Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 241740
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1040 AM MST Tue Jan 24 2017

Aviation Section updated

.UPDATE...
Only minor updates to raise PoPs for our areas west of the
Continental Divide especially tonight, with weak upslope flow but
plentiful moisture in the prime dendritic growth zone. Expect any
accumulations to be light with only minimal impacts. No changes to
the forecast otherwise. Cassell

&&

.AVIATION...
Updated 1740Z.
Expect improving conditions in Southwest MT this afternoon as snow
exits the region and ceilings increase. Mountains will be obscured
though through into the evening hours. A area of light snow showers
will develop over the Rocky Mountain Front late tonight...mainly
affecting areas west of the divide and the passes. Some haze will
affect the Helena Valley...mostly after 6z Wed. Brusda

&&

.PREV DISCUSSION...
/ISSUED 440 AM MST Tue Jan 24 2017/

Today through Thursday...Longwave upper level trough remains
across the region today for continued cool northerly flow aloft.
Compact vort/mid level circulation centered over central WY this
morning will move off to the east today with light snow on the NW
periphery of this feature across SW MT this morning, diminishing
by noon today. Weak embedded shortwave energy and moist low
levels will continue to produce areas of low cloud-cover, fog and
some flurries/very light snow showers across much of
central/N-central MT today, though measurable precipitation will
be isolated and mainly limited to the mountains. Upper level
pattern takes on a positive tilt tonight through Wednesday as the
upper level trough slowly progresses into the central CONUS while
a ridge moves into Western Canada. This will bring drying to the
area tonight through tomorrow though a few lingering flurries
cannot be ruled out over the mountains. Wednesday night and
Thursday, The upper level ridge to the NW expands inland and
across the Northern Rockies and MT for additional drying. Warming
aloft spreads into the region as well on Thursday while at the
surface high pressure shifts to the interior West/Great Basin
with lower pressure across the Plains. This will bring breezy W/SW
winds to N-central MT as well as moderating temperatures. SW MT
valleys will likely remain cool however on Thursday with light
winds and a strengthening temperature inversion with cold air
pooling in the valleys beneath the warming conditions at higher
elevations. Hoenisch

Thursday night through Tuesday...Quiet conditions to start the
long term...with perhaps a more active pattern returning early next
week. Ridge of high pressure will dominate our weather pattern to
start the long term. Mainly dry conditions...with a few clouds...and
a gradual warming trend are expected through Saturday. Sunday we see
the ridge flatten and strong westerly flow is expected for the
region. The northern half of the CWA may see breezy to windy
conditions at times. With 700 mb winds near 50 Knots...will have to
monitor for potential high wind products. Our long range models then
differ on what happens early next week. Both showing a clipper
system may move across Montana in some capacity. GFS much more
aggressive than recent model runs. Bringing a sharp cold front
across the region Sunday night through Monday...lingering into
Tuesday morning. This would hint at scattered light snow and colder
temperatures to much of our CWA. Meanwhile the Euro solution has
this clipper as more of a glancing blow..with little precip.
Introduced some slight chances for snow Sunday night through Tuesday
morning...although will have to monitor the exact track of this
clipper system. As mentioned temperatures will be on a gradual
warming trend through Sunday. Warm downsloping air could even bring
high temperatures in the low to mid 40s for the plains of northern
Montana on Sunday. The mentioned cold front then cools down temps
for Monday into Tuesday to near normal readings. Anglin

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  23  12  27  12 /  10  10  10  10
CTB  23  11  29  14 /  10  10  10  10
HLN  21   8  21   7 /  10  10  10  10
BZN  19   5  19   3 /  20  10  10  20
WEY  19  -8  15  -6 /  70  10  10  30
DLN  21   6  22   5 /  20  10  10  10
HVR  22  10  24   8 /  20  20  10   0
LWT  21  11  25  10 /  20  10  10  10

&&

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

&&

$$

weather.gov/greatfalls


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