778
FXUS65 KRIW 080515
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1115 PM MDT Tue Oct 7 2025

.KEY MESSAGES...

- Elevated fire weather conditions expected Wednesday afternoon
  across portions of central Wyoming. There is a 30 percent
  chance of critical fire weather conditions (wind and relative
  humidity) across Natrona and southern Johnson Counties.

- Warming temperatures and mostly clear skies persist through
  Thursday for most areas.

- Precipitation chances return late Thursday and Thursday night
  as moisture tracks north into the region. This leads to
  scattered showers and a cooling trend Friday into the
  weekend.

&&

.UPDATE...
Issued at 1226 PM MDT Tue Oct 7 2025

With the previous system now fully departed, clear skies and warming
temperatures will be the trend through the next few days. One of the
few weather concerns during this period will be elevated fire
weather conditions on Wednesday as winds come up across the Wind
Corridor and humidity drops to around 20 percent. This will be
brought on by the arrival of an upper level jet as well as a
building surface pressure gradient. Otherwise, the forecast remains
on track, with the next precipitation system arriving by the
weekend.

&&

.DISCUSSION...
Issued at 247 AM MDT Tue Oct 7 2025

A chilly start to the day across the Cowboy State this morning as
many locations east of the Divide look to see their first hard
freeze of the season. Temperatures this morning will range from the
low to mid 20s west of the Divide and upper 20s to lower 30s east of
the Divide. A few areas of patchy fog cannot be ruled out this
morning, especially near bodies of water due to the warm water
temperatures. Fortunately, a warming trend is on its way as the cold
Canadian air mass is ushered to the east and high pressure builds in
over the Intermountain West. Highs today will still be on the cooler
side with temperatures in the mid to upper 50s. However, warmer
temperatures settle in for Wednesday with highs returning to the
upper 60s to lower 70s. Warm and dry conditions persist through the
remainder of the work week as high pressure sits over the region.

Looking ahead, long range models are showing a rather potent cut-off
low developing off the coast of the PACNW during the middle of the
week. This low may be the next big weather maker as it gradually
tracks east and inland as early as Friday. However, ahead of the low
will be a plume of tropical moisture associated with the
decaying tropical disturbance Priscilla in the eastern Pacific.
Above normal PWATs attempt to make their way into the CWA
largely due to the anti-cyclonic flow of the high pressure over
the central CONUS. As a result of this moisture, chances for
showers and thunderstorms increase across the state. The timing
of the precipitation and determining the most favorable
locations still remains up in the air at this time due to the
multiple components involved. Models currently paint a bullseye
just to the south of the CWA across portions of Colorado.
However, a slight deviation in one or two components may shift
this bullseye farther north closer to the CWA.

The aforementioned cut-off low looks to eventually near the CWA
by the weekend. Another round of high elevation accumulating
snowfall is certainly possible as a result of this system.
Lower elevations, mainly across western WY, could see a cold
rain with the potential for a transition over to wet snow during
the overnight and early morning hours. Confidence is low at
this time regarding the timing and impacts as a result of this
system. Looking back at the previous system, its possible
impacts may be pushed back to the end of the weekend into early
next week as models may be a little too quick with the lows
track. Either way, cold Canadian air accompanies this system as
it moves across the region, which would lead to a return of
chilly daytime highs and overnight lows. Overall, this system is
still multiple days out and confidence in the exact impacts and
timing remains low at this time. A better idea of what to
expect will likely come into focus over the next few days.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1110 PM MDT Tue Oct 7 2025

A ridge axis extends north through the Central Rockies and
across Wyoming during the forecast period. The upper flow does
begin to back to the southwest, which leads to breezy southwest
surface wind at KCPR and KRKS late Wednesday morning and
afternoon. Otherwise, conditions remain VFR with most other
terminals seeing surface wind 10kts or less. Patchy fog in the
Wind River Basin between 11Z and 15Z/Wednesday is not expected
to impact the KRIW terminal.

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

&&

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

&&

$$

UPDATE...Myers
DISCUSSION...Dziewaltowski
AVIATION...CNJ/LaVoie