Casper, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

449
FXUS65 KRIW 041714
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1114 AM MDT Mon May 4 2026

.KEY MESSAGES...

- The next weather system brings valley/basin rain and mountain
  snow Monday and Tuesday, with the highest totals most favored
  on and around the Wind River Mountains.

- Colder temperatures this week, with Freeze Watches for lower
  elevations east of the Continental Divide Tuesday night and
  Wednesday morning when lows drop below 32 degrees.

- Another weather system skirts across northern and central
  Wyoming Thursday into Friday with additional precipitation
  chances (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 /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1114 AM MDT Mon May 4 2026

A complex weather pattern through the next 24 hours (and beyond).
Today, afternoon heating combined with an approaching front will
help to create showers and thunderstorms across the area, generally
through about 02z. Locations generally have a 15 to 40 percent
chance of seeing a shower or storm, with the main hazard being gusty
outflow winds up to 40 knots. Chances don`t completely end this
evening, however, as the front begins to move through. Precipitation
mode should chance from a showery coverage to more widespread
precipitation, and will change from rain to snow or rain/snow mix
overnight for most locations. Between the hours of 00z and 12z is
challenging due to the complex transition of afternoon showers
ending, widespread precipitation starting, the front moving through,
and when/if a transition from rain to any snow occurs. For most
locations, precipitation continues through the end of the period
once it begins this evening or overnight. KCOD, KJAC, and KWRL would
be the least favored for this continuous precipitation.

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...Wittmann