433
FXUS65 KRIW 061721
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1121 AM MDT Sat Jul 6 2024

.KEY MESSAGES...

- Elevated to Critical fire weather conditions expected today
  across portions of central and southern Wyoming. The
  combination of low humidity and gusty west winds can be
  expected through this evening.

- Showers and a few thunderstorms will move across northern
  Wyoming this afternoon and linger into the day Sunday.

- Strong ridging brings a return to hot and dry weather next
  week.

&&

.DISCUSSION...
Issued at 209 AM MDT Sat Jul 6 2024

Northwesterly flow will continue to agitate the weather across
northern and central Wyoming today and Sunday. With dewpoints
still in the 30s and 40s east of the Divide, the next passing
shortwave will be able to tap some of this moisture to spark
showers and a a few thunderstorms this afternoon and evening.
Main focus is across the Bighorn Basin and Natrona and Johnson
Counties. Inverted-V profile indicates access to gusty winds
aloft, so some storms could be accompanied by gusty winds.
Shower activity will fade during the evening, but some lingering
shower activity is possible for central WY overnight tonight,
and will regenerate during the day Sunday. Wind field aloft on
Sunday will be much weaker, so Showers will be more isolated,
and confined to higher elevations, and downwind into
Johnson/Natrona Counties. Any precip that does fall will be
light.

On the other side of the Divide, moisture is much more lacking,
both sfc and aloft, so shower activity will not be a threat.
Instead, gusty winds translating to the sfc during the afternoon
will combine with the dry sfc atmosphere to bring an elevated to
critical fire weather threat. See Fire weather section below for
details.

Beyond Sunday, the H5 ridge centered over California will begin
to shift east, setting up across Utah by midweek. This will
push the storms track into Canada, allowing increased daily
heating across Wyoming. Temperatures will be well into the 90s
by Wednesday, and several triple-digit readings are likely by
the end of the week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1114 AM MDT Sat Jul 6 2024

Brief reductions to MVFR possible at TAF terminals east of the
divide late this afternoon through overnight hours with showers
and thunderstorms moving through. The best chances for direct
impacts due to rain showers and thunderstorms are at KCOD,
KWRL, and KCPR, but showers are possible at KRIW and LND later
this evening. In addition, gusty north winds 25 to 35 knots are
expected ahead of and along the frontal passage through this
evening. Generally light and variable winds expected overnight
with clearing skies, following the rain showers and
thunderstorms.

&&

.FIRE WEATHER...
Issued at 209 AM MDT Sat Jul 6 2024

Warm temperatures today across central and southern WY will
bring very dry conditions this afternoon. Humidity levels will
be 10 to 15 percent generally south of a line from Riverton to
Casper, with the driest conditions across Sweetwater County. A
passing weather system will bring along gusty winds aloft, which
will mix down to the sfc during the afternoon. Expect frequent
gusts above 30 mph for this region during the afternoon,
decreasing around 8 PM this evening. Winds aloft turn more from
the north overnight, pulling increased moisture in from the
north. This will bring improved humidity readings for Sunday, so
fire weather threat will be decreased.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 8 PM MDT this evening for WYZ280-283.

&&

$$

DISCUSSION...Straub
AVIATION...Gross
FIRE WEATHER...Straub