961
FXUS65 KTFX 081209
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
509 AM MST Fri Nov 8 2024

Aviation Section Updated.

.KEY MESSAGES...

 - It will be warm today and Saturday before it cools down
   slightly on Sunday and then warms back up on Monday.

 - It will be windy across the area Monday through Wednesday with
   cooler temperatures on Tuesday and Wednesday.

 - Precipitation will return to the Rocky Mountain Front and
   Southwestern Montana on Sunday, with higher amounts expected
   Monday evening through Wednesday evening.

&&

.DISCUSSION...
/Issued 302 AM MST Fri Nov 8 2024/

 - Meteorological Overview:

There is an upper-level ridge in place over North-central, Central,
and Southwestern Montana through Saturday this will bring warm (well
above seasonal average) temperatures and clear skies to the area
through Saturday. Due to clear skies and light winds tonight through
this morning fog will likely form in some of the valleys of
Southwestern Montana especially the West Yellowstone area and
Gallatin valley. Today due to a strong surface pressure gradient
there will be breezy conditions along the Rocky Mountain Front. On
Sunday a weak upper-level shortwave quickly moves through the area
which will bring precipitation along the Continental Divide and in
the Gallatin and Madison ranges for Sunday and Monday. Additionally
high temperatures on Sunday will be slightly cooler due to the
shortwave.

On Monday an upper-level ridge builds back in over North-
central, Central, and Southwestern Montana which will warm
temperatures back up to well-above seasonal averages. Monday evening
an upper-level trough associated with a surface cold front begins to
move through North-central, Central, and Southwestern Montana. This
combined with a strong surface pressure gradient will bring strong
winds to the area especially along the Rocky Mountain Front Monday
through Wednesday. On Tuesday and Wednesday the upper-level
trough remains over North-central, Central, and Southwestern
Montana until Wednesday evening. This will bring cooler (about
seasonal average) temperatures to the area with precipitation
chances along the Rocky Mountain Front and south of the Montana
Highway 200 Corridor. To close out the work week the upper-level
ridge remains over North-central, Central, and Southwestern
Montana. This will dry out the area and warm temperatures back up
for Thursday and next Friday.

 - Forecast Confidence & Scenarios:

There is high forecast confidence in dry and warm weather through
Saturday and light precipitation along the Continental Divide and
the Gallatin and Madison ranges with cooler temperatures on Sunday.
However the location and track of the upper-level shortwave that
brings the precipitation on Sunday varies between models and
ensembles so as result there is some uncertainty in the
precipitation amounts. On Sunday there is a 40 - 70% chance for
greater than trace of liquid precipitation and a 50 - 80% chance for
greater than a tenth of an inch of snow along the Rocky Mountain
Front and the Gallatin and Madison ranges. Today, Saturday, and
Monday there is a 40 - 70% chance for temperatures of 60 degrees or
greater across the plains of North-central Montana.

On Monday there is low confidence in the timing of the upper-level
ridge breaking down and the strength of the upper-level trough with
high confidence that the upper-level ridge will break down with an
upper-level trough replacing it. This results in uncertainty in the
wind speeds and gusts and how much colder temperatures will get
Monday through Wednesday. On Monday, Tuesday, and Wednesday there is
a 40% chance for wind gusts greater than 45 mph across North-
central, Central, and Southwestern Montana. On Monday, Tuesday and
Wednesday there is a 30 - 60% chance for wind gusts of greater than
55 mph along the Rocky Mountain Front and Adjacent Plains.

Monday evening through Wednesday morning there is a 50 - 80% chance
for greater than a tenth of an inch of liquid precipitation south of
the Montana Highway 200 Corridor. Monday evening through Wednesday
evening there is a 50 - 80% chance for 2 inches of snow or greater
along the Rocky Mountain Front and the mountains of Southwestern
Montana. Clusters show high confidence in an upper-level ridge
building in over the area on Wednesday and keeping it over the area
on Thursday. On next Friday clusters begin to show an upper-level
ridge moving toward North-central, Central, and Southwestern
Montana but there are differences in the timing and strength of
the trough. - IG

&&

.AVIATION...
08/12Z TAF Period

VFR conditions are expected over the next 24 hours across North
Central and Southwestern Montana. Only concern is that there may
be some brief fog in some of the valleys of Southwest Montana for
an hour or two this morning, but I do not have enough confidence
to put in any TAFs. Ludwig

The KWYS TAF will not be issued until airport operations resume next
spring.

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  62  35  58  40 /   0   0   0   0
CTB  63  34  57  33 /   0   0   0  10
HLN  54  28  55  33 /   0   0   0  10
BZN  52  24  54  28 /   0   0   0  10
WYS  45  13  42  18 /   0   0   0  10
DLN  52  25  53  29 /   0   0   0   0
HVR  59  30  55  33 /   0   0   0   0
LWT  60  33  58  33 /   0   0   0   0

&&

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

$$
http://www.weather.gov/greatfalls