Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 250453
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1050 PM MDT Fri Mar 24 2017

UPDATED AVIATION SECTION

.UPDATE...

Little changes needed this evening, with the ongoing forecast
holding firm. Despite some radar returns across North Central
Montana this evening, the underlying atmosphere is very dry,
which is leading to evaporation of any falling precipitation
before it reaches the ground. This dry atmosphere is supported by
KTFX 00z sounding, which suggests strong subsidence in the lowest
3km of the atmosphere. With this being said, the underlying
atmosphere is expected to moisten throughout the remaining
nighttime hours as a fast moving upper level disturbance crosses
the region. This will help to bring a chance for rain/snow to
Southwest and Central Montana, or generally along and south of a
KGTF to KLWT line. Elsewhere, some light rain/snow showers were
beginning to develop along the Continental Divide, with a general
increase in coverage expected over the next couple of hours. -
Moldan

&&

.AVIATION...
Updated 0450Z.

VFR conditions are expected over the next 24 hours, but lower
conditions are possible with showers. A moist southwest flow aloft
will bring mountain obscuring rain and snow showers to the area
through around 14Z. Some showers may bring brief periods of MVFR
conditions to the southwest valley terminals (KHLN KBZN KEKS). A few
showers may also fall through 10Z east of Interstate 15. The passage
of a cold front will also bring gusty westerly winds to the area
through around 18Z, as clouds clear over the plains. Gusts of 30 to
40 kt are possible. Winds will decrease somewhat after 18Z, but they
will remain breezy. Another disturbance may then bring another round
of mountain showers, mainly after 20Z.
Coulston

&&

.PREV DISCUSSION...
/ISSUED 308 PM MDT Fri Mar 24 2017/

Tonight through Sunday...Ridge of high pressure has exited the CWA
as evident by increasing clouds and winds. Increasing
southwesterly winds are bringing some breezy areas and mountain
wave clouds this afternoon. As moisture increases with the
southwest flow associated with a weak river event...rain showers
and snow showers above 6000 feet...possibly lowering to 5000 feet
late tonight...are expected through the overnight hours across
western and southern portions. These showers could also spread
across central portions early Saturday morning with a weak
shortwave embedded in the flow. Chances for rain showers and snow
showers above 5000 feet then linger through Saturday across
western and southern portions...while some scattered showers may
return across central portions Saturday afternoon. Precip could
then linger across the west and south through Saturday
evening...then a ridge of high pressure will bring drying
conditions overnight Saturday night into Sunday. A dry and
slightly breezy day is expected for Sunday. So overall some active
but low impact weather is expected across the west and south
through Saturday...with scattered showers central...and little
precip north. This time of year it seems difficult to accumulate
snow other than at night. Snow accumulations from pass levels and
higher could reach the 2 to 6 inch range in southwest
MT...however...impacts are expected to be low as the March sun
will keep roads warm. Slightly cooler but still above normal temps
in the low to mid 50s are generally expected for Saturday...with
some 40s southwest. Warming temps in the mid to upper 50s are
expected Sunday. Rivers will continue to be monitored...however no
warnings are in effect currently. Fire danger has probably peaked
today...although may increase again slightly on Sunday. Anglin

Sunday Night through Friday...The region comes under
influence of an upper level trough late Sunday into Monday, with the
potential for splitting upper level energy resulting in a snow/rain
mix across much of the area, but especially across SW MT, where the
highest precipitation chances look to be Monday into Monday night
before the system departs to the east. Conditions improve later
Tuesday through Wednesday aside from scattered, mainly mountain
showers. Uncertainty increases with the following system for late-
week. This system looks to push a cold front south and east through
the region, with a round of upslope flow and moisture that would
allow for some accumulating snow across parts of the High Plains as
well as parts of SW MT. The GFS and Canadian models indicate a quick
burst of snow in a short amount of time (6 hours or less), while the
European model indicates up to a 24-hour period of snow from
Thursday into Friday for some parts of our area. This system will
bear watching through the middle of next week. Cassell

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  38  55  32  57 /  20  20  10   0
CTB  34  49  29  51 /  10  10   0   0
HLN  36  53  32  56 /  30  20  40  10
BZN  36  51  30  54 /  50  50  30  10
WEY  29  38  20  40 /  70  70  40  10
DLN  34  49  28  52 /  30  20  20   0
HVR  38  57  31  56 /  20  10  10   0
LWT  37  51  31  52 /  20  20  20   0

&&

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

$$

weather.gov/greatfalls



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