692
FXUS65 KRIW 280359
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
959 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
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 /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 959 PM MDT Mon May 27 2024

VFR conditions will prevail through the period, with SKC skies
by sunrise. Isolated convection will be possible Tuesday
afternoon for areas west of the Divide, however confidence
remains too low to include in any terminal forecast. Wind gusts
up to 20 kt will be possible at these terminals from this
convection between 21Z and 02Z.

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