Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 281746

1045 AM MST Sat Feb 28 2015

Aviation section updated

.UPDATE...Skies have cleared across portions of the forecast area
but a swath of central Montana remains cloudy, foggy and snowy
this morning. Satellite imagery suggests that this swath of clouds
will move southeast and breakup but latest model runs also suggest
that cloud cover could increase once again during the afternoon as
heating causes moist air to rise. Have updated the forecast to add
flurries and fog to the area extending from just south of Havre to
Helena. Have also updated sky cover to introduce more clouds and
scattered flurries this afternoon. Accumulations will be light,
generally less than one half inch, and any sun this afternoon will
help to melt off the light snow on roadways. Afternoon high
temperatures appear to be on track so have not made any changes to
the expected max temp. mpj


A band of light snow showers will mainly affect Central MT thru
22z...and mainly the LWT airport. Otherwise...a few low clouds
linger at the other terminals...but those low clouds should burn off
by 21z or so. A weak upper level disturbance will move thru the
Havre/Lewistown area between 6z and 12z Sun...with mainly just a few
flurries. Conditions improve to VFR over much of the region for
Sunday afternoon. Looking ahead...widespread snow and IFR conditions
expected in many areas Monday afternoon thru Tue morning. Brusda


/ISSUED 417 AM MST Sat Feb 28 2015/

Today through Monday...The overall weather pattern changes little
today with an upper level trough extending from Central Canada
southwestward into the SW US while at the surface, a cold airmass
remains in place over much of MT. Upper level low located in the
SW extension of the large scale trough will continue to sink south
through the Great Basin today, allowing drier air in the mid to
upper levels to spread south into the region. This should bring an
end to most of the snow flurry/light snow shower activity by late
this afternoon with skies partially clearing from north to south.
The airmass continues to dry Sunday and Sunday night with some
warming as well as the cold airmass at the surface shifts east
into the Northern Plains states. Shortwave and upper level jet
energy currently moving over the top of a sharp upper level ridge
located around 140W dives south through western Canada Sunday
night, causing the downstream upper level trough to amplify/deepen
Monday. A strong Arctic cold front will surge south into N-Central
MT Monday afternoon with falling temperatures and increasing north
winds as surface pressure rises behind the frontal passage. Snow
will accompany and follow the front spreading south through
N-central and central MT by late Monday afternoon. Hoenisch

Monday night through Saturday...A low pressure trof will move across
Central Montana Monday night and the associated cold front, already
into the central zones, will move through the southwest zones during
the evening. Widespread snow will continue through the night but
begin to taper from the north towards morning. The trof will be east
of the zones Tuesday night, the airmass will dry and some clearing
skies are expected. The surface high will be over the zones and very
cold overnight lows are expected...negative numbers across the
region with some negative teens in Southwest Montana. Winds will be
strong enough to create dangerous wind chills in some locations.
High pressure will continue over the West Coast Wednesday through
Saturday. This will generally put Central Montana underneath
northwest flow aloft. Several disturbances will move through this
flow. The first of these on Wednesday will help deepen the surface
trof along the lee of the Rockies. This will cause strong winds
across the slopes of the Rockies by late Wednesday. Another
disturbance aloft will strengthen winds across the Rockies again
Thursday night through Friday. This latter disturbance will also
bring a chance of snow across the Rockies into Central and Southwest
Montana Friday and Friday night. Zelzer


GTF  20   3  34  14 /  20  20   0   0
CTB  20   2  32  15 /   0  10  10   0
HLN  25   4  34  14 /  20  10   0   0
BZN  24   0  31   9 /  30  10   0   0
WEY  28 -10  32   4 /  30  10   0   0
DLN  25   2  33   9 /  30  10   0   0
HVR  23   2  30  12 /  10  20   0   0
LWT  19   2  31  14 /  30  20  10   0




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