Casper, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

209
FXUS65 KRIW 180445
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
945 PM MST Fri Jan 17 2025

.KEY MESSAGES...

- Heavy snow continues through the afternoon, ending overnight.
  Lingering snow showers across east of the Divide Basins are
  possible into Saturday morning.

- Arctic cold following the snow still looking on track with
  Monday being the coldest day.

- Uncertainty beyond Monday regarding temperatures, as a quick-moving
  shortwave could bring gusty winds that would help to erode
  out the cold air.

- Another weather system looking possible for late week, but
  significant uncertainty exists regarding timing and track.

&&

.DISCUSSION...
Issued at 136 PM MST Fri Jan 17 2025

Snow behind the cold front this morning tracked a bit faster than
what models had indicated, but amounts remain on track with what
forecasts have been over the past several days. Winds aloft remain
southwesterly, hence gusts 30 to 40 mph across portions of the I-80
corridor continuing through most of the day. East of the Divide,
northerly flow exists up to ~10kft, leading to considerable upslope
conditions for locations like Lander and Casper.

Most of the moisture and energy behind the front is currently
focused along the Divide as of 1200L, with steady moderate snow
falling from Crowheart to Casper and points southward towards the
Divide including Lander, South Pass, and Beaver Rim. This focus will
continue to shift southward through the afternoon and evening,
bringing snow into southern portions of the CWA towards 00Z (1700L)
this evening. Gusty north winds at the surface are accompanying the
snow, creating some blowing and drifting in places and reducing
visibility. Snow will persist for upslope favored locations
well into the evening. With persistent northeast flow, light
snow showers and potential snowbanding looks to continue through
the night into Saturday morning for the Bighorn Mountains, Wind
River Basin and Natrona County. Additional accumulations
overnight look to be minimal, but could be notable where
persistent snow bands develop.

Any lingering snow showers Saturday morning will gradually end by
midday. Skies remain mostly cloudy and a secondary shortwave
embedded in the larger trough will slide southward into the region
Sunday. This will bring another blast of colder air and the
potential for some weak snow showers, mainly across the mountains,
Sunday afternoon. Any accumulations from this shortwave will be
light, less than an inch. Today`s cold front certainly brought cold
air with it, with highs only reaching the single digits to low
teens expected Saturday. The coldest air will filter in behind
the shortwave on Sunday, with lows Monday and especially by
Tuesday morning, reaching -20F in many locations. Tuesday
morning will be the coldest for most basin locations with
clearing and strong inversions setting up late Monday night.

Tuesday`s high temperatures have quite a bit of uncertainty with
them, however. A quick-moving short wave barrels through the region
Tuesday, which would enhance winds and downsloping winds will help
to erode out the cold air from most areas. Highs Tuesday could thus
reach the mid 20s for many locations. However, there is low
confidence in winds being able to erode out the deeper cold pools
such as in the Wind River Basin. Have continued to drop temps lower
than NBM for the Wind River Basin beyond Day 4 in anticipation
of the cold pool there persisting and not being impacted by
downsloping winds Tuesday.

Looking ahead to the later half of next week, models continue to
indicate an active pattern, with a trough moving through
Wednesday/Thursday and perhaps another one for next weekend.
That being said, there is significant model disagreement beyond
Tuesday, and confidence regarding any kind of details, including
timing and track with these storm systems is very low.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 944 PM MST Fri Jan 17 2025

West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals

Northwest flow will occur behind the weather system through the TAF
period. This will bring in frigid arctic air and keep some light
snow going at KRKS for a few hours to begin the TAF period. MVFR
conditions to prevail at KRKS until 22Z/Sat and VFR to prevail at
all other terminals for the next 24 hours. Wind will increase at
KBPI/KPNA Saturday afternoon to around 10 knots. Mountaintop
obscuration will occur at times during the period.

East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals

Northwest flow will occur behind the weather system through the TAF
period. This will bring in frigid arctic air and keep some light
snow going at terminals early in the TAF period, with most snow
tapering off early Saturday morning. Conditions will predominantly
be MVFR where snow falls, but IFR is possible at KCPR before sunrise
as indicated by the TEMPO group. There is also a chance (30%) of
snow showers and IFR conditions at KCPR Saturday afternoon. IFR
conditions at KLND will improve to MVFR by around 07-08Z/Sat. Wind
will increase at KWRL Saturday afternoon, with gusts of 20-25 knots
until 00Z/Sun. Mountain obscuration will continue through Saturday
morning, with improvement Saturday afternoon.

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...
Winter Weather Advisory until 11 PM MST this evening for
WYZ005-007>009-017-019-020-022.

Winter Storm Warning until 8 AM MST Saturday for WYZ018.

Winter Weather Advisory until 2 AM MST Saturday for WYZ030.

&&

$$

DISCUSSION...Hensley
AVIATION...Rowe