Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 280525
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1025 PM MST Thu Nov 27 2014

Updated Aviation Discussion

.UPDATE...
Minor updates to the forecast tonight but nothing of note. Dropped
POP over the plains through the day Friday as the incoming cold
front looks arrive sometime in the evening to night hours. Still
expecting sharply colder temperatures after a warm but windy day.

&&

.AVIATION...
UPDATED 0525Z.
Strong west flow aloft continues across the Northern Rockies and MT,
while at the surface, several waves of low pressure will move east
along the US/Canadian border, maintaining strong westerly surface
winds along and adjacent to the Rocky Mtn Front with breezy winds
further south and east through tonight. KHLN and KBZN terminals, as
well as other SW MT valley locations, will see light winds with a
wind shear layer just above the surface where moderate west flow
exists. Low clouds extending along and just north of the Canadian
border have moved south into the KHVR area and will impact that
location with low clouds/fog through much of tonight before the low
cloud deck retreats back to the north Friday morning. Otherwise, VFR
conditions will prevail through most of the day on Friday with an
Arctic cold front surging south into North Central MT late Friday
afternoon and evening, shifting winds to the North with snow
developing at North-central MT terminals by late Friday evening.
Hoenisch

&&

.PREV DISCUSSION...
/ISSUED 500 PM MST Thu Nov 27 2014/

Today through Saturday....Very strong west flow ahead of an
elongated upper level trof is moving across Central Montana.
Surface pressure falls over North-central Montana are
strengthening the pressure gradient and allowing strong winds to
mix down to the surface. Down-slope compression combined with warm
advection in this westerly flow has resulted in mild temperatures
across the region this afternoon. Highs reached the 40s and 50s
and visible satellite imagery shows snow cover eroding from the
west. Mild temperatures and strong gusty winds will continue
overnight. The high wind warning was expanded to include counties
adjacent to the Rocky Mountain Front and Norris Hill. Winds may
settle overnight but are expected to strengthen again Friday. Will
leave the High Wind Warning in place for subsequent shifts to
evaluate.

A cold front will move from Canada across the border late
Friday afternoon and move south through the zones during the
evening. Current timing shows low-level moisture crossing the
Canadian border as early as 2 in the afternoon, into Cut Bank by
5, and into Great Falls during the evening. This front will have
a tight surface pressure with it and strong gusty winds are
expected north of the front. Temperatures will fall rapidly and
Saturday will see bitter cold temps across the north and central
zones. Up-slope forcing will generate a period of heavy snow
Friday night into early Saturday along the Rocky Mountain Front.
A Winter Storm Watch is posted in these areas to anticipate
travel impacts over area passes. Snow is also expected Friday
night and Saturday across most of the region. With snowfall
amounts of 1 to 5 inches anticipated at lower elevations, will
let subsequent shifts evaluate the need for Winter Weather
Advisories for snow and blowing snow. Nutter

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  40  51  -3   7 /   0   0  70  80
CTB  37  45 -10  -3 /   0  30 100  80
HLN  36  50  14  26 /   0  10  50  80
BZN  32  49  28  37 /  10  10  30  70
WEY  28  38  25  34 /  20  20  70  70
DLN  35  47  33  39 /  10  10  30  70
HVR  31  43  -1   4 /   0   0  70  60
LWT  37  52   5  13 /   0   0  50  70

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

HIGH WIND WARNING until Midnight MST Friday Night Cascade...
Central and Southern Lewis and Clark...Eastern Glacier...Eastern
Pondera...Eastern Teton...Liberty...Northern Rocky Mountain
Front...Southern Rocky Mountain Front...Toole.

HIGH WIND WARNING until Midnight MST Friday Night For Route 287
over Norris Hill in Madison County.

WINTER STORM WATCH from Friday afternoon through Saturday
evening Central and Southern Lewis and Clark...Eastern Glacier...
Northern Rocky Mountain Front...Southern Rocky Mountain Front.

&&

$$

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