Riverton, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

722
FXUS65 KRIW 152303
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
503 PM MDT Sun Mar 15 2026

.KEY MESSAGES...

- Breezy north to northwest winds will persist through the day
  today, but gusts will be notably less than those on Saturday,
  with 15 to 25 mph gusts in the forecast for most locations.
  Gusts closer to 35 mph are expected in the Upper Green River
  Basin and Sweetwater County.

- Temperatures on Sunday will be about 15 to 40 degrees colder
  than those experienced Saturday.

- Snow showers are expected off the east slopes of the Bighorns
  this afternoon, impacting the I-25 corridor in the southern
  half of Johnson County. Reduced visibilities will be the main
  impact with minor snowfall accumulations.

- Widespread windy conditions return Tuesday, with high winds
  possible (30-50%) over the Cody Foothills and Wind River
  Basin.

- Confidence is high (90%) for well above average temperatures
  from Tuesday into next weekend, with record-breaking heat
  expected from Wednesday into the weekend. Some locations east
  of the Divide could have the earliest 80 degree day on record.

&&

.UPDATE...
Issued at 1226 PM MDT Sun Mar 15 2026

The current temperature at the office is 22 degrees, which is
the normal low temperature for today. Visible satellite imagery
shows the freshly fallen snow already starting to erode as
late winter/early spring higher angle sunshine warms things up.
For the most part, skies will remain mostly clear, allowing for
some more melting through sunset. Enough melting may occur in
the areas that received the most snowfall that some freezing fog
formation is possible, especially around Lander and along I-25.
Signal is not overly strong, but added moisture in the
atmosphere does not rule it out. Overnight temperatures still
on track to fall back into the single digits and teens east of
the divide, and in the 20s to the southwest.

Longer term outlook for the week still looks like an
unprecedented warm spell, with highs pushing 30 degrees above
normal...

&&

.DISCUSSION...
Issued at 122 AM MDT Sun Mar 15 2026

Snow continues to end from north to south early this morning, with
most of the snow ending over central portions between midnight and
1AM (07Z). On average, temperatures rapidly dropped 20 degrees in 30
minutes Saturday evening behind the front, with the Riverton Airport
dropping 11 degrees in 5 min. Temperatures will continue to slowly
drop through the rest of the night, with readings in the single
digits and teens by sunrise. It will be a raw day today across the
Cowboy State, with readings 15 to 40 degrees colder from Saturday,
leaving daytime highs in the 20s and 30s. The southern end of
Flaming Gorge looks to be the warmest location, with a high near
40F. Winds will also continue to decrease through the rest of the
morning, before increasing again over the western half of the CWA by
18Z. North to northwest winds will occur across the forecast area
today, with gusts of 25 to 30 mph in the aforementioned area. Snow
showers will develop off the east slopes of the Bighorns this
afternoon as a result of these winds and impact the I-25 corridor in
the southern half of Johnson County. This would include Kaycee and
the I-25 Divide. Snowfall amounts will be minor, less than 1 inch,
but visibilities could be reduced so caution is advised for any
travelers this afternoon. Winds will decrease again this evening,
but will increase back toward 25-30 mph over Sweetwater County
by the predawn hours Monday morning. Snow showers will redevelop
over northwestern portions of the CWA after 06Z Monday, as a
fresh round of Pacific moisture rounds the ridge and over this
area within a northwest flow pattern. This snow will continue
through the day Monday, with minor accumulations. The western
slopes of the Absarokas along the eastern edge of YNP will have
the highest amounts of 2-4 inches.

The cold conditions today will be temporary though (it is March
after all), as a strong ridge builds over the West Coast. Monday
morning will be cold again, with readings in the single digits to
middle 20s. Temperatures will quickly rise through late morning into
the early afternoon, with some locations having about a 40 degree
swing from the morning low to the afternoon high. Gusty west to
northwest winds will aid in the warmer temperatures, with gusts of
25 to 40 mph occurring over the Upper Green River Basin and the Wind
Corridor (Rock Springs to Casper), as well as the Upper Wind River
Basin.

The story from Tuesday onward will be the above normal temperatures
as the high center from the ridge begins to move over southern CA.
This high center will slowly track eastward over the Desert
Southwest and the Four Corners through Saturday. The high center
will start as high as 591dm (at 500mb), strengthening to
594-597dm by Thursday over the Desert Southwest. This is very
anomalous for this time of year and can expect highs in the 60s
and 70s by Tuesday. The gradient will tighten again Tuesday,
with northwest flow aloft remaining in place. 700mb winds will
increase to 30-40kt for much of the CWA. High winds are looking
likely again in the Cody Foothills and the Wind River Basin, as
models prog 700mb winds of 50-60kt off the east slopes the
Absarokas and the Upper Wind River Basin. Tuesday was already
looking to be a windy day across the CWA again, but High Wind
Warnings look likely now ("Just when I thought I was out, they
pull me back in").

Gusty winds look to continue Wednesday as the gradient remains
tight, however this will change by Thursday as the influence from
the PFJ gets shunted northward and the high center moves over the
Desert Southwest. Several locations could reach 80 degrees Thursday
and Friday, which would be the earliest 80 degree day on record by
about 4 weeks. Here are some dates for reference: Casper - April 11;
Lander - April 11; Worland - March 28; Riverton - April 23. Lastly,
river levels may begin to rise by next Friday as a result of these
anomalously warm temperatures, but soil conditions remain very dry
and are expected to absorb any extra water.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 503 PM MDT Sun Mar 15 2026

VFR conditions prevail through the period, mid-to-high-level clouds
around the area. Winds are relatively light overnight, but increase
early in the morning (around 15z). Gusty winds occur more most
locations through Monday afternoon. One concern overnight is fog,
given recent moisture and some melt during Sunday. Places like KCPR,
KJAC, KLND, and KRIW would be the most likely place. Given the
colder temperatures and lack of models indicating saturation at the
lower levels, have held off any fog in the TAFs for now. Light snow
is also possible at KJAC starting around 10z, with 30 to 40 percent
chances continuing 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...Straub
DISCUSSION...LaVoie
AVIATION...Wittmann