Mills, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

238
FXUS65 KRIW 220449
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
949 PM MST Fri Feb 21 2025

.KEY MESSAGES...

- Colder temperatures in the single digits/teens tonight across
  southern portions and the Wind River and Bighorn Basin.

- Continuing to watch for the possibility of ice jamming and
  flooding Sunday through Tuesday across the Bighorn Basin and
  Johnson County. This is due to warming temperatures and
  current snowpack in those areas.

- Snow chances return to western Wyoming Sunday as a weak
  weather system passes. Lower elevations/valleys may see rain
  or rain/snow mix.

- Gusty to strong winds Sunday through Tuesday, with the
  strongest winds along the east slopes of the Absarokas
  (Cody/Clark), over the mountains and the Wind Corridor
  (roughly Rock Springs to Casper, including South Pass).

&&

.UPDATE...
Issued at 820 PM MST Fri Feb 21 2025

Mid to high clouds will continue to increase across area tonight
and into Saturday morning. Low clouds infiltrated into much of
Yellowstone late this afternoon. Some of these clouds could
filter southward into the Jackson Valley and the north end of
Star Valley through the night. Fog will also be possible early
Saturday morning along the Bighorn River and the Boysen
Reservoir toward Riverton. Winds will become stronger over the
Wind Corridor (Rock Springs to Casper) Saturday afternoon, with
gusty winds also occurring near Dubois and Cody. This will be a
precursor of a more active pattern, wind-wise, starting Sunday.

The next weather system is still on track to arrive over western
Wyoming starting Sunday. This system will bring gusty winds to
portions of the area Sunday through Tuesday. The locations of focus
are the mountains and the Wind Corridor from roughly Rock Springs to
Casper. Gusts in excess of 50 mph look possible, with gusty
winds continuing overnight in that time period. Strong/high
winds could also occur near Clark/Cody by Sunday morning. Will
have to keep an eye on model trends to see if/when any wind
highlights would be needed.

&&

.DISCUSSION...
Issued at 1230 AM MST Fri Feb 21 2025

IR currently depicts clearing skies across much of the state as
upper level ridging builds in from the west. Some cooler cloud
tops across far southern reaches of the CWA along the Colorado
state line with some light lingering snow flurries pushing out.
The main finger of the PFJ continues to stay to the northeast
diving into the Great Plains keeping the colder temperatures
away. The weak distortion of the jet diving south of the CWA
has supported this previous disturbance that now will push to
the southeast giving way to tranquil weather conditions for
Friday and into the weekend. Increasing upper level convergence
will allow for higher pressure at the surface and warming
temperatures even into early next week. As a result, the main
concern will be for ice jamming and flooding for areas in the
northern Bighorn Basin and Johnson County due to the recent
snowpack in lower elevations. Temperatures east of the Divide
will push into the 40s Friday and Saturday and 50s to near 60
Sunday through Tuesday. West of the Divide will remain in the
30s for much of this time as the next disturbance will start to
affect these areas come Sunday through mid week.

The main PFJ dips further south across Montana to northern
reaches of Wyoming by Sunday afternoon giving way to the Pacific
Northwest moisture once again. This will increase snow chances
west of the Divide, mainly for the western mountains through mid
week. A mix to even just liquid precipitation possible for the
lower valleys as temperatures could remain above the freezing
mark for much of this period. Time will tell, but a forward look
on snow accumulations look to be modest at best to possible
advisory level criteria for the western mountains to include the
main passes as per usual with the zonal westerly flow. The main
trough looks to pass through the rest of the state to the east
late Tuesday and into early Wednesday, which gives really the
only chance for precipitation east of the Divide in the long
term period. With the warmer temperatures above freezing
(although cooler Tuesday and Wednesday) liquid rain the likely
precipitation for the lower elevations and likely snow for the
Bighorns. Otherwise, ridging builds back in for the remainder of
the week and into the following weekend with decreased
divergence aloft looking to be a possible Omega Block to end
the rest of the month and into March. Winter is still not done,
but it is in its waning hours in the longer term outlook.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 949 PM MST Fri Feb 21 2025

VFR conditions prevail across all terminals through much of the TAF
period. Mid to high level cirrus will begin to fill skies over all
terminals through the overnight into Saturday morning. A SCT/BKN200
cloud deck will linger across the region through much of the
afternoon on Saturday. Winds increase at KCPR, KCOD, and KRKS during
the early afternoon on Saturday. Westerly winds of 20 to 30 knots
with gusts of 35 to 40 knots will be possible at these terminals
with slightly weaker winds for KRKS. KRIW will need to be monitored
as Hi-res models are showing a northwesterly drainage wind develop
during the evening. This drainage wind may be quite gusty at times
with winds of 15 to 25 knots with periodic gusts near 30 knots.
Winds gradually decrease by the late evening with KCOD possibly
seeing gusty winds linger through the end of the period.

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...
None.

&&

$$

UPDATE...LaVoie
DISCUSSION...Lowe
AVIATION...Dziewaltowski