475
FXUS65 KRIW 080821
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
221 AM MDT Tue Sep 8 2026

.KEY MESSAGES...

- Near-freezing temperatures will be possible this morning and
  Wednesday morning around sunrise in the western valleys and
  Upper Green River Basin. Sensitive outdoor plants could be
  affected by freeze and frost.

- Elevated to critical fire weather conditions will be in place
  through the week due to breezy winds and low humidity.

- Temperatures remain near seasonal normals through the week as
  well, with abundant sunshine and minimal chances for rain,
  even in the mountains.

- Confidence continues to increase for a storm system this
  weekend to bring colder temperatures to the Cowboy State.

&&

.DISCUSSION...
Issued at 210 AM MDT Tue Sep 8 2026

Clear skies are in place across the CWA this morning and will be
the norm for the next few days. This will help temperatures to
drop this morning, in addition to the cooler airmass in place
in the wake of yesterday`s cold front. Freezing temperatures
will be possible in the more cold-prone locations west of the
Divide, like Jackson, Pinedale and Hoback Junction. Dewpoints
are around 27 degrees as of 07Z (1am), with nearly calm winds so
would not be surprised if temperatures drop below freezing in
these areas. Dewpoints are slightly higher in Star Valley,
around 32 to 34 degrees at Afton and Alpine so temperatures look
to stay just above freezing.

The trend this week will be the dry conditions along with breezy
winds, along with seasonal temperatures and mainly clear skies.
Red Flag Warnings are in effect again today across areas east
of the Divide, from the Cody Foothills to the Wind River Basin
and over Natrona County. West winds, with gusts of 25 to 35 mph,
will be widespread across much of the CWA again this afternoon.
Eastern portions of the Bighorn Basin and most of Johnson County
will be the exceptions. A second cold front will reach northern
portions around 00Z and quickly push southward through the
evening hours. The front will be dry, as there is no available
moisture in place after yesterday`s cold front.

Wednesday will be the calmest day of the week. Seasonal
temperatures will remain in place and the winds will not be as
strong as today or yesterday. West winds with gusts up to 30 mph
will be mainly confined to more wind prone locations, mainly
from southern Lincoln County to Natrona County. Red Flag
Warnings will be likely in these areas, as critically low RH
values become widespread. Stronger winds return for Thursday,
with widespread gusts of 30 to 40 mph occurring for most areas.
Daytime temperatures will also be slightly above normal for
areas east of the Divide. Another cold front will move over the
area Friday, causing another day of gusty winds of 30 to 40 mph
impacting much of the CWA.

Models continue to trend toward a strong cold front impacting
the Cowboy State this weekend and have come more inline wrt
timing. Confidence is medium for widespread precipitation ahead
of the system on Saturday. If there is any snow with this storm,
it would be confined to the northwestern mountains and the
northern end of the Bighorns Sunday night into Monday morning.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1020 PM MDT Mon Sep 7 2026

VFR conditions will prevail across all terminals throughout the TAF
period. Skies will remain SKC with the only caveat being a few fair
weather cumulus above 10,000 feet developing over northern
portions late in the afternoon into the evening. Winds will be
light at 5 to 10 knots through the overnight hours into Tuesday
morning. Winds increase by about 18-19Z Tuesday with all
terminals seeing winds of 10 to 20 knots with gusts of 20 to 30
knots. The strongest winds are forecast to be at KCPR. Winds
should begin to gradually weaken after 00Z Wednesday with most
terminals seeing light winds return by the end of the TAF
period. A few terminals may see breezy winds linger into the end
of the TAF period.

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 210 AM MDT Mon Sep 7 2026

West winds with gusts of at least 25 mph and critically low RH
values will occur in various locations today through Thursday.
Red Flag Warnings are in effect this afternoon for areas east of
the Divide. Winds will shift to southern portions of the state
Wednesday, as critical RHs become widespread. Thursday will have
the strongest winds, with gusts of 30 to 40 mph occurring in
most zones. Another cold front will move through the area
Friday, but RH values are expected to range between 16 and 25
percent.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon today to 7 PM MDT this evening for
WYZ276-283-285-287.

Red Flag Warning from noon today to 9 PM MDT Thursday for
WYZ280-289-300.

&&

$$

DISCUSSION...LaVoie
AVIATION...LaVoie/Dziewaltowski
FIRE WEATHER...LaVoie