Cody, Wyoming Weather Forecast Discussion

731
FXUS65 KRIW 170759
AFDRIW
Area Forecast Discussion
National Weather Service Riverton WY
159 AM MDT Wed Sep 17 2025
.KEY MESSAGES...
- One more day of scattered showers and storms today, with the
  most numerous East of the Divide.
- Dry and warmer weather expected for Thursday and Friday.
- Other than today and possibly Monday, above normal
  temperatures are expected through much of next week.
&&
.DISCUSSION...
Issued at 153 AM MDT Wed Sep 17 2025
The main weather maker today remains a slow moving upper level
low swirling over the Cowboy State early this morning. And we
continue to have areas of showers swirling across the area, mainly
in central Wyoming. It has brought some needed rain, with over
an inch in some areas around Casper yesterday. And, we could
have some decent rainfall amounts again today as the last in a
series of waves rotates around the low though Wyoming. Emphasis
continues to be East of the Divide, especially our eastern
counties of Johnson and Natrona. Ensemble guidance gives a
greater than 1 in 2 chance of a quarter of an inch or rain over
through tonight in this area, although most would fall before
midnight. Areas along and east of Interstate 25 have a 1 in 2
chance of an additional half an inch or rain over the same time
period. There could be some localized flooding though if showers
persist over an area though. Chances of showers generally
decrease as you go west, with mainly dry conditions expected in
far northwestern Wyoming.
Showers should end after midnight tonight as the last shortwave
exits the area and the upper level low finally gets evicted
into Nebraska and the Dakotas. Ridging should then build into
the area and bring a return to dry and warmer weather for
Thursday and Friday, with Friday looks especially warm with
highs in the 80s for many of the warmer spots.
On Saturday, most of the area should have another dry and warm
day with highs rising into the 80s, possibly a few spots in the
upper 80s in the Big Horn Basin. Just enough moisture may sneak
into the western mountains from the south for stray shower or
storm, but the chance is less than 1 out of 5 in any particular
location. Things look a bit more active for Sunday as a Pacific
cold front and though move across the area. The best forcing and
moisture should remain to the north of Wyoming though. It may
be close enough to bring a few showers and storms to northern
Wyoming though. The main concern would be elevated fire weather
though, as a gusty breeze develops with the passage of the front
and relative humidity will be low ahead of it, falling into the
teens in some locations. Following a brief cooldown for Monday,
dry and warm weather should return for Tuesday and Wednesday as
ridging builds back across the state.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1030 PM MDT Tue Sep 16 2025
VFR conditions at all but CPR for the entirety of the period.
Lingering scattered rain showers east that has brought upslope
flow to MVFR conditions. A more steady rainfall 10-15Z that
could see even IFR conditions as a PROB30 group. CPR will see
the on and off chances for rain showers all day Wednesday
through about 01Z before finally pushing east with lingering
overcast skies hovering above the VFR mark around 5kft.
Otherwise, west of the Divide will remain dry as the upper level
low pivots east keeping any activity to the east of even COD.
RIW/LND should see the activity between the 19-00Z timeframe
and WRL around 17-21Z as rain showers push southeast from there
first before ending at CPR around 01Z. Light winds no more than
10kts with scattered mid to upper level clouds west of the
Divide, and mid level ceilings starting to lift after the 00-01Z
timeframe into the upper levels. This should clear out by
Thursday morning reflected in the next TAF cycle.
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...
None.
&&
$$
DISCUSSION...Hattings
AVIATION...Lowe

NWS RIW Office Area Forecast Discussion