Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 131044
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
344 AM MST Fri Jan 13 2017

.DISCUSSION...

Today through Saturday Night...The main concerns through the first
half of the weekend will continue to be how strong the wind will get
across central Montana and how significant the impacts from
blowing/drifting snow will be. Temperatures will also be a
challenge. What does not look like an issue, for a change, is
precip. A dry, westerly flow aloft and general subsidence should
keep the entire area precip-free through Saturday night.

Regarding the wind, the lee-side trough from last night will
continue to weaken this morning allowing the pressure gradient at
the SFC to continue relaxing. This will result in a gradual decrease
in the strong winds this morning along the Rocky Mtn Front and
the adjacent plains from Cut Bank to Great Falls. That said, the
wind will likely remain strong enough this morning for areas of
blowing snow to continue for much of the morning. For this reason,
we are going to extend the current Blizzard Warning and Winter
Weather Advisories through Noon to capture impacts that may linger
later into the morning hours. Please continue to monitor MDT for
the latest road conditions, especially in the Blizzard Warning
area, where roads remain closed in and around the Browning area
as of 340am. If weather conditions improve quicker than expected,
the warning/advisory may be cancelled early.

The lee-side trough then strengthens again tonight through Saturday
night with an increase in the wind expected once again. The wind
will continue to be driven by the pressure gradient as winds aloft
remain fairly light. The pressure gradient tonight through Saturday
night look similar to last night/this morning, but not quite as
strong. But, I still expect some impacts from blowing/drifting snow
and it is possible that winter weather products for blowing snow
will once again be needed to cover the tonight through Saturday
night period.

Regarding temps, the downsloping SW/W wind over-achieved across the
foothills of central MT from Cut Bank to Lewistown, so it appears
the models actually have a good handle on temps through Saturday
there. However, in the greater Havre area and across the valleys
of SW MT, the models appear a bit too warm as the Arctic air will
have a tougher time mixing out, and I went a bit below guidance. Martin

Sunday through Friday...A fairly quiet weather pattern will start
the extended period...before becoming a bit more active by late in
the work week. An upper level ridge of high pressure will be
building over the Pacific Northwest from Sunday into
Monday...resulting in mostly dry conditions and a gradual warming
trend. For Monday night through Wednesday, weak upper level
disturbance will move eastward through the region and try to break
down the ridge. Expect a slight chance for a shower over the
northern Plains during this period, with a slightly better chance
for precipitation over the front range and across Southwest MT. The
airmass will be warm enough during this period that rain is likely
to fall for elevations below 6000 feet. It will be mild for this
time of the year for Tue/Wed, with lows possibly in the 30s and
highs in the 40s for many areas. For Wednesday night through Friday,
a cold front will move through the region...lowering temperatures
back closer to seasonal normals by Friday...and changing most of the
precipitation type back to mostly snow. However, the chances for
snow look to be on the low side...and confined mainly to the front
range and Southwest MT. Brusda

&&

.AVIATION...
Updated 0536z.

Area remains under a dry NW flow aloft through Friday with surface
high pressure centered over western and SW MT and in the Dakotas
while a surface trough remains along the east slopes of the Rockies.
Clear skies and light winds will prevail across SW MT terminals,
though some patchy fog cannot be ruled out for a period tonight. To
the north, breezy SW surface winds will continue through the
night before tapering off Friday morning as the lee surface trough
weakens. Strongest winds will be concentrated along and adjacent
to the Rocky Mtn Front where blowing snow has reduced surface
visibility as far east as the KCTB terminal. Cassell

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  27   9  30  18 /   0   0   0   0
CTB  23   3  29  15 /   0   0   0   0
HLN  13  -2  19   5 /   0   0   0   0
BZN  16  -7  20   2 /   0   0   0   0
WEY  19 -15  21  -6 /   0   0   0   0
DLN  19  -1  24   4 /   0   0   0   0
HVR  13  -5  21   6 /   0   0   0   0
LWT  30   5  33  15 /   0   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 11 AM MST this morning Cascade...
Eastern Glacier...Eastern Pondera...Eastern Teton...Fergus...
Judith Basin...Liberty...Southern Rocky Mountain Front...Toole.

Blizzard Warning until 11 AM MST this morning Northern Rocky
Mountain Front.

&&

$$

weather.gov/greatfalls



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