Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 260533
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1132 PM MDT THU JUN 25 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

A SHORT WAVE TROUGH ALOFT WITH A 90 KT JET MAX WILL MOVE
SOUTHEAST OVER A COLD FRONTAL BOUNDARY ALONG THE CONTINENTAL
DIVIDE. CONVECTION OVER THE BIGHORN AND OWL CREEK MOUNTAINS HAS
FIRED SO FAR AND EXPECT THE ABSAROKA AND WIND RIVER MOUNTAINS
AND GREEN/RATTLESNAKE MOUNTAINS TO BE AREAS OF FOCUS FOR
CONVECTION THIS AFTERNOON AND EVENING.  THE EASTERN PLAINS...
JOHNSON AND NATRONA COUNTIES HAVE THE BEST POTENTIAL FOR STRONG
TO SEVERE THUNDERSTORMS WITH HAIL LARGER THAN ONE INCH ALONG WITH
HEAVY DOWN POURS. CLEARING WILL OCCUR IN THE WEST WITH LOW
STRATUS CLOUDS A THREAT BEHIND THE COLD FRONT IN THE WIND RIVER
BASIN AND OVER THE EASTERN PLAINS. BUFFALO AND CASPER BEST CHANCES
FOR CLOUDY NIGHT WITH SOME POTENTIAL FOR RIVERTON AND LANDER
LATER TONIGHT. RIDGE BUILDING WITH WARMING ALOFT WILL DECREASE THE
COVERAGE OF SHOWERS AND THUNDERSTORMS ON FRIDAY AND EXPECT THEM TO
BE MOST NUMEROUS OVER THE ABSAROKA...BIGHORN AND WIND RIVER
MOUNTAINS WITH DRY CONDITIONS WEST OF THE CONTINENTAL DIVIDE.
TEMPERATURES SHOULD WARM WITH LESS CLOUD COVER AND THE COLD FRONT
WILL RETREAT TO THE NORTH AND EAST THROUGH THE AFTERNOON.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

DRY CONDITIONS WILL PERSIST THROUGH FRIDAY NIGHT. RIDGE OF HIGH
PRESSURE WILL REMAIN ACROSS THE GREAT BASIN THROUGH MUCH OF THE
WEEKEND. WIDESPREAD HIGHS IN THE LOW TO MID 90S WILL BE FOUND EAST
OF THE DIVIDE. ALTHOUGH RECORD HIGHS MAY NOT QUITE BE
REACHED...HIGHS WILL BE WELL ABOVE THE MID 80S THAT ARE THE NORM FOR
THIS TIME OF YEAR EAST OF THE DIVIDE. EVEN AREAS ACROSS THE WEST
WILL SEE HIGHS IN THE MID 80S...WHICH IS ALSO WELL ABOVE NORMAL.
LIMITED AMOUNTS OF MID LEVEL MOISTURE...AND WEAK DISTURBANCES IN THE
FLOW...WILL ATTEMPT TO RIDE OVER THE RIDGE SATURDAY AND SUNDAY.
ISOLATED MOUNTAIN THUNDERSTORMS WILL BE POSSIBLE...ESPECIALLY ACROSS
THE ABSAROKA...WIND RIVER...AND BIGHORN RANGES. 0-6KM SHEAR COULD
INCREASE SLIGHTLY THIS WEEKEND...AS A PIECE OF THE MAIN JET
MEANDERS INTO WYOMING. THIS COMBINED...WITH AMPLE HEATING CREATING
STEEP LAPSE RATES...AND LIMITED CAPE...COULD ALLOW A FEW OF THESE
MOUNTAIN STORMS TO HOLD TOGETHER AND ENTER INTO THE BIGHORN AND
WIND RIVER BASIN. STORMS WILL BE ISOLATED IN NATURE...AND GUSTY
WINDS WILL BECOME THE MAIN THREAT.

MONDAY THROUGH THURSDAY...SIMILAR CONDITIONS ARE EXPECTED ON
MONDAY...WHICH WILL LIKELY BE THE WARMEST DAY OF THE EXTENDED
PERIOD...WITH HIGHS IN THE MID TO UPPER 90S EXPECTED. ISOLATED
MOUNTAIN THUNDERSTORMS WILL AGAIN BE POSSIBLE...HOWEVER A STRONGER
CAP MAY MAKE IT HARD FOR THUNDERSTORMS TO SURVIVE AWAY FROM THE
HIGHER ELEVATIONS. RIDGE WILL FLATTEN AND PUSH WEST TUESDAY THROUGH
THE END OF THE WEEK. THIS WILL BRING MORE NORTHWESTERLY FLOW...AND A
SERIES OF COLD FRONTS ACROSS THE REGION...WHICH COULD RETURN
SLIGHTLY MORE ACTIVE WEATHER TO THE REGION...WITH SEVERAL CHANCES
FOR ISOLATED TO SCATTERED THUNDERSTORMS. BY THE END OF THE NEXT WEEK
TEMPERATURES COULD COOL TO MORE NORMAL READINGS OF MID 80S.

