Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 181139
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
539 AM MDT Thu Sep 18 2014

.DISCUSSION...
Today through Saturday...A low pressure moving in over the Pacific
Northwest continues to push moisture and instability into the
region from the southwest. Scattered showers and thunderstorms
will be seen today over Southwest and South Central Montana, with
the best chance for precipitation over Southwest Montana. Things
look quieter for the weekend as high pressure nudges towards the
region, but isolated showers cannot be ruled out, mostly for
Southwest Montana. High temperatures will be in the 80s today
before cooling 5 to 10 degrees Friday and Saturday.

Saturday night through Thursday...High pressure will be building
over the region Saturday night and the ridge will be over Central
Montana by Sunday. Moisture will begin to move north underneath the
ridge but convection will remain south of the zones. The ridge will
begin to move east of the zones Monday and a shortwave will
approach the Rockies. The air mass will remain very dry and only the
extreme southwest should see any convection. Moisture will slowly
increase across the region Monday night and Tuesday and by Wednesday
afternoon a low pressure trof over the Eastern Pacific will be
approaching the West Coast. The GFS is faster with this feature and
has it moved over the West Coast by 00z Thu. The ECMWF, slower, has
it hanging back over 135W. The GFS solution would bring moist,
unsettled flow aloft across the zones Thursday night and Friday, It
would also create an unstable air mass with showers and
thunderstorms likely lasting into the night as the trof continues to
approach the Rockies. However, with the ECMWF keeping the trof west,
and the GEM more in line with the ECMWF as well, will keep pops near
climo and wait for the models to come more into agreement.
Temperatures will remain well above normals through the period
although the GFS solution would bring significant cooling on
Thursday. Will keep more moderate temps due to the disagreement in
the models. Zelzer

&&

.AVIATION...
UPDATED 1136Z.
An upper level low pressure shortwave over the Pacific Northwest
will approach the Rockies today. Moist, unsettled flow ahead of this
system will bring a chance of showers and thunderstorms across
mainly the central and southwest portions of the region. The chance
for precipitation will diminish this evening and this shortwave will
move east of the region Friday

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  83  53  74  47 /  20  10  10   0
CTB  81  47  71  42 /  10  10  10   0
HLN  82  52  75  47 /  40  20  10   0
BZN  79  46  74  42 /  40  30  10   0
WEY  71  38  66  33 /  70  60  20  10
DLN  78  47  73  44 /  60  30  10   0
HVR  86  53  77  48 /  10  10  10   0
LWT  83  52  75  47 /  30  30  10  10

&&

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

$$

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