Area Forecast Discussion
Issued by NWS Great Falls, MT

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000
FXUS65 KTFX 250004
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
500 PM MST Wed Dec 24 2014

UPDATE TO AVIATION SECTION

.DISCUSSION...

Tonight through Friday...An upper level low pressure trof will move
over the Rockies tonight and across the zones Thursday. The
associated cold front has brought widespread snow across the
northern and central portions of the CWA and is pushing into
Southwest Montana. Good lift will be in place across the zones by
this evening and mainly over the southern portions of the CWA after
midnight. Low-level winds strengthen near the Hiline this evening
and spread south. The snow is rather wet but some areas of blowing
snow are possible. The airmass will dry Thursday but northwest flow
aloft Thursday night through Friday will keep the region on a
cooling trend. A weak shortwave will move through the northwest flow
Friday and a cold front associated with this shortwave will cross
the Canadian border early Friday and bring another period of snow
and a further drop temperatures. Zelzer

Friday night through Wednesday...Expect mostly quiet conditions to
generally start the period...as the region will be in between storm
system. There is a small chance for a passing snow shower Friday
night/Saturday...but the bulk of the light snow arrives Saturday
night into Sunday. Snow accumulations should be on the low side with
this event...with 1 to 3 inches at lower elevations and 3 to 6
inches in the mountains. Again the Havre region should be the area
that receives the least snowfall. Behind the cold front on
Sunday...much colder air will move into the region. Forecast models
for the last 2 nights have been consistent in bringing down the
arctic air. I have not gone as cold as this system could potentially
be...to keep consistent with adjacent NWS Offices...but I could
easily see temperatures for both highs/lows about 10 to 15 degrees
colder than currently forecast for Sunday night through Wednesday
morning. Thus later shifts will continue to monitor this closely for
possible adjustments. Most models start to move the cold air out on
Wednesday...I have followed suite...but this currently forecast warm
up beginning on Wednesday is a bit uncertain at this time.
Additionally only a scattered light snow shower is possible from
time to time Monday thru Wednesday...with little to no snow
accumulation expected. Brusda

&&

.AVIATION...
UPDATED 0000Z.
Snow, along with breezy northerly winds and IFR/LIFR conditions, is
currently widespread across most of north central (KCTB KGTF KLWT)
and central (KHLN) Montana behind the cold front moving south
through the area. The cold front will continue to move south through
the remainder of southwest Montana through 06Z, spreading similar
IFR/LIFR conditions into KBZN by 04Z. Snow will begin to very
gradually decrease from the north beginning around 04Z, but the
lower flight conditions are expected to continue through at least
12Z. Conditions will further improve to MVFR/VFR between 12Z and 18Z
with decreasing northerly winds, with continued improvement through
00Z.  Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  18  24   8  23 / 100  50  10  30
CTB  15  24   9  21 / 100  10  20  20
HLN  21  24   7  21 / 100  80  30  30
BZN  19  22  -1  19 / 100 100  40  20
WEY  16  26  -5  19 / 100 100  40  20
DLN  22  27   5  23 / 100  90  30  20
HVR  20  27  14  26 / 100  20  20  30
LWT  19  22   6  22 / 100  80  20  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until 5 PM MST Thursday Beaverhead...
Broadwater...Fergus...Gallatin...Jefferson...Judith Basin...
Madison...Meagher.

WINTER WEATHER ADVISORY until 5 PM MST Thursday Cascade...
Central and Southern Lewis and Clark...Chouteau...Eastern Teton.

HIGH WIND WARNING until 9 PM MST this evening For Route 287 over
Norris Hill in Madison County.

WINTER WEATHER ADVISORY until 11 AM MST Thursday Eastern
Glacier...Eastern Pondera...Northern Rocky Mountain Front...
Southern Rocky Mountain Front...Toole.

&&

$$

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