Area Forecast Discussion
Issued by NWS Great Falls, MT

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123
FXUS65 KTFX 300521
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1120 PM MDT FRI JUL 29 2016

Updated Aviation Discussion

.DISCUSSION...

The region remains under high pressure and the air mass will
remain dry with overnight temperatures slightly above seasonal
averages. Updated to freshen first period POPs, WX, and QPF.
Zelzer

&&

.AVIATION...Updated 0520Z.

VFR conditions will prevail through Saturday evening as dry
Northwest flow aloft backs to Southwesterly and gradually increases
as a broad upper level trough moves into BC. At the surface, a trough
of low pressure will shift east across the Northern Rockies and MT
Saturday with light east winds tonight becoming W to SW Saturday
and increasing during the afternoon period. Hoenisch

&&

.PREV DISCUSSION...
/ISSUED 528 PM MDT FRI JUL 29 2016/

THE REST OF THIS AFTERNOON THROUGH SUNDAY...High pressure aloft
will continue to build into North Central and Southwest Montana
through tonight, which will keep most of the area dry. However,
daytime heating has caused isolated weak thunderstorm to develop
over some mountain areas of North Central and move just off the
mountains. Am anticipating these storms to generally diminish
after 7 or 8 pm. An upper level low pressure trough will then move
east across British Columbia and into Alberta Saturday into
Saturday night, bringing an increasing southwest flow aloft to the
area. Weak energy in the flow will combine with a weak cold front
approaching from the northwest and daytime heating to bring
another chance for isolated thunderstorms Saturday afternoon and
evening, mainly over and near the mountains. A relative lack of
available moisture will limit potential storm coverage. As the
trough moves east across Alberta into Saskatchewan on Sunday and
in the wake of the passing cold front, west to northwest winds
will become breezy across much of the area. There will also be
another chance for isolated thunderstorms in the vicinity of the
cold front in the mountain areas of Southwest Montana, as well as
along the Hi-Line closer to the low pressure center. Temperatures
ahead of the trough on Saturday will warm to between 5 and 10
degrees above normal, but the passage of the cold front will cool
temperatures closer to normal on Sunday.  Coulston

SUNDAY NIGHT THROUGH FRIDAY...Period begins with a closed upper
level low tracking east across central AB/SK Sunday night.
Associated upper level jet energy tracks east along the
US/Canadian border with some lingering showers possible near the
border while drier air moves in from the west across central/SW
MT. Upper level ridging builds in the wake of this system Monday
before another upper level low moves onshore Tuesday, taking a
slightly further south track eastward just north of the border
Tuesday night and Wednesday. Surface cold front looks to shift
east across the region Tuesday for a somewhat better chance of
showers/thunderstorms, through moisture is limited and better
upper level dynamics again stay along or just north of US/Canadian
border. Upper level ridging rebuilds again behind this system on
Thursday and Friday. Temperatures will remain warm and slightly
above seasonal averages Monday and Tuesday with slight cooling
occurring Wednesday before temperatures climb back above normal
again late next week. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  59  94  56  87 /  10  10   0  10
CTB  56  88  54  79 /  10  10  10  10
HLN  61  97  60  90 /  10  10  10  10
BZN  54  93  53  90 /  10  10  10  10
WEY  43  82  47  80 /  10  10  20  20
DLN  54  90  53  87 /   0  10  10  10
HVR  59  93  58  87 /  10  10  20  10
LWT  57  89  57  87 /  10  10  10  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
&&

$$

weather.gov/greatfalls



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