Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 202231
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
430 PM MDT Sun Jun 20 2021

.SHORT TERM...(This evening through Monday night)
Issued at 139 PM MDT Sun Jun 20 2021

The C-O-L-D F-R-O-N-T remains hung up along the Continental
Divide, but will start moving farther south later this afternoon,
being nudged southward by the next piece of the H5 trough moving
in from the northwest. This is being noted by the increase in
convective activity across Park County, with a few lightning
strikes expected from time to time. The chances for showers
continue east of the divide, increasing across the Bighorn Range
and the I-25 corridor overnight. The front will move across areas
south of the Divide this evening, but will be limited to an
increase in dewpoints. Behind the front, temperatures will
definitely feel much cooler, with lows tonight in the 40s for the
lower elevations, and widespread temperatures near freezing for
higher elevations, including Yellowstone NP. The rainfall will be
moving east late tonight as high pressure moves in.

Monday will be a great day across Wyoming, with high pressure
dominating the sfc and aloft. Temperatures will recover into the
70s and lower 80s, with skies remaining sunny and winds remaining
light.

.LONG TERM...(Tuesday through Sunday)
Issued at 139 PM MDT Sun Jun 20 2021

After a couple of cooler days the heat will return on Tuesday as a
transitory ridge moves over the area. Highs will likely peak in the
low to mid-90s across the lower elevations, or about 10 to 15
degrees warmer than normal. Much of the same expected Wednesday, but
with a weak shortwave in the flow some isolated convection is
possible across mainly the northwest. A Canadian trough swings down
on Thursday, bringing a decent chance for showers and thunderstorms
across the entire area through Friday. An associated cold front will
also decrease Friday highs to around normal. Model solutions become
much more varied by next weekend. Ensemble guidance does show a
strengthening ridge across the northwestern CONUS, so have kept the
NBM solution of warm and mainly dry for now.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday)
Issued at 430 PM MDT Sun Jun 20 2021

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

Predominately VFR conditions will continue this evening as scattered
showers and isolated thunderstorms move south. Brief MVFR conditions
have been noted at KCOD and are possible with any shower activity at
terminals this evening. Precipitation will end around sunset, with
skies clearing overnight.

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

VFR conditions will continue to prevail through the period.
Scattered showers around KJAC will end around sunset. The breezy
wind at KRKS will decrease after 07Z, with skies generally clearing
at terminals overnight.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on icing and turbulence forecasts.

&&

.FIRE WEATHER...
Issued AT 139 PM MDT Sun Jun 20 2021

The front stretches across the state this afternoon, with light
rain and some thunder across northern WY and drier air across
southern WY. The precip will continue through tonight before
ending by sunrise. The front will also move south this evening,
bringing higher humidity to far southern WY for Monday.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...Straub
LONG TERM...Myers
AVIATION...NM
FIRE WEATHER...Straub


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