&&

.AVIATION.../06Z ISSUANCE/

VERY ISOLATED SHRA/TSRA COULD STILL OCCUR THROUGH ABOUT 09Z ACROSS
S. JOHNSON...NATRONA AND SE FREMONT. OTHERWISE SOME MVFR CEILINGS
AND POSSIBLY FOG IS EXPECTED TO DEVELOP OVER NATRONA AND JOHNSON
COUNTIES. THIS IS EXPECTED TO LAST THROUGH AROUND 16Z.
OTHERWISE...VFR CONDITIONS WITH ONLY FEW TO SCT CLOUDS ARE EXPECTED
WITH MAINLY LIGHT WINDS THROUGH THE TAF PERIOD. VERY ISOLATED
AFTERNOON CONVECTION IS POSSIBLE FRIDAY OVER THE MOUNTAINS...BUT
CONVECTION WILL BE HARD PRESSED TO DEVELOP AS A STRONG UPPER RIDGE
BUILDS INTO THE AREA. LATE FRIDAY NIGHT...BOUNDARY LAYER MIGHT
MOISTEN UP ENOUGH FOR THE POSSIBILITY OF FOG/LOW CLOUDS OVER JOHNSON
AND NATRONA COUNTIES. HOWEVER FOG/LOW CLOUDS WILL BE LESS WIDESPREAD
THAN WHAT OCCURS FRIDAY MORNING.

&&

.FIRE WEATHER...

A SHORT WAVE TROUGH ALOFT WITH A 90 KT JET MAX WILL MOVE
SOUTHEAST OVER A COLD FRONTAL BOUNDARY ALONG THE CONTINENTAL
DIVIDE. CONVECTION OVER THE BIGHORN AND OWL CREEK MOUNTAINS HAS
FIRED SO FAR AND EXPECT THE ABSAROKA AND WIND RIVER MOUNTAINS
AND GREEN/RATTLESNAKE MOUNTAINS TO BE AREAS OF FOCUS FOR
CONVECTION THIS AFTERNOON AND EVENING.  THE EASTERN PLAINS...
JOHNSON AND NATRONA COUNTIES HAVE THE BEST POTENTIAL FOR STRONG
TO SEVERE THUNDERSTORMS WITH HAIL LARGER THAN ONE INCH ALONG WITH
HEAVY DOWN POURS. CLEARING WILL OCCUR IN THE WEST WITH LOW
STRATUS CLOUDS A THREAT BEHIND THE COLD FRONT IN THE WIND RIVER
BASIN AND OVER THE EASTERN PLAINS. BUFFALO AND CASPER BEST CHANCES
FOR CLOUDY NIGHT WITH SOME POTENTIAL FOR RIVERTON AND LANDER
LATER TONIGHT. RIDGE BUILDING WITH WARMING ALOFT WILL DECREASE THE
COVERAGE OF SHOWERS AND THUNDERSTORMS ON FRIDAY AND EXPECT THEM TO
BE MOST NUMEROUS OVER THE ABSAROKA...BIGHORN AND WIND RIVER
MOUNTAINS WITH DRY CONDITIONS WEST OF THE CONTINENTAL DIVIDE.
TEMPERATURES SHOULD WARM WITH LESS CLOUD COVER AND THE COLD FRONT
WILL RETREAT TO THE NORTH AND EAST THROUGH THE AFTERNOON. MID TO
LOWER TEEN RELATIVE HUMIDITY EXPECTED ACROSS THE SOUTHWEST AND
INTO THE WIND RIVER BASIN WITH INCREASING WEST WINDS THESE AREAS.
MIXING HEIGHTS SHOULD COMBINE WITH FAVORABLE TRANSPORT WINDS FOR
GOOD TO EXCELLENT SMOKE DISPERSAL FRIDAY AFTERNOON...EXCEPT EAST
OF THE BIGHORNS WHERE LOW CLOUDS AND COOLER TEMPERATURES WILL
LOWER MIXING HEIGHTS FOR GENERALLY FAIR SMOKE DISPERSAL.

&&

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

&&

$$

SHORT TERM...C.BAKER
LONG TERM...ANGLIN
AVIATION...WM
FIRE WEATHER...C.BAKER



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