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768
FXUS65 KTFX 210541
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1141 PM MDT Fri Sep 20 2024

...AVIATION SECTION UPDATED...

.SYNOPSIS...

This afternoon there will be showers and thunderstorms
primarily along the Hi-Line. This afternoon through this evening it
will be windy in North-central Montana with the strongest winds
along the Rocky Mountain Front over to the Hi-Line. Tomorrow morning
it will be cold with numerous lower-elevation locations seeing
frost. An upper-level shortwave will bring precipitation chances to
the area Sunday evening through Monday. A ridge builds into the area
on Tuesday which will bring warm temperatures and dry conditions for
the middle of next week.

&&

.UPDATE...

Main update this evening was to lower temperatures a few degrees
across the plains, as temperatures are generally 5 degrees cooler
than the hourlies suggested they would be at this time. Watch for
some frost during the early morning hours, and any those with
sensitive vegetation that would like to keep it going for just a
bit longer should protect it. Ludwig

&&

.AVIATION...
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21/06Z TAF Period

A northwesterly flow aloft will maintain some low VFR/MVFR
cloudiness through 21/12Z,  mostly for Central/North-central MT and
over the higher terrain of the southwest. Some patchy morning fog
can`t be ruled out over areas that happen to clear out before
sunrise. Otherwise, widespread VFR conditions are expected on
Saturday. North to northwesterly surface winds will also slowly
decrease tonight and become light easterly on Saturday. - RCG

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

.PREV DISCUSSION...
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/ISSUED 140 PM MDT Fri Sep 20 2024/

This afternoon through Saturday...A cold front is moving south from
Canada. This will bring showers and thunderstorms to the Hi-Line
this afternoon through this evening. The showers will slowly spread
south to the rest of North-central Montana by midnight tonight
before they fizzle out. An isolated thunderstorm along the Hi-Line
will produce strong to severe wind gusts. The Storm Prediction
Center has issued a Marginal Risk (5% chance within 25 miles of a
point)for severe wind gusts along the Hi-Line today. The Hi-Line
has a 15 - 30% chance for seeing a tenth of an inch of rain or
greater through midnight tonight. The front combined with an
upper-level shortwave trough is bringing strong winds to North-
central Montana. The strongest winds will be along the Rocky
Mountain Front over to the Hi-Line where gusts of 40 to 50 mph are
expected. The Rocky Mountain Front and adjacent plains have a 50 -
80% chance for winds of 47 mph or greater through midnight
tonight. The cold front and upper-level shortwave trough will
lower snow-levels to 5500 feet in Glacier National Park. Areas at
5500 feet and above are likely to see a dusting of snow this
afternoon through Saturday morning. There is a 20% chance for
patchy fog to form in some valley locations Saturday morning.
Surface high pressure moves over North-central, Central, and
Southwestern Montana on Saturday. This combined with the cold
front will bring cold temperatures and clear skies to the area.
This will result in numerous lower-elevation locations across
North-central, Central, and Southwestern Montana having frost.
Saturday morning will be the coldest morning of this early fall
period. On Saturday morning lower-elevations of Southwestern
Montana and the Cut Bank area have a 10 - 30% chance of seeing low
temperatures of 32 degrees or colder.

Sunday through Tuesday...On Sunday the upper-level ridge remains
over North-central, Central, and Southwestern Montana. Then late
Sunday afternoon an upper-level shortwave moves through the flow.
This will bring precipitation chances to North-central, Central, and
Southwestern Montana. On Sunday temperatures will warm up to
slightly above seasonal averages. Sunday morning it will be cold
with some valley locations of Southwestern Montana seeing frost.
On Sunday morning lower-elevations of Southwestern Montana have a
10 - 25% chance of seeing low temperatures of 32 degrees or
colder. On Monday the upper-level shortwave remains over the area
for most of the day. This will cool temperatures back down to
about seasonal averages with precipitation chances for North-
central, Central, and Southwestern Montana. Sunday through Monday
there is a 10 - 30% chance for a tenth of an inch of rain or
greater across North-central, Central, and Southwestern Montana.
On Tuesday an upper-level ridge moves over North-central,
Central, and Southwestern Montana. This will bring dry and warm
weather to the area. Temperatures look to be up to 10 degrees
above seasonal averages. -IG

Wednesday through next Friday... The latest 3 to 7 day cluster
analysis unanimously agree with high pressure aloft building over
the Northern Rockies by the middle of the workweek for a return to
well above normal temperatures and dry conditions. Over 60% of
ensemble suites flatten the ridge by next weekend while the
remaining members more or less maintain its strength. Additional
opportunities for breezy to windy conditions, cooling temperatures,
and shower chances can be expected should the ridge become
compromised. Otherwise, the less likely scenario will be a
continuation of dry conditions and above normal temperatures. -
RCG
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&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  35  62  39  74 /  30   0   0   0
CTB  30  61  35  69 /  40   0   0   0
HLN  37  66  40  74 /   0   0   0   0
BZN  34  63  34  72 /   0   0   0   0
WYS  27  62  26  65 /  10   0   0   0
DLN  33  61  34  71 /   0   0   0   0
HVR  35  62  36  72 /  20   0   0   0
LWT  33  58  36  71 /  10   0   0   0

&&

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

$$

http://www.weather.gov/greatfalls