Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 252104
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
304 PM MDT Tue Apr 25 2017

.DISCUSSION...

Tonight through Thursday...Surface analysis this afternoon
reveals a trough aligned north-south broadly along I15. This
trough is associated with a stationary front, and is producing low
level converge and surface vorticity. This, combined with
divergent flow aloft associated with an approaching shortwave
trough is spawning numerous showers and thunderstorms across
N-central Montana. These showers will produce lightning, brief
heavy rain and small hail, along with a rapid drop in temperature.
One or two cold-air funnels may be possible in this environment.
All of this activity will advance west to east this evening along
with the upper level trough. Precipitation tapers overnight, but
only for a few hours as a surge of Pacific moisture spreads inland
on a westerly flow aloft. Showers initiate by late morning
Wednesday east of the Continental divide, then become
widespread/numerous while spreading east across the forecast area
through Wednesday night. Cool and unsettled weather follows on
Thursday, again with numerous rain and mountain snow showers.
Temperatures remain below seasonal averages through this mid-week
period, with snow levels dropping near to below 4000 feet.
Accumulating snow should remain above about 5500 feet. PN

Thursday night through Tuesday...An overall unsettled weather
pattern will reside over the region during the extended period.
Scattered/likely areas of precipitation are likely to continue
Thursday night through Monday, with the lowest chance for
precipitation being Sat/Saturday night. By Tuesday of next week,
the GFS model progs a fairly deep upper level trof of low pressure
to develop over the region, resulting in a fairly good spring
snowstorm over Central MT. However, it is too early to feel
confident in this storm at this time. Otherwise cool afternoon
temperatures on Thursday and Friday will warm a touch over the
weekend, only to cool a bit by next Tuesday. Brusda

&&

.AVIATION...
Updated 1800Z.

Abundant moisture for widespread cloudiness through the period as
several waves ripple through the area. CIGS should tend toward VFR
or MVFR, but lower CIGS are possible at times. In addition, periods
of rain showers, mountain snow showers, and mountain obscuration are
expected. Isolated thunderstorms are possible this afternoon and
early evening, but confidence in a storm impacting an aerodrome is
low. Britton

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  35  54  36  47 /  70  60  60  60
CTB  33  50  34  44 /  70  70  70  70
HLN  38  56  37  50 /  40  60  60  50
BZN  35  54  34  46 /  50  80  80  60
WEY  27  41  27  37 /  50  90  90  70
DLN  35  52  32  46 /  30  80  80  50
HVR  34  54  35  49 /  30  50  50  60
LWT  32  50  33  43 /  50  70  70  70

&&

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

$$

weather.gov/greatfalls



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