Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 271217
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
517 AM MST Fri Feb 27 2015

.DISCUSSION...

Today through Sunday...Cold and somewhat unsettled weather pattern
continues today through Saturday as an upper level trough remains
over the region. Main lobe of shortwave energy is currently moving
south along the WA coast early this morning and will dig SE into
the Great Basin by Saturday. This keeps the bulk of the forcing
well S and W of the forecast area, but weaker embedded energy does
move move through the Northern Rockies today with deformation
axis behind the main trough axis shifting south through the region
Saturday. This will keep the airmass moist with scattered snow
showers becoming more widespread across western and SW portions of
the forecast area later today and tonight, though snowfall should
be very light in most areas with accumulations in excess of an
inch mainly limited to the Mtns. At the surface, a cold airmass
remains in place with a reinforcing surge of cold high pressure
moving south from AB into north central MT later today and tonight
in response to low pressure deepening in the Great Basin. Saturday
night and Sunday, the airmass drys as upper level ridging builds
into the region from the NW. By Sunday afternoon, lee-side
toughing develops along the east slopes of the Rockies, bringing
warmer temperatures to much of north-central MT. Hoenisch

Sunday night through Friday...Heights aloft will begin to drop again
Sunday night ahead of a shortwave trof moving through the northwest
flow aloft. Moisture ahead of this trof will move over the Northern
Rockies Monday and the associated cold front will cross the Canadian
border early in the day. The cold front will move through the zones
during the day and move through the southwest zones by evening.
Widespread precipitation will accompany this front and 2-4 inches of
snow by Tuesday currently looks reasonable across the plains and
southwest valleys, and higher amounts in the mountains. The trof
will be moving east of the zones late Tuesday and Tuesday night. The
airmass will be drying and a cold surface airmass will allow for low
overnight temps Tuesday night, single digits or less in many
locations. A high pressure ridge will be building Wednesday through
Thursday. Several disturbances will move move through the ridge
in British Columbia and this will deepen the surface lee trof along
the Rockies and bring a period of brisk winds along the slopes of
the Rockies late Wednesday and Thursday. Other than the winds, high
pressure will generally remain aloft and keep the the airmass dry
and mild through Friday. Temperatures will drop well below normals
Monday night and Tuesday, and some dangerous wind chill values will
be possible. Temps will begin to trend upwards Wednesday and reach
near and above normals again Thursday. Zelzer

&&

.AVIATION...
UPDATED 1215Z.
An upper level low pressure trof will move through Central Montana
today. The associated cold front has crossed the Canadian border and
will move south through the region this morning. Local MVFR
conditions are expected behind the front as snow develops and cigs
lower. Winds will shift to the north with frontal passage although
strong winds are not expected. Local IFR conditions are possible
tonight after midnight as low level moisture and cool conditions
develop fog.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  19   0  18   3 /  20  40  20  10
CTB  16  -2  19   4 /  40  30  10  10
HLN  26   6  26   4 /  20  40  20   0
BZN  28   4  23   1 /  20  40  30  10
WEY  29   0  29  -7 /  30  40  20  10
DLN  30   6  26   0 /  30  40  20  10
HVR  18  -2  19   2 /  10  10  10  10
LWT  22  -1  20   1 /  10  30  20   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

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