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000
FXUS65 KRIW 190201 AAA
AFDRIW

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RIVERTON WY
801 PM MDT TUE JUN 18 2013

.UPGRADED FIRE WEATHER WATCH TO RED FLAG WARNING.

.SHORT TERM...TONIGHT THROUGH WEDNESDAY...

CLEARING TONIGHT OVER THE FORECAST AREA WITH SEASONABLE
TEMPERATURES EXPECTED.

A STRONG SOUTHWEST FLOW WILL BRING IN DRY AND MORE STABLE AIR
ON WEDNESDAY. THE ONLY EXCEPTION SHOULD BE FAR NORTHWEST WYOMING.
MID/UPPER LEVEL LOW OVER THE PACIFIC NORTHWEST WILL BRING SOME
DYNAMICS BY LATE AFTERNOON. ENOUGH MOISTURE SHOULD GENERATE WIDELY
SCATTERED THUNDERSTORMS...MAINLY FROM THE TETONS INTO YELLOWSTONE
NATIONAL PARK.

OTHERWISE...DRY SLOT OVER WEST CENTRAL WYOMING WILL RESULT IN
DECENT MIXING. BREEZY TO WINDY SOUTHWEST WINDS WILL OCCUR ON
WEDNESDAY...INCREASING DURING THE AFTERNOON HOURS.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY

ANY ISOLATED THUNDERSTORMS SHOULD BEGIN TO END BY THE EVENING HOURS
AS WE LOSE THE DAYTIME HEATING WITH THE BALANCE OF THE NIGHT LOOKING
CLEAR AND COOL. ACROSS THE WESTERN VALLEYS IT WILL BECOME QUITE
COOL. THERE COULD EVEN BE SOME PATCHY FROST IN THE MORE PROTECTED
SPOTS BUT AT THIS POINT IT DOES NOT LOOK TO BE WIDESPREAD.

MOST OF THE REGION LOOKS TO BE DOMINATED BY DRY WEST TO
SOUTHWESTERLY FLOW SO MOST AREAS LOOK TO HAVE A FAIRLY NICE DAY WITH
HIGH TEMPERATURES AVERAGING 5 TO 10 DEGREES COOLER THAN ON
WEDNESDAY. THERE WILL STILL BE A BREEZE ACROSS THE FAVORED SPOTS
LIKE FROM THE RED DESERT THROUGH CASPER BUT MUCH LIGHTER THAN ON
WEDNESDAY. THERE IS A CONCERN FOR TWO AREAS HOWEVER. ACROSS FAR
NORTHWESTERN WYOMING THERE COULD BE AN ISOLATED THUNDERSTORM WITH
THE CLOSER PROXIMITY TO AN UPPER LEVEL LOW SWIRLING OVER THE PACIFIC
NORTHWEST BUT NOTHING WIDESPREAD. THE OTHER AREA IS ACROSS THE BIG
HORN RANGE AND JOHNSON COUNTY WHERE SOMEWHAT HIGHER PRECIPITABLE
WATER AND UPPER LEVEL FLOW MORE SOUTH SOUTHEASTERLY WHICH WILL
INTRODUCE AN UPSLOPE COMPONENT THAT COULD BRING ISOLATED
THUNDERSTORMS. AGAIN...ACTIVITY DOES NOT LOOK WIDESPREAD AT THIS
TIME.

BY FRIDAY THE UPPER LEVEL LOW CONTINUES TO MOVE A BIT FURTHER EAST
OT A POSITION OVER IDAHO. EXACT POSITION VARIES A BIT DEPENDING ON
WHICH MODEL IS BELIEVED. FOR NOW...THE NEW GFS AND EUROPEAN KEEP
MOST OF THE NORTHWESTERN PORTION OF THE COUNTY WARNING AREA DRY SO
WE WENT WITH ONLY SLIGHT CHANCE POPS FOR NOW IN THE HIGHER
ELEVATIONS. THERE COULD ALSO BE A FEW SHOWERS IN THE NORTHERN BIG
HORN RANGE WITH A SHORTWAVE BRUSHING BY TO THE NORTH. AT THIS TIME
IT LOOKS LIKE ANY MORE WIDESPREAD SHOWERS WILL LIKELY HOLD OFF UNTIL
FRIDAY NIGHT OR SATURDAY IN THE NORTHERN PORTIONS OF THE COUNTY
WARNING AREA.

