329
FXUS65 KRIW 111838
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1238 PM MDT Fri Jul 11 2025

.KEY MESSAGES...

- A brief relief from the recent summer heat across the Cowboy
  State today.

- Isolated to scattered showers and thunderstorms are expected
  to develop this afternoon and evening. A few strong to severe
  thunderstorms may be possible.

- Hot and dry conditions return for the weekend into the start
  of next week with the potential for fire weather conditions by
  Monday.

&&

.UPDATE...
Issued at 1236 PM MDT Fri Jul 11 2025

A cold front has moved across much of the Cowboy State overnight.
The frontal passage has brought relief to the recent heat that
enveloped the region over the past week. Highs today will reflect
this relief with temperatures in the mid to upper 70s east of the
Divide and upper 70s to low 80s west of the Divide. Scattered
showers and isolated thunderstorms moved across northern WY this
morning but have now dissipated. Another round of showers and
thunderstorms is expected to develop this afternoon. The best
chances of seeing a shower or thunderstorm look to be east of the
Divide, especially across central WY. CAMs have highlighted portions
of the Wind River Basin, eastern Sweetwater County and southern
Natrona County. Overall, dynamics are not overly impressive but
there does look to be some favorable components that may lead to a
strong or near severe storm. CAPE values are marginal ranging from
500 to 1000 J/kg with some shear present but not overly
impressive. PWAT values look to be above normal with values
ranging from 0.75 to 1.00 in. These dynamics will lead to the
possibility of a few hazards as a result of any strong storms
that develop. These hazards look to be hail, strong gusty
outflow winds, and isolated heavy downpours. Very isolated flash
flooding cannot be ruled out, especially in poor drainage
locations but the overall concern for this is not very high. As
mentioned earlier, CAMs highlight central WY especially portions
of the Wind River Basin. SPC`s day 1 outlook supports this with
a sliver of marginal chances for severe thunderstorms being
drawn across central WY into southwestern WY. Showers and
thunderstorms look to start developing shortly after noon over
northern WY and gradually tracking southeast through the
remainder of the afternoon and evening. Convection moves out of
the area around sunset with quiet weather prevailing overnight
through the weekend.

The weekend sees warmer and drier conditions return to the area with
highs reaching the upper 80s to mid 90s. These warm temperatures and
dry conditions may lead to fire concerns by Monday. Winds are
looking to increase Monday along with low min RH values and warm
temperatures. These components may lead to portions of the state
seeing elevated to near critical fire weather conditions. This
possibility will continue to be monitored as we head into the
weekend. The next chance for precipitation does not look to arrive
until the start of next week as a trough moves across the region.
Another front moves through the area around Tuesday night bringing
in a brief period of cooler temperatures. The remainder of the week
looks to have increased chances for precipitation as multiple
disturbances move through the region.

&&

.DISCUSSION...
Issued at 259 AM MDT Fri Jul 11 2025

When I was surfing the net before I left for work, I happened
upon an old commercial I have not seen since my youth, many eons
ago. It is for the antacid Rolaids. And the question asked in
it is: How do you spell relief? And the answer is spelled out:
R-O-L-A-I-D-S. And this relates to this question, how do you
spell relief from the heat? And the answer is C-O-L-D F-R-O-N-T.

A cold front is currently moving through the area, having
passed through the humble Riverton weather abode a bit ago with
wind gusts close to 50 mph with the strong cold advection. Both
Greybull and Buffalo have gusted over 50 mph as well. These
strong wind gusts should slowly end though. The big change today
will be much cooler temperatures that will move in today East
of the Divide, where some locations will be up to 20 degrees
cooler than yesterday, with a place like Buffalo struggling to
get out of the 60s. It will feel more like May than July. It
will remain warm West of the Divide though, with temperatures
close to yesterday`s highs though. As for convection, we do have
some instability but not a ton, maximum CAPE values max out at
around 1000 J/Kg in some of the mountains but it is generally
around 500 J/Kg or less. Lifted indices generally drop down as
low as minus 2. Much of the area, except for southwestern
Wyoming, may see a shower or storm but the chance is generally
at most 1 out of 4, with up to a 2 in 5 chance in some of the
mountain ranges. Most of this looks like an early show, with
most over around 6 pm and all over by sunset.

The weekend at this point looks relatively uneventful with mainly
dry conditions under northwest flow. Many people will be suffering
from temperature whiplash though with near to above normal
highs returning Saturday and especially Sunday with widespread
90s in the lower elevations East of the Divide and some
locations getting close to 100. Fire weather concerns look low
though with wind remaining light to moderate.

Active weather then begins ramping up again starting Monday. On
Monday a shortwave will approach the area and bring a chance of
showers and storms, mainly across northern portions of the
state. This will also tighten the pressure gradient across the
area and bring a gusty wind which will likely increase fire
weather concerns, especially in southern Wyoming. Following
that, a more potent cold front will drop southward into the area
and bring a better chance of showers and storms, possibly both
on Tuesday and into Wednesday. Details on which day will be
wetter and details of where the storms may fire are still highly
uncertain though. Cooler temperatures will also move in for
midweek as a trough lingers across the area. So, it looks like
we will be riding the temperature rollercoaster as we head into
through the middle of July.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1115 AM MDT Fri Jul 11 2025

West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals...

Mostly clear skies with only FEW to SCT high clouds this afternoon.
Winds remain mostly light, with gusts briefly reaching 15 to 20kts
at KJAC (30% chance) and more frequent gusts at KBPI and KPNA through
the afternoon. Northeasterly winds this afternoon will favor KRKS
where gusts up to 25kts are expected through around 07Z Saturday.
Light winds are expected overnight with SKC for all terminals
through the end of the period.

East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals.

Behind the overnight cold frontal passage, most terminals will
persist with northeasterly winds, however, wind speeds should
continue to decrease through the early afternoon. Skies remain BKN
to OVC through the late afternoon as well, but breaks in the clouds
are expected to start to develop from west to east. This will allow
for convective initiation during the late afternoon (around 22Z)
over the Absaroka and northern Wind River Mountains. Showers and
thunderstorms will then move east from 22Z through 03Z. Most likely
chances for thunderstorm impacts are at KRIW and KLND (60% chance)
with lesser chances (30%) at KWRL and KCPR. Gusty winds and small
hail are possible with these thunderstorms, particularly for KRIW
and KLND.

Skies quickly clear after 05Z, with light winds and mostly SKC
prevailing through the rest of the period.

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.

&&

$$

UPDATE...Dziewaltowski
DISCUSSION...Hattings
AVIATION...Hensley