287
FXUS65 KRIW 182255
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
455 PM MDT Tue Jun 18 2024

.KEY MESSAGES...

- Cool and breezy weather continues as the trough slowly exits
  this evening.

- Ridging redevelops Wednesday, prompting a warming trend that
  will persist through the weekend. First triple-digit temps of
  the season are possible Sunday and Monday.

- There is a 30 to 40% chance for widespread showers and
  isolated thunderstorms east of the Divide Friday. &&

.DISCUSSION...
Issued at 311 PM MDT Tue Jun 18 2024

Wild and Wonderful Wyoming graced us with a dusting of snow last
night and this morning across the mountains and some portions of the
western valleys and Yellowstone National Park. Temperatures have
since warmed above freezing this afternoon with some sunshine poking
through the clouds as the trough exits, and that snow has mostly
melted as I write this around 230 PM. Additional showers and high
elevation snow showers will remain possible through the rest of the
afternoon and evening as the trough slowly exits. PoPs are only
around 20 to 25% and mainly isolated to the northern half of the
region and showers have remained isolated through the day. Breezy
winds will also continue to persist with the trough, but will
decrease this evening towards sunset.

Wednesday, ridging begins to become re-established across the region
and thus a warming trend will begin. Temperatures will return to
near normal values by Thursday across the region. With the ridge,
much direr air also moves in for Wednesday and Thursday and RHs will
reach critical values both days across much of the region. However,
winds will be light and thus, fire weather concerns are limited. The
warming trend will not be limited though. Temperatures continue to
warm through the weekend and by Sunday and Monday we could be
looking at our first triple-digit temps across portions of the
region. Model indications are that the heat will not last
forever, but will stick around at least for a while. Both GFS
and ECMWF solutions prog a trough bringing some relief for the
later half of next week, but confidence on widespread cooler and
wetter weather remains low.

With the ridge building, there is little hope for a widespread
soaker between now and then either. Our best opportunity for wetting
precipitation will come Friday as a southerly push of Gulf moisture
moves up into WY with the help of a weak shortwave. Latest forecast
trends have decreased QPF, and indicate that "widespread" could be
instead "widely scattered", and given dry air and little
surface moisture to enhance PWATs, I would tend to agree with
the drying trend suggested by the latest model solutions.
Furthermore, instability will be limited and models indicate
that inhibition could outweigh instability for much of the
region through Friday afternoon, which would limit thunderstorms
somewhat. That being said, I have left 30 to 50% PoPs across
the region for Friday, and I will not discount the potential for
some stronger storms to develop Friday afternoon if we can get
a few cells to break the cap. Localized flash flooding may also
be a possibility as winds will be light, leading to a chance for
slow- moving or training cells, particularly across the eastern
and northern portions of the CWA. After Friday, however,
precipitation chances return to near zero as the ridge
intensifies through the weekend.


&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 453 PM MDT Tue Jun 18 2024

Mainly VFR conditions with clearing skies over the next 12 to 24
hours across northwest and central Wyoming. Showers and
thunderstorms are lingering across north-central Wyoming that
may affect KCOD and KWRL, but they are expected to be clearing
between now and 02Z. Lighter winds, less than 10 knots,
expected tomorrow.

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...Hensley
AVIATION...Gross