Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 270946
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
346 AM MDT WED MAY 27 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT

A CLOSED LOW IS SPINNING OVER THE WASHINGTON/OREGON/IDAHO TRIPLE
POINT AND HAS EJECTED A SHORTWAVE MOVING EAST NORTHEAST ACROSS
WYOMING THIS EVENING. THE MAIN FEATURE WITH THE ASSOCIATED
THUNDERSTORMS THIS EVENING HAVE BEEN LOCALLY HEAVY RAINERS. THE
CONVECTION HAS SINCE STRATIFORMED OUT WITH SOME AREAS OF MODERATE
RAIN REMAINING. TODAY THE CLOSED LOW WILL BEGIN TO OPEN UP AS IT
MOVES TO IDAHO AND THE ASSOCIATED SHOWERS AND THUNDERSTORMS AHEAD OF
IT MOVE INTO AND DEVELOP OVER WYOMING TOWARDS AFTERNOON...ESPECIALLY
IN THE WEST. SHOWERS SHOULD LAST WELL INTO THIS EVENING AND SOME
WILL LINGER PAST MIDNIGHT. THEN BY THURSDAY EXPECT NUMEROUS SHOWERS
AND AFTERNOON THUNDERSTORMS JUST ABOUT EVERYWHERE WITH THE OPEN
TROUGH RIGHT OVER WY. THUNDERSTORMS WILL LAST WELL INTO THE EVENING
BEFORE STRATIFORMING OUT BY MIDNIGHT AND LASTING WELL PAST MIDNIGHT
AND ENDING SLOWLY FROM THE WEST. A PACIFIC COOL FRONT WILL PUSH
SOUTH AROUND THE BACK SIDE OF THE TROUGH THURSDAY NIGHT STABILIZING
THE AIR BEHIND IT. AS THE TROUGH PULLS AWAY AND THE RIDGE BUILDS IN
FROM THE WEST EXPECT MORE SHOWERS FRIDAY BUT LESS IN THE WAY OF
THUNDERSTORM ACTIVITY. SHOWERS WILL COME TO AN END FRIDAY NIGHT.
SNOW LEVELS SHOULD DIP TO ABOUT 8500 FEET BOTH THURSDAY AND FRIDAY
MORNING IN THE NORTHWEST AND NORTHERN MTNS. OTHERWISE EXPECT
RELATIVELY MILD TEMPERATURES FOR THE REST OF THE WEEK.

.LONG TERM...SATURDAY THROUGH WEDNESDAY

GENERAL FLAT RIDGING OVER THE WEEKEND WITH INSTABILITY CONFINED
GENERALLY TO THE AFTERNOON AND EVENING HOURS AND MAINLY OVER THE
MOUNTAINS. DRIEST DAY WILL PROBABLY BE SATURDAY WITH RIDGE BUILDING
IN FROM THE WEST. SOME MOIST MAY TRY AND SNEAK IN FROM THE WEST BY
SUNDAY FOR A LITTLE BETTER CHANCE OF MAINLY LATE DAY SHOWERS AND
THUNDERSTORMS ACROSS THE WEST. PACNW TROUGH WILL BE A SIGNIFICANT
PLAYER EARLY NEXT WEEK END BEYOND AS IT STALLS OUT EARLY NEXT WEEK
BEFORE MOVING EAST TOWARDS WYOMING DURING THE MIDDLE OF NEXT WEEK.
INCREASED SW FLOW WITH EMBEDDED SHORTWAVES WILL LIKELY LEAD TO
INCREASED SHOWER AND TSTM COVERAGE MONDAY...ESPECIALLY WEST AND
NORTH. ON TUESDAY...BACKING SLY FLOW AND POTENTIAL DEVELOPING
SURFACE LOW OVER ERN MT OR NERN WYO COULD FOCUS THE STORMS FURTHER
NORTH WITH DRIER SWLY FLOW IN THE SRN HALF. EVEN IF THE DRIER AIR
TEMPORARILY MOVES IN...IT`S JUST THAT...TEMPORARY AS BOTH THE GFS
AND ECMWF CONTINUE TO MOVE THE TROUGH INTO IDAHO ON WEDNESDAY WITH
PLENTY OF TROUGH DYNAMICS AND MOISTURE TO FIRE SHOWERS AND
THUNDERSTORMS ACROSS THE AREA. THE UNSETTLED/STORMY PERIOD WILL
LIKELY LAST BEYOND THIS PERIOD INTO AT LEAST THURSDAY. CONSIDERABLY
WARMER UNDER THE RIDGE THIS WEEKEND AND INTO EARLY NEXT WEEK WITH
GRADUALLY WARMER WEATHER EACH DAY SATURDAY THROUGH MONDAY FOR MOST
AREAS. 60S AND 70S WARMING INTO THE 70S AND SOME 80S BY MONDAY FOR
THE LOWER ELEVATIONS.

&&

.AVIATION.../12Z ISSUANCE/

SOME PATCHY FOG MAY PARTIALLY OBSCURE TERRAIN ACROSS THE AREA
THROUGH 15Z.

SCT-NMRS -SHRA AND WDLY SCT TSRA ARE EXPECTED TO SPREAD ACROSS THE
AREA FROM THE SOUTH AND WEST THROUGH THE AFTERNOON RESULTING IN
POSSIBLY BRIEF MVFR/IFR CONDITIONS AT ALL TERMINALS PRIMARILY
BETWEEN 21Z WED-02Z THUR.  ISOLD-SCT -SHRA WILL LINGER OVER THE AREA
WEDNESDAY NIGHT WITH LCL MVFR CONDITIONS AND HIGHER MTN
OBSCURATIONS.

&&

.FIRE WEATHER...

SHOWERS AND THUNDERSTORMS ARE POSSIBLE EACH AFTERNOON AND EVENING
WITH A GOOD CHANCE OF WETTING RAIN EACH DAY. THERE WILL BE A CHANCE
FOR DRIER AND WARMER WEATHER A DAY OR TWO THIS WEEKEND BUT THERE
IS ANOTHER STORMY PERIOD EXPECTED IMMEDIATELY FOLLOWING. SMOKE
DISPERSAL EACH DAY WILL BE GOOD TO EXCELLENT...EXCEPT FOR SHORT
PERIODS IN THE VERY EARLY MORNING HOURS.

&&

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

$$

SHORT TERM...LIPSON
LONG TERM...SKRBAC
AVIATION...AEM
FIRE WEATHER...LIPSON




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