Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 251545

Area Forecast Discussion
National Weather Service Great Falls MT
845 AM MST Sat Feb 25 2017


No major changes to today`s forecast. Just freshened the high
temperature and wind grids per latest observations and short-term
model guidance. As a shortwave trough departs our area, isolated
snow showers should impact eastern portions of North-Central MT
the rest of this morning, but amount to less than 1 inch.
Elsewhere, upslope flow amidst sufficient moisture should
continue triggering scattered snow showers along the Continental
Divide and western aspects of the Central and Southwest MT
mountains. Here, additional snow amounts of 1-3 inches are
expected through nightfall.



Lingering -SN at KBZN this morning is expected to dissipate through
13Z. Otherwise, VFR conditions prevail today with partial mountain
obscurations. Gusty west winds develop for KCTB/KGTF/KHVR this
afternoon with a passing upper level disturbance. A cold front
arrives from the north early Sunday. Light snow could begin at KCTB
as early as 12Z Sunday as a strong weather system advances into the
Pacific NW.


/ISSUED 440 AM MST Sat Feb 25 2017/

Today through Monday...A subtle shortwave feature crossed southwest
MT early this morning and produced accumulating snowfall over Bozeman
and surrounding areas. This area of snow is exiting to the east as
an elongated upper level trough sweeps through the state today.
Downslope westerly winds strengthen behind the trough this
afternoon. Most areas will remain dry, but isolated to scattered
snow showers should be expected today and tonight over elevated
terrain. On Sunday morning attention turns to a vigorous shortwave
trough digging straight south along the British Columbia coast
into the PacNW. Backing winds aloft turn to west-northwest and
direct moisture across the northern Rocky Mountains. At low
levels, cold advection directs a shallow Canadian airmass into
North- central MT. The combination of shallow upslope flow and
mid-level overrunning aloft will produce widespread light snow
Sunday afternoon through early Monday. Snowfall rates increase
Sunday night as the system turns inland and moves just south of
our forecast area. Winter weather headlines may be needed on
subsequent shifts with potential hazards for Monday morning
travel. However, heavy snow is not anticipated as this system
moves quickly with snow tapering Monday afternoon.

Monday Night through Saturday...Upper level trough axis shifts east
across the Northern Rockies and MT Monday night and Tuesday with
weak low pressure tracking east through central MT. Moisture is
fairly limited but a marginally unstable airmass and weak energy
associated with the upper trough should provide enough lift for
scattered snow showers continuing through Tuesday before drier and
more stable air moves in with a building upper level ridge Tuesday
night. Fast moving shortwave and upper level jet push east along the
US Canadian border Wed/Wed night for a period of increasing winds
and moderating temperatures. Some cold air will spill back south
across northern zones Wednesday night through Thursday morning
behind a clipper type surface low that moves east into the Dakotas
this period. Warming ensues for Thursday and Friday as upper level
ridge rebuilds ahead of the next shortwave moving in from the Gulf
of AK. Medium range models continue to advertise fairly deep surface
low emerging across the Canadian Prairies Friday night as this
energy moves across the Rockies with a strong upper level jet
punching east across MT. This is a favorable setup for strong winds
across the region with very strong winds currently depicted by GFS
model, though EC/CMC solutions are not as extreme at this point.
Situation will continue to be monitored through the upcoming week.


GTF  34  18  27  10 /  10  30  60  60
CTB  32  16  21   5 /  10  50  50  50
HLN  32  14  27   8 /  10  30  40  60
BZN  28   9  27  10 /  70  20  30  40
WEY  16   0  18   7 /  50  40  40  70
DLN  25   9  24  11 /  30  20  30  30
HVR  32  18  27  11 /  20  20  20  40
LWT  28  17  27  11 /  20  20  40  70



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