366
FXUS65 KRIW 252038
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
238 PM MDT Sat May 25 2024

.KEY MESSAGES...

- Scattered showers and thunderstorms will continue through the
  evening.

- Showers will me more limited to northern Wyoming on Sunday. Gusty
  winds elsewhere.

- Warmer and dry Memorial Day.

- Unsettled conditions are favored to return by midweek.

&&

.DISCUSSION...
Issued at 231 PM MDT Sat May 25 2024

After a day of quieter weather, unsettled conditions have returned
to Wyoming. This is due to increased Pacific moisture and a fast-
moving shortwave currently visible on water vapor imagery.
Showers and thunderstorms will become more widespread early this
afternoon from west to east as this feature pushes farther in.
The best coverage of convection will be across western and
southern Wyoming which will generally see instability in the 400
to 600 J/kg range. All areas though will have a good chance of
seeing a shower or storm in the vicinity at some point through
this evening (at least 25 percent for most). On the flip side,
cloud cover across western Wyoming could limit instability there
later this afternoon.

Otherwise, the system is not very cold; snow will be limited to the
mountains, with only light accumulations on the highway passes. As
for rain accumulations, western and southern areas will have the
best chance of at least a quarter inch (~50 percent chance). East of
the Divide, amounts will generally be less than a tenth of an inch.

Showers will come to an end this evening save for some
lingering activity across northern Wyoming into Sunday morning
due to another quick shortwave clipping the area. Sunday
continues to trend drier for most locations with Saturday`s wave
moving off to the east. The exception will still be across
northern Wyoming, and especially the Bighorns and the Powder
River Basin. These areas will see another weak wave dipping down
from Montana, as well as a better moisture pool for an
additional round of showers in the afternoon. Again, though,
these are looking more isolated as of late; we expect most of
the area to be dry on Sunday. Otherwise, it will be a much
breezier day for most, especially across southern Wyoming which
will see gusts over 35 mph during the afternoon.

Memorial Day will be dry all around as stronger ridging returns to
the area. Temperatures will return to around or a few degrees above
normal. The warming trend will continue on Tuesday as highs reach
into the 80s east of the Divide and upper 70s west. There will be a
chance of some afternoon convection, however, as the ridge begins to
break down. By Wednesday guidance is showing a stronger trough
pushing into the northwestern US. This will push east through
Wednesday, though how far south it drops will have a large impact on
the weather across Wyoming. For now, the forecast continues to show
increased precipitation chances on Wednesday, with the best
chances across the northern half of the area. Further out,
guidance is hinting at a continued active pattern through the
end of the week, though there is quite a bit of uncertainty at
the moment.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1132 AM MDT Sat May 25 2024

West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals.

A convective line along the western Wyoming border late Saturday
morning will traverse the western terminals between 18Z-
21Z/Saturday, lingering until 23Z in the vicinity of KRKS. Gusty
outflow wind of 20-30kts accompanies the stronger convection. While
there could be brief MVFR conditions, VFR prevails for the most
part. Any persistent showers will fade between 01Z-03Z/Sunday with
the setting sun, and clouds dissipate and rise as shortwave
energy clears the region after 06Z/Sunday. Mid-level cloud deck
of 060-090 prevails much of the night at KJAC. Gusty westerly
wind increases late in the period at the three southwest
terminals in favorable west-northwest flow aloft. KJAC wind
increases to southwest 10-20kts after 16Z/Sunday. Mountain tops
occasionally obscured through 03Z/Sunday.

East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals.

Convective line to the west makes its way east of the Continental
Divide during the afternoon hours, generally between 20Z-23Z in the
lee of the Absaroka and Wind River Ranges. Temperature-dew point
spreads favor 25-35kt outflow gusts, with KRIW the most favored
given expected outflow from the west-northwest. KCPR sees the
remnants of this convection between 01Z-04Z/Sunday as shortwave
energy reaches central Wyoming. Light showers linger in the
vicinity of KCOD into the early morning hours. Otherwise, drier
west-northwest flow envelops the region for Sunday. Westerly
wind does increase late Sunday morning at most terminals.

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...Myers
AVIATION...Jones