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000
FXUS65 KTFX 211033
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
430 AM MDT Mon Aug 21 2017

...UPDATED AVIATION SECTION...

.SYNOPSIS...

Areas of mid and high level clouds will mostly move east out of
the region by this afternoon. High pressure aloft will then keep
skies mostly clear into Wednesday. Smoke will also thin out
somewhat today due to light north winds, but it will linger
through mid week along the Continental Divide. Temperatures will
warm from near normal today to around 10 degrees above normal by
Wednesday. A disturbance may then bring a chance of thunderstorms
to southwest Montana Wednesday afternoon and evening.

&&

.DISCUSSION...

Today through Wednesday...Mid level clouds associated with a broad
shortwave trough will exit the area to the east this morning. The
likely mostly sunny/partly cloudy skies will make for good viewing
of today`s solar eclipse. However, there is a chance that another
batch of mid level cloudiness could move southeast out of British
Columbia and Alberta over north central Montana. A shift to light
northerly winds should also help move some of the smoke out of
the area today, keeping it closer to the Continental Divide in
the vicinity of the wildfires. A high pressure ridge will also
move into the forecast area tonight through Tuesday night, which
will help keep skies mostly clear. The ridge will also help warm
temperatures from near normal today to around 10 degrees above
normal by Wednesday. A disturbance will then move through the
ridge Wednesday afternoon, which will bring a chance of mainly
weak thunderstorms to southwest Montana.
Coulston

Wednesday Night through Monday...Period begins with an upper-
level trough digging southward and eastward from British Columbia
Wednesday night into Thursday. In addition, a Pacific cold front
accompanying this trough should sweep eastward over the CWA on
Thursday. Isolated to scattered showers and thunderstorms are
expected, especially Thursday afternoon and evening, when some
storms may be strong. The aforementioned upper trough looks to
continue digging over our region through Friday morning.
Thereafter, the trough should begin lifting northeastward Friday
afternoon as high pressure aloft builds-in from the south and
west. Accordingly, the potential and coverage of showers and
thunderstorms should dwindle on Friday. Drier weather is then
expected during the upcoming weekend and next week Monday as the
aforementioned high pressure ridge aloft continues building over
the area. Sightly above- normal temperatures on Thursday (e.g.
highs in the mid to upper 80`s for most) will be followed by a
cooler day on Friday, when the CWA will reside in a post-frontal
environment. On Friday, readings are expected to be several
degrees below-normal (e.g. highs generally in the mid 70`s to
near 80 degrees). Temperatures are then expected to rebound to
near or slightly above-normal this weekend through Monday of next
week.  Jaszka

&&

.AVIATION...
Updated 1030Z.

VFR conditions will continue across the forecast area through at
least 12Z Tuesday. Areas of mid and high clouds will generally move
east out of the area today as high pressure aloft moves east into
Montana. Forecast models are hinting at mid clouds moving through
the area through this evening, but the upstream cloudiness is fairly
sparse, so do not have confidence in this solution. Otherwise, winds
will remain light through the period. Wildfire smoke will continue
hazy skies, but the greatest threat of brief MVFR visibilities due
to smoke will be across southwest Montana today, but the winds will
shift more northerly then easterly which will lessen smoke tonight.
Coulston

&&

.FIRE WEATHER...

Fire weather highlights are not anticipated through the middle of
this week, but very dry conditions on Wednesday may combine with
increasing west winds to increase fire concerns. The potential for
critical fire weather conditions increases further on Thursday as
a cold front moves into the area. Gusty winds will be possible
with the frontal passage, especially along the Rocky Mountain
Front, and gusty erratic winds will also be possible from
scattered thunderstorms. Will continue to monitor this situation
for potential fire weather highlights.
Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  81  50  90  55 /   0   0   0   0
CTB  78  47  88  50 /   0   0   0   0
HLN  82  51  92  57 /   0   0   0   0
BZN  83  47  89  51 /   0   0   0   0
WEY  76  36  80  40 /   0   0   0   0
DLN  80  46  88  50 /   0   0   0   0
HVR  80  50  89  53 /   0   0   0   0
LWT  78  50  86  53 /   0   0   0   0

&&

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

$$

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