055
FXUS65 KRIW 090823
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
223 AM MDT Thu Oct 9 2025

.KEY MESSAGES...

- Dry and warm conditions prevail across the CWA today.

- Chances for precipitation increase by the early morning hours Friday
  with precipitation chances spreading north through the day.

- Showers will be possible across lower elevations throughout
  the weekend with the best chances over western WY.

- A nearing disturbance will bring widespread chances for accumulating
  snow across western mountains by the second half of the
  weekend.

&&

.DISCUSSION...
Issued at 221 AM MDT Thu Oct 9 2025

Warm and dry conditions persist across the Cowboy State today.
Temperatures this morning will still be on the chilly side
especially across western WY. Temperatures this morning are expected
to range from the upper 20s to low 30s west of the Divide and upper
30s to low 40s east of the Divide. Highs will be above normal with
temperatures in the low to upper 70s across the state. Near elevated
fire weather conditions will be possible once again this afternoon
along the Wind Corridor from Rock Springs to Casper. Winds will
become breezy with periodic gusts of 20 to 25 mph across the Wind
Corridor. Min RH still remains rather low sitting around 20%. Fire
weather concerns will quickly diminish by Friday as an
unsettled active pattern develops for the weekend.

There are a lot of moving parts regarding the upcoming forecast
for Friday through the weekend. The first thing to note is that
the time frame as expected has slowed down. The high pressure
that has been across the region through much of the week has
gradually shifted to the east. The center of the high will
settle over portions of Texas and New Mexico. The anti-cyclonic
flow should help funnel tropical moisture associated with
Hurricane Priscilla and its eventual remnants across parts of
the Desert Southwest starting today. This plume of monsoonal-
like moisture looks to eventually make its way into the southern
CWA by the early morning hours Friday. This may lead to a few
isolated showers and storms early Friday across Sweetwater,
southern Lincoln, and Sublette Counties and possibly further
north by the later morning hours Friday. Friday will have
chances for showers and storms as above normal PWATs enter the
region. However, models have started to trend down on the
coverage of these showers with the best chances (20-50%) being
limited to southern and western WY. The bulk of the moisture
arrives by Saturday spreading further north across nearly all of
the CWA. Southwesterly enhances throughout Saturday aiding with
the funneling of moisture across much of the region. A trough
moving in from the PACNW will begin to shift east towards the
CWA. The nearing trough should provide some favorable upper-
level dynamics that look to interact with the surplus of
tropical moisture. All of this should combine to create a push
of precipitation Saturday afternoon and evening across the CWA,
starting from the southwest into central basins and possibly
northern areas. The nearing trough axis will supply enhanced jet
dynamics late Saturday into early Sunday over western WY where
flow looks to be the most favorable for a period of upsloping.
The trough will also bring with it colder air leading to
accumulating snowfall over western mountains. Lower elevations
of western WY may see a brief transition from cold rain to a wet
heavy snow early Sunday morning. Parts of Jackson Hole and Star
Valley may end up with a wet slushy coating of snow by Sunday
morning. Precipitation will shift eastward through the day
Sunday as the trough moves across the state and to the east.
Looking at snowfall amounts model guidance is showing a 30-60%
chance for advisory criteria amounts (6 inches or more) mainly
across the higher elevations of the Tetons, Absarokas and YNP
such as Pitchstone Plateau.

A brief lull in activity looks to occur Monday into Tuesday. Cold
temperatures may be possible as the trough moves out the area Sunday
night into Monday morning. There are early indications of widespread
sub freezing morning lows possible for Monday. Western WY may see
temperatures in the low 20s and possibly upper teens with lows
around the upper 20s east of the Divide. Still being a few days out
this may be subject to change. It is worth keeping an eye on
especially with some areas still not seeing a hard freeze yet.
Chilly temperatures will persist across the region with highs likely
in the 50s for Monday and Tuesday. The upcoming week is looking
messing and active with the potential for another disturbance moving
in from Canada for the middle of next week. Timing and impacts are
still very uncertain at this point and a better idea of what to
expect likely wont happen until the weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 943 PM MDT Wed Oct 8 2025

VFR conditions, with relatively light winds through the period.
Clouds increase from the southwest later in the TAF period as
increasing moisture advects in the area. Therefore, increasing
clouds expected for western/southwestern terminals (KBPI, KJAC,
KPNA, and KRKS) later in the period. Models differ in the onset of
rain chances late in the period, but current consensus would have
the best chances occurring right at the end, or right after the
period. Therefore, has left any precipitation chances out of the
TAFs.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on icing and turbulence forecasts.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Dziewaltowski
AVIATION...Wittmann