820
FXUS65 KRIW 271800
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1200 PM MDT Mon Jul 27 2026

.KEY MESSAGES...

- Increased cloud cover will keep temperatures down a few
  degrees from yesterday`s record high temperatures. Afternoon
  highs will still reach the 90s across the state.

- Scattered showers and thunderstorms will again develop early
  this afternoon and move to the northeast during the day.
  Monsoon moisture will be on the increase this morning, leading
  to better chances for thunderstorms than previous days.

- This pattern remains in place through the week, with above
  normal temperatures in the 90s and thunderstorms developing
  each afternoon.

&&

.UPDATE...
Issued at 1007 AM MDT Mon Jul 27 2026

More clouds today as monsoonal moisture lingers over the area with a
weak weather system moving through. Showers, and the occasional
storm, has persisted through the morning. Thunderstorms should
become more common by early afternoon as the shortwave moves through
in conjunction with peak daytime heating. Gusts to 50 mph are
possible with these storms. Interestingly, the HRRR model has a long
line of gusty winds 50 to 55 mph accosted with the main push of
showers and storms from western WY starting about 2pm, moving east
through the area through about 9pm. Will see if this trend holds for
each hour`s update. Otherwise, have kept temperatures today less
than yesterday given the expected cloud cover. Increasing smoke will
also occur over the area, mainly northern WY tonight into tomorrow
with the fires in the western US, as well as a plume of smoke coming
from the southwest associated with the Nevada fires.

&&

.DISCUSSION...
Issued at 231 AM MDT Mon Jul 27 2026

The dominant western ridging pattern holds firm again today, the
the H5 ridge still anchored on the Four Corners region. The
southwest tap of monsoon moisture continues today, and most
models are bringing an increase in moisture during the next 6 to
12 hours. With warm temperatures still in place, daytime showers
and thunderstorms will again develop late this morning and
continue into the afternoon, moving to the northeast. The
increased moisture and shortwave energy passing through today
will bring a better chance for measurable rainfall from any
thunderstorms, but the good forward motion of any storms will
keep the chance for flooding low. Current cloud cover and any
cover from thunderstorms today will keep temperatures lower
than Sunday. Highs will still be above normal, but will hold in
the low to mid 90s through the afternoon.

Tuesday will be similar to today, with very warm temperatures
during the day. Ample moisture will tap this heat for scattered
showers and thunderstorms during the afternoon. Midlevel support
may be more limited, so showers might end up more isolated.

Wednesday another more vigorous shortwave comes around the ridge
through Wyoming, which is expected to bring a much better chance
for showers and thunderstorms. After this feature passes
through, models are shifting the ridge slightly to the west
through the rest of the week into the upcoming weekend. Models
are noting a significant drop in moisture, as the monsoon
moisture gets cut off. This would lead to much drier and warmer
period heading into the weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1155 AM MDT Mon Jul 27 2026

VFR conditions prevail over the next 24 hours. Rain showers
over much of the region this morning will continue into the
afternoon hours, and eventually there will be a 20 to 30% chance
for most TAF sites to be affected by isolated thunderstorms,
starting as early as 27/2000Z. Brief heavy rain reducing
visibility, lightning, and erratic gusts 30 to 40 kt will be
the biggest threat in the vicinity of storms. Thunderstorms will
dissipate quickly after sunset, but isolated showers may linger
overnight, especially over central Wyoming. Another day of
isolated thunderstorms is forecast for Tuesday.

&&

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

&&

$$

UPDATE...Wittmann
DISCUSSION...Straub
AVIATION...VandenBoogart