Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 261750
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1150 AM MDT Sun Mar 26 2017

Aviation Section Updated

.UPDATE...

Quiet and dry weather across the forecast area through this
afternoon as a shortwave ridge of high pressure drifts east across
the region. Afternoon temperatures on track to warm to about 10
degrees above seasonal averages and with winds generally 15 mph or
less for a pleasant afternoon across most areas. Initial
shortwave energy ahead of the next Pacific trough moving onshore
will reach the northern Rockies this evening for increasing clouds
and perhaps a few light showers moving into western portions of
the forecast area this evening. Hoenisch

&&

.AVIATION...
Updated 1750Z.

VFR conditions expected through the 18Z TAF cycle. A shortwave will
move through the area this evening bringing increasing low/mid
clouds, possible mtn obscurations, and a few showers. The best
chance of showers is expected across SW MT, but even there,
confidence remains too low to include any prevailing or TEMPO groups
for showers. Any terminal that does see a shower could see a brief
drop in CIGS/VIS, potentially down to MVFR. Precip type should be
rain or a rain/snow mix with any shower. Also worth noting, with
several prescribed fire burns this afternoon, there will be some
smoke plumes around at times, especially below 10,000 feet. Martin

&&

.PREV DISCUSSION...
/ISSUED 530 AM MDT Sun Mar 26 2017/

Today through Tuesday...Isolated mountain snow showers will
continue this morning as subtle shortwave features move through
an unsettled zonal flow aloft. This activity ends later this
afternoon as shortwave ridging develops over the forecast area.
The next wave of Pacific moisture advances up to the Continental
Divide late tonight into early Monday morning, transported through
a splitting longwave trough. The mid-level center of circulation
moves across southern Idaho on Monday, turning winds to a
northwesterly direction over southwest MT. Convergence along a
surface trough in this area will provide a focus for rain and
mountain snow Monday night. Skiers might anticipate 2-5 inches of
mountain snowfall by Tuesday morning, with a slushy accumulation
possible on some of the southwest highway passes. Precipitation
moves away to the east on Tuesday with ridging aloft behind the
departing system. Temperatures remain above seasonal averages
through the period. PN

Tuesday Night through Sunday...A progressive pattern will be in
place for much of the workweek. A transitory upper ridge builds over
the area Wednesday. Beneath this ridge, somewhat anomalous
heights/temps and downsloping effects should allow for a fairly mild
day, potentially the mildest of the week.

The ridge is then followed by a fast-moving yet digging upper level
system that will dive from the Northeast Pacific to the Southwest US
and close off into an upper low. This will bring unsettled weather
to our region in the late-week timeframe (ie THU/FRI) with the
potential for a more widespread precipitation event, especially
Southwest Montana and southern sections of central MT. Of note, a
more widespread precip combined with mild temperatures next week
could lead to some hydrology concerns, but it is too early to get
too specific on this threat, especially since the models could
easily trend further south/drier with the system. But, something to
keep an eye on. By next weekend, a drier/breezy pattern looks to
develop but with temperatures normal to above normal.
Cassell/Martin

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  57  35  59  34 /   0  10  30  30
CTB  51  31  54  32 /   0  10  20  10
HLN  57  35  55  34 /   0  20  40  30
BZN  55  34  55  32 /  10  10  50  70
WEY  38  26  40  23 /  20  50  50  50
DLN  52  32  50  29 /   0  20  60  50
HVR  56  32  61  35 /   0   0  10  20
LWT  54  34  57  34 /  10  10  30  60

&&

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

$$

weather.gov/greatfalls



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