637
FXUS65 KRIW 080916
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
316 AM MDT Mon Jul 8 2024

.KEY MESSAGES...

- A nice day today with seasonable temperatures and light wind.

- Heat will build through the week, with triple digits highs for
  many locations from Thursday through at least Saturday.

- Coverage of any showers or thunderstorms will be very limited
  through at least Saturday.

&&

.DISCUSSION...
Issued at 313 AM MDT Mon Jul 8 2024

We are now entering a period where the threat of convection will be
decrease and the threat of heat will be increased through the next
several days. This will not be the case today though. All in all,
today looks fairly nice with high pressure building into the area.
Today will see seasonable temperatures and mainly light wind. As for
showers, there is just enough moisture for a few, emphasis on few,
showers or storms in the Absarokas, Wind Rivers or Bighorns.
But even here, the chance is less than 1 in 5. In the lower
elevations, it is close to zero. Tomorrow looks similar,
although 700 millibar temperatures increasing around 2 to 3
degrees celsius this will raise high temperatures around 5
degrees or so.

The heat really begins to increase as we head into Wednesday as
the ridge that will responsible for the heat wave shifts from
California toward the Great Basin and then the central Rockies
by Saturday. The aforementioned 700 millibar temperatures
continue to climb around 2 to 3 degrees each day, with some
peaking as high as 22 of 23 celsius by Friday and Saturday. The
result will be possibly the hottest weather of the year so far.
Most of the lower elevation locations East of the Divide will
have a chance of high temperatures over 100, with the best
chance from Thursday through Saturday. The best chance, over a 1
in 2 chance will be in the usual suspects, like Greybull and
Worland, with somewhat smaller chances in areas with slightly
higher elevations. Even West of the Divide, highs in the 90s
will be have at least a 3 out of 5 chance in the population
centers.

As for convection, chances will decrease. The 500 millibar
temperatures are a good gage for this, and these will top minus 6
celsius starting Thursday and continuing into Friday and
possibly Saturday as well. It is very difficult to get
convection with this cap in this part of the county. A stray
shower may occur Wednesday in the mountains but the chance is
less than 1 in 10. On Saturday, a very subtle shortwave may be
able to pop the cap briefly but again, this would be mainly in
the mountains and a less than 1 in 5 chance. There is some
indication the ridge may break down enough for a few more
showers and storms Sunday along with slightly cooler
temperatures, but we kept chances less than 1 in 3 until more
certainty moves in.

As for fire weather, there are few concerns through Wednesday as
wind remains light to moderate for the most part. There could be
more of a breeze for Thursday or Friday to increase this a bit so we
will have to watch it.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1047 PM MDT Sun Jul 7 2024

VFR conditions through the TAF period. High pressure building in
brings relatively light wind to the area, with only a little wind
increase during the peak mixing of the afternoon Monday. Otherwise,
a mostly clear sky with some afternoon clouds.

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...Hattings
AVIATION...Wittmann