WE HAVE TRENDED THE FORECAST A BIT MORE PESSIMISTIC FOR SATURDAY AS
THE MODELS HAVE TRENDED A BIT FURTHER TO THE SOUTH AS THE UPPER
LEVEL LOW BEGINS TO OPEN UP AND PROGRESS EAST. AS A RESULT WE HAVE
INCREASED POPS ACROSS NORTHERN WYOMING WITH THE HIGHEST POPS ACROSS
YELLOWSTONE PARK AND THE BIG HORN RANGE. WE ALSO LOWERED
TEMPERATURES A BIT ACROSS THE NORTH WITH MORE CLOUD COVER.

ON THE FLIP SIDE OF THE COIN...WITH THE OPENING OF THE LOW AND
FASTER PROGRESSION...WE DID MAKE THE FORECAST MORE OPTIMISTIC FOR
SUNDAY. BOTH THE GFS AND EUROPEAN MOVE ALL PRECIPITATION OF THE AREA
FOR SUNDAY. AS A RESULT WE HAVE REMOVED THE POPS FOR SUNDAY AND ALSO
RAISED TEMPERATURES A FEW DEGREES.

AS FOR EARLY NEXT WEEK...MADE A FEW TWEAKS TO THE FORECAST. BOTH THE
GFS AND EUROPEAN HAVE DRIER WEATHER FOR MONDAY AS WELL SO WE
CONFINED THE POPS TO FAR NORTHWESTERN WYOMING WITH CLOSER PROXIMITY
TO MOISTURE IN THE PACIFIC NORTHWEST. BY TUESDAY POPS SPREAD A BIT
FURTHER TO THE EAST WITH A SHORTWAVE MOVING OVER THE TOP OF A
BUILDING RIDGE IN THE SOUTHWEST SO THUNDERSTORMS WERE ADDED ACROSS
THE NORTHERN MOUNTAINS. TEMPERATURES WILL CLIMB TO ABOVE NORMAL
LEVELS WITH THE BUILDING RIDGE WITH 90S POSSIBLE IN THE BASINS BY
EARLY NEXT WEEK.

.AVIATION.../00Z ISSUANCE/

AFTER A FEW LINGERING SHOWERS AND THUNDERSTORMS EARLY THIS
EVENING...CLEARING WILL OCCUR TONIGHT OVER THE REGION WITH VFR
CONDITIONS. IN THE SHORT TERM...IT WILL BE GENERALLY DRY AND
WINDY...AS THE LOW TO MID LEVEL PRESSURE GRADIENT INCREASES. AS A
RESULT...SOUTHWEST SURFACE WIND SHOULD GUST TO 35-40 MPH BY
WEDNESDAY AFTERNOON. KCPR COULD HAVE GUSTS APPROACHING 45 MPH.
AGAIN...VFR CONDITIONS TO DOMINATE INTO THURSDAY AND FRIDAY.

.FIRE WEATHER...

..RED FLAG WARNING FOR CASPER DISPATCH ON WEDNESDAY...

DRY...WINDY CONDITIONS ARE EXPECTED MOST OF THE DAY WEDNESDAY.
RELATIVE HUMIDITIES WILL FALL SHARPLY BY WEDNESDAY AFTERNOON...
ESPECIALLY EAST OF THE CONTINENTAL DIVIDE. WINDS WILL MIX DOWN
TO THE SURFACE AND COULD GUST TO 40 MPH...WITH SLIGHTLY HIGHER
GUSTS ACROSS THE WIND CORRIDOR TO NEAR CASPER AND OTHER PARTS OF
NATRONA COUNTY. MOST DISTRICTS WILL REMAIN BREEZY THROUGH
WEDNESDAY NIGHT AS A DRY COLD FRONT MOVES FROM WEST TO EAST ACROSS
THE REGION. AIRMASS OVER WEST CENTRAL WYOMING REMAINS DRY AND
STABLE ON THURSDAY WITH GENERALLY LOW RELATIVE HUMIDITIES.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM 11 AM TO 10 PM MDT WEDNESDAY
WYZ280-281-285-300.

&&

$$

SHORT TERM...KPL
LONG TERM...HATTINGS
AVIATION...ALLEN
FIRE WEATHER...KPL