Lost Twin Lakes, Wyoming Weather Forecast Discussion

912
FXUS65 KRIW 051843
AFDRIW
Area Forecast Discussion
National Weather Service Riverton WY
1243 PM MDT Sun Oct 5 2025
.KEY MESSAGES...
- Lower elevation rain showers and mountain snow continues
  through today. Precipitation ends from west to east through
  tonight, ending almost everywhere by noon Monday.
- Freeze Warnings have been posted for portions of the area
  tonight. More widespread freezes are possible Monday night
  into Tuesday morning.
&&
.UPDATE...
Issued at 1238 PM MDT Sun Oct 5 2025
As the sun came up this morning, there was the clear evidence of
snow over the mountain passes, with some snow even sticking to the
roads. The forecast remains on track today, with more mountain snow
and low elevation rain. The mountains could see periods of moderate
to heavy snow this afternoon and evening. Elevations above about
9500 feet should see an additional 4 to 9 inches through sunrise
Monday. Models indicate snow lasting a little longer over the
Bighorn Mountains, so have extended the Winter Weather Advisory
through 11pm MDT.
For freezes, have kept the Freeze Warnings for tonight. Cloud cover
may keep temperatures just above freezing, but this is the first
chance for freezing temperatures for these locations, so taking
necessary precautions is recommended. The watches that were in place
tonight have been cancelled due to lack of confidence of widespread
32 degree or lower temperatures. Some cold prone locations may see
freezing temperatures and frost, however. Confidence is much higher
in freezing temperatures Monday night into Tuesday morning as clouds
clear out. Freeze Watches have been issued for areas that have yet
to see season ending freezes.
&&
.DISCUSSION...
Issued at 219 AM MDT Sun Oct 5 2025
The first round of precipitation from the large-scale trough is
shifting east this morning, leaving behind a nice coating of
snow across area passes and higher elevations. There will be a
brief gap in most precip this morning before the next round
sweeps in on the back side of the trough from the northwest.
This will bring more lower elevation rain/higher elevation
snowfall today and tonight. Forecast remains above 0.10" for all
areas through sunrise Monday, with a quarter to a half inch
additional rainfall across Fremont and Natrona Counties. Higher
elevations will also continue with snowfall, with another 3 to 6
inches above 8000 feet.
As the next wave sweeps to the east tonight, skies will
gradually clear from west to east. The amount of cloud cover
overnight will directly impact how cold temperatures fall.
Models have held on to cloud cover longer overnight, so
confidence in overall coverage of freezing temperatures is
lower. Confidence and probabilities are best across Sweetwater
County into the Green Mountains, and across the Cody Foothills
(both 60 to 70%), so have upgraded to Freeze Warnings for those
zones for tonight, with remaining areas of central WY holding
onto Watches for now, to monitor newer forecasts for changes in
cloud cover. Any cloud cover remaining Monday morning will clear
out during the afternoon, leaving a better opportunity for a
freeze for remaining areas of central WY Monday night/early
Tuesday morning.
By midweek, H5 ridging reestablishes across the Rockies,
bringing temerpatures back closer to normals in the 60s for
highs and 40s for lows.
&&
.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1227 PM MDT Sun Oct 5 2025
Widespread MVFR to IFR conditions continue for most terminals today
as a system impacts Wyoming. Rain and mountain snow will persist
through the afternoon, shifting mainly east of the Divide after
sunset. Thus, conditions will improve for western terminals late
this evening, including at KJAC which is expected to return to
prevailing VFR by 06Z Monday. Lower ceilings and visibilities will
persist tonight for most terminals east of the Divide, before
precipitation begins tapering off through sunrise Monday. Frequent
mountain obscurations are expected through most 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...
Winter Weather Advisory until 6 PM MDT this evening for WYZ002-
012-015.
Freeze Warning from 1 AM to 10 AM MDT Monday for WYZ003-016-
019-028>030.
Freeze Watch from late Monday night through Tuesday morning
for WYZ003>006-010-011-017>020-028>030.
Winter Weather Advisory until 11 PM MDT this evening for
WYZ008-009.
&&
$$
UPDATE...Wittmann
DISCUSSION...Straub
AVIATION...Myers

NWS RIW Office Area Forecast Discussion