685
FXUS65 KRIW 021047
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
447 AM MDT Wed Jul 2 2025

.KEY MESSAGES...

- Warm temperatures prevail across the state with widespread
  chances for showers and thunderstorms during the afternoon
  and evening.

- An influx of moisture will create chances for heavy downpours
  and localized flash flooding in poor drainage areas today and
  especially Thursday.

- The 4th of July is not looking like a complete washout with a
  period of showers and thunderstorms during the afternoon and
  evening with drier conditions possible after sunset.

&&

.DISCUSSION...
Issued at 223 AM MDT Wed Jul 2 2025

July started off hot and unsettled across the Cowboy State.
Temperatures reached the mid to upper 90s east of the Divide and mid
to upper 80s west of the Divide. Showers and thunderstorms developed
during the afternoon and evening with some locations seeing brief
downpours along with gusty outflow winds.

Wednesday will see much of the same with warm above normal
temperatures and afternoon showers and thunderstorms. The one
difference will be the start of an influx of well above normal
moisture. An upper level low over the western CONUS will begin to
funnel moisture into the region. Models show PWAT values of 0.60 to
0.90 inches which would be nearly 100 to 150% above normal.
Convection is expected to be more widespread as a result of this
moisture starting to move in. However, there will still be some
dryness lingering through the atmosphere. This dryness and lack of
dynamics will limit stronger thunderstorm development. The main
concern will be strong gusty outflow winds as a result of dewpoint
depressions ranging between 40 to 60 degrees. Portions of northern
and central WY look to have the best chances to see these gusty
winds. Showers and thunderstorms linger into the evening before
gradually dissipating by the early morning hours on Thursday.

Thursday will see the warm and unsettled pattern continue. However,
moisture is expected to increase further with PWATs nearing 1 inch
translating to almost 200% above normal values. This will increase
the chances for periods of heavy downpours as showers and
thunderstorms develop and move across the state during the afternoon
and evening. Storms will have potential to produce localized flash
flooding as a result of this increased influx of moisture. The other
concern that develops on Thursday will be increased chances for
strong thunderstorms. These increased chances are due to higher CAPE
values along with more favorable dynamics as a result of a shortwave
trough moving across the region. While still a few days out the best
chances for strong thunderstorms looks to be over central and
eastern WY.

Looking towards Friday the 4th of July, unsettled weather looks to
be possible. However, there is still some uncertainty regarding how
widespread the showers and thunderstorms may be. Temperatures will
cool slightly compared to earlier in the week, returning to near
seasonable values. Above normal PWATs linger which would create
another day with chances for heavy downpours. Models show another
shortwave move across the region with the track differing slightly
between models. Some show a more northerly track which would bring
favorable chances for showers and thunderstorms to northern WY.
Other models keep it farther south leading to move widespread shower
and thunderstorm chances. The good news is that convection is
expected to dissipate by sunset leading to drier conditions by the
time it gets dark. Overall, there does look to be a period of
unsettled weather for Friday afternoon and evening but to where the
best chances will be is still to be determined.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 445 AM MDT Wed Jul 2 2025

VFR conditions for the entirety of the period for all TAF sites.
Light winds will increase this afternoon after 18Z, with RIW/PNA
to see the higher gusts up to 18-25kts. Afternoon thunderstorm
chances at all TAF sites with widely scattered activity after
19-22Z. These will be heat driven with strong outflow winds
expected up to 35kts with the strongest storms. These will last
through around 03-04Z diminishing after sunset due to
radiational cooling. This will also see diminished winds to
less than 8-10kts into the overnight hours into Friday morning.

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...
None.

&&

$$

DISCUSSION...Dziewaltowski
AVIATION...Lowe