737
FXUS65 KRIW 260740
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
140 AM MDT Sat Sep 26 2026

.KEY MESSAGES...

- A largely tranquil start to the weekend with above normal
  temperatures and only a small chance of a virga shower in and
  near the mountains.

- Increasing moisture brings an increased chance of showers
  later Sunday and especially Monday, with the best chance is
  western and southern Wyoming.

- Warm and tranquil weather returns starting Tuesday and
  continuing through at least Friday.

&&

.DISCUSSION...
Issued at 136 AM MDT Sat Sep 26 2026

One of my interests outside of meteorology is also something
involved with looking at the sky. As I was driving into work this
evening listening to classic rock (because I`m old), I heard a song
that fits with tonight, Harvest Moon by Neil Young, it looked
beautiful when I was driving in. Much of the area, not all but
a decent amount will be mostly clear through sunrise so I
highly suggest going out and taking a look if you can.

Otherwise, things look relatively tranquil today. A weak cold front
will approaching from the north, and this will bring some breezy
conditions to some locations. And, there could be just enough mid
level moisture for an isolated shower mainly in and near the
mountains. The chance is now more than 1 in 10 and chances were
added mainly for fire weather purposes. Most locations will see
nothing and remain dry through at least Sunday morning. And it will
be a warm day, with high temperatures rising into the 80s across the
warmer spots like Worland and Thermopolis and possibly Casper. As
for potential fire weather issues, relative humidity should remain
above critical levels. However, with values dropping to around 20
percent, locally elevated fire weather is possible in the breezier
locations for a time this afternoon.

The next chance of rain moves in Sunday afternoon into Monday as
some moisture moves into the area, with an upper level low driving
some moisture from Hurricane Polo off of the Mexican coast.
This, along with some upper level divergence and the front
being in the area. This does not look like a big rainfall event
though. This mornings model runs have come in somewhat drier,
keeping the bulk of the moisture to the south of Wyoming. Much
of the southern and western portions of the area still have a
greater than 1 in 2 chance of over a tenth of an inch or rain,
although this would fall over a greater than 1 day period.
Chances of greater than a quarter of an inch or rain greater
than 2 out of 5 are largely limited to the mountains and
possibly the far southern portions of the area. And, we also
have to talk about a bit of snow. There is not a ton of cold air
with this system, with 700 millibar temperatures only falling
to around 4 celsius, which would put snow levels around 10000
feet. There will likely be some snow in the air. Accumulations
would be light though. The NBM ensemble shows the only area with
a greater than 1 in 2 chance of an inch or more to be in the
Wind River Range, largely above 11500 feet with no impacts to
travel corridors. Most of the showers should end by sunrise on
Tuesday.

Following that, largely tranquil conditions should move back into
the area for most of the period as ridging builds over the northern
Rockies, That means another fairly lengthy period of above normal
temperatures and little chance of precipitation. We will will have
to keep and eye to the south though. It looks quite wet down there
as an upper level low moving from the California combines with the
remnants of Hurricane Polo to bring some soaking rain and
possible problems with flooding. Almost all guidance keeps this
moisture to the south and east of western and central Wyoming.
However, upper level lows and tropical systems are fickle so we
will continue to watch this. Looking way out to next weekend, we
may really have a taste of fall as one of the first Canadian
cold fronts may drop southward into Wyoming, bringing some much
cooler temperatures. With the continental origin of the system,
moisture looks limited though. It is still a week out so a lot
can change, but we may finally have a decent taste of mid autumn
Saturday or Sunday.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 951 PM MDT Fri Sep 25 2026

VFR conditions prevail through the TAF period. Skies will remain
mostly clear through Saturday morning with increasing clouds
Saturday afternoon into Saturday evening. There is a low chance
(20%) of a light rain shower around KRKS Saturday afternoon and
evening, but will mostly be scattered virga showers.

Wind will remain around 10 knots at KCPR tonight through Saturday
morning, with other terminals 10 knots or less. Wind will increase
from the southwest across the area Saturday afternoon. Wind will
average 10-20 knots with gusts of 20-30 knots Saturday afternoon.
Wind should subside after sunset Saturday evening. A weak cold front
will pass through northern portions of the area late Saturday
afternoon into Saturday evening, which will bring a northerly wind
shift to KCOD and KWRL.

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...Hattings
AVIATION...Rowe