595
FXUS65 KRIW 180946
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
346 AM MDT Sun Aug 18 2024

.KEY MESSAGES...

- Showers and thunderstorms will be a little more widespread today,
  though still most prevalent west of the Continental Divide.

- Brief heavy rain and strong wind gusts of 35 to 45 mph will
  be possible with this activity.

- Very similar conditions Monday before monsoonal moisture
  decreases Tuesday through midweek.

&&

.DISCUSSION...
Issued at 338 AM MDT Sun Aug 18 2024

Wyoming continues to be situated on the western edge of the
persistent ridge, with the associated high now centered over the
Texas/Oklahoma panhandles. Another shortwave will traverse the
southwesterly mid/upper level flow this afternoon, accompanied by an
associated monsoonal moisture surge. This will result in more
widespread showers and thunderstorms today, though still most
prevalent west of the Continental Divide where the best instability
will set up (500-1000 J/kg CAPE). PWAT values will again approach an
inch here, and any stronger or training storms could present a flash
flooding threat. Otherwise, the primary concern will again be strong
wind gusts, though we should not see the widespread strong to
severe winds that were observed on Saturday. This activity will
begin to decrease after sunset, coming to an end around
midnight.

Monday is shaping up to be very similar to today as the next wave
moves in. Available moisture will slightly increase, bringing a
better chance of convection along and east of the Divide. A low end
flash flooding threat will continue across southwestern Wyoming.

Further ahead, the general synoptic pattern will remain in place,
though a decrease in available moisture will keep precipitation
chances a little lower Tuesday through at least midweek.
Temperatures will remain on the warmer side, generally around normal
to five degrees above normal for this time of year. As we reach the
weekend, ensemble cluster guidance is hinting at the potential for
deeper troughing across the western US. This may bring a pattern
change as it approaches Wyoming, but confidence on this solution is
very low for now.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1010 PM MDT Sat Aug 17 2024

Virga showers will continue to end through the first couple of
hours of the TAF period. Winds have already subsided across much
of the area, however winds of 15 to 20 kt will continue/develop
at KCPR and KRIW through 12Z respectively. The winds at KRIW
will subside by 16Z, while the winds at KCPR gradually decrease
through 19Z and turn more north-northwest. Showers and
thunderstorms will develop across areas west of the Divide and
the Bighorn Basin between 19Z and 21Z, spreading toward the
northeast through 00Z. Confidence is low on the timing of these
storms, so have left PROB30 groups for impacted terminals for
now. These storms are expected to cross into the Wind River
Basin after 00Z, possibly impacting KLND/KRIW through 05Z. Any
remaining showers/thunderstorms will be isolated toward the end
of the TAF period, as gusty outflow winds continue across the
forecast area. Gusts of 20 to 30 kt are expected with the storms
Sunday, although isolated gusts of 40 to 45 kt cannot be ruled
out.

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...Myers
AVIATION...LaVoie