772
FXUS65 KRIW 011804
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1204 PM MDT Thu Oct 1 2026

.KEY MESSAGES...

- October starts off with pleasant dry weather and slightly
  above seasonable temperatures.

- Warmer and breezy Friday with elevated fire weather likely (2
  out of 3 chance) from eastern Sweetwater County through
  Natrona County.

- Above normal temperatures continue through much of next week
  with only small chances for any showers.

&&

.UPDATE...
Issued at 1145 AM MDT Thu Oct 1 2026

Little to update regarding the previous forecast discussion.
October is starting off quite pleasant with dry conditions, near
seasonable temperatures and plenty of sunshine. Friday is
looking quite warm with highs forecast to be 10 to 15 degrees
above normal. Model guidance is showing most basins east of the
Divide such as the Bighorn and Wind River Basins having a 40-70%
chance of seeing highs reach 80F. Locations west of the Divide
see warm temperatures as well with highs getting into the low
to mid 70s. Near elevated fire weather conditions do remain
possible Friday mainly along the Wind Corridor from Rock
Springs to Casper. Otherwise, not much else to add forecast wise
with a brief cool down for Saturday. A prolonged period of
above normal temperatures in association with a large ridge
moves over the western CONUS for the end of the weekend into the
start of next week. Record daily high temperatures may be in
jeopardy for Monday with highs possibly getting into the low 80s
east of the Divide. These warm temperatures look to persist
through much of next week as a potent ridge remains locked in
place across the western CONUS.

&&

.DISCUSSION...
Issued at 1233 AM MDT Thu Oct 1 2026

Welcome to the final quarter of the 2026. And if there is a rule of
thumb for the past nine months, it is that has been a very warm year
on average. Most of our major climate sites have had either their
warmest or second warmest year on record so far this year. And most
of the next several days will be more of the same.

There are some minor concerns to worry about. The main feature of
the day is a weak cold front that will drop southward into the
northern Wyoming today. There is not a ton of moisture to work with
and the best jet forcing should remain in Montana. There may be just
enough moisture and forcing for a stray shower over the Bighorns or
Johnson County, but the chance is generally 1 out of 6 or less, with
most locations remaining dry. There will also be a bit of a breeze
in that location, but nothing out of the ordinary. Otherwise, it
will be another dry and nice autumn day, although somewhat cooler
East of the Divide.

On Friday the concern shifts to fire weather. Another weak cold
front will be approaching from the north. Flow will turn
southwesterly ahead of the front, bringing downsloping flow and a
warm day, with some locations seeing high temperatures rising into
the 80s in the warmer spots. With the tightening pressure gradient,
a gusty breeze will develop in the favored southwesterly flow areas
from eastern Sweetwater County to Natrona County. As for potential
fire weather highlights, there will be enough wind. However,
humidity looks borderline at best. The NBM ensemble gives a mean
minimum humidity generally only around 18 to 22 percent even in the
favored areas, and it may not occur for three hours. So, no fire
weather highlights at this point. There will likely be elevated fire
weather for a time in the afternoon in the favored locations.
Otherwise, it will be another dry and warm day.

Saturday will see temperatures all back a bit East of the Divide
following the frontal passage. Like today`s front, it has little
moisture to work with so few or no showers are expected. There will
be a somewhat tighter pressure gradient though, especially across
the northwest flow / cold advection areas. The NBM ensemble gives at
least 1 out of 2 chance of wind gusts over 30 mph, with a 1 in 2
chance of gusts over 40 mph in northern Johnson County. Fire weather
should remain below critical though as cooler temperatures and
higher humidity move into the area.

Sunday looks like a dry and mild day with few concerns. Another weak
system then approaches Monday into Monday night and could bring a
few showers. but again chances are small, generally less than 1 out
of 4 in any locations and mainly in western Wyoming. There will
likely be more fire weather concerns at times next week, with Monday
looking like the day of the most concern with breezy conditions and
low humidity developing with the southwest flow ahead of the system.
Much of next week looks like a continuation of above average
temperatures and little chance of rain as ridging controls the
weather across most of the western United States.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1030 AM MDT Thu Oct 1 2026

VFR conditions at all TAF sites under clear skies and relatively
light winds 10kts or less. RKS might experience a brief stronger
gust up to 12 to 15kts but with minimal operational impact.
Otherwise, winds diminish to 5kts or less towards sunset after
02-03Z with radiational cooling through the overnight hours and
into Friday morning. No other weather elements are 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