Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 172005
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
205 PM MDT WED SEP 17 2014

.SHORT TERM...TONIGHT THROUGH THURSDAY

HIGH PRESSURE RIDGE ALOFT WILL CONTINUE TO BUILD OVER THE AREA.
LIMITED MOISTURE AND INSTABILITY IN WEST FLOW ALOFT WILL BRING
SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS THIS EVENING AND
AGAIN THURSDAY AFTERNOON. TEMPERATURES WILL CONTINUE WARMING TREND
WITH SOME LOWER 90S POSSIBLE THURSDAY AFTERNOON IN JOHNSON COUNTY.

.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY

THE BROAD SCALE LIFT ASSOCIATED WITH AN APPROACHING TROUGH TO OUR
WEST WILL ENCOURAGE A FEW MORE SHOWERS AND STORMS ON THURSDAY THAT
WILL LIKELY LAST WELL INTO THURSDAY NIGHT AS AN ASSOCIATED COLD
FRONT PLOWS ACROSS THE AREA. WEST WINDS WILL BE BREEZY EARLY IN THE
EVENING AS THE AFOREMENTIONED PACIFIC TROUGH APPROACHES FROM THE
WEST...TIGHTENING THE GRADIENT ALOFT AS A LEE SIDE TROUGH DIGS AT
THE SURFACE.

A SPLITTING TROUGH MOVES ACROSS THE AREA ON FRIDAY KEEPING SOME
SHOWERS AND STORMS GOING...ESPECIALLY EAST OF THE DIVIDE WHERE SOME
MORE MOISTURE WILL ENCOURAGE SOME MORE ROBUST CAPE VALUES. A
REINFORCING SHORTWAVE MAY ALSO AID IN THUNDERSTORM DEVELOPMENT AND
COVERAGE DEPENDING ON WHEN IT ARRIVES. SHEAR WILL BE DECENT ACROSS
THE AREA SO STORMS WILL BE ABLE TO SUSTAIN THEMSELVES FOR A
WHILE...HIGH END SCATTERED COVERAGE IS EXPECTED GIVEN THEIR
SUSTAINABILITY AND MODERATE 20 TO 30KT STORM MOTION.

THE ATMOSPHERE DRIES OUT QUICKLY ON SATURDAY WITH VERY PLEASANT
TEMPERATURES IN THE 70S ACROSS THE STATE WITH LIGHT WINDS. THERE IS
STILL A LITTLE MORE UNCERTAINTY AS WE GO INTO SUNDAY. THE MODELS
HAVE BEEN HAVING A TOUGH TIME WITH THIS NEXT SYSTEM THIS
WEEK...PREVIOUS RUNS HAVE GONE FROM SOLUTIONS THAT WERE COMPLETELY
OUT OF PHASE WITH ONE ANOTHER TO BRINGING A CLOSED UPPER LOW RIGHT
INTO THE EASTERN GREAT BASIN AND OVER OUR REGION SOMETIME ON SUNDAY
NIGHT OR MONDAY...NOW IT LOOKS LIKE THE MODELS ARE STICKING CLOSER
TO THE LATTER SOLUTION EXCEPT THE ECMWF IS MORE BULLISH THIS TIME AS
IT FORMS A COLD CORE LOW OVER NEVADA WHILE THE GFS STICKS WITH A
LESS ORGANIZED UPPER LOW...NOT FAVORING ANY SOLUTION AT THIS POINT
BUT THE FORMATION OF A SLOW MOVING LOW WITH A CORE THAT COOL SEEMS
UNLIKELY. EITHER WAY...THE SYSTEM IS EXPECTED TO SLOWLY TRACK
EAST-NORTHEAST FROM NV/UT SUNDAY NIGHT INTO NORTHEASTERN COLORADO BY
TUESDAY MORNING. IT COULD BE PEELING OFF SOME MOISTURE FROM
TROPICAL STORM POLO EARLY NEXT WEEK...IN COMBINATION WITH SOUTHERLY
FLOW AT THE SURFACE DRAWING UP SOME LINGERING MOISTURE OVER THE
PLAINS...LEFTOVERS FROM ODILE...WHICH COULD RESULT IN SOME DECENT
RAINFALL POTENTIAL BUT GIVEN THE RECENT UNCERTAINTY OF MODEL
SOLUTIONS LATELY...WENT VERY CONSERVATIVE WITH POPS BUT AT IS STANDS
NOW...IT LOOKS LIKE THE SOUTHERN HALF OF THE STATE HAS THE BEST
CHANCE OF A WETTING RAIN SUNDAY AND MONDAY WITH SOME QUESTION AS TO
WHETHER OR NOT IT WILL LINGER INTO TUESDAY.

&&

.AVIATION.../00Z ISSUANCE/

SCATTERED SHOWERS...WITH ISOLATED THUNDERSTORMS...WILL CONTINUE
THROUGH 06Z MANLY SOUTH OF A KP60 TO KCPR LINE. LOCAL MVFR
CEILINGS AND VISIBILITIES REDUCED IN RAIN SHOWERS WILL OBSCURE
HIGHER MOUNTAIN AREAS...OTHERWISE VFR CONDITIONS ARE EXPECTED TO
PREVAIL AT THE AIRPORTS. WIND GUSTS TO 45 KTS CAN BE EXPECTED
VICINITY OF THUNDERSTORMS. ISOLATED SHOWERS WILL BE A THREAT FROM
06Z TO 18Z THURSDAY WITH THE MAJORITY OF CONVECTION OVER THE
WESTERN MOUNTAINS. SHOWERS WILL AGAIN BECOME SCATTERED WITH
ISOLATED THUNDERSTORMS AFTER 18Z WITH LOCAL MVFR CEILINGS AND
VISIBILITIES REDUCED IN RAIN SHOWERS OBSCURING HIGHER MOUNTAIN
AREAS...OTHERWISE VFR CONDITIONS ARE EXPECTED TO PREVAIL AT THE
AIRPORTS. WIND GUSTS TO 45 KTS CAN BE EXPECTED VICINITY OF
THUNDERSTORMS.

&&

.FIRE WEATHER...

HIGH PRESSURE RIDGE ALOFT WILL CONTINUE TO BUILD OVER THE AREA.
LIMITED MOISTURE AND INSTABILITY IN WEST FLOW ALOFT WILL BRING
SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS THIS EVENING AND
AGAIN THURSDAY AFTERNOON. TEMPERATURES WILL CONTINUE WARMING TREND
WITH SOME LOWER 90S POSSIBLE THURSDAY AFTERNOON IN JOHNSON COUNTY.

&&

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

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER






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