Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 150239
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
839 PM MDT Mon Aug 14 2017

.UPDATE...

The forecast for the rest of tonight appears valid per latest
observations and model data. See previous discussion for further
details.
Jaszka

&&

.SYNOPSIS...

Isolated to scattered thunderstorms remain possible into this
evening across the Hiline and across Southwest Montana south of
Interstate 90. Gusty winds and perhaps some hail will be possible
with the stronger storms. Thunderstorms will mainly be confined over
the higher terrain on Tuesday. The rest of the work week looks
mostly dry with gradually warming temperatures.

&&

.DISCUSSION...

General troughing across the western US at this time gradually
transitions to zonal flow over the upcoming week. This may then be
followed by troughing again by next weekend, but the models show
more variance by that point. The main impacts, then, look to be
isolated to scattered thunderstorms today/Tuesday, and possibly
again over the weekend, as well as at least elevated fire weather
conditions.

Visible satellite imagery early this afternoon shows increasing
cumulus development from Great Falls north into SW AB, associated
with a shortwave moving into western AB. Thunderstorms have already
begun to form in Alberta, and there remains a threat of
thunderstorms developing along or just south of the International
border this afternoon and evening as that area is glanced by
somewhat better lift. The best shear/instability looks to stay in
AB, but a strong storm capable of gusty winds/hail cannot be ruled
out there. It is also moderately unstable across SW MT, but lift is
weaker. Still, a few thunderstorms remain possible through this
evening, with coverage possibly hampered by cooler temps/high
clouds. On Tuesday, thunderstorms look to be confined to the higher
terrain of SW MT.

Generally dry conditions along with moderating temperatures are
expected for the remainder of the work week. By the weekend, the
pattern appears favorable for increasingly breezy conditions,
especially over the plains of central MT. This may come after a
warm/dry period and certainly bears watching for at least elevated
fire concerns. In addition, a wind shift with a cold front may add
to the concerns Saturday night. MARTIN

&&

.AVIATION...
Updated 2247Z.

Westerly flow aloft and mainly VFR will persist next 24-hours. A mid-
to upper-level disturbance embedded within this flow will advance
E`ward over the region and should begin exiting the area around
12Z/Tue. Also, a weak surface cold front will move S`ward across the
Canada border and Hi-Line this evening, and then dissipate before
reaching Central MT. A few showers and thunderstorms are possible
through ~06Z/Tue, especially along/near the Hi-Line and over SW MT.
Patchy smoke/MVFR VSBY are possible throughout the TAF period. This
includes KHVR. Additionally, patchy fog/MVFR VSBY may develop over
SW MT late this evening through daybreak Tue.
Jaszka

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  49  79  50  85 /  10   0  10  10
CTB  46  77  46  81 /  20   0  10  10
HLN  52  81  51  84 /  10   0  10  10
BZN  48  78  48  82 /  20  10  20  10
WEY  42  66  36  73 /  50  20  30  10
DLN  46  77  46  81 /  30  10  10  10
HVR  52  80  50  86 /  20  10  10  10
LWT  50  76  49  82 /  10  10  10  10

&&

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

$$

weather.gov/greatfalls


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