423
FXUS65 KRIW 121707
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1107 AM MDT Sat Jul 12 2025

.KEY MESSAGES...

- A typical mid summer day to start the weekend today with dry
  conditions and near normal temperatures.

- Hot temperatures return Sunday and continue into Monday.

- The chance of convection returns on Monday and lasts into next
  week. Details of the most active day and placement of storms
  remains uncertain, especially from Tuesday on.

&&

.DISCUSSION...
Issued at 325 AM MDT Sat Jul 12 2025

Friday night was one of those nights you really appreciate in the
middle of summer. After a couple of really hot days, it was really
refreshing stepping outside. Temperatures in the 50s with the nearly
full moon out. However, these days are rare in the climatologically
warmest time of year, and these will come to an end fairly quickly.

The weather will be dominated by dry northwest flow today with
convergence aloft. This will lead to a fairly typical summer day
across western and central Wyoming. That means a good deal of
sunshine, temperatures returning to near normal levels (warm but not
overly hot) and light to moderate wind. So, a nice day to start the
weekend. We turn the heat machine back on for Sunday through as
thicknesses climb across the area. Highs in the lower elevations
will see a lot of upper 80s to 90 west of the Divide to 90s to near
100 to the east. There may be just enough mid level moisture
returning for a stray shower or thunderstorm of the late day variety
in the northern mountains. However, with the chance only around 1
out of 10, we kept the forecast dry for now.

Things look to turn more active for the first part of next week. A
cold front will move toward the area for Monday but will remain far
enough north for another hot day, with temperatures similar to
Sunday`s highs. It will be close enough to bring a somewhat better
coverage of showers and storms. This would be limited to the
northern half of the state. Even here though, the chance is only
around 1 out of 3 in the mountains and 1 out of 5 in the lower
elevations. The other concern will be elevated fire weather as the
pressure gradient tightens a bit. Sustained winds only look to be in
the 12 to 15 knot range though across southern Wyoming, where the
main concern would be. This makes critical fire weather unlikely at
this time (about a 1 in 5 chance at this time) despite humidity
under 15 percent.

There is more model disagreement for Tuesday and Wednesday in
regards to the front and associated trough. Some guidance has trough
moving over Wyoming, bringing a rather active 48 hours. Other
guidance keeps the main impacts over Montana with only scattered
convection. We made few changes at this time as details this far out
are nearly impossible to hash out. We do have high confidence in
cooler temperatures returning for this period, generally retreating
to near to slightly below normal levels. This uncertainty extends
into the end of next week as well, as Wyoming will be near the top
of the ridge and any shortwaves could bring convection. But timing
and position of these waves is hard to predict this far out. So to
summarize the next week, there will an increased chance of
convection and cooler temperatures, but details of the timing and
placement of storms remains highly uncertain.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1107 AM MDT Sat Jul 12 2025

VFR prevails at all terminals through the forecast period. Mid/high
clouds drift across the region Saturday afternoon and evening in
northwest flow aloft. There appears to be enough moisture and
instability to generate a few virga showers over the far southern
end of the Wind River Range early Saturday evening. Gusty westerly
wind 10-18kts blows most of Saturday afternoon until around
02Z/Sunday at terminals west of the Continental Divide.

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...Hattings
AVIATION...CNJ