Severe Thunderstorm Warning 4, NWS Riverton, WY

Area Forecast Discussion
National Weather Service Riverton WY
1256 PM MDT Thu May 25 2023

.DISCUSSION...(This afternoon through Thursday)
Issued at 1248 PM MDT Thu May 25 2023

The stubborn trough set up across the western US remains in place,
keeping an active weather pattern across Wyoming. Accordingly,
widespread showers and thunderstorms are expected again this
afternoon. While mixing has brought dewpoints down into the upper
30s and lower 40s for most, diurnal heating will still aid in
relatively widespread MLCAPE values of 500-1000 J/kg. A slightly
better environment for convection will exist in the northern
portions of the CWA where moisture and instability will be
maximized. Given the dewpoint depressions and high LCLs, gusty
outflow winds will be the primary concern with storms today (as
usual). Otherwise, warmer than normal high temperatures will
continue this afternoon.

While the scattered convection will end after sunset this evening,
less widespread showers will linger overnight as the trough nudges
closer and the nose of a slight jet maxima pushes into southern
Wyoming. As has been the trend, another active afternoon is expected
Friday. With increased moisture and instability, storms could be
more widespread and perhaps a bit stronger across the eastern
portion of the area tomorrow. Strong winds will be the main concern
again, though a better shear and moisture environment across Johnson
County will also favor a hail threat there.

The general troughiness continues through the weekend as low
pressure remains to our west and a blocking high to the east. This
means more daily rounds of showers and thunderstorms, with highs
peaking above normal for most. Another thing to note will be the
continued threat of snowmelt flooding given the expected
temperatures. Locally heavier precipitation with any convection
could exacerbate concerns further.

Looking ahead, there is currently not much indication of a major
change from this active pattern. Ensemble guidance continues to
favor precipitation chances through next week with above normal high
temperatures.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1035 AM MDT Thu May 25 2023

VFR conditions expected at all TAF sites through the entirety of
the period. Ceilings and visibility due to low stratus and fog has
lifted for JAC rapidly clearing early in the period. Another round
of scattered rain showers and isolated thunderstorms expected for
much of the CWA this afternoon after the 19-21Z time period south
to north. Spotty in nature with weaker mid level steering flow,
confidence is low to exact locations, so only carried VCTS at all
TAF sites through the sunset timeframe after 00-01Z due to
radiational cooling and exiting to the north and northeast.
Otherwise, expect a breeze up to 20-25kts possible with any of the
strongest storms with 15-18kts otherwise this afternoon and early
evening. Overnight, mid level cloud decks will scatter out with
winds diminishing to less than 10kts as the inversion sets up.
After sunrise, winds will remain light and variable through the
end of the period before increasing once again tomorrow afternoon
again with increasing rain shower and storm activity.

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 1248 PM MDT Thu May 25 2023

The continued active pattern will bring another round of scattered
showers and thunderstorms to the area through the afternoon. Strong
and erratic outflow winds are the main concern with this
activity, which will mostly end after sunset. There will still be
some lingering showers overnight, though not very widespread.
Friday will bring another day of showers and thunderstorms, with
the possibility of some stronger storms across the eastern
portions of the forecast area, especially across Johnson county
and the Bighorns. Otherwise, high temperatures will continue to
peak above normal. Looking ahead, not much change is expected
through the weekend, with continued convection chances and warmer
than normal temperatures.

&&

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

&&

DISCUSSION...Myers
AVIATION...Lowe
FIRE WEATHER...Myers

Hazardous Weather Outlook
National Weather Service Riverton WY
142 AM MDT Thu May 25 2023

WYZ001>020-022>030-261300-
Yellowstone National Park-Absaroka Mountains-Cody Foothills-
North Big Horn Basin-Southwest Big Horn Basin-
Southeast Big Horn Basin-Owl Creek and Bridger Mountains-
Bighorn Mountains West-Bighorn Mountains Southeast-
Northeast Johnson County-Southeast Johnson County-
Teton and Gros Ventre Mountains-Jackson Hole-
Wind River Mountains West-Wind River Mountains East-
Upper Wind River Basin-Wind River Basin-Lander Foothills-
Green Mountains and Rattlesnake Range-
Natrona County Lower Elevations-Casper Mountain-Star Valley-
Salt River and Wyoming Ranges-Upper Green River Basin Foothills-
Upper Green River Basin-South Lincoln County-
Rock Springs and Green River-Flaming Gorge-East Sweetwater County-
142 AM MDT Thu May 25 2023

This Hazardous Weather Outlook is for Western and Central Wyoming.

.DAY ONE...Today and Tonight.

More showers and thunderstorms, with the best coverage across
northern and western Wyoming. Strong wind gusts and heavy rain are
the main threat. The highest possibility of strong thunderstorms is
in northern Wyoming.

Mountain snowmelt continues to keep water levels elevated on western
Wyoming creeks and rivers.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday through Tuesday...The coverage of showers and
thunderstorms increases, with the best chance coming across far
west and northern Wyoming. Mountain snowmelt continues.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions according to standard operating procedures.

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