Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 110546
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1045 PM MST Sun Dec 10 2017

Aviation Section Updated

.UPDATE...

Satellite imagery this evening shows a compact shortwave/clipper
type system diving SE across SK with some cloud-cover extending
from this feature SW into central MT. While the clipper and it`s
main impacts will remain far east of the forecast area,
scattered-broken high cloud-cover will stream SE across northern
portions of the forecast area overnight. Have made some
adjustments to increase cloud-cover tonight. Otherwise, previous
forecast is in good shape with overall quiet and dry conditions.
Much colder conditions persist beneath temperature inversions in
SW MT valleys, where patchy fog development is anticipated again
later tonight. Hoenisch

&&

.SYNOPSIS...
With an upper level ridge of high pressure to our west, expect
mostly sunny skies over the region for the next few days. Afternoon
temperatures will be about 10 degrees above normal over the northern
Plains, while near normal temperature and morning fog can be
expected in the valleys of Southwest MT. A change in the weather
pattern is possible by next weekend, with a better chance for rain
and snow showers.

&&

.AVIATION...
Updated 0545z.
VFR conditions will prevail across much of the region through the
period. The exception will be the valleys of Southwest MT, mainly
around Helena/ West Yellowstone where some patchy freezing fog could
develop towards 12z before thinning around 17z. Otherwise no other
aviation impacts are expected at this time. Brusda

&&

.PREV DISCUSSION...
/ISSUED 456 PM MST Sun Dec 10 2017/

Tonight through Wednesday night...Strong upper level ridge remains
anchored along the West Coast with north to northwest flow aloft
persisting over Montana through the short term period. Models
continue to indicate that Pacific moisture will move over the top
of the ridge bringing variable mid- and high-level clouds over the
region but am expecting generally dry conditions to prevail at the
surface. Breezy to windy conditions are expected along the Rocky
Mountain Front and over the adjacent plains with mild temperatures
expected in northern portions of the CWA. However, strong
inversions will control the weather in the valleys of Southwest
Montana with overnight temperatures remaining very cold and areas
of freezing fog reducing visibilities at time, especially during
the early mornings. mpj

Thursday...The start of a changing weather pattern begins. Expect
more widespread westerly winds by late in the day across the
region. This will help mix out some of the colder air in the
Southwest valleys. A mix of rain/snow is possible over the western
mountains, especially by late in the day.

Friday into Sunday...Periods of rain/snow will move from west to
east through the region as weak upper level disturbances move
through. Precipitation amounts look light, but with the potential
for rain on top of snow covered roads, or wet daytime roads
freezing at night, some travel impacts are possible next weekend.
Afternoon temperatures are still progged to be a touch above
normal next weekend at this time. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  29  47  33  53 /   0   0   0   0
CTB  26  48  28  51 /   0   0   0   0
HLN  19  38  22  42 /   0   0   0   0
BZN  14  36  17  41 /   0   0   0   0
WEY  -3  31   0  34 /   0   0   0   0
DLN  17  41  20  42 /   0   0   0   0
HVR  25  45  25  50 /   0   0   0   0
LWT  28  46  30  53 /   0   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

http://www.weather.gov/greatfalls



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