-- Discussion containing changed information from previous version are highlighted. --
582
FXUS65 KRIW 122214
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
414 PM MDT Sat Jul 12 2025

.KEY MESSAGES...

-- Changed Discussion --
- A pleasant, seasonable, dry, and mostly sunny summer day
  across the Cowboy State today.

- Warm temperatures return for Sunday and Monday with above
  normal highs for much of the area.

- Cooler temperatures and precipitation chances return for much
  of the first half of the upcoming week.
-- End Changed Discussion --

&&

.UPDATE...
Issued at 1241 PM MDT Sat Jul 12 2025

The brief break from summer heat we saw on Friday across much of the
Cowboy State will come to an end today. Warm July temperatures
return with highs in the low to mid 80s west of the Divide and upper
80s to low 90s east of the Divide. Today will be very pleasant
overall with plenty of sunshine and dry conditions. Temperatures
continue to warm for Sunday with highs back around 90 west of the
Divide and in the mid to upper 90s east of the Divide. Conditions
remain dry with a small chance for a shower or two across the higher
elevations of northern WY.

A cold front is expected to near the state by Monday but will remain
just out of reach, allowing temperatures to stay warm for another
day. Highs for Monday are expected to be similar to Sunday with
temperatures in the upper 80s west of the Divide and mid to upper
90s east of the Divide. The nearing front will create some scattered
showers and thunderstorms mainly across northern WY. The front will
bring increased winds with a breeze developing during the afternoon.
Winds will range from 10 to 15 mph with periodic gusts of 15 to 25
mph. These winds combined with low min RH values may create elevated
fire weather conditions especially over southern WY. However, with
winds remaining mostly marginal the concern for widespread near
critical fire weather conditions looks to be low at this time.

Model disagreement remains in terms of the timing of the frontal
passage and the track of the associated trough. As of today the
front will work its way across the state Tuesday, this will lead to
cooler temperatures over northern WY with warmer values lingering
across central and southern WY. Northern WY will see increased
chances for showers and thunderstorms with the frontal passage. The
exact extent that precipitation chances spread south will depend on
the front speed and track of the trough. Currently, Tuesday looks to
see the best chances over northern WY will an isolated shower or two
possible for central WY. Widespread chances for showers and
thunderstorms arrive by Wednesday after the frontal passage. As
mentioned earlier, just how far south these chances spread still
remains to be seen. Cooler temperatures are expected for Wednesday
but do not look to be to the same degree as originally thought. The
current forecast has highs in the upper 70s to mid 80s. Earlier
forecasts showed cooler temperatures in the 70s for much of the
state. Either way this still does look to be another break from the
heat with increased chances for showers and thunderstorms. The rest
of the week will see gradual warming return with the possibility
of another disturbance by the end of the week into the weekend.

&&

.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 /00Z TAFS THROUGH 00Z SUNDAY/...
-- Changed Discussion --
Issued at 414 PM MDT Sat Jul 12 2025

All terminals to be VFR through the forecast period. A few virga
showers drift southeast off the southern end of the Wind River Range
early Saturday evening. Otherwise, nothing more than mid/high cloud
cover early in the period, which gives way to a clear sky by sunrise
Sunday. More cumulus anticipated Sunday afternoon, but there is only
a very low chance of convective impacts at terminals. Gusty westerly
wind 10-18kts at terminals west of the Continental Divide diminishes
around 02Z/Sunday. Speeds at these terminals will be around 10kts
Sunday afternoon.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on smoke, icing, and turbulence
forecasts.
-- End Changed Discussion --

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...Dziewaltowski
DISCUSSION...Hattings
AVIATION...CNJ