034
FXUS65 KRIW 130909
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
309 AM MDT Sun Jul 13 2025

.KEY MESSAGES...

- A hot finish to the weekend with highs in the 90s widespread
  in the lower elevations East of the Divide.

- Elevated to possibly critical fire weather is expected Monday
  afternoon.

- The chance of thunderstorms increases Monday, with the best
  chance of storms on Tuesday and Wednesday.

&&

.DISCUSSION...
Issued at 306 AM MDT Sun Jul 13 2025

All in all, the reasoning in the forecast has changes little from
yesterday. Northwest flow will continue to dominate today.
Thicknesses continue to climb today though, so it will be a rather
hot day today with widespread 90s in the lower elevations East of
the Divide. Almost all areas will be dry as well. However, notice
the modifier, almost. There will be a very subtle shortwave moving
across the area this evening. And this may be just enough to bring
an isolated shower or thunderstorm in and near the northern
mountains. The chance is very small though, small with a capital S.
We have some slight POPs in spots but the chance is at most 1 out of
6 with the vast majority of locations seeing nothing.

Things start turning more active next week. A cold front will start
approaching the area from the north. It will remain north of the
area though, so it will be another hot day with temperature fairly
similar to todays. We have two concerns. And it reminds me of one of
my favorite songs from the 70s, Fire and Rain by James Taylor.
Although starting Monday will should not see sunny days we thought
would never end. We will start with fire. With the approaching
cold front, the pressure gradient will tighten ahead of it and
bring some breezy conditions. Humidity will be very low on this
day, falling as low as 10 percent. This brings the possibility
of elevated to critical weather into the forecast. Wind looks
borderline though. The most likely place to see it would be
across portions of Sweetwater, Sublette and Fremont counties in
the afternoon. At this time, it is uncertain if we will get 3
hours of wind gusts past 25 mph for Red Flag criteria though.
So, we will let the day shift take another look to see if any
watches are needed and then we can upgrade tomorrow night if
needed.

Now for the rain, or more specifically thunderstorm part. Chances of
storms will increase but mainly across the northern portions of the
state. Chances here range anywhere from 1 in 5 in the lower
elevations to 1 in 3 in the mountains. There is not a lot of upper
forcing with on this day. However, what we do have are very large
dew point depressions (as high as 60 degrees) and inverted V
soundings with any afternoon convection being high based, strong
wind gusts are possible with any shower or storm, although many may
end up bring rain free. The chance of rain increases in the evening
and at night as temperatures cool and the atmosphere moistens
somewhat.

Tuesday and Wednesday still look like the most active days. The
models do agree on the northwestern half of the area and areas East
of the Divide seeing the best chance of seeing showers and storms,
with tapering chances further south. There are still disagreements
though on the timing and rainfall amounts of the storms each day,
with some models showing Tuesday as the most active day with the
system more progressive. Others have it on Wednesday with a slower
progression. So, there is still little confidence in the details at
this time. Temperatures will be substantially cooler though,
especially in northern Wyoming. Some guidance shows Buffalo
remaining in the 50s on Wednesday. Don`t know if I believe that with
it being the middle of July though. Some areas will be around 30
degrees cooler on Tuesday or Wednesday when compared to Sunday and
Monday.

Flat ridging should then control the weather for Thursday through
Friday and bring near normal temperatures. A few storms may be
around each afternoon but most areas should be dry. Above normal
temperatures are then favored to return for next weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 934 PM MDT Sat Jul 12 2025

High pressure dominates through the entire TAF period and beyond,
with little to no weather impacts at terminals. Some scattered
cumulus will develop Sunday afternoon between FL100-150, but skies
will remain clear overall over the next 24 hours. Wind may be a
little gusty at KRKS Sunday afternoon, otherwise wind will remain 5-
10 knots across the area.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on icing and turbulence forecasts.

&&

.FIRE WEATHER...
Issued at 306 AM MDT Sun Jul 13 2025

No fire concerns today despite low humidity as wind should
remain light to moderate. A cold front approaching from the
north will bring elevated to possibly critical fire weather
Monday afternoon as breezy conditions develop ahead of it, with
the the southern half of Wyoming having the greatest chance of
critical fire weather.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Hattings
AVIATION...Rowe
FIRE WEATHER...Hattings