230
FXUS65 KRIW 182307
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
507 PM MDT Thu Jul 18 2024

.KEY MESSAGES...

- Near to slightly above average temperatures are expected today
  through next week.

- Scattered afternoon showers and thunderstorms remain in the
  forecast through the weekend, with Friday and Saturday looking
  to have more widespread coverage of storms. Severe storms are
  unlikely (less than 10% chance).

- 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 cooldown is expected.

&&

.DISCUSSION...
Issued at 208 PM MDT Thu Jul 18 2024

A large-scale upper-level ridge with its axis to the west of
Wyoming will continue to preside over the region through next
week. Persistence will be a hard forecast to beat. In other
words, no big changes to the warm and dry pattern; however,
there are a few subtle day-to-day differences to mention.

Temperatures today (Thursday) will be about 5 degrees above
normal, and a slight cooling to near normal conditions are
forecast by Saturday. Sunday and Monday will see near normal
highs. Temperatures then slowly begin warming back up on Tuesday
and into the later part of next week, bringing the region back
to slightly warmer than normal conditions.

Precipitation-wise, scattered showers and thunderstorms will be
a daily occurrence, especially over the mountains. Tomorrow
(Friday) and Saturday look to feature more widespread showers
and storms, given ample moisture in place and a few vorticity
maxima moving over the ridge. Convective activity appears to
then wane Sunday into early next week as the upper level flow
becomes more northerly, thus bringing in a drier and more
continentally-sourced air mass.

Thunderstorms over the next few days don`t have a lot of
dynamic support, are therefore are likely to be "air mass"
(a.k.a. "ordinary" or "garden variety") with not a lot of
instability or shear, keeping the severe weather threat low.
That being said, localized damaging downdraft wind gusts and
lightning remain low-likelihood threats to consider with any
summer storms.

By the end of next week, the upper level flow shifts to be more
southwesterly. If this pans out, a southwesterly flow pattern
often supports more widespread thunderstorms, as well as a few
stronger thunderstorms. However, confidence is still low for
this timeframe.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 505 PM MDT Thu Jul 18 2024

Lingering showers and thunderstorms continue across portions of the
area through about 06Z/Fri. A few high-resolution models are
bringing some rain into the KJAC area roughly 03Z to 05Z/Fri, but
low confidence has kept mention out of the TAF; gusty outflow winds
up to around 30 knots are possible if convection forms near KJAC.

Overnight, winds become light with dry conditions by 10Z/Fri. A
similar day Friday, with afternoon showers and thunderstorms
starting to develop around 19Z/Fri. Gusty outflow winds will be
the main concern, with potential MVFR conditions if heavy rain
occurs directly over terminals.

Smoke continues across the area. The 18Z HRRR smoke shows a band of
thicker smoke entering northwest Wyoming Friday morning, spreading
into central Wyoming through the day. Some mountain obscuration
continues.

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...VandenBoogart
AVIATION...Wittmann