383
FXUS65 KRIW 022151
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
351 PM MDT Tue Jul 2 2024

.KEY MESSAGES...

- An unsettled weather pattern continues through this week as a
  trough remains over the region.

- Scattered rain showers and thunderstorms will develop across
  northern Wyoming Wednesday afternoon. Isolated large hail will
  be possible with these storms. Elevated fire weather
  conditions will occur across southern Wyoming at the same
  time.

- The weather pattern favors breezy to windy conditions for the
  next 7 days and mostly dry conditions beyond Thursday.

&&

.DISCUSSION...
Issued at 347 PM MDT Tue Jul 2 2024

Troughing will be the general weather pattern through this weekend,
with several waves within the trough sliding through Wyoming. Today
could be called the calm before the storm in some regards as the
flow is mostly zonal behind the wave that passed through the last
couple of days. Even so, some isolated thunderstorms have developed.
One developed in southern Johnson county earlier today and has since
moved into Converse County. There will remain a chance (20-30%) for
isolated rain showers and thunderstorms across the northern third of
the area through this afternoon. Temperatures are cool this
afternoon in the 60s and 70s F. Although temperatures will rise
slightly later this week it does not look like a heatwave until
(possibly) next week. In fact, Independence Day (The 4th of July)
looks very pleasant temperature-wise. The current high
temperature forecast is for upper 60s to middle 70s across the
area. This is thanks to the wave that will move through Wyoming
on Wednesday.

The wave on Wednesday will bring a good chance for rain showers
and thunderstorms for the northern half of the area. Who gets a
good wetting rain with these showers and storms will depend on
where they develop, but about from YNP eastward through the
Bighorn Basin and into Johnson County is likely to have
measurable precipitation from Wednesday through Thursday.
Currently, the SPC has a Marginal risk of severe weather in the
Bighorn Basin eastward into Johnson County for large hail, which
looks like the main threat, but wind is always a threat in
Wyoming. Once the wave passes by, the cooler air aloft will
allow for isolated convection to develop. The best chance will
be along/near the Absaroka Mountains/Bighorn Mountains where
afternoon upslope will contribute to lift. Localized heavy rain
will be a threat on Thursday, especially in or near the Bighorns
as northwest flow sets up and may lead to the formation of some
training convection in the Bighorns. PWAT`s don`t look
excessive, so not expecting widespread flash flooding.

Northwest flow greatly weakens on Friday and this should be a quiet
weather day overall. Mostly clear skies on Friday will allow for
temperatures to get back to about normal. Model guidance has another
wave coming down in northwest flow this weekend, which will bring
low chances for isolated convection to mainly northern Wyoming. This
looks like the last gasp for the trough that has been sitting over
the region as a large amplified ridge pushes into the western US
early next week. This ridge will bring hotter temperatures back to
Wyoming and heat will become the most impactful weather well into
next week based on what long-range model guidance is depicting.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1059 AM MDT Tue Jul 2 2024

Primarily VFR conditions expected to prevail across central and
northwest Wyoming TAF terminals through the 18Z TAF period.
There is the potential for a brief shower/thunderstorm to impact
KCOD this afternoon between 19Z and 23Z. In addition, showers
and thunderstorms may develop within the VC of other TAF
terminals and result in gusty outflow winds. Gusty 15 to 25+
knot winds are expected across nearly all TAF terminals through
this afternoon and early evening, decreasing overnight, then
increasing once again tomorrow late morning. More showers and
thunderstorms are expected tomorrow afternoon, mainly across
northern Wyoming.

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

&&

.FIRE WEATHER...
Issued at 347 PM MDT Tue Jul 2 2024

Elevated fire weather conditions will continue across southern fire
zones this week. The worst days will be Wednesday and Saturday as
wind increases ahead of weather systems and RH will drop into the
teens each afternoon. For northern zones wetting rain is possible
(50%) Wednesday afternoon/evening and even into Thursday for The
Absarokas Mountains/Bighorn Mountains. Lightning will be frequent
with thunderstorms on Wednesday and Thursday, but the storms
should have a good amount of moisture with them, so the chance
of dry lightning is low (<10%). Smoke dispersal looks to be at
least good in the afternoon for the next few days at least.

&&

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

&&

$$

DISCUSSION...Rowe
AVIATION...Gross
FIRE WEATHER...Rowe