730
FXUS65 KRIW 252313
AFDRIW

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

.KEY MESSAGES...

- Scattered showers and thunderstorms will continue through the
  evening.

- Showers will be 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 /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 512 PM MDT Sat May 25 2024

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

Ongoing lingering convection fades between 01Z-03Z/Sunday with the
loss of solar heating. A few light showers may persist over far
northwest Wyoming through the evening hours before shortwave energy
clears the region after 08Z/Sunday. VFR conditions prevail with
cloud heights rising during the early morning. Mid-level cloud deck
of 060-090 prevails much of the night at KJAC. Gusty westerly wind
increases to 15-25kts between 15-18Z/Sunday at the three southwest
terminals in favorable west-northwest flow aloft. KJAC wind
increases to 10-20kts between 16Z-18Z/Sunday. Other than a few
orographic showers over Yellowstone, Sunday afternoon is dry and VFR
regionwide. Mountain tops occasionally obscured through 06Z/Sunday.

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

VFR conditions prevail through the entire forecast period.
Convection lingers over mainly central Wyoming through mid-evening,
although coverage and intensity decrease with the loss of solar
heating. Outflow wind gusts 25-35kts are the greatest hazard.
Shortwave energy across the Northern Rockies keeps light showers
over far northern Wyoming in the vicinity of KCOD into the early
morning hours. Sunday finds only isolated showers along and north of
a Cody-to-Casper line within drier west-northwest flow aloft.
Westerly surface wind increases to 13-25kts between 17Z-20Z/Sunday
at all terminals but KWRL.

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...CNJ