Manderson, Wyoming Weather Forecast Discussion

975
FXUS65 KRIW 121824
AFDRIW
Area Forecast Discussion
National Weather Service Riverton WY
1224 PM MDT Fri Sep 12 2025
.KEY MESSAGES...
- Shower and thunderstorm chances today, with the main hazards
  being gusty outflow winds, lightning, and brief small hail.
- Another round of showers and storms moves through the state
  during the late evening and overnight, with higher chances
  for measurable rainfall.
- Chances for showers and thunderstorms persist through
  Saturday.
- Cooler temperatures will lead to very light snow accumulations
  across the higher elevations above 9500 feet.
&&
.UPDATE...
Issued at 1218 PM MDT Fri Sep 12 2025
No major changes to the forecast with this update. Showers and
thunderstorms will be around this afternoon. Increasing moisture
moving into the area this evening will continue rain chances
overnight and through Saturday. Along with this moisture, there will
better chances for higher liquid accumulations.
Temperatures also trend down with this incoming system. Lower
temperatures are expected today compared to yesterday, with cooler
highs tomorrow in the upper-60s to mid-70s across the area. Saturday
night could see some freezing temperatures across the western basins
and valleys. As of now, confidence is not high enough in widespread
32F temperatures or lower, so have not issued any highlights. Colder
places, like along rivers, around Cokeville, and around Bondurant,
will likely see freezing temperatures. Potential cloud cover is the
major consideration at the moment.
&&
.SYNOPSIS...
Issued at 128 AM MDT Fri Sep 12 2025
A trough continues to dig across the Great Basin today gradually
making its way eastward. Impacts as a result of this disturbance
have continued to lessen over the past few days. Originally two lows
were expected to develop across the northern and southern portions
of the trough. However, recent trends have shown the southern low
quickly becoming disorganized west of the area and possibly not
reorganizing until its to the east of the area. As a result the bulk
of the impacts will remain to the north and south of the CWA.
Embedded shortwaves associated with the trough will move
through the region bringing chances for precipitation in the
form of daily showers and thunderstorms. Long range models
indicate the chance for another disturbance arriving by the
first half of next week. As of this morning impacts have shifted
slightly south bringing chances for precipitation into parts of
central WY.
&&
.DISCUSSION...
Issued at 128 AM MDT Fri Sep 12 2025
Showers and thunderstorms return to the state today with coverage
being more widespread as the trough axis nears. Cooler temperatures
slightly below normal are forecast west of the Divide with highs in
the upper 60s to low 70s. East of the Divide remains warm but with
temperatures beginning to gradually cool as highs range in the upper
70s to low 80s. Winds increase during the afternoon with occasional
breezes mainly around 20 mph. The atmosphere remains dry but not to
the same extent as Thursday with lesser dewpoint depressions of only
30 to 40 degrees. Showers and thunderstorms will be possible once
again starting in the early afternoon and spreading to the
northeast. Strong gusty outflow winds of 40 to 50 mph nearby any
showers or storms will be possible. Moisture looks to increase
during the evening as a second round of showers and storms moves
across the state. The influx of moisture should allow for rainfall
to reach the surface resulting in some measurable precipitation.
These showers and storms look to gradually move out of the area
by the late evening into the early morning hours on Saturday.
The trough axis enters the area by Saturday with shortwaves moving
across the state through the day. This will lead to continued
chances for showers and thunderstorms Saturday through Sunday
morning. Temperatures will continue to cool over the weekend with
highs west of the Divide in the mid 60s and highs east of the Divide
in the mid to upper 70s. Some high elevation mountain snow is
possible as these showers move through on Saturday. Snow
accumulation will be very minimal and limited to the highest
elevations above 10000 feet.
Long range models show a brief lull in activity for most of Sunday
before the next disturbance moves in from the PACNW. The exact
impacts from this disturbance remains uncertain at this time but
trends have shown a slight shift south. If this were to occur
precipitation chances would not only be limited to northern and
western WY but also central WY. Cooler temperatures will be
associated with this disturbance for the middle of the week leading
to below normal highs for much of the CWA. Along with cooler highs
overnight low temperatures may be chilly in some areas, leading to
the potential for morning frost, especially across western and
southern WY. These cooler temperatures will increase the chances for
some more light snow accumulation across the highest elevations
mainly above 10000 feet as this disturbance enters the region.
At this time confidence remains low regarding the track of this
disturbance and its impacts. Depending on its track we could see
cooler temperatures and greater chances for precipitation or
the opposite.
&&
.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 517 AM MDT Fri Sep 12 2025
Unsettled southwesterly flow will continue across the area today.
Scattered showers and thunderstorms will become widespread again
through the afternoon. Strong outflow wind gusts of 30 to 40 knots
will be possible with this activity through the evening. Guidance is
suggesting more persistent showers or storms will move in late this
evening, and have prevailing impacts at several terminals through
06Z-09Z. Most of this will end overnight leaving broken ceilings for
most. There is a hint of ceilings lowering to MVFR/IFR for some
terminals east of the Divide but have not included this for now.
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...Wittmann
SYNOPSIS...Dziewaltowski
DISCUSSION...Dziewaltowski
AVIATION...Myers

NWS RIW Office Area Forecast Discussion