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978
FXUS65 KTFX 272056
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
256 PM MDT Thu Jun 27 2024

.SYNOPSIS...

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Showers and thunderstorms diminish later this afternoon and
evening, but showery, windy, and much cooler conditions are
expected tonight into Friday, with most precipitation falling over
North-central Montana. Drier and milder weather is expected for
the first half of the weekend, followed by a return of more active
weather Sunday into early next week.
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&&

.DISCUSSION...

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Showers and embedded thunderstorms continue to move through the
eastern portions of Central/North-central Montana this afternoon
while a much more isolated brand of activity is situated farther
to the west. Instability never really sufficiently recovered for
any widespread stronger to severe thunderstorm development, but
there were a a few instances of wind gusts over 40 mph and some
small hail along the Hi-Line and the southwest. This trend should
continue, with only isolated small hail and or wind gusts, if any,
for the remainder of the afternooon.

Post frontal westerly winds have already begun to increase and
westerly flow aloft will become stronger this evening and tonight
while the mid- level low moves along the Canadian border. This
will maintain breezy to windy conditions along the Rocky Mountain
Front and the plains during the overnight hours. Wind speeds
should generally stay in the 20 to 35 mph, except along the Rocky
Mountain Front and adjacent high plains where there is around a 60
to 80% chance for wind gusts exceeding 55 mph this evening into
the overnight hours. Given the higher criteria (75 mph) for high
winds along the Rocky Mountain Front and the lower wind exceedance
probabilities over the high plains, I opted for a Special Weather
Statement and weather stories to address the expected impacts.

Precipitation chances remain on the low side this evening before
wrap around moisture brings showers and stratiform rains southward
over northern areas as the night progresses. There will be
sufficient cold air aloft for some higher mountain snow over the
higher terrain of Glacier National Park, though accumulations look
to be negligible and impacts are expected to be limited to cool
and wet outback conditions.

Showers and perhaps a few thunderstorm will move deeper into
Central and North-central Montana on Friday while cool
northwesterly winds keep temperatures a good 10 to 20 degrees
below average for this time of year. H700 to H500 flow in the 40
to 45 kt range combined with cold air advection and lower end
shower/thunder activity may result in a few surface wind gusts
over 50 mph, mostly along the Hi- Line and Fergus/Judith Basin
Counties. There are no plans for high wind products on Friday
either with the expected isolated nature of higher end wind gusts
and NBM probabilities for criteria winds remaining well under 80%
at this time.

Transient ridging brings a period of lighter winds and drier
conditions Friday night and much of Saturday before a more
unstable southwesterly flow aloft develops ahead of the next
approaching Pacific weather system by Sunday and brings a return
of shower thunderstorm chances. Most ensembles favor a
northwesterly flow aloft for the first half of next week with
passing disturbances maintaining daily chances for showers and
thunderstorms and near to slightly below average temperatures.
- RCG
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&&

.AVIATION...
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27/18Z TAF Period

Showers and thunderstorms will move from west to east through the
late afternoon hours with low VFR/MVFR conditions in addition to
erratic, gusty winds, downpours, and lightning. The severe threat
has diminished some, but a few strong to severe storms can still be
expected, mostly for the KHVR and KLWT. Gusty westerly winds and
partial clearing take place tonight with locations along the
Northern Rocky Mountain Front and adjacent high plains (KCTB)
potentially seeing wind gusts over 40 kts along with mountain wave
activity after 28/00Z. Wrap around moisture then moves in from
northwest to southeast into Central/North-central Montana tonight
and Friday for MVFR clouds and showery/windy conditions. - RCG

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.
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&&

.PRELIMINARY POINT TEMPS/POPS...
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GTF  49  61  43  74 /  10  80  10   0
CTB  48  61  42  70 /  50  90   0   0
HLN  50  68  45  84 /   0  30   0   0
BZN  42  68  40  81 /  10  10   0   0
WYS  36  65  34  80 /  10   0   0   0
DLN  41  69  40  82 /   0   0   0   0
HVR  50  63  43  74 /  30  70  10   0
LWT  45  59  38  71 /  10  50  10   0
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&&

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

$$

http://www.weather.gov/greatfalls