818
FXUS65 KRIW 192303
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
503 PM MDT Fri Jul 19 2024

.KEY MESSAGES...

- Scattered afternoon showers and thunderstorms today and
  Saturday with brief gusty winds and lightning being the
  primary concerns. Severe storms are unlikely (less than 10%
  chance).

- Near average temperatures this weekend warm to slightly above
  average next week.

- The overall weather pattern does not look to change much over
  the coming week. Apart from brief hit-or-miss showers and
  storms, no widespread rain or big cooldown is expected.

&&

.DISCUSSION...
Issued at 245 PM MDT Fri Jul 19 2024

The stable and stagnant weather pattern of the past several days
will not change much through the weekend. A strong upper-level
ridge is keeping the Intermountain West warm and dry, apart from
afternoon and evening showers and thunderstorms. Additionally,
smoke from western US and Canadian wildfires will continue to
stream into the region, lowering visibility of mountain vistas.

Thunderstorms today and Saturday will have a bit more
moisture/fuel to work with than in past days, so expect brief
heavy rain if you happen to be caught directly under a storm
core. CAPE values of 400 to 600 are slightly higher than the 300
to 500 of previous days, but still lower than typical for a
more widespread severe weather day. Additionally, the lack of
deep layer shear (less than 20 kt) for most locations will cause
downdrafts to interfere with updrafts, leading to ordinary
thunderstorms, which typically dissipate in 20 to 30 min and are
unlikely to form large hail.

Daily isolated afternoon thunderstorms are forecast next week,
but most look to remain over the high terrain as subsidence
hinders storm growth. The continental air mass is slightly
drier as well, keeping fuel for storms limited.

The presiding ridge amplifies early next week, and temperatures
Tuesday begin warming to above average values through the end
of the week. Thursday is forecast to be the warmest day, with
temperatures 8 to 10 degrees above average. Near the end of the
week, the ridge begins migrating to the east, allowing for
southwesterly flow aloft. This subtle shift in weather pattern
is more favorable for showers west of the Divide, but convective
details remain of low confidence at this point. No models show
any widespread rain event in the foreseeable future.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 503 PM MDT Fri Jul 19 2024

Showers and thunderstorms continue across portions of the area the
first few hours of the TAF period. Winds decrease overnight, with a
clearing sky. Smoke lingers across portions of the area, thickest
over northwestern Wyoming. Some mountain obscuration continues as a
result.

Showers and thunderstorms are once again possible Saturday
afternoon. As with the previous few days, these will be isolated, so
have PROB30 groups to cover the storm chances as well as the
associated gusty outflow chances. Gusts up to around 40 knots are
possible.

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...
Air Quality Alert until 1 PM MDT Saturday for WYZ001-012-013.

&&

$$

DISCUSSION...VandenBoogart
AVIATION...Wittmann