121
FXUS65 KRIW 011748
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1148 AM MDT Fri Aug 1 2025

.KEY MESSAGES...

- Another day of showers and thunderstorms during the afternoon
  and evening. Best chances persist across locations east of
  the Divide.

- Daily chances for afternoon showers and thunderstorms will continue
  through the weekend.

- Elevated to near critical fire weather conditions develop
  across portions of southern WY and likely become more
  widespread remaining into the weekend.

- Warmer temperatures and drier conditions return for much of
  the area by the start of next week.

&&

.DISCUSSION...
Issued at 225 AM MDT Fri Aug 1 2025

July ended with unsettled and active weather as much of the state
saw daily showers and thunderstorms. This will continue into the
start of August with another round of scattered afternoon showers
and thunderstorms today. Temperatures will be slightly warmer than
yesterday with highs in the low to upper 80s. One change from
yesterday to today will be less moisture across the region. The
previous days we saw low-level southeast/east flow which helped
usher in above normal moisture. This looks to change today as
southwesterly flow prevails leading to lower dewpoints. That being
said, there still will be ample moisture mainly east of the Divide
with values in the upper 40s to low 50s. However, these values are
much lower than compared to earlier in the week. Which will lead to
less instability to aid in storm development, likely limiting the
chances for any strong to severe storms across the area. The shift
in lower-level flow will also impact storm development as this will
lead to more uniform flow aloft and less shear throughout the
atmosphere. Overall, showers and thunderstorms can still be expected
this afternoon/evening with the best chances remaining east of the
Divide. Dynamics are expected to be less favorable compared to
previous days so the concern for any strong storms will be low.
There still could be a strong storm or two that may be capable of
producing strong gusty outflow winds and small hail.

The increase in southwesterly flow will create elevated fire weather
concerns across southern WY as drier air pushes further into the
region. Min RH values across the southern half of the state will
likely be below 15 percent. Winds increase during the afternoon with
periodic gusts of 20 to 25 mph. Dry thunderstorms and virga showers
are possible and may produce strong gusty outflow winds as they
develop across the area. Lightning may be a concern as well with any
dry thunderstorms that develop this afternoon. Low min RH values
will persist across the region into the weekend with winds being the
limiting factor in regards to any fire related highlights.

Weak shortwaves will continue to move across the region through the
weekend. This will lead to daily chances for showers and
thunderstorms. However, dry air will begin to work its way back into
the area gradually spreading farther north. So while shower and
thunderstorms will be possible daily, their strength and ability to
produce wetting rains is expected to decrease. Long range model
guidance continues to hint at warmer temperatures returning as
ridging attempts to build in for the start of next week. High
temperatures currently are forecast to range from the low to mid 90s
east of the Divide and upper 80s west of the Divide. These warmer
temperatures will likely mean dry conditions and in turn increased
fire weather concerns.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1145 AM MDT Fri Aug 1 2025

Isolated thunderstorms will be the main aviation weather concern
today, mainly for terminals east of the Continental Divide,
including KCOD, KCPR, and KRIW. Storms are not expected to be
quite as widespread as yesterday, but there is high confidence
in isolated storms developing across basins after 01/2000Z and
moving east-northeastward as the evening progresses. Any nearby
storm could quickly shift wind direction, with brief gusts of
35 to 40 kt. Storms are likely to exit into eastern Wyoming by
02/0300Z. Breezy afternoon winds gusting 15 to 20 kt will
decrease after sunset, with light overnight winds. Another round
of isolated thunderstorms is forecast for Saturday afternoon.

&&

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

&&

$$

DISCUSSION...Dziewaltowski
AVIATION...VandenBoogart