Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 180315
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
815 PM MST Wed Jan 17 2018

.UPDATE...

Tonight`s forecast remains on track with no significant changes
necessary. We will continue to see increasing cloud cover well
downstream of a very strong Pacific low pressure area right off
the coastline of British Columbia. Thicker cloud cover, and breezy
southwesterly winds will keep temperatures from falling too far
area wide tonight. Look for snow to increase in coverage across
far western Glacier County, including Maria`s Pass and Logan`s
Pass around sunrise Thursday morning. Prognostic model trends
continue to show consistency with increasing coverage of rain, and
rain snow mix into central portions of the CWA by later Thursday
afternoon, then spreading south overnight Thursday night/Friday
morning. The better feed of moisture looks to reside across
central and southwestern areas early Friday morning, where winter
weather highlights may likely follow in later shifts. Snowfall
amounts of 4 to 6 inches in Kings Hill Pass, to 6 to 8 inches in
Lost Trail Pass will certainly lead to difficult travel conditions
early in the day. Additionally, the onset of light rain across
central areas, combined with falling temperatures overnight into
Friday morning may cause wet roads to freeze over leading to
difficult travel conditions. KLG

&&

.SYNOPSIS...
An upper level ridge of high pressure over the region today will
slowly move eastward tonight as a Pacific cold front approaches
the region. Expect light snow to develop by Thursday morning over
the Rocky Mountain Front, with a mix of rain and snow developing
Thursday night over Central and Southwest MT. Afternoon temperatures
will be mild on Thursday, but gradually cool down into the 20s and
30s over the weekend and into early next week.

&&

.AVIATION...
Updated 2355Z.

An impressive chinook arch remains positioned across portions of
North Central and Central Montana this late afternoon, generally
along and east of a White Sulphur Springs, to Great Falls, to Cut
Bank line. While ceilings associated with this chinook arch have
generally been above 12,000ft, some scattered ceilings approaching
MVFR are possible. Turbulence from mountain wave activity is
possible, especially near the Rocky Mountain Front. A storm system
will begin to move into the Northern Rockies then by the late
morning hours on Thursday, with precipitation overspreading portions
of North Central Montana during the afternoon hours and then into
portions of Southwest Montana by the evening hours. This storm will
bring mountain obscuration, especially to the mountains of Southwest
and Central Montana, along with the Rocky Mountains. Lowering
ceilings are anticipated, however, confidence in
ceilings/visibilities and the onset of precipitation remains low
this far out for the 1800/1900 TAF period. - Moldan

&&

.PREV DISCUSSION...
/ISSUED 455 PM MST Wed Jan 17 2018/
Tonight through Friday...Main concern over the next few days will
be the Pacific cold front approaching from the west. The front
will move through the region Thursday night, bringing an end to
the milder conditions. Light rain/snow will develop ahead of the
cold front. However, any period of rain should be fairly
light/short lived as the cold air will move in fairly quick. The
snow will begin up along the northern Rockies by Thursday morning,
and then generally continue into the evening hours. Further south,
the snow is not expected to begin until the evening hours. Most of
the snow will fall south of a line from Great Falls to Lewistown.
The snowfall will likely affect the Friday morning commute,
especially along the I-90 corridor from Whitehall to Bozeman. An
additional winter weather highlight might be needed for this
region in later forecasts. Mild temperatures on Thursday will cool
to a few degrees above normal on Friday. Brusda

Friday night through Thursday...The weather pattern will be more
active west of the divide during this period, as the flow aloft
will generally be out of the west. The westerly flow will create
downslope conditions east of the divide, limiting the amount of
precipitation. However, temperatures will be closer to January
normals, as temperatures continue a trend of slowly getting
colder. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  38  46  28  38 /   0  20  40  20
CTB  37  43  28  36 /   0  10  20  10
HLN  25  39  21  31 /   0  20  90  30
BZN  25  41  26  33 /   0  10 100  70
WEY  23  36  27  31 /  10  50  90  80
DLN  28  43  28  34 /   0  20  80  50
HVR  28  41  24  34 /   0  10  20  10
LWT  36  47  26  35 /   0  10  70  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 6 AM to 9 PM MST Thursday Northern
Rocky Mountain Front.

&&

$$

http://www.weather.gov/greatfalls



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