505
FXUS65 KRIW 301747
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1147 AM MDT Wed Sep 30 2026

.KEY MESSAGES...

- A pleasant end to September is expected across the Cowboy
  State today. Skies remain mostly clear with dry conditions and
  warm above normal temperatures.

- A weak weather system may bring cooler temperatures Thursday
  and Friday and isolated showers to northern Wyoming.

- Mainly dry conditions and unseasonably warm temperatures will
  dominate for most of this weekend and into next week.

&&

.UPDATE...
Issued at 1129 AM MDT Wed Sep 30 2026

Not much to update regarding the forecast as there has been
little to no change compared to the previous discussion.
Pleasant, dry, and warm conditions are expected across the
Cowboy State today. Highs may get into the low 80s across the
Bighorn Basin while most locations see high temperatures in the
mid to upper 70s. Conditions look to remain dry through the
remainder of the week with warm temperatures returning by
Friday through the start of next week. There are early
indications of unseasonable warmth with temperatures nearly 10
to 15 degrees above normal by the end of the weekend into the
start of next week. Current model guidance is showing a 40-70%
chance of highs reaching or exceeding 80F across most locations
east of the Divide on Monday. There is still time for things to
change but at this time there is fairly good consensus among
models. That being said, it is looking like the first week of October
is going to start off quite warm, which is not much of a
surprise when you look back at how the past 9 months have been.

&&

.DISCUSSION...
Issued at 1250 AM MDT Wed Sep 30 2026

We have now reached the end of the ninth month of the year, about
75 percent through the year (74.5 percent to be exact). And we are
now in, as a rule, on of the nicest times of year in Wyoming. This
generally runs from after Labor Day through the middle of October.
Yes, I realize we have had some snowstorms, and some substantial
ones during this time frame, but most days are nice. And most of the
next several days will be no exception.

For most of the area today, the weather will be described by a
couple of songs popular around the turn of the millennium. The better
known one is by U2, the lesser known one, at least on this side of
the Atlantic, is by the British band 3 Colours Red. And those songs
are "Beautiful Day" and "A Beautiful Day", respectively. Today will
feature a cool morning, a comfortably warm afternoon and a good
deal of sunshine. As for cloud cover, the most would be across the
far north, and in southern Wyoming, where some high level moisture
may move up from the remnants of Hurricane Polo. However, showers
will remain to the south and east of our area. It could become
breezy late today across portions of northern Wyoming, but nothing
by Wyoming standards. So, if you can, get out and enjoy it.

A weak cold front will make a run at Wyoming Thursday into Thursday
night. Impacts from it look minimal at this time. Guidance has
trended further north with the jet forcing than at this time
yesterday. The front also is of continental origin and has little
moisture to work with. As a result, the chance of showers Thursday
into Thursday night has also dropped. There is still a small chance
of shower Thursday night, but it is 1 out of 6 at the most and
largely limited to north of a Lovell to Buffalo line. The main
impact we will be somewhat breezier conditions and a small reduction
in temperatures, but only 5 to 10 degrees with the biggest drop in
the northern Bighorn Basin and Johnson County.

Friday at this point looks like a mild and quiet day. Another cold
front will make a run at northern Wyoming Friday night into
Saturday. However, the same criteria applies to this front as the
last one. The chance of showers is minimal and largely restricted to
far northeastern portions of the area. Again, the main impacts will
be for somewhat cooler temperatures East of the Divide and breezy
conditions in the favored cold advection locations like the northern
Big Horn Basin and Johnson County.

In the longer term, ridging will set up across much of the western
United States and bring a period of mainly dry conditions and above
normal temperatures from Sunday through much of next week. There
will be another fast moving system moving west to east into the area
Monday night into Tuesday. It could bring some showers during this
time frame. The main impact may be some increasing wind ahead of it.
This, combined with low humidity and unseasonably warm temperatures,
may bring elevated fire weather Monday afternoon to portions of the
area. Otherwise, things look relatively uneventful next week with
some, shall I say, beautiful days a very good possibility.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1030 AM MDT Wed Sep 30 2026

VFR conditions expected throughout the entire period at all TAF
sites. Light winds and mainly clear skies 10kts or less
expected, becoming 5kts or less after 02Z towards sunset with
radiational cooling. No other weather elements expected at this
time.

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...Dziewaltowski
DISCUSSION...Hattings
AVIATION...Lowe