Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 242345
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
545 PM MDT WED AUG 24 2016

UPDATED AVIATION SECTION

.DISCUSSION...

Tonight through Friday...An upper level low pressure trof over
Central and Southwest Montana will slowly move east this evening
and the air mass will dry. However, weak instability will remain
over the extreme southwest zones early this evening and a chance
for a thunderstorm will continue over this area. As the trof
moves east, the region will be underneath northwest flow aloft. A
weak disturbance in this flow will move through Alberta and
approach the zones late Thursday afternoon. This will bring a
chance of showers across the region Thursday night and Friday.
The air mass will warm slowly and temperatures will trend upwards
but remain below seasonal normals through Friday.
Zelzer

Friday night through Wednesday...Medium range models continue to
show an upper level positive-tilt trough over Montana moving
eastward into the Dakotas by Saturday morning. Montana will be
left beneath westerly flow aloft that backs to the southwest by
the end of the weekend. GFS and ECMWF each depict some degree of
upper level troughing along the British Columbia coast by Sunday
night. However, the GFS keeps energy associated with this feature
as a closed upper low over Southeast Alaska, while the ECMWF
develops a narrow, weaker trough that extends southward into
Northern California. Model solutions diverge significantly after
Monday morning with the closed low and associated trough of the
GFS remaining along the West Coast for persistent anti-
cyclonically curved southwest flow aloft over Montana. The ECMWF
gradually broadens the upper trough across western Canada as well
as the Pacific Northwest and the Northern Rocky Mountain region
for cyclonically curved south to southwest flow over the state.

These model trends continue to support temperatures warming back
up to near or above seasonal averages for the weekend with mostly
dry conditions prevailing through Sunday night. Unfortunately,
the forecast for next week remains low confidence at this time but
model consensus tools support temperatures remaining near seasonal
averages under a southwest flow aloft with isolated to scattered
showers with possible thunderstorms each day. mpj/Coulston

&&

.AVIATION...
UPDATED 2345Z.
Circulation around an upper disturbance located over southern
Saskatchewan is bringing clouds and light precipitation to portions
of northeast Montana. Precipitation should gradually end by 06z
followed by partial clearing. Breezy northwest to north winds will
also decrease after 03z. VFR conditions prevail.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  44  68  46  69 /  10  10  20  20
CTB  41  67  45  68 /  10  10  20  20
HLN  45  70  47  71 /  10  10  10  20
BZN  41  72  42  71 /  20  10  10  20
WEY  36  63  34  63 /  20  20  20  30
DLN  40  69  42  71 /  20  20  10  20
HVR  47  71  49  71 /  10  10  20  20
LWT  43  68  46  67 /  10  20  10  40

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

weather.gov/greatfalls



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