Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 170119
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
615 PM MST Thu Nov 16 2017

...UPDATED AVIATION SECTION...

.SYNOPSIS...

An upper level trof will move through the region tonight. Expect
scattered rain and snow showers to become mostly snow showers after
Midnight. A few inches of snow are expected tonight through Friday
over the Rockies and across Southwest MT. Afternoon temperatures
will be a few degrees cooler on Friday as well. Expect windy
conditions along with seasonable temperatures over the weekend along
with mostly dry conditions.

&&

.DISCUSSION...

Tonight through Saturday...Initial cold front has already pushed
across the region bringing some snow showers to the Rocky Mountain
Front and scattered rain and snow to the southwest. Gusty winds
have also accompanied this frontal passage with a few areas seeing
gusts over 50 MPH. The rest of the evening will be much of the
same as we wait for the secondary clipper disturbance associated
with this front. Forecast still remains on track for impactful
snow across the Rocky Mountain front and portions of the
southwest tonight into tomorrow. Kept the Winter Weather advisory
across the south, while adding another advisory for the northern
Rocky Mountain Front above 4500. NAM has hinted that this
secondary wave may lead to an area of enhanced lift from about
Helena south to Ennis, including I-90. Here some convective bands
could bring localized moderate to perhaps heavy snow and a quick 2
to 4 inches of snow, mainly later tonight through Friday morning.
Confidence is low to moderate on this occurring. Will have to
monitor through the night for these potential snowband. Gusty
winds may diminish slightly overnight, however, the progressive
westerly pattern we transition to looks to leave us in a breezy
pattern through at least the short term and likely into the long
term. With these winds has come some blowing snow potential and
will continue to do so, especially for areas with fresh snow.
Temperatures will be cooler for tomorrow behind the mentioned
front, and be slightly below normal. Similar, and slightly below
normal temps, will also be found for Saturday. Mainly dry
conditions will also be found for Saturday as a weak ridge builds
to our south. Anglin

Saturday night through Thanksgiving Day...Mostly dry and
windy conditions start off the medium range period across Montana.
Northwest flow aloft will prevail Saturday night and Sunday with a
low pressure surface trough in Alberta and mountain-top level winds
in excess of 70 mph helping to fuel strong winds along the Rocky
Mountain Front. Model discrepancies are not as pronounced for the
Monday/Tuesday time frame as they have been and suggest that an
upper level trough will move over the region while a Canadian cold
front pushes southward through Montana. This suggests cooler
temperatures and an increasing chance for precipitation, especially
over the western mountains. However, is should still be noted that
models are not in very good agreement with regard to timing and
placement of precipitation during this period. Model solutions
continue to diverge through the Wednesday/Thursday time frame but
continue to suggest that warmer temperatures and breezy conditions
will be on-tap for the holiday. Unfortunately, however, neither
model is 100 percent dry so the possibility of rain/snow during this
travel period can not be ruled out. mpj

&&

.AVIATION...
Updated 0115Z.

VFR conditions will generally persist across most of the area for
much of the next 24 hours, but mountain snow will obscure many
mountain tops, and MVFR to possibly IFR conditions are possible in
snow at some terminals.

Snow showers will persist in the vicinity of a lingering Pacific
cold front over much of southwest Montana (including KBZN and KEKS)
through 06Z. A secondary Canadian cold front will then move south
through the forecast area, bringing fairly widespread snow to
southwest Montana between 12Z and 00Z. Although westerly downsloping
winds will keep the east slopes of the Rockies dry (KCTB and KGTF),
less of a downsloping influence over the eastern TFX plains (KHVR
and KLWT) will allow light snow to fall there between 15Z and 21Z.
Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  31  40  26  40 /  10  10   0  10
CTB  23  36  23  37 /  10  10   0  10
HLN  26  37  26  38 /  20  20  10  10
BZN  27  38  17  33 /  50  50  10  10
WEY  24  29   9  25 /  80  60  10  10
DLN  27  35  16  32 /  30  30  10  10
HVR  24  38  16  38 /  20  30  10  10
LWT  29  38  23  38 /  20  20  10  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 PM MST Friday Beaverhead...
Gallatin...Madison.

Winter Weather Advisory from 11 PM this evening to 3 PM MST
Friday above 4500 feet for Northern Rocky Mountain Front.

&&

$$

http://www.weather.gov/greatfalls



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