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Area Forecast Discussion (AFD)

Issued by Great Falls, MT (TFX)

FXUS65 KTFX 161151

Area Forecast Discussion 
National Weather Service Great Falls MT 
450 AM MST Fri Nov 16 2018


A fast moving Alberta Clipper system will spread rapidly cooling 
temperatures, gusty north winds, and periods of snow over the 
region today. The winds will cause areas of blowing snow that will
reduce visibility at times. The system will exit the area this
evening, allowing the snow and winds to decrease. However,
overnight lows will likely fall into the single digits above zero.
A high pressure ridge will then bring drying and warming
conditions for Saturday through the middle of next week.



Today through tonight...This will be the main period of concern 
over the next week or so. A fast-moving Alberta Clipper weather
system will bring rapidly cooling temperatures, rain changing over
to snow, and gusty northerly winds to the forecast area today.
Precipitation is already spreading over much of north central
Montana this morning, but above freezing temperatures are limiting
snowfall to the mountains. However the strong cold front
associated with this system will likely move south of the Canadian
border by 5 am or so, moving through Cut Bank by about 6 am, then
through Havre and Great Falls by around 7 am, and through 
Lewistown by 9 am. The rapid fall in temperatures behind the front
will cause the rain to change over to snow within an hour or so of
frontal passage and cause wet roads to become very icy. Also, 
northerly winds of up to 25 mph will likely gust to 40 mph at 
times, causing significantly reduced visibility in blowing snow.
Some drying in the mid levels may also cause brief periods of
freezing drizzle late this morning into early this afternoon, but
significant ice accumulation is unlikely. This transition of
conditions will spread into southwest Montana by noon, but the
changeover to snow in the valleys south of Interstate 90 will
likely not occur until mid afternoon. Winds will also blow through
favored north-south oriented valleys, causing similar issues with
blowing snow. Snow and wind will decrease from the north as the 
system exits the area this evening. While temperatures are
expected to fall into the teens and 20s north by this afternoon, 
temperatures will be slower to fall in the southwest. Will continue 
the Winter Weather Advisories that are currently in effect for snow 
and blowing snow, but there is a good chance this blowing snow will 
impact valleys of Beaverhead County as well, so will add them to the 
Advisory as well. Overnight lows will be quite cold, with many areas 
falling into the single digits above zero. Coulston

Saturday through Friday...A high pressure ridge will keep the
forecast area dry with gradually warming temperatures and breezy
southwest winds at times during this period. Temperatures will 
still be about 10 degrees below normal on Saturday, but they 
should warm back to slightly above normal by Monday and remain
there through the rest of the week. Two weak low pressure troughs
will then break down the ridge Thursday and Friday, bringing a few
showers to the western and southwest Montana mountain areas.


Updated 1150Z.

VFR/MVFR conditions are expected to worsen as a low pressure system 
with a strong cold front moves south out of Canada through 18Z. As 
gusty westerly winds shift more northerly behind the front over the 
plains of north central Montana, areas of low level wind shear 
turbulence are likely through around 18Z. Otherwise, MVFR/IFR 
conditions with mountain obscuration and rain changing over to snow 
(heavy at times) will impact the Hi-Line (KCTB KHVR) first by around 
13Z, central Montana (KGTF KHLN KLWT) between 13Z and 16Z, then into 
southwest Montana (KBZN KEKS) after 16Z. Pavement will likely ice up 
before the heavier snow develops. Conditions slowly begin to improve 
after 21z Fri from north to south. Coulston/Brusda


GTF  37  11  32  19 / 100  50   0   0 
CTB  31   4  32  14 / 100  10   0   0 
HLN  39  11  31  12 / 100  70   0   0 
BZN  38  11  27   7 / 100  80  10   0 
WEY  33   6  30  -3 /  60  70   0   0 
DLN  42  12  30   8 /  80  70   0   0 
HVR  37   9  32  16 / 100  20   0   0 
LWT  37   8  29  13 /  90  60   0   0 


Winter Weather Advisory until 9 PM MST this evening Broadwater...
Cascade...Central and Southern Lewis and Clark...Fergus...
Jefferson...Judith Basin...Meagher.

Winter Weather Advisory until 2 PM MST this afternoon Blaine...
Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...
Hill...Liberty...Northern Rocky Mountain Front...Southern Rocky 
Mountain Front...Toole.

Winter Weather Advisory from 9 AM this morning to midnight MST 
tonight Beaverhead...Gallatin...Madison.