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000
FXUS65 KTFX 011006
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
306 AM MST Sun Mar 1 2015

...STRONG ARCTIC COLD FRONT WILL BRING A PERIOD OF SNOW AND
BLOWING SNOW TO MUCH OF NORTH CENTRAL AND SOUTHWEST MONTANA MONDAY
AFTERNOON AND MONDAY NIGHT...

.DISCUSSION...

Today through Tuesday...Northwest flow aloft persists over the
region today and tonight with generally dry conditions expected.
Cold airmass in place over the region will will modify and
slightly warm today as surface high pressure currently centered
over MT moves off to the east by this afternoon and weak lee-side
troughing begins to extend south along the east slopes of the
Rockies tonight. Upper level shortwave and Jet, currently moving
From AK into the YT, will dig sharply south late tonight through
Monday and continue south through the Northern Rockies Monday
night and Tuesday. This will allow an Arctic cold front to surge
south into north central MT by mid-day Monday, continuing south
through SW MT Monday evening. Models have been reliably consistent
with this feature producing a period of snowfall across much of the
area begining Monday morning along the Canadian border and
spreading south into central MT Monday afternoon and eventually
into SW MT Monday evening. Strong pressure rises following the
frontal passage will likely produce a period of very windy
conditions with blowing and drifting snow likely impacting travel
for a period late Monday afternoon and evening. Short duration of
this event will limit snowfall amounts somewhat with 2 to 4 inches
across much of the lower elevations and 4 to 8 inches in the
mountains. lowest snowfall totals will be across NE portions of
the forecast area where accumulations look to remain less than 2
inches. Much colder air flows into the region following the front
as well Monday night and Tuesday with many locations seeing wind
chill values 10 below to 20 below zero by late Monday night. Will
issue a winter weather advisory to highlight Wind/Snow/Blowing
Snow and Wind chill impacts Monday and Tuesday. Snow and winds
diminish Tuesday with Cold airmass settling over the region and
temperatures mainly in the single digits and low teens above zero.
Hoenisch

Tuesday night through Sunday...The upper level low pressure trof
will move east of the zones Tuesday night, high pressure will build
aloft, and the airmass will dry. This will lead to an end of
precipitation and clearing skies. At lower levels, the surface high
pressure will be over Central Montana and, with the clearing skies,
cold overnight low temps are expected. Some dangerous wind chills
are thus expected across the region. The surface high will be moving
east Wednesday and temperatures will begin to trend upwards. With a
high pressure ridge building over the West Coast, Central Montana
will be underneath northwest flow aloft. A disturbance moving
through this flow will bring some increased cloud cover to the area
and strengthen a surface trof along the lee of the Rockies. Brisk
winds along the slopes of the Rockies will result. Southwest flow
across the Rockies will also hasten the warming across western
portions of the region. A shortwave will move across the West Coast
Thursday and flatten the ridge. Moisture ahead of this system will
cross the Rockies late Thursday and bring a chance of precipitation
across the region. This shortwave will also strengthen winds and
breezy conditions will continue over the Rockies. The shortwave will
move east of the Rockies Friday and the airmass will dry again
Friday night. High pressure will build again through Saturday but
another shortwave will move through the Pacific Northwest Saturday
night. This will bring another chance of precipitation to the area
Saturday night and Sunday but any snow accumulations should remain
low and at higher elevations. Temps will begin the period below
normals Tuesday night and Wednesday but rise to near and above
normals Thursday. Temps will remain moderate thought the end of the
period. Zelzer

&&

.AVIATION...
UPDATED 0545Z.
Northwest to northerly flow aloft will continue. A weak disturbance
aloft moving across the area is responsible for areas of low clouds
and very light snow. These clouds will continue to push south
overnight with skies clearing from the north after 12z. VFR
conditions prevail with areas of MVFR possible in the vicinity of
light snow showers due to low ceilings.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  30  16  29  -4 /  10   0 100  90
CTB  30  14  22  -6 /  10  10 100  30
HLN  32  14  32   5 /  10   0  80 100
BZN  28   9  34   2 /   0   0  30 100
WEY  31   2  34  -5 /   0   0  20  80
DLN  31  10  38   4 /   0   0  20  90
HVR  29  12  28  -2 /  10   0  80  30
LWT  27  10  31  -4 /  10   0 100  80

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY from 5 PM Monday to 11 AM MST Tuesday
Beaverhead...Broadwater...Gallatin...Jefferson...Madison...
Meagher.

WINTER WEATHER ADVISORY from 11 AM Monday to 5 AM MST Tuesday
Cascade...Central and Southern Lewis and Clark...Chouteau...
Eastern Teton...Fergus...Judith Basin...Southern Rocky Mountain
Front.

WINTER WEATHER ADVISORY from 5 AM Monday to 5 AM MST Tuesday
Eastern Glacier...Eastern Pondera...Northern Rocky Mountain
Front...Toole.

&&

$$

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