096
FXUS65 KRIW 181102
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
502 AM MDT Mon Aug 18 2025

.KEY MESSAGES...

- Warming trend and dry conditions through mid week.

- Near record high temperatures possible Tuesday and Wednesday.

- Next chance for thunderstorm activity Thursday becoming more
  widespread Friday and into next weekend.

&&

.DISCUSSION...
Issued at 130 AM MDT Mon Aug 18 2025

WV imagery starting to move towards a more broad and weaker
southwest flow across the CWA with a shortwave evident pushing
out of northern Wyoming into Montana through the overnight hours
into Monday morning. Otherwise, radar is becoming quiet with
much of the weak shower activity pushing northeast out of the
area into Montana and northeastern portions of Wyoming.

In wake of this shortwave, an upper level 595 dm high pressure
centered near the four corner region will start to build due to
increased convergence aloft. This will give way to a warming
trend and dry conditions through mid week Wednesday, although
some weak shower activity is possible across the Absarokas
(<10%) Monday afternoon. This high will keep the bulk of any
storm activity well to the north with the main jet across the
Pacific northwest and into southern Canada around a GOA low
making its way through the Alaskan Panhandle. Temperatures will
push back into the 80s west of the Divide and well into the 90s
east, and nearing the 100 degree mark for some by Wednesday
afternoon. Record high temperatures will be flirted with if not
broken Tuesday and Wednesday(the most likely afternoon).

The aforementioned high pressure will begin to weaken with
convergence aloft decreasing by Thursday and beyond through the
weekend. This will bring increased storm activity allowing for
an upper level low to skirt past the CWA to the north. Thursday
will see more isolated chances but becoming more scattered and
widespread for Friday and next weekend IAW the ensemble clusters
and longer term deterministic models. As such, this will be
what to watch for long term as the short term through mid week
will be all heat and no wet stuff, in which is needed for the
ongoing fires. However, synoptic nor outflow winds will be of a
concern Monday through Wednesday and hopefully give the break
that is needed for no new fire starts due to lightning nor gusty
outflows enhancing current ones.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 501 AM MDT Mon Aug 18 2025

VFR conditions and light winds less than 15kts will prevail at all
terminals through the period. High pressure will begin to build
today, bringing quieter weather for the next several days. Shower
and thunderstorm chances will be much less widespread today. 20 to
30% chances will generally remain isolated to the Absarokas, but
there is enough confidence in weak showers spreading over the Cody
Foothills to include a PROB30 group for KCOD. The only other note in
the forecast is possible wildfire smoke impacts for KWRL. HRRR smoke
forecasts indicate that despite light winds, smoke from the Red
Canyon fire east of Thermopolis will again plume out today, and that
smoke could drift north, briefly impacting KWRL with MVFR vsby
possible at times through the period.

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...Hensley