Coulter Creek Tail, Wyoming Weather Forecast Discussion

426
FXUS65 KRIW 241045
AFDRIW
Area Forecast Discussion
National Weather Service Riverton WY
445 AM MDT Wed Sep 24 2025
.KEY MESSAGES...
- Fog is forecast this morning across portions of the Green
  River Basin and Sweetwater County, including portions of I-80
  east of Rock Springs. Any fog that does develop should
  dissipate by 10AM.
- Dry weather with above temperatures 5 to 15 degrees above
  normal through Saturday.
- Shower and thunderstorm chances (20% to 50%) return Sunday
  afternoon across the west and continue into early next week.
&&
.DISCUSSION...
Issued at 148 AM MDT Wed Sep 24 2025
07Z satellite imagery shows mostly clear skies across the forecast
area. Yesterday, most areas were able to dry out from Monday`s rain
thanks to abundant afternoon sunshine. Sweetwater County and
portions of the Green River Basin were not as lucky and kept cloud
cover through most of the day, leaving grounds largely saturated.
With prime radiational cooling conditions, light winds, and saturated
grounds, areas of fog development are possible across portions of
the Green River Basin and Sweetwater County this morning. A
potential area of concern would be east of Rock Springs along I-80
through 9AM-10AM. This will continue to be monitored through the
morning for any fog highlights.
Apart from morning fog potential, expect a pleasant day with warm,
dry, and sunny conditions as high pressure dominates the region. An
upper-level ridge, currently (07Z) west of Wyoming, will gradually
shift into the Intermountain West today. The only thing of note as
the ridge shifts east, is an embedded weak vorticity and wind
maximum over southeast Fremont, Johnson, and Natrona Counties today.
This is will result in 15 mph to 25 mph gusty southwest winds across
the aforementioned locations beginning after 6AM and continuing
through the early evening.
Thursday is forecast to be dry and slightly warmer with the upper-
ridge directly overhead. These slightly warmer temperatures can be
attributed to abundant sunshine and above normal 500mb temperatures
directly aloft. There remains consensus amongst guidance members
that the upper-ridge will continue to shift southeast into the
Central CONUS by early Friday morning. A weak upper-level trough and
it`s surface reflection, a weak cold front, is forecast to trek
across the region Friday afternoon. However, precipitation chances
are close to zero given a lack of deep moisture. The lack of
moisture is thanks to an upper-low over southern California cutting
off moisture to the region. The only somewhat noticable cues in a
cold front is temperatures being a degree or two cooler, breezy
winds, and a slight uptick in cloud cover.
By Sunday, ensemble guidance is somewhat aligning in the upper-low
being absorbed into a longwave trough and trekking northeast into the
Intermountain West. As it does so, a slight uptick in moisture is
expected. Despite this slight increase in available moisture,
support aloft looks minimal at this time so any precipitation look
to remain confined to the western mountains. As we get into early
next week, there is consensus that a separate longwave trough will
push into the region from the west and bring increased precipitation
chances (20% to 50%) to western Wyoming.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 445 AM MDT Wed Sep 24 2025
VFR conditions expected at all TAF sites for the entirety of the
period. Fog possible for RKS/JAC but confidence low carrying
VCFG and a few low level clouds less than 1kft. Otherwise,
relatively light winds less than 6-8kts and clear skies. Dry
conditions with 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 icing and turbulence forecasts.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Gerhardt
AVIATION...Lowe

NWS RIW Office Area Forecast Discussion