Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 231642
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
942 AM MST Fri Jan 23 2015

.UPDATE...

Forecast area remains under a dry NW flow aloft downstream of an
upper level ridge axis along the US West Coast. Area will also
remain between shortwave disturbances today with one system
exiting to the south into WY this morning and another just moving
onto the BC Coast. The weak system now moving into WY managed to
weaken inversion/cold-pools that were lingering in some SW MT
valleys, including the Helena and Bozeman areas, and have warmed
temperatures some in those locations through this afternoon. Have
also decreased cloud-cover some for today based on clearing seen
on Satellite imagery behind the exiting system. Hoenisch

&&

.AVIATION...
UPDATED 1145Z.
A weather disturbance will result in a few snow showers over
southwest Montana until 15z. There will be local MVFR ceilings and
visibilities with the snow showers. Otherwise expect clear skies in
the north early this morning will spread south. This afternoon
ceilings well above 15000 ft will spread east over the area then
these ceilings will lower overnight and should range from 10000 ft
to 15000 ft after midnight. Meanwhile mountains of the Rocky Mountain
Front will become obscured in snow this evening with some mountain
obscurement developing over the southwest mountains after midnight.
The valleys of southwest Montana could see isolated rain or snow
showers also after midnight. There will even be a small risk of
brief freezing rain in the southwest valleys. With this
precipitation in the southwest valleys expect a threat of MVFR
ceilings and or visibilities. Unlike the typical diurnal trend winds
should increase after midnight over the plains with gusts of 50 to
60 knots possible in the windiest areas and there will even be a
threat of wind gusts to 50 knots at KCTB. Blank

&&

.PREV DISCUSSION...
/ISSUED 445 AM MST Fri Jan 23 2015/
Today through Sunday...A weather disturbance aloft will be moving
out of southwest Montana early this morning but do expect a few
associated snow showers into the morning commute. Moisture will be
increasing in a northwest flow aloft tonight and this pattern will
continue through Saturday night. There will be precipitation over
the mountains of the Rocky Mountain Front with scattered
precipitation for the other mountains. Snow levels from 4500 to
5500 feet tonight will rise to between 6500 and 7500 feet Saturday
night. Gusty downslope winds will keep the plains mostly dry. A
slight chance of freezing rain has been added to some of the
southwest valleys as nighttime temperatures are expected to fall to
below freezing. Should freezing rain happen to develop it should
not last very long. The approach of an upper ridge Sunday will
result in a little warmer temperatures along with a generally dry
day. As for the high wind warning it looks like periods of high
winds will continue into Sunday night so have extended the high
wind warning through Sunday evening.

Sunday Night through Friday...Medium range forecast models agree on
keeping an upper level ridge of high pressure over the western
United States through the early part of next week. This will keep
the area dry, breezy, and unseasonably warm through Tuesday, as
temperatures will likely remain 15 to 20 degrees above normal. A
shortwave trough will then move from off the southern California
coast Monday night through the southwestern U.S. on Tuesday and into
the central Rockies Tuesday night. This will bring a cooler and more
moist westerly flow aloft to the area Wednesday into Thursday, as
temperatures cool closer to normal with a chance of mainly mountain
precipitation. Models then indicate that the Hudson Bay low will
deepen into Friday, causing the flow aloft to shift more
northwesterly. This will cool temperatures close to freezing for the
plains, along with bringing an increased chance for snow. This
situation will continue to be monitored for a potential prolonged
weather pattern shift too cooler weather as January transitions into
February.  Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  46  36  48  40 /   0  10  20  10
CTB  44  35  45  38 /   0  10  10  10
HLN  44  27  43  31 /   0  10  20  30
BZN  41  22  43  27 /  10  10  20  30
WEY  30  12  29  20 /  20  20  30  30
DLN  42  27  47  30 /   0  10  20  20
HVR  42  34  44  35 /   0  20  20  10
LWT  45  31  45  33 /   0  10  30  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING until 11 PM MST Sunday Eastern Glacier...
Northern Rocky Mountain Front...Southern Rocky Mountain Front.

&&

$$

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