364
FXUS65 KRIW 251656
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1056 AM MDT Fri Sep 25 2026

.KEY MESSAGES...

- Low shower and thunderstorm chances (up to 30%) from Rock
  Springs to southern Johnson County late this morning and this
  afternoon. However, most will remain dry with highs in the
  upper 60s and 70s.

- Breezy west to southwest winds each afternoon through Sunday,
  especially across the Wind Corridor and higher elevations.

- Showers and thunderstorms are forecast Sunday afternoon
  through Tuesday morning across western and central Wyoming.
  Elevations above 10,500 feet could see a few inches of snow.

&&

.DISCUSSION...
Issued at 100 AM MDT Fri Sep 25 2026

IR currently depicts mainly clear skies for the northern half of
the CWA with mid and upper level clouds spilling in from the
south for southern portions of the state from a weak trough
across northern Colorado. WV shows the main finger of the PFJ to
the north dipping down from the Gulf of Alaska to the Pacific
Northwest around the next main L/W trough that will affect the
upper Rockies by Sunday. For Friday, expect a bit warmer than
average temperatures and gusty winds due to an increasing
pressure gradient ahead of an approaching west to east moving
cold front Friday night into Saturday morning. Gusty winds 15 to
25 mph will be common for much of the area in the afternoon
during peak heating and mixing, stronger for the Wind Corridor
from Sweetwater to Natrona Counties where gusts could reach 30
to 35 mph. Winds look to weaken but remain elevated after sunset
as the aforementioned cold front starts to push in out west
before stalling along the Divide by sunrise Saturday morning. A
little bit of model disagreement on how far it reaches, but
overall, dry conditions will be expected. With the weak trough
to the south, expect some isolated rain showers and
thunderstorms to push across far eastern reaches of Sweetwater
County through Muddy Gap to Casper early to late afternoon with
minimal accumulations and/or impacts expected. Otherwise,
increased clouds throughout the CWA in the mid and upper levels
ahead of the deepening trough to the west with increased
divergence aloft ahead of it.

More seasonable temperatures west of the Divide Saturday with a
bit above average to the east, dependent on how far east the
cold front pushes. Gusty winds continue Saturday as well similar
to Friday. As the main low skirts to the north across southern
Canada late Saturday into Sunday, the southern end of the trough
begins to cut off near California. This will deepen as well with
the increased upper level divergence as it progresses slowly
eastward bringing the more conducive southwest flow across the
CWA. Expect scattered shower activity west of the Divide late
Sunday morning, expanding to the east later Sunday evening and
into the overnight hours and into Monday morning. The low pushes
east, across the Southern Rockies and into the High Plains by
Tuesday that will end precipitation chances. Accumulations at
this time don`t look overwhelming, but all areas have a decent
chance for a wetting rain (>.1") around 50 to 90% in coverage,
and again best chances west of the Divide. Mountain snow is
likely as well, as temperatures become more seasonable and
freezing levels drop to the 10-11kft range. An inch or two is
possible in the higher elevations of the Winds (mainly the
western side), along with the Absarokas and northern Bighorns.
Any mountain passes should stay void of any snowfall but there
is time for change being a few days out. Stay tuned for updated
forecasts in the coming day or two for the models to come into
better agreement on the movement of the cut-off low from
California through the southern Rockies.

Beyond Tuesday, expect upper level ridging to build back in from
the southwest for the rest of the week and into the weekend.
Temperatures will moderate back to seasonable Wednesday onward
with dry conditions expected there on. The next system looks to
impact the CWA and Northern Rockies heading into the following
weekend looking at the longer term model solutions but time will
tell.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1050 AM MDT Fri Sep 25 2026

VFR conditions expected across the area through the TAF period.
Confidence for showers to impact KCPR this afternoon has
decreased and have removed the PROB30 group from the forecast.
Mid to high level clouds, SCT-OVC FL120-250, for most areas
along and east of a KRKS to KBYG line through 00Z with skies
becoming SKC west of this line. These clouds will gradually
clear east of Johnson/Natrona counties by 06Z, as additional
FEW-SCT clouds push in from the west.

Winds will generally be light, with gusts up to 20kt occurring
for several terminals this afternoon. A cold front will move
southward through Johnson/Natrona counties after 09Z, turning
winds northerly. This front will also reach KCOD by 11Z, which
could bring lower clouds to the terminal. However, there is
currently a less than 10% chance for MVFR ceilings or lower to
occur.

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.

&&

$$

DISCUSSION...Lowe
AVIATION...LaVoie