Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 160416
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
910 PM MDT Mon Sep 15 2014

AVIATION SECTION UPDATED

.UPDATE...
Only very minor updates to the overnight forecast this evening.
Models have been forecasting temperatures a few degrees warmer
than what has actually been occurring with the clear skies. Have
therefore lowered overnight lows about 3 to 5 degrees across all
of north central and southwest Montana. The remainder of the
forecast is in good shape, but I did adjust the wind directions
for the rest of this evening to better match up with current
conditions.  Coulston

&&

.AVIATION...
UPDATED 0410Z.
High pressure ridge continues to dominate the regional weather
pattern, bringing dry conditions, mostly clear skies and light
winds. Expect those conditions to continue tonight and Tuesday,
with just some SCT-BKN high clouds moving in from the west/southwest
tomorrow aftn/eve.  Isolated showers may develop over higher terrain
vcnty KBZN after 00Z.
Waranauskas

&&

.PREV DISCUSSION...
/ISSUED 535 PM MDT Mon Sep 15 2014/
Tonight through Wednesday...An upper ridge of high pressure from
the Pacific Northwest will move to western Montana Tuesday and
then to central Montana Wednesday. This will continue the warming
trend. High- level moisture will spread over the forecast Tuesday
and continue through Wednesday. For Tuesday afternoon weak
instability could develop over southwest Montana and will add a
mention of thunderstorms to the forecast for that area. Then for
Wednesday afternoon instability is forecast to increase but
guidance differs on how much. Do not see any weather disturbances
aloft to help in the development of showers/thunderstorms but
models indicate a weak trough of low pressure near the surface
over the east slopes. Due to this trough and also terrain effects
have expanded the mention of thunderstorms from southwest Montana
to the Rocky Mountain Front and east slopes of the Rocky
Mountains. Any precipitation that falls from the showers and
thunderstorms should be light. Blank

Wednesday night through Monday...An upper level low pressure trof
will move over the West Coast early Thursday and into the Pacific
Northwest by afternoon. This will begin to knock down the high
pressure ridge over Central Montana and bring moist, unsettled,
southwest flow aloft over the zones. The increase in moisture and
lowering of heights aloft will bring continued instability to the
region, especially over the southwest zones. A chance of showers
or thunderstorms will be greatest in this area. The trof will move
across Central Montana Friday, the air mass will cool and, with
the passage of the trof, a chance of showers will continue. With
the trof moving east, high pressure will build aloft again
Saturday. This ridge will continue to build through Sunday. A
shortwave will move into the ridge Monday but the air mass will
remain quite dry precipitation isn`t expected. Temperatures will
remain well above normals through the period. Zelzer

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  42  82  52  85 /   0   0  10  20
CTB  37  80  45  81 /   0   0   0  10
HLN  45  85  52  88 /   0   0  10  10
BZN  40  82  47  84 /   0   0  10  10
WEY  31  72  37  74 /   0  10  20  20
DLN  43  81  49  84 /   0  10  10  10
HVR  39  80  47  85 /   0   0   0  10
LWT  40  82  51  85 /   0   0  10  10

&&

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

$$

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