Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 030926
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
326 AM MDT WED JUN 3 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT

A BRIEF REPRIEVE FROM SHOWER AND THUNDERSTORM ACTIVITY IS CURRENTLY
PRESENT OVER THE FORECAST AREA...AS THE SYSTEM FROM LAST EVENING
CONTINUES TO MOVE INTO THE CENTRAL PLAINS. THIS BREAK FROM SHOWER
ACTIVITY WILL BE SHORT LIVED AS ANOTHER PUSH OF MOISTURE MOVES INTO
THE AREA LATE THIS MORNING AND THROUGH THE AFTERNOON. WITH GROWING
INSTABILITY ACROSS THE AREA...SOME STORMS THIS AFTERNOON AND EARLY
EVENING COULD BECOME STRONG TO SEVERE...ESPECIALLY ACROSS
FREMONT...NATRONA...AND JOHNSON COUNTIES. DAMAGING WIND AND LARGE
HAIL WILL BE POSSIBLE. MOST STORMS WILL ALSO HAVE THE POTENTIAL FOR
FREQUENT LIGHTNING. MODELS DEMONSTRATE ENHANCED PWAT VALUES THIS
AFTERNOON...ADDING TO THE POTENTIAL FOR PERIODS OF HEAVY RAIN.

WITH THE POTENTIAL FOR HEAVY RAIN OVER ALREADY SATURATED
SOILS...HAVE ISSUED A FLASH FLOOD WATCH FOR MUCH OF CENTRAL AND
EASTERN WYOMING. AREAS SUSCEPTIBLE TO MUD OR ROCK SLIDES MAY
EXPERIENCE SLIDE ACTIVITY THROUGH THE AFTERNOON AND EVENING.
ADDITIONALLY...MANY RIVERS ARE RUNNING HIGH DUE TO ONGOING SNOWMELT
AND RECOVERING FROM PAST RAINS, THESE AREAS MAY BE SUSCEPTIBLE TO
FLOODING AS STORMS DEVELOP.

ACTIVITY SHOULD AGAIN WANE THROUGH THE LATE EVENING AND OVERNIGHT
HOURS. THE TREND FOR AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH FRIDAY...WITH GUSTY WIND AND SMALL HAIL BEING
POSSIBILITIES WITH STORM ACTIVITY. OVERALL...TEMPERATURES WILL COOL
SLIGHTLY OVER THE NEXT COUPLE OF DAYS...THOUGH SOUTHERN WYOMING MAY
SEE A SOME WARMER TEMPERATURES TODAY WITH A BIT LESS CLOUD COVER.

.LONG TERM...SATURDAY THROUGH WEDNESDAY

AN UPPER LOW OVER THE SOUTHERN GREAT BASIN SATURDAY MORNING IS
EXPECTED TO PUSH NORTHEAST INTO NORTHERN NEVADA/UTAH BY SUNDAY. IT
IS THEN EXPECTED TO SHEAR OUT SUNDAY NIGHT AND MONDAY WITH A PIECE
OF IT PUSHING ACROSS THE ROCKIES INTO THE PLAINS MONDAY. DIFLUENT
FLOW AHEAD OF THIS UPPER LOW...IN COMBINATION WITH A WEAK BOUNDARY
PROBABLY ALONG THE DIVIDE AND PLENTY OF MOISTURE AND SOME INSTABILITY
WILL RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS THIS WEEKEND.

CHANCES FOR CONVECTION BEGIN TO DECREASE MONDAY AS THE SYSTEM
BECOMES SHEARED OUT AND BEGINS TO MOVE INTO THE PLAINS.

TUESDAY AND WEDNESDAY...A WEAK RIDGE DEVELOPS OVER THE AREA...BUT
ENOUGH MOISTURE AND INSTABILITY REMAINS FOR ISOLATED TO LOCALLY
SCATTERED DIURNAL CONVECTION ESPECIALLY OVER THE HIGHER TERRAIN
AND ADJACENT FOOTHILLS.

SEASONAL TO ABOVE AVERAGE TEMPERATURES ARE EXPECTED THROUGH THE
EXTENDED.

&&

.AVIATION.../12Z ISSUANCE/

MVFR CEILINGS ARE EXPECTED THROUGH 15-16Z ACROSS MUCH OF JOHNSON
AND NATRONA COUNTIES IMPACTING THE CPR TERMINAL. THERE ALSO COULD
BE PATCHY FOG IN FAR WESTERN VALLEYS. ATTENTION THEN TURNS TO
SCATTERED STRONG TO SEVERE CONVECTION IN THE AFTERNOON AND
EVENING. CONVECTION SHOULD BEGIN TO BREAK OUT AFTER 18Z...BUT
REMAIN ISOLATED THROUGH 21Z. CONVECTION IS THEN EXPECTED TO
INCREASE IN COVERAGE AND INTENSITY QUICKLY BETWEEN 21Z AND 00Z
OVER CENTRAL WYOMING AND HEAD NORTHEAST THROUGH THE EVENING. THIS
ACTIVITY WILL LIKELY LINGER PAST MIDNIGHT OVER PORTIONS OF THE
BIGHORN MTS AND JOHNSON COUNTY. ALTHOUGH ANY TERMINAL COULD BE
IMPACTED BY THUNDERSTORMS THIS AFTERNOON AND EVENING...THE BEST
COVERAGE AND STRONGEST ACTIVITY WILL BE EAST OF THE DIVIDE. LARGE
HAIL AND DAMAGING WINDS ARE EXPECTED WITH THE STRONGER ACTIVITY
THIS AFTERNOON THROUGH LATE EVENING. IN WAKE OF THE
STORMS...EXPECTED LOCAL FOG AND LOW CEILINGS AFTER O6Z...WITH
PERHAPS WIDESPREAD MVFR CEILINGS AND LOCAL FOG OVER NATRONA AND
JOHNSON COUNTIES.

&&

.FIRE WEATHER...

AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL RETURN TODAY TO
CENTRAL AND EASTERN WYOMING. SOME STORMS COULD BECOME STRONG TO
SEVERE WITH STRONG WINDS AND LARGE HAIL. ADDITIONALLY...MODERATE TO
HEAVY RAINFALL MAY ACCOMPANY STORMS. THIS RAIN WILL FALL ON ALREADY
SATURATED SOILS OR NEAR FULL RIVERS TO POTENTIALLY CAUSE SOME FLASH
FLOODING OR MUD AND ROCK SLIDES. A FLASH FLOOD WATCH HAS BEEN ISSUED
TO COVER THIS POTENTIAL. SLIGHTLY COOLER TEMPERATURES AND INCREASED
DAYTIME HUMIDITY WILL KEEP FIRE BEHAVIOR ON THE LOW SIDE...OUTSIDE
OF THUNDERSTORM ACTIVITY WHOSE WINDS COULD BE ERRATIC.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM NOON MDT TODAY THROUGH THIS EVENING FOR
WYZ004>011-017-018-020.

&&

$$

SHORT TERM...BRANHAM
LONG TERM....WM
AVIATION...WM
FIRE WEATHER...BRANHAM


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