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000
FXUS65 KTFX 091800
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1100 AM MST Mon Dec 9 2013

...UPDATE TO AVIATION...

.AVIATION...
UPDATED 1800Z.
Strong northwest flow aloft will continue and several
disturbances will move through the region bringing lowered cig and
vis in snow showers. MVFR conds are expected in and near snow
showers with temporary IFR possible. Strong winds with gusts in excess
of 50 kts, especially near the Rockies and adjacent plains, will
continue until about 20Z when they should begin to diminish to a
degree. Winds will remain breezy after 20Z with gusts probably only
in the 30kt range. Expect widespread terrain obscuration.

&&

.UPDATE...
Minor update to the forecast this morning. Dropped the Wind Chill
Advisory for a lot of locations but kept it going for Southwest
Montana as wind chill readings remain very cold. Overall not much
change to the expected weather as snow showers and gusty winds will
continue through the day.

&&

.DISCUSSION...
/ISSUED 436 AM MST Mon Dec 9 2013/
Today through Wednesday...Strong winds have developed this morning
over the Rocky Mountain Front...thus a high wind warning has been
issued until Noon today for this region. There is the potential
that the Southern Rocky Mountain Front and Glacier and Blaine
Counties could be added to the high wind warning. Wind chill
advisory remains in effect...and wind chills should generally be
above advisory criteria by 10 am or so this morning. With the
strong winds over North Central MT...blowing snow advisory looks
good. A weak upper level disturbance will move southward through
the region today. This disturbance should be a bit weaker than the
disturbance on Sunday...so snowfall amounts still generally look
to be less than an a half inch at lower elevations and up to an
inch in the mountains today. Afternoon temperatures will warm a
touch today...but still remain 15 to 20 degrees below normal for
most areas. For Tuesday...another upper level disturbance will
move southward through the region. This disturbance will be a bit
stronger and snowfall amounts of 1 to 2 inches will be possible at
lower elevations with a 2 to 4 inch snowfall possible in the
mountains. There is the potential for isolated higher
amounts...especially in the mountains...and a winter weather
highlight may be needed for a portion of the region on Tuesday. By
Wednesday...quieter weather is expected to reside over the
region...with just a few passing snow showers. Warmer air will
also start to move back into the region...with afternoon highs
expected to be just a few degrees below normal. Brusda

Wednesday night through Sunday...An upper level high pressure ridge
will be over the Pacific Northwest Wednesday night. Weak
disturbances will continue to move over the ridge and into Alberta.
This will keep surface low pressure along the lee of the Rockies and
brisk surface winds across the Northern Rockies and adjacent plains.
The best chance for precip will be over the Rockies but the west
flow should keep points east quite dry. A fast-moving shortwave will
approach the West Coast by late Thursday afternoon and approach the
Rockies by early Friday.  This will increase the chance of snow over
the Rockies but most of the forecast area will continue dry. The
ridge will rebuild Friday night although several disturbances will
flatten the ridge and keep the air mass unsettled through Sunday.
Snow accumulations will generally only be significant over the
Rockies but winds will strengthen late Saturday and become strong
and gusty winds Saturday night. These strong winds could eventually
require high lights and will continue through Sunday. Temperatures
across the region will generally remain slightly above seasonal
normals through the period. Zelzer

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  20   7  20   4 /  20  20  70  20
CTB  17   4  17   1 /  10  30  50  20
HLN  14   8  22   8 /  30  20  60  30
BZN  10   3  20   3 /  50  30  60  30
WEY   3 -13  13 -10 /  50  40  60  30
DLN  10   0  20   2 /  10  10  30  20
HVR  19   2  14  -9 /  50  30  60  20
LWT  23   8  21   2 /  50  30  80  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

WINTER WEATHER ADVISORY until 5 PM MST this afternoon Blaine...
Cascade...Chouteau...Eastern Glacier...Eastern Pondera...Eastern
Teton...Fergus...Hill...Judith Basin...Liberty...Northern Rocky
Mountain Front...Southern Rocky Mountain Front...Toole.

WIND CHILL ADVISORY until 1 PM MST this afternoon Beaverhead...
Gallatin...Madison.

WINTER WEATHER ADVISORY until 5 PM MST this afternoon Central
and Southern Lewis and Clark.

HIGH WIND WARNING until Noon MST today Eastern Glacier...
Northern Rocky Mountain Front...Southern Rocky Mountain Front.

&&

$$

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