543
FXUS65 KRIW 292303
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
503 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 /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 500 PM MDT Wed May 29 2024

Shower and thunderstorms, which are associated with the weak
shortwave trough passing through the area this evening, will
continue to shift east. KWRL and KCPR are the only remaining
terminals with >10% of thunderstorms. 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 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. By
late morning to early afternoon, winds become predominantly
westerly, and will increase through the afternoon. Gusts will
generally be less than 30kts, but favored locations may see
gusts of 25 to 35kts for a portion of the late 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.

&&

$$

DISCUSSION...CNJ
AVIATION...Hensley