834
FXUS65 KRIW 070846
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
246 AM MDT Sun Jul 7 2024

.KEY MESSAGES...

- Cooler today with a few lingering showers and thunderstorms
  East of the Divide.

- A nice start to the workweek Monday with seasonable
  temperatures.

- A heat wave is likely starting Wednesday and continuing
  through Saturday with a greater than 1 in 2 chance of 100
  degree high temperatures in the normally warmer locations.

&&

.DISCUSSION...
Issued at 230 AM MDT Sun Jul 7 2024

A cold front has swept through the area and brought some good wind
gusts to the area, mainly in the northwest flow areas with some over
50 knots. With some moisture and jet energy lingering over the area,
there will be a few showers and thunderstorms around into the
evening, but coverage should be less than yesterday. Most models, of
the synoptic and high resolution variety, are showing the best
coverage of the Big Horns and south and southeastward, including
Casper. A few others are expected in the Wind Rivers and Absarokas.
Chances are fairly low in any given spot, mainly from 1 out of 5 to
2 out of 5. Even here, most of the area should time should be rain
free. A bit of a northwesterly breeze will continue in the favored
locations, like Buffalo and Greybull. Fire weather concerns should
be lower though, given somewhat cooler temperatures and higher
humidity.

Following today, the main concern will shift away from convection
and toward heat, likely the hottest seen so far this year. And to
present this, we will have a more musically themed discussion, with
songs from the 50s into the 2000s (sorry, no current hits, I`m
old). And if you don`t like hot weather, by the end of the week
there will be no cure for the Summertime Blues.

Ridging begins move in Monday, moving in from the southwest. Monday
all in all looks like a decent mid summer day, with temperatures
near normal and light wind. For many it will be, A Lovely Day,
Lovely Day, Lovely Day and a good day to Soak Up The Sun if you
happen to be off work. We can`t rule out a stray afternoon shower or
thunderstorm in and near the mountains, but the chance looks to be 1
in 10 or less at this time. So, we left the forecast dry for now.

Tuesday will turn warmer, close to normals with highs in the 80s to
low 90s around the lower elevation. The average temperature of the
lower elevations looks be about 88, a chance to hop in the water plug
just for old times sake, so in other words, Summertime. The one
fly in the ointment will be a subtle shortwave passing through.
There will be just enough moisture to touch off isolated
thunderstorms in the mountains, but even here the chance is 1 in
5 or less. However, you should be use caution if hiking in the
mountains, because you could be, Thunderstuck.

The ridge really begins to flex it`s muscles on Wednesday, as the
500 millibar heights climb to over 5900 to as high as 5940 as the
core of the ridge shifts from California into the Great Basin. And
as a result, it will be getting Hot in Here. The 700 millibar
temperatures climb to anywhere from plus 16 to plus 20, which could
be give most lower elevations locations highs well into the 90s. The
warmer spots may touch 100, but the chance of that happening is less
than 1 out of 4 at this point. So, although Some Like it Hot and
sweat when heat is on and having Hot Fun in the Summertime,
others will think it is Too Hot and be running for shelter and
shade. Like Monday, we can`t rule out a stray shower or storm in
or near the mountains. The chance is less than 15 percent
though, so we left the forecast dry for now.

The heat will peak on the days from Thursday through Saturday, when
we will just feel Hot! Hot! Hot! as Here Comes the Hotstepper,
otherwise known as the death ridge as it sets up just to our south.
Or, in other words, the hottest temperatures of the year are very
likely. On these days, these are the following upper air parameters,
500 millibar heights climbing to as high as 5980 dm in parts of the
area. The 700 millibar temperatures will climb to over 20 degrees in
most of the area. The result will be at least a 1 in 2 chance for
most of the population centers East of the Divide to see high
temperatures of 100 degrees or higher on any of these three
days, with the best chance in the normally hot places like
Greybull, Basin and Worland with many areas potentially having
record highs on any of these days. The other parameter are the
500 millibar temperatures. These climb to minus 6 on both
Thursday and Friday. In this part of the country, it is very
difficult to break the cap to get convection on these days, so
the forecast is dry. These upper level temperatures fall to
around minus 8 to minus 9 on Saturday, which could allow for
some cooling afternoon showers or storms to develop. This is
still uncertain this far out though so for now we kept chances
generally 1 in 5 at most and mainly in the mountains. So, as we
head into the Wednesday through Saturday, we will burning like a
Heat Wave and Hot Stuff will linger into the evening each day.
And earliest time for a Cool Change will have to wait until next
Sunday or early next week as the ridge weakens a bit and moves
eastward and may allow some cooler air in. As for fire weather
through the period, conditions should remain below critical. It
will be hot with low humidity. However, with the ridge in place,
wind should remain light to moderate through the period except
around any very isolated shower or thunderstorm that may
develop.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 948 PM MDT Sat Jul 6 2024

VFR conditions prevail through the TAF period. Lingering
showers remain east of the Continental Divide; these continue
to dissipate through the first few hours of the period. Winds
will increase late morning and early afternoon Sunday, with
gusts to around 20 knots for many sites. Afternoon showers and
thunderstorms are possible Sunday afternoon, mainly east of the
Divide, However, current high-resolution models are showing too
few coverage and consistency to put any mention in the TAF at
this range.

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