Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 290945
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
345 AM MDT Thu Sep 29 2016

.DISCUSSION...

Today through Saturday...Mainly clear skies are being found across
the CWA this morning. With higher dewpoints and light winds...a
few areas of patchy fog will be possible this morning...however
impacts of this fog will remain low. WV imagery currently showing
the story of the day as limited amounts of monsoonal moisture
slowly making its way north in SW flow. A few more clouds and
warmer temps in the 70s will be found today. This pattern will
bring some weak instability today...however much of the area will
be capped under warming temps aloft. Areas across the sw will have
the best chances for isolated to scattered thunderstorms...along
with the western mountains. Any precipitation will diminish
shortly after sunset this evening. Monsoonal moisture will
continue to stream into the area tonight into Friday morning.
Mainly dry conditions are expected...however...increased cloud
cover may block the view of those trying to catch the potentially
lingering northern lights show. This weak monsoonal sw flow then
continues through the day Friday. Daytime heating will see temps
near 80 for some areas by Friday afternoon. Weak to modest
instability will again be found across the CWA by late Friday
afternoon through Friday evening. An approaching disturbance in
the Pac NW could provide slight cooling aloft to break down the
cap for Friday. As a result isolated to scattered thunderstorms
will be possible across the west...south...and central portions.
The mentioned disturbance slides down the west coast Saturday
sending a cold front across the region. This will bring showers
and a few thunderstorms from west to east for Saturday. Severe
weather is not expected with any thunderstorms in the short term.
Despite the increased monsoonal moisture...Pwat values will remain
on the moderate side for this system. Some areas of moderate to
heavy rain may be possible...however...the progressive nature of
this system does not provide for prolonged periods of heavy rain.
This cold front will also start a cooling trend...with highs in
the 60s and 70s for Saturday. Anglin

Saturday night through Thursday...Weather in the medium range period
continues to be dominated by the movement and subsequent development
of an upper level trough. This feature starts out as a closed low
off the Washington coast. Both medium range models have trended
toward developing this system into an open trough over the western
USA with bulk of energy associated with the system moving as far
south as the Four Corners region. As a result, models continue to
trend toward warmer (but still chilly) temperatures with the bulk of
expected precipitation trending towards Eastern Montana. There still
appears to be a good chance for showers through North Central and
Southwest Montana for much of the forecast period; but, if models
continue to trend this way, it is quite possible that any chances
for significant wetting rains may need to be dropped from the
forecast in the coming days. mpj

&&

.AVIATION...
Updated 0600Z.

Clear skies...light winds...and VFR conditions are expected for
tonight through Thursday morning. Some very patchy fog is possible
late tonight or early Thursday morning...however...confidence is too
low to place in TAF forecasts at this time. Mid level southwest flow
will increase moisture and mid level clouds for Thursday
afternoon...however VFR conditions will prevail through Thursday
evening. A few isolated thunderstorms will be possible Thursday
afternoon and evening...mainly across SW Montana...with some VCTS
possible near the KBZN area. Isolated thunderstorms activity will
then diminish shortly after sunset Thursday evening. Anglin

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  75  48  79  51 /  10  10  10  20
CTB  70  44  74  48 /  10  20  20  30
HLN  80  45  78  49 /  10  20  10  20
BZN  79  47  78  49 /  20  20  10  20
WEY  66  38  68  39 /  30  30  20  10
DLN  76  44  74  46 /  20  20  20  20
HVR  75  47  77  52 /   0  10  10  10
LWT  79  50  77  53 /  20  20  10  10

&&

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

$$

weather.gov/greatfalls



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