Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 242001
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
201 PM MDT Sun Sep 24 2017

.SYNOPSIS...

One final day of well below normal high temperatures is in store
for Southwest and North Central Montana today, before temperatures
moderate into the upcoming work week. A few isolated afternoon
showers are possible over the Little Belt and Snowy Mountains and
in the West Yellowstone area, but otherwise most locations will
enjoy partly to mostly sunny skies today.

&&

.DISCUSSION...

Rest of today through Tuesday...The upper level trough over the
western US will begin to edge eastward over the next couple of days,
but it won`t be a quick process. As it pushes east, a NW flow will
develop aloft, allowing some low/mid level moisture to advect into
the area. While there does not appear to be any significant lifting
mechanism, steep lapse rates, increasing moisture, and an upslope
flow should allow a few showers to develop, especially over and
downwind of the mountains. Any precip amounts will be light. The
clouds will keep temps in check through Tuesday before milder air
arrives by mid-week. It will be cool overnight as well, but the
increasing cloudcover should keep temps from falling too low, even
in the typically colder valleys. The clouds should also tend to
limit fog development, especially Monday night. MARTIN

Tuesday night through Sunday...We begin to see a clear transition in
the synoptic pattern as we get into the middle of the upcoming week.
Large, highly amplified ridging returns to the Pac NW while the
lingering longwave trough responsible for the previous days cool
and wet weather finally pulls off to the NE. This will lead to the
big story, moderating temperatures. Highs on Wednesday will likely
return to near normal for many with highs reaching the mid to upper
60`s across the Plains, while the mountains stay cooler. But by
Thursday and Friday, the aforementioned ridge across the Pac NW will
slowly transition eastward, which is reflected by steadily
increasing height anomalies per the latest ensemble model forecast.
This supports a continued warming trend through the rest of the week
ahead with highs easily reaching the lower to mid 70`s across the
Plains. Long-range models have started showing increasing trends in
confidence over the idea that the ridge will eventually break down
by next weekend. This will be followed by a slow downward trend in
temperatures back to near normal, with isolated rain chances
returning into Sunday. Overall, the upcoming weather pattern
continues to suggest no extreme cold/winter weather concerns for the
next 7-10 days. KLG

&&

.AVIATION...
Updated 1700z.

VFR conditions are expected through this evening. Tonight through
early Monday morning, VFR conditions are likely, but MVFR/IFR
conditions are possible across SW MT.

Generally quiet conditions are expected through Monday as an
upper level ridge begins to build in across the area. A few
showers cannot be ruled out in the mountains or near KWYS this
afternoon, with dry conditions elsewhere. Tonight, BR/FG will be
possible across the valleys of SW MT, which may lead to MVFR/IFR
VIS/CIGs. This potential will continue to be monitored in later
forecasts. MARTIN

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  35  61  41  64 /   0  10  20  10
CTB  34  63  40  64 /  10  10  10  10
HLN  34  60  41  63 /   0  10  10  10
BZN  30  56  36  60 /  10  10  10  10
WEY  26  49  27  53 /  10   0  10  10
DLN  31  54  33  57 /   0   0  10  10
HVR  34  64  40  68 /   0   0  10  10
LWT  33  58  38  62 /   0  10  10  20

&&

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

$$

weather.gov/greatfalls



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