipitation has mostly ended across the area. Most sites will
see lingering cloud cover and VFR conditions through the night.
Some mist or patchy valley fog is possible across southwest
Montana. Confidence is high enough to include some mention of
lower vis in the KEKS and KBZN TAFs. MVFR to brief IFR conditions
are possible. Mist and fog will diminish Saturday morning...with
dry and partly cloudy conditions expected. Some sites could see
cloud decks approach MVFR ceilings...especially in the southwest.
For now have kept them at VFR heights. Breezy winds are also
possible for Saturday...with some LLWS across the Hi-
Line...especially in the KCTB area. Confidence was to low to
include in TAF at this time. Patchy fog may then return Saturday
night...especially across southwest MT. Anglin


GTF  35  24  34  25 /  10  10   0  10
CTB  35  20  34  22 /  10  10   0  20
HLN  31  12  27  13 /  10  10   0  20
BZN  26   6  24   4 /  10  10  10  20
WEY  23  -5  22   7 /  10   0   0  30
DLN  25  12  26  15 /  10  10   0  30
HVR  30  17  27  13 /   0  10   0  10
LWT  31  18  32  18 /   0  10   0   0



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