Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 291700
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1100 AM MDT MON JUN 29 2015

.SHORT TERM...MONDAY THROUGH WEDNESDAY NIGHT

CONVECTION WAS A LITTLE MORE WIDESPREAD TODAY THEN I THOUGHT
YESTERDAY. AT THIS TIME ALL IS QUIET WITH THE RIDGE OF HIGH PRESSURE
MAINTAINING ITS GRIP OVER THE AREA. AS FOR TODAY...IT LOOKS LIKE THE
HEAT WILL PEAK TODAY. ALL LOWER ELEVATION SHOULD MAKE IT INTO THE
90S WITH THE WARMER SPOTS LIKE GREYBULL AND WORLAND LIKELY CRACKING
THE CENTURY MARK. AS FOR THE CHANCE OF CONVECTION...WITH THE HEIGHTS
A BIT HIGHER AND MORE OF A CAP...THERE WILL BE LESS COVERAGE THAN
THE PREVIOUS COUPLE OF DAYS. HOWEVER...WE HAVE BEEN BURNED ON THIS.
WE DID INCREASE POPS MAINLY ACROSS THE HIGHER ELEVATIONS AND
ADJACENT FOOTHILLS. HOWEVER...MOST AREAS WILL BE DRY MOST OF THE
TIME. ALSO..WITH THE WEAKER STEERING FLOW THERE WILL BE LITTLE
CHANCE TO MOVE INTO MOST OF THE BASINS. LIKE PREVIOUS DAYS...MOST
CONVECTION SHOULD DIE OFF WITH THE LOSS OF DAYTIME HEATING.

ON TUESDAY THE RIDGE WILL BEGIN TO SHIFT WESTWARD AND ALLOW A COLD
FRONT TO DROP TOWARD THE AREA FROM THE NORTH. AS A RESULT...WITH THE
LOWER HEIGHTS AND ADDITIONAL LIFT PROVIDED BY THE BOUNDARY...THIS
LOOKS TO BE THE BEST CHANCE OF SHOWERS AND THUNDERSTORMS IN THE
FORECAST. MODELS HAVE SOME DIFFERENCES ON THE PLACEMENT OF THE BEST
COVERAGE...SO WE KEPT POPS GENERIC AT THIS POINT. TEMPERATURES WILL
STILL BE HOT...BUT A LITTLE COOLER THAN ON MONDAY.

THEN ON WEDNESDAY WE ENTER INTO A PERIOD OF NORTHWESTERLY FLOW WHICH
WILL MEAN MORE SEASONABLE TEMPERATURES. THIS ALSO MEANS A CHANCE OF
SOME SHORTWAVES AND COLD FRONTS MOVING ACROSS THE STATE. FOR
WEDNESDAY...THE NAM HAS MAINLY DRY CONDITIONS WITH ONLY SOME HIGH
ELEVATION CONVECTION. THE GFS IS A BIT WETTER. FOR NOW...WE LEFT THE
FORECAST AS IS UNTIL THE DETAILS CAN BE BETTER RESOLVED.

.LONG TERM...THURSDAY THROUGH MONDAY

A STRONG UPPER LEVEL RIDGE WILL BE CENTERED OVER THE GREAT BASIN
THURSDAY THROUGH SATURDAY...WITH A MODERATE NORTHWEST FLOW OVER
THE FORECAST AREA. MEDIUM RANGE MODELS VARY ON THE AMOUNT OF
MOISTURE AVAILABLE AND TIMING OF ANY WEAK DISTURBANCE. HOWEVER
ENOUGH MOISTURE AND INSTABILITY AND PERHAPS A QUASI-STATIONARY
FRONTAL BOUNDARY AT TIMES WARRANT SOME ISOLATED AFT/EVEN POPS
OVER THE MTS AND ADJACENT FOOTHILLS ESPECIALLY EAST OF THE DIVIDE
THUR - SAT.

EARLY NEXT WEEK...MODELS ARE HINTING AT SOME MONSOONAL MOISTURE
WORKING INTO THE AREA AS THE UPPER HIGH RECENTERS ACROSS THE
SOUTHERN ROCKIES. THIS WOULD GIVE THE ENTIRE FORECAST AREA A
BETTER CHANCE OF DAILY CONVECTION...ESPECIALLY BEGINNING MONDAY.
FOR NOW WILL INCREASE THE COVERAGE OF POPS ACROSS THE AREA MONDAY...BUT
STILL KEEP IT MAINLY SLIGHT AS MODELS ARE TYPICALLY A BIT FAST ON
THE INITIAL SURGE OF TRUE MONSOONAL MOISTURE.

TEMPERATURES THROUGH THE EXTENDED ARE EXPECTED TO BE 5 TO 10
DEGREES ABOVE AVERAGE.

&&

.AVIATION.../18Z ISSUANCE/

VFR CONDITIONS WILL PREVAIL AT ALL TERMINAL SITES THROUGH THE
FORECAST PERIOD. ISOLATED LATE DAY THUNDERSTORMS WILL DEVELOP OVER
THE MOUNTAINS WITH PERHAPS A COUPLE OF THESE MAKING IT ONTO THE
LOWER ELEVATIONS THIS EVENING...BUT THEY LOOK TO BE FEW AND FAR
BETWEEN OUTSIDE THE MOUNTAINS. THE MAIN THREAT FROM THESE STORMS
WILL BE LIGHTNING AND GUSTY OUTFLOW WINDS OVER 40 MPH. BY TUESDAY
MORNING...MOISTURE WILL BE ON THE INCREASE AS A SURFACE FRONT AND
MID LEVEL DISTURBANCE BEGIN MOVE THROUGH THE FORECAST BY LATE
MORNING. SHOWERS AND ISOLATED THUNDER WILL INCREASE ACROSS THE WEST
AND NORTH THROUGH THE MORNING...WITH HIGHER MOUNTAIN OBSCURATIONS
BECOMING MORE LIKELY AS THE MORNING WEARS ON.


&&

.FIRE WEATHER...

EXPECT A HOT AND MAINLY DRY DAY ACROSS THE AREA WITH MAINLY RELATIVE
HUMIDITY FALLING INTO THE MIDDLE TO HIGH TEENS IN THE HOTTER AREAS.
WIND SHOULD REMAIN LIGHT TO MODERATE HOWEVER. ISOLATED AFTERNOON AND
EVENING THUNDERSTORMS MAY FIRE ACROSS THE MOUNTAINS BUT THERE IS
LITTLE CHANCE OF STORMS DRIFTING INTO THE LOWER ELEVATIONS. SMOKE
DISPERSAL SHOULD BE GOOD IN MOST AREAS. A COLD FRONT DROPPING
SOUTHWARD WILL BRING A BETTER CHANCE OF THUNDERSTORMS FOR TUESDAY.

&&

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

&&

$$

SHORT TERM...HATTINGS
LONG TERM...WM
AVIATION...BRAUN
FIRE WEATHER...HATTINGS


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