756
FXUS65 KTFX 261122
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
520 AM MDT Thu Sep 26 2024

UPDATED AVIATION SECTION

.SYNOPSIS...

Breezy to windy conditions and seasonably mild temperatures are
expected for the next day or so before brief warming takes place
for the first half of the weekend ahead of the next weather
system. The aforementioned system will bring another brief cool
down, slight chances for showers, and more breezy to wind
conditions for Sunday and Monday.

&&

.DISCUSSION...

An initial wave of stronger winds, with gusts in the 40 to 55 mph
range, moved through the Northern Rocky Mountain front and nearby
high plains earlier tonight. Wind speeds have leveled off since
then, but a stripe of 40 to 50 kt H700 winds arrives for another
opportunity for strong surface wind between now and 29/16Z. Then
winds aloft relax and diurnal mixing takes over and maintains
windy conditions in the aforementioned areas through this
afternoon. Given the anticipation of a second wave of winds, I
will leave the High Wind Warning as is for now. Other plains
locations will see elevated westerly winds as well, but wind gusts
will mostly remain in the 25 to 45 mph range. Temperatures in the
wake of the front will cool closer to the seasonal average for
this time of year. Similar conditions are expected on Friday as
westerly flow aloft remains elevated, but the lack of cold air
advection and shortwave energy will result in overall lighter wind
speeds and warmer temperatures than today.

Ensembles generally favor a continued progressive west to
southwesterly flow aloft this weekend into early next week, though
there are still differences among members in regards to the
timing of passing shortwave disturbances. Overall, this looks to
result in temperatures oscillating from near average to above
average and back again, along with periods of breezy to windy
conditions. I maintained the NBM solution which features frontal
passages and associated cool downs/windier periods and slight
chances for showers Sunday into Monday and again Tuesday into
Wednesday. - RCG

&&

.AVIATION...
26/12Z TAF Period

VFR conditions are forecast to continue across North Central (KCTB,
KHVR), Central (KLWT, KGTF, KHLN), and Southwest (KBZN, KEKS, KWYS)
Montana through at least 27/12Z. However, precipitation along the
Continental Divide may obscure mountain tops there through around
16Z.

The main concern during this period will be the winds. A passing
Pacific cold front ahead of a shortwave trough will cause gusty
southerly winds to shift more westerly and increase through around
18Z or so from west to east. This will cause mountain wave
turbulence and periods of low-level wind shear. Strong winds of 20
to 35 kt with gusts in excess of 50 kt have already developed on the
Rocky Mountain Front and east into the KCTB area. However, most
areas will see sustained winds of 15 to 25 kt with gusts in the 30
to 40 kt. High- and mid-level cloudiness will also move over the
area. Winds and clouds are forecast to decrease from west to east
after 21Z or so as the shortwave exits the area.
-Coulston

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  72  49  81  46 /   0   0   0   0
CTB  64  46  74  41 /  10   0   0   0
HLN  76  48  82  49 /   0   0   0   0
BZN  78  43  82  44 /   0   0   0   0
WYS  71  33  73  33 /   0   0   0   0
DLN  75  42  80  44 /   0   0   0   0
HVR  71  45  82  46 /  10   0   0   0
LWT  71  45  80  47 /   0   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 3 PM MDT this afternoon for East Glacier
Park Region-Eastern Glacier, Western Toole, and Central Pondera-
Eastern Toole and Liberty-Northern High Plains-Southern High
Plains-Southern Rocky Mountain Front.

&&

$$

http://www.weather.gov/greatfalls