224
FXUS65 KRIW 020438
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1038 PM MDT Fri Aug 1 2025

.KEY MESSAGES...

- Elevated to near critical fire weather conditions will continue
  across southern Wyoming through the weekend.

- Additional shower and thunderstorm chances through the weekend,
  with the best coverage along and east of the Divide.

- Warmer and drier conditions are expected through at least
  early next week, with temperatures returning to the upper 80s
  and mid 90s for most.

&&

.UPDATE...
Issued at 117 PM MDT Fri Aug 1 2025

The forecast is on track early this afternoon, with showers and
thunderstorms now building across the western half of our area.
Mesoanalysis indicates 500 to 1000 J/kg of MLCAPE focused mainly
east of the Divide where the storms will soon track into. As noted
below, moisture and shear is not as high as the previous couple of
days and we expect storm coverage and strength to be a little
decreased today. With the overall drier environment, strong outflow
wind gusts may be just as widespread. This is backed up by
several persistent hi-res model runs showing gusts of 40 to 50
mph this afternoon for much of central and northern Wyoming.
There will still be a lesser isolated large hail threat,
especially across Johnson and eastern Natrona County where
better shear will be observed. Storms will end or move out
around sunset.

&&

.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 /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1038 PM MDT Fri Aug 1 2025

VFR conditions prevail tonight through Saturday morning. Scattered
rain showers and thunderstorms will develop Saturday afternoon and
linger into Saturday evening across the area. Either prevailing -
SHRA and VCTS or PROB30 -TSRA at terminals where the best chance of
impacts from convection will be. The only terminal with no -SHRA,
VCTS, or -TSRA is KJAC, although there is still a 20% chance of
showers and storms at KJAC Saturday afternoon.

Drier air is now in place across the area, which means showers and
storms will be capable of strong downdrafts and outflows. This will
be the predominant driver of wind Saturday afternoon into Saturday
evening. It is possible even a light shower could produce strong
downdraft wind. While widespread severe weather is not expected
tomorrow the strongest wind gusts from showers and storms may reach
50-60 mph in the afternoon.

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...
None.

&&

$$

UPDATE...Myers
DISCUSSION...Dziewaltowski
AVIATION...Rowe