058
FXUS65 KRIW 121102
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
502 AM MDT Wed Aug 12 2026

.KEY MESSAGES...

- Wildfire smoke remains present across Wyoming, especially the
  northern portions of the state through at least early
  Wednesday afternoon.

- Rain shower potential increases today and becomes more
  numerous across western and central Wyoming. Rain chances
  (50%-90%) become more widespread on Thursday with cooler
  temperatures and rain chances continuing into the weekend.

&&

.DISCUSSION...
Issued at 150 AM MDT Wed Aug 12 2026

A pattern shift is currently underway that will lead to chances for
precipitation each day through the rest of the week and through the
weekend. This shift will also put an end to the latest heat wave
with temperatures remaining at or slightly below normal through the
weekend. The culprits for this cooler and wetter pattern will be a
broad area of high pressure over the Deep South/Gulf Coast and a
longwave trough over the West Coast. The Cowboy State will be
sandwiched between these two features resulting in a moist
southwesterly flow pattern. Embedded shortwaves will rotate
northward over the region, bringing widespread chances for showers
and thunderstorms across the CWA each day through Sunday. The threat
for locally heavy rain will also return as monsoonal moisture will
return as well. Precipitable water values of 0.75" to 1" will be in
place across the region today and remain in place through the
forecast period. Chances for precipitation will increase over
western portions after sunrise this morning, spreading across areas
east of the Divide through the rest of the morning and continue
through the rest of the day. A separate wave of showers looks
to move over Sweetwater County after 20Z. Most showers will be
ending in the evening, with some lingering over the central
basins through 08Z Thursday. Any thunderstorm is likely to be
very isolated due to a lack of instability for the mostly
cloudy/overcast skies. These clouds will also be the reason why
temperatures will be 4 to 10 degrees cooler today. The
hazy/smoky conditions will begin to thin today, with improving
conditions expected by Thursday as the increased chances for
precipitation allow the atmosphere to become more mixed.
Additionally, the southwest flow aloft will cut off the source
region of most of the smoke (the large fire complexes in OR/WA).


Showers and possible thunderstorms will return across areas west of
the Divide by early Thursday afternoon and spread across the rest of
the CWA through the rest of the day into the evening. There will
still be a threat for locally heavy rain, with a higher focus over
Johnson County and portions of Natrona County. This will be due to
Gulf moisture advecting into the region, pushing PWAT values to
1.25" in this area. Strong thunderstorms are possible as well, with
forecasted CAPE values of 1500 to 2000 J/kg and a lifted index of
minus 4 to minus 6. However localized flash flooding will likely be
the highest threat as bulk shear will only be up to 30kt. WPC
Excessive Rain Outlook is also forecasting a Slight risk for
this area for Thursday.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 450 AM MDT Wed Aug 12 2026

Light rain will continue to move over western portions of the
forecast area from UT/ID this morning. The main impact will be
wind gusts up to 25kt. Most terminals have at least a 30
percent chance of rain showers, and associated breezy winds,
through the day today, with showers impacting KRKS by 20Z.
Most activity is forecast to diminish by 01Z Thursday. A few
rumbles of thunder cannot be completely ruled out later this
afternoon. Although conditions are expected to remain largely
VFR, a heavier rain shower could cause brief periods of MVFR
visibilities and ceilings in addition to gusty 25 kt to 30 kt
winds. Outside of any shower activity, winds are forecast to
remain 12 kt or less at most terminals. Occasional gusts around
20 kt are possible at KRKS, KCPR, KRIW, and KBPI from outflow
boundaries. Smoke is expected to continue across the state,
especially in the area of KCOD and KWRL, through at least
sunrise on Wednesday. However, visibilities are forecast to
remain VFR.

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...
Air Quality Alert until noon MDT today for WYZ001>011-019.

&&

$$

DISCUSSION...LaVoie
AVIATION...LaVoie/Gerhardt