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000
FXUS65 KTFX 101510
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
810 AM MST Tue Dec 10 2013



.UPDATE...
Winds have diminished considerably over the southern Rocky Mounain
Front so have cancelled the high wind warning for this morning in
that area. Blank

&&

.AVIATION...
UPDATED 1144Z.
An upper level low pressure short wave will move through the
northwest flow this morning. Light snow will reduce visibilities and
lowered cigs will also cause IFR/MVFR conditions near snow showers.
Mountain obscuration should be expected through the day. Conditions
will improve this evening as the high pressure again builds over
central Montana.

&&

.HYDROLOGY...
The flood advisory for the Gallatin River near Gallatin Gateway
will continue until the threat from flooding has ended. Ice jams
can be very slow to break up...especially as cold air continues to
reside in the Gallatin Valley. There is the potential for this
highlight to continue for several days.

&&

.PREV DISCUSSION...
/ISSUED 445 AM MST Tue Dec 10 2013/
Today through Thursday...
Highlights...
High wind warning until Noon today for the Southern Rocky Mountain
Front. Strong winds continue to affect areas west of Choteau...but
as the cold front moves through later this morning...wind speeds
should decrease below warning criteria.

Winter Weather Advisory for the Rocky Mountain Front and the Cut
Bank area...on track...with snow/blowing snow expected through today.

Winter Weather Advisory for the Great Falls to Lewistown area. A
band of snow will move through Central MT this morning...affecting
Judith Basin/Fergus counties right away. A 2 to 3 inch snowfall is
expected at lower elevations in this region...with 3 to 5 inches
in the Mountains. The snow will back build into the Great Falls
area after 10 am this morning as the cold front moves through. A
1 to 3 inch snowfall is expected in the city of Great
Falls...with up to 5 inches in the foothills of the
southern/eastern portions of Cascade County. The bulk of the
accumulating snow should end around 5 PM across all of Central MT.

Wind Chill advisory for the mountains of Southwest MT...looks on
track...with the worst wind chills expected above 6000 feet this
morning.

Main discussion...An Alberta clipper will move southward through
the region today. As a result...a band of light snow will move
southeastward through the region...affecting the Rocky Mountain
Front and a good portion of Central MT. Scattered snow showers are
expected in Southwest MT...but overall snow amounts should be on
the lower side across much of Southwest MT. The bulk of the
accumulating snow will come to an end by 5 PM Today. High
temperatures are likely to occur early today...especially over
North Central MT. Temperatures will cool a bit behind the cold
front this afternoon...but nothing dramatic. For tonight...expect
snow showers to come to an end for most areas...but generally
linger through the night over the front range. For Wednesday and
Thursday expect warmer air to move back into the region...as an
upper level ridge builds over the Pacific Northwest. Afternoon
temperatures should be slightly below normal on Wednesday...but
could be several degrees above normal on Thursday. However...with
the above normal temperatures expected...a return to more
widespread strong winds are also possible. High wind highlights
may be needed for portions of the Rocky Mountain Front and
adjacent plains for Thursday. In terms of precip...expect a chance
for snow showers to continue over the Rocky Mountain Front through
the period...with isolated snow showers possible over the Central
Mountains. Little/no precip is expected elsewhere. Brusda

Thursday night though Monday...An upper level low pressure
shortwave will move through the Pacific Northwest Thursday night
and cross the Northern Rockies by early morning Friday. This will
bring in increased chance of precipitation across central Montana
Thursday night and Friday, and some accumulations at higher
elevations could be significant. The shortwave will also keep the
surface lee trof in place and the resulting brisk winds across the
Rockies and adjacent plains. High pressure will rebuild aloft
again by late Friday although several weak disturbances will be
moving through the northwest flow aloft. This will keep the air
mass unsettled with at least a chance of precip in most areas. A
low pressure trof in Alberta will rotate across eastern Montana
Saturday. Most of the dynamics will remain to the east however the
chance of precip will increase once again and an associated cold
front will drop south and bring cooler temps across mainly the
northern and central zones. By Saturday night, another shortwave
will cross the Pacific Northwest and increase the threat of
precipitation again. The models disagree somewhat on temps with
the GFS being cooler than the ECMWF. This system will also develop
a strong low pressure trof along the lee of the Rockies. Strong
and gusty winds should develop across the Rockies and adjacent
plains although at this point the models have not been consistent.
Unsettled northwest flow aloft will continue through the end of
the period and a chance of precip and breezy conditions will
continue. Temperatures will not vary too much from normals,
dropping slightly below early in the period and rising back to
near or slightly above normals by Sunday. Zelzer

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  27   6  32  24 /  90  10  10  10
CTB  22   4  31  21 /  50  10  10  10
HLN  25   9  28  15 /  60  10  10  10
BZN  24   1  23   7 /  60  20  10  10
WEY  12 -12  18  -3 /  60  30  10  10
DLN  19   1  25   8 /  30  10   0  10
HVR  22  -6  25  14 /  60  10  10  10
LWT  28   3  34  19 /  90  20  10  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until 5 PM MST this afternoon Eastern
Glacier...Northern Rocky Mountain Front...Southern Rocky
Mountain Front.

WIND CHILL ADVISORY until 11 AM MST this morning FOR ELEVATIONS
ABOVE 6000 FEET FOR Beaverhead...Gallatin...Madison.

WINTER WEATHER ADVISORY until 5 PM MST this afternoon Cascade...
Fergus...Judith Basin.

FLOOD ADVISORY until further notice for the Gallatin River near
Gallatin Gateway.

&&

$$


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