Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 272323
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
523 PM MDT Mon Mar 27 2017

UPDATED AVIATION

.DISCUSSION...

Rest of today through Wednesday...The main focus during this period
is the rest of this afternoon through tonight. Latest satellite
imagery shows a weakening disturbance near Missoula with
scattered/widespread showers associated with it. This feature will
continue to progress east through tonight with an added push from a
large-scale upper level trough that is currently moving through
the western US. There have been a few lightning strikes around
the region this afternoon with the ongoing shower activity and
latest LAPS analysis shows enough instability for a continued
potential of an isolated thunderstorm. That said, Confidence is
too low to include any thunder in the forecast for now. And, where
the greatest instability lies may not see showers until this
evening when the instability should be much weaker.

The best chance of showers through tonight will be along/south of a
Great Falls to Lewistown line as the weak disturbance and upper
trough move through. The temp forecast is still tricky tonight
and I upped lows a degree or two compared to the previous
forecast. This still leaves the potential for a rain/snow mix at
lower elevations, but I still don`t expect any impacts there. At
pass level, especially over Bozeman Pass, there could be a slushy
inch or two, but even there, impacts should be relatively minor.
For this reason, we`ll not plan to issue any winter weather
products at this time. For the Great Falls area, the precip may
move out before the coldest temps are realized, so confidence in
a rain/snow mix there is even lower than elsewhere (confidence is
highest from Lewistown to Bozeman to West Yellowstone). Dry air
moves in quickly by Tuesday morning putting an end to any shower
activity from west to east. For Tuesday and Wednesday, any shower
activity should be confined to the western Mountains. It will turn
breezy across the plains in the wake of tonight`s system,
especially by Wednesday afternoon. Martin

Wednesday night through Monday...The main concern in the extended
period is the storm system for Thursday/Thursday night. Widespread
precipitation will affect Central and Southwest MT during this
period as an upper level disturbance moves southeastward along the
California coast. The best chance for accumulating snow looks to be
above 6500 feet...but some snow could mix in for elevations as low
as 4500 feet. Precipitation amounts of 0.25 to 0.40 look reasonable
with this system...mainly south of a line from Great Falls to
Lewistown. A second weather system could affect the region next
Monday, but the 12z runs very quite a bit from almost nothing to
another half inch, but further north, over the northern Rockies.
Thus, quite a bit more uncertainty for early next week. Otherwise,
temperatures will be seasonable during the extended period generally
running from the lower 50s to lower 60s, with overnight lows mostly
in the 30s. Brusda

&&

.AVIATION...
Updated 2323Z.

Predominantly VFR expected next 24-hours. However, a weather
disturbance will move E`ward over the area during the period, and
the accompanying Pacific cold front should sweep E`ward between
about 03Z and 12Z/Tue. Scattered showers of rain and/or snow will
accompany this front and may be accompanied by MVFR to IFR CIGS and
perhaps MVFR VSBY for a short period of time. The best chance for
these lower conditions exists along and south of a KGTF to KLWT
line. Periods of mountain obscuration are also possible.
Jaszka

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  32  57  34  60 /  60   0   0  10
CTB  32  54  32  55 /  30   0  10  10
HLN  32  54  32  59 /  40   0   0  10
BZN  28  50  23  57 /  70  20   0  10
WEY  20  38  10  42 /  50  10   0  10
DLN  25  49  26  55 /  40   0   0  10
HVR  33  62  32  63 /  30  10   0   0
LWT  32  52  30  58 /  70  20   0   0

&&

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

$$

weather.gov/greatfalls


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