096
FXUS65 KRIW 290411
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1011 PM MDT Tue May 28 2024

.KEY MESSAGES...

- Another mostly sunny and mild day across the Cowboy State.

- Isolated showers and thunderstorms will be possible over southern/southwestern
  WY this afternoon and evening.

- Wednesday will bring the possibility for scattered showers and thunderstorms
  with a few strong storms possible over parts of Johnson and
  Natrona Counties as well as the Bighorn Basin.

&&

.DISCUSSION...
Issued at 135 PM MDT Tue May 28 2024

Another beautiful late May day across the Cowboy State. Temperatures
will continue to warm today, with highs in parts of the Wind River
and Bighorn Basins having a (60-80%) chance of meeting or exceeding
80 degrees. Other parts of the state will still be warm, with highs
in the 70s. Much of the state will remain dry today with the only
exception being SW/S WY where there is a (10-40%) chance for showers
this afternoon and evening. These showers will create some breezy
winds with gusts of 20-30 mph, but much of the CWA will see
light winds through the day. Wednesday sees the warming trend
continue with areas east of the Divide having a (60-90%) chance
of seeing highs at or greater than 80 degrees. These
temperatures may create some river flooding issues, due to
melting of mountain snow. Many ranges across the state currently
have snowpack values greater than 100%, which may overload
rivers depending on how quickly the snow melts. This is not
expected to be a significant concern at the moment, but will
need to be monitored over the next week.

Wednesday will see the upper-level ridging be ushered out by a
trough digging across the PACNW. The bulk of the disturbance is
expected to remain to the north of the CWA, but a cold front
will begin to sweep across the region during that time. CAMs
continue to show the possibility of some convective showers and
thunderstorms developing ahead of the front. Any storms that do
develop look to initiate off high terrain during the late
morning and afternoon. Some instability will be present with
highs in the 70s to low 80s and dew points in some places
ranging from the mid 30s to low 40s. This, combined with steep
lapse rates across the region, should create CAPE values of
1000-1500 J/kg. Shear values are lacking across most of the CWA,
meaning storms will pop up then quickly collapse. Overall,
thunderstorms are possible with much of the state seeing a
(20-50%) chance during the late morning and afternoon Wednesday.
A few isolated strong storms cannot be ruled out with the best
chance being across parts of Johnson and Natrona Counties where
the most favorable dynamics may be present. Recent CAMs have
begun to show there being a possibility for an isolated strong
thunderstorm to develop across parts of western WY and
especially the Bighorn Basin. These areas look to have favorable
dynamics with dewpoints near 40 and some shear present through
the low to mid atmosphere. If any strong storms were to develop,
the main hazards would be strong gusty outflow winds and small
hail.

The cold front sweeps across the state during the evening Wednesday
and early morning hours Thursday. A few isolated showers are
possible across the northern CWA Thursday, as the northern
shortwave slowly moves east. Temperatures for the second half of
the week return to seasonable values, with quiet weather
returning through Friday. Models are mostly coming into good
agreement regarding the weekend. The consensus seems to be
scattered showers and thunderstorms possible as a weak shortwave
moves through the region. Most of the CWA looks to remain dry
with temperatures returning to above seasonable values.
Ensembles continue to agree on a pretty large warm-up for the
first week of June, with a large potent ridge moving in over the
western CONUS. The magnitude of this ridge and the warm
temperatures that come along with it are still uncertain.
However, early indications are showing possibly some of the
warmest temperatures so far this year. It is starting to look
like there will be a possibility (20-40%) of some areas seeing
their first 90 degree temperatures of the year.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1010 PM MDT Tue May 28 2024

VFR conditions will prevail through the first half of the TAF
period. Clouds will begin to increase over northwestern
portions after 12Z, as a cold front approaches the area. Showers
will be confined to this area through 18Z as well. Winds will
increase at all terminals after 18Z, as the cold front makes its
way over the area, resulting in gusts of 25 to 30 kt through
the afternoon. Showers and thunderstorms will become more
widespread through the afternoon, as the cold front progresses
eastward. Most, if not all, terminals have a chance to be
directly impacted, with KCOD and KWRL having the best chances.
The wind will be the main impact, but IFR visibilities/MVFR
ceilings and higher wind gusts could occur if a thunderstorm
moves directly over a terminal. Showers and thunderstorms will
become more confined over northern portions of the forecast area
after 00Z, becoming more isolated through 06Z.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on smoke, icing, and turbulence forecasts.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Dziewaltowski
AVIATION...LaVoie