551
FXUS65 KRIW 291737
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1137 AM MDT Wed May 29 2024

.KEY MESSAGES...

- A weather system brings more widespread rain shower and thunderstorm
  chances to the area today. It will also be breezy across the
  area.

- The end of the week looks dry and a bit cooler after the
  system passes on Wednesday. Then, slight chances for
  thunderstorms on Saturday and Sunday.

- Monday looks hot and dry once again before another shortwave
  clips the area on Tuesday, with more rain shower/thunderstorm
  chances.

- Long-range model guidance continues to indicate a hot and dry
  period beginning late next week as a dominant ridge sets up
  over the western US.

&&

.DISCUSSION...
Issued at 316 AM MDT Wed May 29 2024

A more meaningful shortwave will pass through today, with more
widespread rain showers and thunderstorms this afternoon/evening.
The SPC has upgraded northern portions of the State to a Marginal
risk for severe weather this afternoon. The only threats are strong
to damaging wind gusts and frequent lightning, but small hail is
possible (40%) as well. This shortwave will bring breezy conditions
today. Temperatures will be about 10 degrees cooler across
northwestern portions of the area due to increased cloud cover and
rain, elsewhere temperatures will be similar to Tuesday. A Rangeland
Fire Danger Statement has been issued for this afternoon due to the
breezy wind, low RH, and warm temperatures. After this system moves
through it will be warm and mostly dry through Friday. Another
slight chance (20-30%) of rain showers/thunderstorms this weekend as
another quick moving shortwave will slide through the Cowboy State.
Minor river flooding is possible (30-40%) through tonight due to
mountain snowmelt as temperatures remain warm today, but as it
stands right now all rivers are behaving.

Overall, it will be an unsettled weather pattern with shortwaves in
mostly zonal flow through this weekend into next week. The
shortwaves will all be quick moving and weak, so not expecting big
precip makers or highly impactful weather into next week. It will be
fairly breezy for most locations beginning today and continuing into
next week. The breezy conditions, combined with low RH will lead to
elevated fire weather conditions later this week through this
weekend, although greenup will limit this threat. The amplified
ridge that model guidance was indicating for next week now looks
like it will develop a bit later as another trough slides through on
Tuesday. Regardless of the active pattern temperatures will not drop
all that much as each trough/shortwave should stay north as they
pass through the region.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1136 AM MDT Wed May 29 2024

A weak shortwave will pass through the region today. With it,
varying chances for showers and thunderstorms will exist across the
region today. Light winds to start the period will increase through
the afternoon for most terminals. Shower and thunderstorm chances
will generally move west to east through the period. TEMPO groups
have been included to cover the most likely period of thunderstorms
at each terminal. With the thunderstorms, gusty and erratic outflow
winds are expected. Locally strong gusts up to 40kts are possible
with stronger storms (20% chance).

After 06Z, showers and thunderstorms are no longer expected, with
VFR prevailing at all terminals. East of the Divide terminals will
see a light northerly wind push behind the showers and thunderstorms
overnight, which will decrease and become light by around 06Z. Winds
also generally become light and variable overnight for most other
terminals. Models are hinting at low clouds (as a result of moist,
weak northerly surface flow) at KCPR overnight. Have left VFR for
now, but there is a 50% chance of MVFR cigs and a 30% chance of IFR
cigs developing between 06Z and 09Z at KCPR. These cigs will scatter
out Thursday morning, between 13Z and 16Z.

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.

&&

$$

DISCUSSION...Rowe
AVIATION...Hensley