943
FXUS65 KRIW 120746
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
146 AM MDT Sun Oct 12 2025

.KEY MESSAGES...

- Wind gusts of 35 to 45 mph will be ongoing across much of the
  forecast area by sunrise. These winds will begin to decrease
  by midday and subside through the rest of the afternoon.

- Light showers and mountain snow (10-20% chance) will continue
  over northern portions through the morning, with isolated (10%
  chance) showers possible over western portions through the
  afternoon.

- Freezing temperatures will be widespread tonight under clear
  skies, with areas west of the Divide dropping into the 20s.
  Readings near 30 degrees will occur east of the Divide.

- Gusty southerly winds return for Tuesday and Wednesday as
  another storm system approaches the Cowboy State.
  Precipitation chances will be confined to far western portions
  Tuesday, spreading across the rest of the forecast area
  Wednesday as a cold front moves over the area.

&&

.DISCUSSION...
Issued at 127 AM MDT Sun Oct 12 2025

Thunderstorms are exiting northward into the BYZ CWA as of 06Z. The
cold front has passed through Greybull and Riverton and will
progress eastward, exiting the CWA by sunrise this morning. Wind
gusts of 35 to 45 mph will continue across much of the area this
morning, decreasing after 18Z (12 PM). Light precipitation will also
continue over northern portions through the morning, with light snow
in the higher elevations as well as the Wind River Mountains and
Salt and Wyoming Ranges. Isolated showers will then be possible over
western portions through the afternoon. A Freeze Watch remains in
effect for eastern portions of the Bighorn Basin and northern
Johnson County, as temperatures have trended upward closer to 30
degrees and making the chances for a hard freeze less likely. Have
continued with the Watch for now, as skies will become clear early
this evening. Temperatures across the CWA have trended upward as
well, with readings near 30 degrees for most locations east of the
Divide. Readings in the teens are no longer in the forecast for the
western valleys, although locations in the Upper Green River Basin
could still be that cold.

Breezy southerly winds return Monday, with isolated showers possible
over the southern half of the forecast area. Temperatures will be
about 10 degrees warmer west of the Divide, as a result of the
southerly winds. This trend continues Tuesday, as a strong closed
upper low from British Columbia digs southward just off the West
Coast. Southerly winds will be a bit stronger irt this digging
trough, especially across the Wind Corridor (Rock Springs to
Casper). Rain showers will be confined to far western portions of
the CWA.

Models have come into better alignment and bring this storm closer
to the Cowboy State during the day Wednesday. Rain showers will be
ongoing over far western portions Wednesday morning, with snow
levels ranging between 7500 and 8500 ft over the Tetons due to the
proximity of the associated cold front. These showers will become
more widespread through the day. Southerly winds will continue to
increase, with gusts of 35 to 45 mph likely across much of the area.
Coincidentally, this system is progged to play out quite similarly
as the current ongoing storm. The cold front will make its way
eastward over western portions through the day, quickly making its
way across the rest of the CWA through much of the night. There is a
chance for high winds (60+ mph gusts) to occur over portions of
Natrona County in the wake of the front. This system is not expected
to be as cold either, with snow levels ranging between 6500 and 7500
ft Wednesday night as the closed upper low moves over eastern MT by
12Z Thursday. Precipitation chances will continue Thursday, mainly
over northern portions, as winds turn more northwesterly. Gusts up
to 35 mph will be likely over northern portions of the Bighorn Basin
and Johnson County, as well as the Green River Basin and Sweetwater
County.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 950 PM MDT Sat Oct 11 2025

As the weather system pushes through tonight so will a strong cold
front. Along this cold front, scattered rain showers and
isolated storms will make their way from west to east across the
area tonight into Sunday morning. Most terminals will remain
VFR through the TAF period, excluding KCOD, KJAC, and KWRL.
Chances are about 30% that conditions will drop to MVFR/IFR at
the aforementioned terminals, thus PROB30 groups have been added
for them. All rain will dissipate or exit the area by 18Z
Sunday.

The jet stream is strong overhead with this weather system, so that
means wind will continue to be breezy to strong tonight into Sunday.
Ahead of the cold front, wind will be from the south/southwest
and behind it wind will be from the west/northwest. Wind will
gradually drop Sunday as the weather system and associated jet
exit the area to the east. Wind gusts will generally be in the
20-30 knot range tonight into Sunday afternoon, with higher
gusts around 40 knots possible at KRKS and KCPR.

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

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Freeze Watch from late tonight through Monday morning for
WYZ004-006-010.

&&

$$

DISCUSSION...LaVoie
AVIATION...Rowe