022
FXUS65 KRIW 232350
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
550 PM MDT Thu Jul 23 2026

.KEY MESSAGES...

- Isolated showers and thunderstorms will be possible across
  areas east of the Continental Divide through midnight. Locally
  heavy rain will remain possible with any strong storm that
  develops.

- High pressure builds across the Rockies for this weekend,
  bringing another round of heat to the state. Areas of northern
  and central Wyoming could again reach the upper 90s and lower
  100s from Friday through Monday.

- Lingering monsoon moisture and weak disturbances from the
  Great Basin will continue to bring isolated showers and
  thunderstorms over western and northwestern Wyoming as well
  as other higher elevations this weekend into early next week.

&&

.UPDATE...
Issued at 206 PM MDT Thu Jul 23 2026

Convection is well under way this early to mid afternoon across
western and central WY, with most of the storms across southern
and central WY. Still expecting more development over the
eastern portions of the Absarokas, Bighorns, and Wind Rivers,
moving to the southeast, as a shortwave trough rides over the
ridge axis just to our west. The 18Z KRIW sounding not only
shows a very moist lower atmosphere, but a significant cap
around 500 mb which would limit the vertical extent of any
convection. A new-ish Flood Watch remains in effect through 8
PM for some areas due to the possibility of heavy rain falling
on now- saturated soils. However, the ground seems to be taking
in quite a bit of precipitation given the lack of localized
flooding the past two days. Otherwise, welcome showers and
thunderstorms are expected through sunset this evening, moving
toward southeast WY.

The upper-level ridge axis will slide eastward over western WY
on Friday, keeping relatively light winds over the area. A weak
shortwave trough is expected to move from the northern Great
Basin toward northwestern WY during the afternoon, bringing
isolated showers and thunderstorms to west-central WY, then into
northern WY during the evening hours. Locally moderate rain and
gusty winds up to 30 mph are possible from 4 to 8 PM Friday due
to possible thunderstorms. With the ridge axis moving into WY
Friday, temperatures are expected to climb about 7 to 10 degrees
Friday afternoon, ranging from the upper 80s to upper 90s. Even
warmer temperatures are expected on Saturday, with the
expectation that another shortwave trough will bring increasing
afternoon cloudiness and scattered showers and thunderstorms
late in the day.

&&

.DISCUSSION...
Issued at 247 AM MDT Thu Jul 23 2026

After a day of scattered to numerous showers and thunderstorms
yesterday, the overall threat for precipitation decreases some
for Thursday. The shortwave trough that swept across the state
yesterday is moving into eastern WY, taking most of the
thunderstorm activity with it. WV imagery shows the main
moisture pool shifting east with it, while a push of drier air
moves in from the west. The lack of midlevel energy and the
decrease in moisture will keep thunderstorm activity much more
isolated today, mainly along the higher elevations of the
Absarokas and Winds. With PW values holding near 1.00" late
this afternoon, will likely continue the Flash Flood Watch
through this evening, but only for those mountain ranges, after
yesterday`s saturating rainfall keeps some watershed prone for
more runoff.

The H5 ridge builds across the Rockies for the weekend, centered
still on the Four Corners region. Temperatures jump nearly 10
degrees from Thursday to Friday, with highs in the upper 80s to
the mid 90s. Saturday will see continued warming, with highs
from the mid 90s for western valleys and south WY, to upper 90s
and lower 100s for northern and central WY. Monsoon moisture
will still be able to draw into the state, but will be decreased
enough to limit shower activity to higher elevations. The
flooding risk with these will also be much lower. This warmer
pattern with more isolated daytime showers on higher elevations
look to remain the trend well into the upcoming week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 400 PM MDT Thu Jul 23 2026

VFR conditions prevail this afternoon and evening, with brief
MVFR conditions possible east of the Continental Divide due to
isolated thunderstorms. Abundant mid-level clouds continue,
with isolated thunderstorms through 24/0300Z, mainly east of
the Continental Divide affecting TAF sites such as kCOD, KLND,
and KCPR. It continues to look unlikely that locations in the
middle of the basins (such as KWRL and KRIW) receive any rain
today, but there is a small chance (around 10%). Unlike
yesterday (Wednesday) evening, any isolated storms should
quickly end around their more typical time this evening -
shortly after sunset. The air mass dries slightly on Friday,
with notably warmer temperatures but continued small chances (10
to 20%) for isolated showers and thunderstorms.

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...
Flood Watch until 8 PM MDT this evening for WYZ002-003-005-007-
015.

&&

$$

UPDATE...McDonald/Wittmann
DISCUSSION...Straub
AVIATION...VandenBoogart