Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 221156

Area Forecast Discussion
National Weather Service Great Falls MT
440 AM MST Wed Feb 22 2017

Updated Aviation Discussion.


Today through Friday Afternoon... Snow showers will continue to
impact the forecast area for the next couple of days, with variable
yet light snow accumulations across the region depending on smaller
scale features that are difficult to pin down to exact areas. The
most significant shower coverage should be right along a front over
the Plains that extends from near I-15 to US Highway 89 east of
Great Falls and points north and east. This boundary will likely
push north and east toward our northeastern counties today, then
become stationary and weaken overnight tonight. Thus, the best
accumulating snow as well as widespread low ceilings and fog is
expected just north and east of this boundary over north-central MT.
Another weak system moves across SW MT by early this afternoon and
will help to produce snow showers over most mountainous areas. This
region will have more low level instability, so expect the snow
showers to be a bit more intense but also more hit-and-miss than the
shower activity associated with the surface front over the northeast
Plains and along the Canadian border.

Snow shower activity will begin to become more isolated over the
Plains by Thursday and Friday as a broad upper level trough
remains just to the west, with more scattered to possibly
numerous coverage toward higher elevations and across the southern
counties of SW MT with weak lower level northerly upslope flow.

With continued cloud cover across the region, temperatures will
continue to trend cooler but with a relatively smaller diurnal
range with teens and 20s for highs across much of the region, with
colder temperatures in the single digits above zero and teens at
night over the Southwest valleys. Cassell

Friday Night through Wednesday...A surface cold front moves into N-
central MT Friday night. The front could produce areas of light snow
beneath a weak overrunning southwest flow aloft, with flurries
continuing but gradually tapering through much of the day Saturday.
Generally fair, drier, and cold weather follows for Sunday and
Monday. Isolated, mainly mountain snow showers will continue,
associated with weak disturbances in the northwest flow aloft.
Temperatures will fall to around 10 to 15 degrees below average
through Monday night, with overnight lows in the single digits. A
stronger Pacific trough is forecast to develop Monday night
somewhere over the interior U.S. west. This could increase snow
chances for southwest MT on Tuesday, with possible travel hazards
heading into ID. Model solutions bring the cold snap to an end on
Wednesday with broad ridging over the PacNW. A strong Clipper system
developing in the NW flow downstream of the ridge could produce a
period of strong downslope winds Wednesday or Thursday. Confidence
in these late period model solutions remains low. PN


Updated 1140z.

IFR to occasionally MVFR conditions will predominate with -SN and
VCFG over the Plains sites, especially east of I-15, with some
improvement possible by afternoon from I-15 west, though it should
be noted confidence is low. VFR conditions are predominantly
expected over SW MT, but will drop to occasional MVFR or even IFR at
times with -SHSN especially later this afternoon and into the
overnight tonight. Expect mountains to remain obscured by clouds and
snow showers throughout the period. Cassell


GTF  37  21  29  16 /  60  40  40  20
CTB  32  19  25  11 /  60  40  40  20
HLN  39  19  28  13 /  30  30  30  20
BZN  37  15  28  14 /  50  40  50  40
WEY  26   7  23   5 /  50  40  40  40
DLN  33  12  25  10 /  40  40  40  30
HVR  36  27  32  19 /  50  60  50  30
LWT  34  21  29  15 /  80  60  40  30


Winter Weather Advisory until midnight MST tonight Blaine...
Cascade...Chouteau...Eastern Pondera...Eastern Teton...Fergus...
Hill...Judith Basin...Liberty...Meagher...Toole.

Winter Weather Advisory until 6 PM MST this evening Eastern
Glacier...Northern Rocky Mountain Front...Southern Rocky
Mountain Front.


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