249
FXUS65 KRIW 220415
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1015 PM MDT Fri Jun 21 2024

.KEY MESSAGES...

- Scattered thunderstorms expected this afternoon, ending before
  sunset, with damaging winds and flash flooding the main
  concerns. Larger hail cannot be ruled out as well.

- Warming trend for the weekend and beyond with mainly dry
  conditions going forward.

&&

.DISCUSSION...
Issued at 1134 AM MDT Fri Jun 21 2024

IR currently depicts southwest flow across the CWA with ample
mid to upper level moisture pumping in from the base of the
trough. A strong PVA signature can be seen over northwestern
Colorado that will be the main trigger for thunderstorm
development in the coming hours ahead into the afternoon. Radar
shows some dissipating rain showers and a couple of isolated
thunderstorms from eastern Sweetwater County extending through
Natrona.

Stronger storms are expected to continue to develop early this
afternoon across Sweetwater County with possible severe hail the
main concern being for supercellular in nature. Ample shear over
30kts and steep lapse rates yield to at least quarter to ping
pong ball size hail before storms cluster up and push
northeastward becoming more of a wind event. The atmosphere has
destabilized with clear skies further south extending north and
northeastward in the next couple hours. This will allow for
forecasted CAPE values to push well over 1000 J/kg even upwards
to 1500 in parts of this area and further northeastward. CAMs
are showing storms cluster together by 3-4PM through central
portions of the CWA becoming more of a damaging wind threat with
gusts over 60 mph and flash flooding concern going forward into
the evening hours. DCAPE values show similar conditions with
PWAT values up to an inch in some areas east of the Bighorns to
the I-25 corridor. If this main upper level trough progs to stay
more progressive as models suggest, flooding may not be a high
concern going forward. Severe watches are currently issued with
more to come this afternoon and evening before storms weaken and
push east by 7-8PM towards sunset losing the ingredients with
radiational cooling.

Going forward, ridging builds back in from the subtropical high
over west Texas that will bring a warming trend and mainly dry
conditions to the CWA for the weekend and much of the next week.
Temperatures well into the mid to upper 90s for points east of
the Divide to include possible 100 degrees through the Bighorn
Basin. An upper level low looks to come out of the Gulf of
Alaska down to the Pacific Northwest, but the main finger of the
PFJ looks to stay north only clipping any minor impacts to
northern parts of the CWA by week`s end in terms of light
precipitation and general thunderstorm activity for higher
elevations.

All in all, today is the last chance for widespread rainfall
going forward with dry conditions and elevated fire weather
becoming a concern for much of next week into the long term
outlook.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1014 PM MDT Fri Jun 21 2024

Skies will continue to clear, moving toward the northeast, to
start the TAF period, leaving mostly SKC through much of the
forecast. FEW CU will likely again develop for most areas
Saturday afternoon, but no conditions less than VFR are
expected. South to southwest winds are expected to keep any
fog/low ceilings from developing at KCPR Saturday morning.
Conditions will remain dry through the next 24 hours, with
mostly light winds. Gusts up to 20 kt will be possible at a few
terminals during the afternoon, but subside after 00Z.

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...Lowe
AVIATION...LaVoie