312
FXUS65 KRIW 300403
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1003 PM MDT Wed May 29 2024

.KEY MESSAGES...

- Scattered thunderstorms are capable of producing 35-45kt
  outflow wind gusts through early Wednesday evening. The best
  chance for these winds will be east of a line from Cody to Ft.
  Washakie to Green River, with the main threat until 5 PM
  Wednesday.

- Showers and storms end late Wednesday evening over central Wyoming.
  A push of cooler, moist air brings low clouds to Natrona
  County between 2 AM and 8 AM Thursday.

- High temperatures ranging from 5-10F above normal are in store
  Saturday through Monday. Breezy southwest wind Saturday and
  again Monday could heighten rangeland fire conditions on those
  two days.

&&

.DISCUSSION...
Issued at 220 PM MDT Wed May 29 2024

Satellite imagery clearly shows shortwave energy tracking east
through central Idaho early Wednesday afternoon. Following passage
of a weak morning shortwave, clearing skies allowed for
destabilization across central and southwest Wyoming. Scattered
showers and thunderstorms have erupted within this airmass of
negative lifted indices and lapse rates of 8-9C/km. These showers
and storms track east through 5 PM with most of the strong
convection confined to Johnson and Natrona Counties between 5 PM
and sunset. Temperature-dew point spreads indicate the potential
for 35-45kt gusts across the central and southwest. The chance
for small hail is better over the north where dew points are a
bit higher.

Convection begins to fade from west-to-east during the evening, and
most should come to an end by 9 PM. Wrap-around moisture on the
backside of the shortwave in combination with 80kt jet-level winds
should aid lingering isolated showers over the far north much
of the night. Northeasterly moist upslope along the I-25
corridor generates low clouds late tonight and Thursday morning
in that region. Otherwise, the overnight trend will be toward
decreasing clouds. Cyclonic west-northwest flow aloft keeps an
isolated chance (10-20 percent) of showers over the north
Thursday; however, for the most part Thursday is dry with a
breezy westerly wind. The passage of the shortwave leads to
cooler temperatures in the upper 50s and 60s Thursday, with the
far north and far west valleys seeing the coolest temperatures.
Temperatures rebound Friday as the trough and cyclonic flow move
east away from the state. A dry day is in store Friday, and
breezy westerly wind prevails across southwest Wyoming.

Saturday and beyond will be largely characterized by zonal flow, and
shortwave ridges and troughs progressing across the region. Saturday
finds warmer temperatures and breezy conditions in southwest flow
aloft. This may lead to elevated fire weather conditions across
southwest and central Wyoming. Early indications are that a
shortwave trough tracks through Montana Sunday and provides a
better chance of convection, particularly across the north. Next
week dawns with above normal temperatures persisting. A
deepening trough off the Pacific Northwest Coast may pump warmer
southwest flow aloft into the forecast area Monday. Current
temperature projections indicate widespread 80s for Monday
highs. These temperatures in combination with a dry southwest
wind could again lead to elevated rangeland fire conditions.
Any shower chances early next week would largely be confined to
far west and northern Wyoming.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1000 PM MDT Wed May 29 2024

VFR conditions are expected through the TAF period as showers
end across the area. Models continue to hint at MVFR ceilings
near KCPR between 09Z and 11Z as a result of moist, weak
northerly surface flow. Have left VFR conditions for now, but
there is a 30% chance of MVFR cigs. These cigs will scatter out
between 13Z and 16Z. Showers will remain possible over Johnson
County through 09Z. Winds will decrease across the area through
this time as well. By late morning to early afternoon, winds
become predominantly westerly, and will increase through the
afternoon with gusts of 25 to 30 kt.

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...Jones
AVIATION...LaVoie