924
FXUS65 KTFX 221133
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
532 AM MDT Sun Sep 22 2024

UPDATED AVIATION SECTION

.SYNOPSIS...

Westerly winds increase today while temperatures warm closer to
average. An approaching weather system will increase middle and
higher level clouds by this afternoon before bringing isolated
lighter end shower activity tonight into early Monday. Much warmer
and dry conditions are expected for Tuesday and Wednesday.

&&

.DISCUSSION...

Mostly clear skies are being observed early this morning aside
from some passing cirrus and the ongoing potential for AM patchy
fog development for some of the wind protected valleys. Westerly
winds are already increasing along the Rocky Mountain Front and
this will spread onto the plains later today. There is over a 70%
chance for gusts to exceed 40 mph along the Northern Rocky
Mountain Front eastward toward the Cut Bank area; otherwise, most
other Central/North-central locations should see gusts more in the
15 to 30 mph range.

Middle and higher level cloudiness will be on the increase today
as a Pacific shortwave approaches from the northwest. This system
is much weaker than last Friday`s, but it will still bring some
lighter end shower activity, mostly for Central/North- central MT
this evening through early Monday. Temperatures moderate to near
average toady and nearly hold steady on Monday.

High pressure aloft builds in Tuesday and Wednesday for dry and
very warm conditions. Most lower elevation temperatures will peak
in the lower and middle 80s Wednesday afternoon, about 15 to 20
degrees above average for this time of year. Most record highs for
Wednesday run from the upper 80s for the cooler southwest valleys
to the lower and middle 90s over the warmer central/north-central
areas, so widespread record breaking temperatures are not
expected at this time.

Most ensembles bring a trough onto the Pacific NW coast on
Wednesday before brushing the Northern Rockies on Thursday for a
slight cool down, breezy to windy conditions, and perhaps a few
showers or thunderstorms. Temperatures still remain above average
until the next cold front arrives around Saturday and brings more
seasonable conditions. The next chance for more widespread
precipitation looks to hold off until next Sunday/Monday or even
beyond. - RCG

&&

.AVIATION...
22/12Z 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 23/12Z.

Patchy fog may still form between 12Z and 16Z in some Southwest and
Central Montana valleys, but high cloudiness will keep the
probability low for significantly reduced visibility at any of those
terminals.

High- and mid-level cloudiness will increase over the area in the
increasing west-northwest flow aloft through around 00Z; any
precipitation that falls out of the clouds will likely not reach the
ground. As the flow aloft increases, the potential for mountain wave
turbulence increases as well. Westerly downslope winds will also
become gusty after 15Z as well, with the areas of potential 30+ kt
gusts being limited to along and west of a KCTB-KGTF line. These
winds should start to decouple a bit after 02Z, allowing areas of
low level wind shear to develop. -Coulston

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  75  46  73  45 /  10  20   0   0
CTB  69  43  69  46 /   0  10   0   0
HLN  75  50  73  46 /   0  10   0   0
BZN  71  43  70  40 /   0  10   0   0
WYS  67  31  64  30 /   0  10   0   0
DLN  72  41  68  39 /   0  10   0   0
HVR  71  47  71  45 /   0  10   0   0
LWT  70  45  67  42 /   0  10   0   0

&&

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

$$

http://www.weather.gov/greatfalls