968
FXUS65 KRIW 040729
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
129 AM MDT Tue Jun 4 2024

.KEY MESSAGES...

- Drier and warmer weather will arrive this afternoon and
  continue through at least Thursday.

- Windy conditions are expected today and tomorrow, with
  elevated fire weather possible on Wednesday afternoon.

- Warm temperatures will lead to high elevation snowmelt which
  could bring rising river levels and minor flooding late this
  week.

&&

.DISCUSSION...
Issued at 125 AM MDT Tue Jun 4 2024

Summer, at least weather wise, will be arriving, especially
starting on Wednesday. As for now, we still have some showers across
northern portions of the area in response to the Pacific trough
moving across the area and the left front quadrant of an 120 knot
jet providing some upper level divergence. These showers should
continue to decrease through the overnight but a few may linger into
the morning hours before everything ends by around 10 am or so. The
main concern then shifts to wind as we shift from the left front to
right front quadrant of the jet this afternoon, enhancing downward
forcing. Reasoning remains the same as yesterday. The 700 millibar
winds do not look sufficient for high winds, but gusty to strong
winds are certainly possible. Some windier areas, like Rock Springs,
have greater than a 1 in 2 chance of seeing wind gusts over 40 mph.
Temperatures today will average close to slightly above normal.
Humidity should remain high enough to prevent many fire weather
issues.

Wednesday also looks dry. This is where temperatures will begin to
rise, with many locations likely seeing their warmest temperatures
of the calendar year with lower elevations seeing highs well into
the 80s. This a day when elevated fire weather may be a concern. The
low that brought the rain will be held up by a blocking ridge over
eastern Canada, with the low spinning over Manitoba. A tight height
line gradient between the low and ridging building across the desert
southwest. In addition, the jet will be close enough to keep breezy
to windy conditions continuing. With relative humidity falling into
the teens at times, fire weather statements may be needed for
Wednesday.

Thursday looks dry and warmer as well, and probably the first
possibility to see high temperatures hit 90 in our warmer spots.
Also, with the ridge building northward, wind will decrease. The
heat really looks to peak on Friday, with the best chance of seeing
high temperatures in the 90s. This is also the day some mid level
moisture will be introduced to the area, bring a possibly, although
a small one (generally less than 1 out of 4 chance) of some
afternoon or evening convection. And, with the hot temperatures,
rising rivers will likely become a concern. A general rule of
thumb around here is three days with highs in the 80s is when
high level snowpack really starts to melt. So, we will have to
start watching for this, especially starting on Friday.

More uncertainty creeps into the forecast stating on Saturday. The
ridge looks to get suppressed just a bit with some shortwaves moving
into the area, bring chances of convection, mainly of the diurnal
variety. There are still differences in guidance in the timing of
the waves, so details are still hard to come by though. It does look
more active for the weekend and Monday as well. Nevertheless, I
think we can safely say, welcome to summer in western and central
Wyoming.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 945 PM MDT Mon Jun 3 2024

Any showers across the forecast area are expected to end by 09Z.
A cold front will continue its push southward over areas east of
the Divide to start the TAF period, but is only expected to
impact KWRL and KCPR through 12Z, quickly washing out.
Otherwise, gusty winds up to 25 kt will continue to impact
several terminals. Higher gusts close to 35 kt will continue at
KCPR to start the forecast, but will decrease through 12Z,
before the cold front reaches the terminal. Winds will then
increase across the forecast area through 18Z, with gusts of 25
to 35 kt occurring through the afternoon. These winds will begin
to decrease around 02Z/03Z. Apart for isolated showers over far
northwestern portions from 17Z to 20Z, conditions will be dry.

Models are showing some indications of mountain wave activity along
the east slopes of the Wind River and Absaroka Mountains through
18Z. This pattern could create increased winds above the
foothills, but at elevations of 3-8K feet above the ground.

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...Hattings
AVIATION...LaVoie