Casper, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

319
FXUS65 KRIW 040800
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
200 AM MDT Mon May 4 2026

.KEY MESSAGES...

- The next weather system bring valley/basin rain and mountain
  snow for Monday and Tuesday with minimal impacts expected.

- Colder temperatures through the week resulting in freeze
  watches to continue for lower elevations east of the Divide
  for Tuesday night being the coldest morning going forward.

- Another system skirts across the north and east Thursday into
  Friday with additional precipitation chances expected
  (20-40%).

&&

.DISCUSSION...
Issued at 200 AM MDT Mon May 4 2026

IR currently depicts a closed low to the southwest near
California as WV shows the PFJ dipping further south out of
Canada and Montana into northeastern portions of the state.
Current model trends continue the southward progression of the
jet with a jet max of 120kts pushing into the next shortwave
expanding across much of the CWA for Monday. This will drop a
cold front through the area in the morning hours that will see
cooler temperatures from Sunday around 10 to 15 degrees for
afternoon highs. Otherwise, scattered rain showers expected with
the front that will expand into the evening and overnight hours
as the shortwave progressively moves across the CWA. Minimal
impacts expected with any snow accumulations constrained to
higher elevations even above mountain passes.

Tuesday will see a more widespread mountain snow/valley rain
effect as the aforementioned low to the southwest will embed
into the positively tilted trough extending from the Dakotas.
More ample divergence aloft expected, especially across the
southern half of the CWA where QPF amounts could push over a
quarter inch (60-70%) in some spots along the I-80 corridor of
Sweetwater County and points south to the Colorado border.
Otherwise, snowfall rates for the higher elevations will be
greatest during the afternoon and into the evening hours.
Minimal impacts expected to mountain passes (South Pass the only
one to push advisory level amounts). However, with the warm
temperatures ahead of this system and more of a longer duration
time frame, any issuances were held off at this time for Tuesday
and Tuesday night. However, a reinforcement of cooler air
expected into Wednesday morning seeing a widespread below
freezing event for basins east of the Divide. As such, freeze
watches continue with this being the coldest morning of the week
ahead.

Additional precipitation chances with minimal impacts expected
Thursday and Thursday night as the main trough exits to the
east. This will give way to upper level ridging to build back in
Friday and into the weekend with dry conditions and a warming
trend expected. Northwest flow aloft extends through into early
next week with a minor shortwave pushing to the northeast
Saturday afternoon that might see some sporadic showers for the
Bighorns and northeastern counties, but much of the activity
will remain northeast.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1100 PM MDT Sun May 3 2026

VFR conditions to start the period across all terminals. However, a
nearing cold front will start to bring impacts to terminals starting
as early as 12-15Z Monday. Northerly terminals such as KCOD and KWRL
see winds increase around this time along with lowering ceilings to
near MVFR. Gusty northerly winds of 20-30 knots will gradually push
south through the day making it to central terminals by around 18Z.
Development of showers will occur ahead of the front in the
afternoon with nearly all terminals having a chance around a 20-40%
for a brief shower from 18Z Monday through 00Z Tuesday. An isolated
thunderstorm or two cannot be ruled out with terminals west of the
Divide having the best chances. The main concerns as a result of any
showers will be gusty outflow winds of 25-35 knots. A second round
of precipitation looks possible after 00Z Tuesday in association
with the cold front passage. PROB30 groups have been added to
numerous terminals with some seeing showers while others may see a
period of prevailing precipitation to end the TAF 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...
Freeze Watch from late Tuesday night through Wednesday morning
for WYZ003>006-010-011-017-018-020.

&&

$$

DISCUSSION...Lowe
AVIATION...Dziewaltowski