706
FXUS65 KRIW 271922
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
122 PM MDT Mon May 27 2024

.KEY MESSAGES...

- Sunny and pleasant Memorial day across the Cowboy State today.

- Temperatures continue to warm for the first half of the week
  with dry and breezy conditions.

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

&&

.DISCUSSION...
Issued at 119 PM MDT Mon May 27 2024

A gorgeous late May day is in store across the Cowboy State this
Memorial Day. Skies are blue and clear for much of the CWA, with a
few fair weather cumulus across the north. Temperatures will be
seasonable with most seeing highs in the upper 60s to low 70s. The
weather is expected to remain this way through the first half of the
week as upper-level ridging moves over the western CONUS. Conditions
are expected to remain dry with temperatures warming over the next
few days. The warmest temperatures look to be in the Bighorn and
Wind River Basins along with Natrona and Johnson Counties. Highs for
Tuesday likely near 80 in these areas, with a (60-80%) chance
of meeting or exceeding 80 degrees for Wednesday. The remainder
of the state over the next few days will see seasonable to
slightly above normal values, with highs in the low to mid 70s.
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. Models are
starting to pick up on 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 being 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, which may lead to short lived
storms. Overall, thunderstorms are possible with much of the state
seeing a (20-40%) 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. 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. Temperatures for the second half
of the week return to seasonable values, with quiet weather
returning through Friday. The weekend is very much up in the air as
ensemble models continue to differ. Some models show a less active
weekend, which remains mostly dry with warming temperatures. Other
models keep things active with multiple chances for precipitation and
temperatures being limited to near seasonable values. However,
ensembles do mostly agree on a pretty large warm-up for the first week
of June, with a large potent ridge moving in over the western CONUS.
Early indications are showing dry conditions with possibly some of
the warmest temperatures so far this year.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1139 AM MDT Mon May 27 2024

VFR conditions will prevail through the period as ridging sets in
over the area. A few terminals will see a breezy afternoon, but
overall wind will remain on the lighter side. No precipitation is
expected through Tuesday morning.

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...Myers