Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 231720
AFDRIW

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE RIVERTON WY
1120 AM MDT THU OCT 23 2014

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT

OVERNIGHT SATELLITE IMAGERY IS SHOWING THE CLOUD COVER ASSOCIATED
WITH A DISTURBANCE TO OUR WEST CLIPPING OUR WESTERN BORDER WITH
IDAHO. IT WILL RESULT IN LITTLE MORE THAN SOME ENHANCED CLOUD COVER
BEFORE IT SHOOTS OFF TO THE NORTH THIS AFTERNOON. HOWEVER...THE
DYNAMIC SYSTEM TO OUR NORTH AND WEST POWERED BY A STRONG 160KT JET
CORE WILL IMPACT OUR WEATHER THROUGH AT LEAST FRIDAY MORNING BEFORE
THE RIDGE FIGHTING FOR POSITION TO OUR SOUTH FINALLY WINS OUT.

ANOTHER WINDY DAY IS IN STORE FOR THE FORECAST AREA AS THIS SYSTEM
TO OUR NORTHWEST BUTS UP AGAINST THE RIDGE TO OUR SOUTH...LEAVING
OUR AREA RIGHT IN BETWEEN THE TWO. A PERIOD OF 20 TO 40 KNOT
WESTERLY FLOW WILL EVENTUALLY MIX DOWN THIS AFTERNOON...AND WILL
LATER BE FORCED DOWN TONIGHT BY THE SUBSIDENT RIGHT EXIT REGION OF
THE JET TO OUR NORTH. THE AREAS THAT WILL BE IMPACTED THE MOST BY
THIS JET INTERACTION WILL BE THE CODY FOOTHILLS AND THE ABSAROKAS
WHERE A HIGH WIND WATCH REMAINS. STEADY 40 KNOT WESTERLIES ACROSS
THE ABSAROKAS WILL PROVIDE THE PERFECT FLOW FOR BREAKING MOUNTAIN
WAVE ACTION LATER THIS EVENING...THAT COMBINED WITH A LITTLE HELP
FROM THE JET WILL INCREASE THE LIKELIHOOD OF THIS MOUNTAIN WAVE
SURFACING AROUND CLARK AND WEST CODY BETWEEN SUNSET TONIGHT AND
SUNRISE FRIDAY MORNING.

SWIFT WESTERLIES HANG AROUND ON FRIDAY BUT THERE WILL NOT BE MUCH
AROUND TO FORCE THESE WINDS TO THE SURFACE...THE GRADIENT AT THE
SURFACE WILL BE MUCH LOOSER AND THE JET STREAK TO OUR NORTH WILL BE
MORE ZONAL AND THE STRONGEST FORCING WILL BE WELL TO OUR NORTH.
OTHERWISE...WE WILL START TO FEEL MORE INFLUENCE FORM THE RIDGE TO
OUR SOUTH WITH MILD TEMPERATURES AND LOW HUMIDITY.

FLOW TURNS MORE SOUTHWESTERLY ON SATURDAY AS THE RIDGE AXIS SHIFTS
EAST AND THE TROUGH DIGGING TO OUR WEST BEGINS TO ADVANCE. IT WILL
BE ON THE BREEZY SIDE ON SATURDAY AS THE GRADIENT TIGHTENS WITH A
LEE TROUGH DIGGING TO OUR EAST. THE LEADING EDGE OF THIS TROUGH
COULD BEGIN TO IMPACT OUR WEST AS EARLY AS LATE SATURDAY NIGHT...SO
KEPT AT LEAST A SLIGHT CHANCE OF RAIN IN THE FORECAST FOR NOW BUT
TIMING THE PRECIPITATION WITH THIS NEXT SYSTEM IS STILL DIFFICULT TO
PIN DOWN THIS FAR OUT.

.LONG TERM...SUNDAY THROUGH THURSDAY

A WEATHER SYSTEM AND ASSOCIATED COLD FRONT PUSHES INTO THE WEST
SUNDAY MORNING AND THEN MOVES EAST OF THE DIVIDE SUNDAY AFTERNOON
AND NIGHT. BREEZY TO WINDY AREAS AND A CHANCE OF RAIN SHOWERS AND
MOUNTAIN SNOW. MONDAY LOOKS COOL WITH SCATTERED SHOWERS AT THE LOWER
ELEVATIONS WITH SNOW SHOWERS IN THE MOUNTAINS. DECREASING CLOUDS AND
SHOWERS MONDAY NIGHT. DRY ON TUESDAY MOST AREAS AND A LITTLE MILDER.
ISOLATED RAIN OR SNOW SHOWERS MAY DEVELOP LATER TUE AFTERNOON IN NW
WY. THE NEXT WEATHER SYSTEM BRINGS SOME LIGHT PRECIP TO THE
MOUNTAINS OF WY TUE NIGHT INTO WED WITH ISOLATED SHOWERS FOR THE
LOWER ELEVATIONS ON WED. THE GFS AND ECMWF MODELS ARE CLOSE WITH THE
TIMING AND STRENGTH OF THIS SYSTEM. HIGHS WED LOOKS A TAD WARMER.
NEXT THURSDAY LOOKS MOSTLY DRY PER THE MODELS WITH ISOLATED MOUNTAIN
SHOWERS...AND THAT MAY BE OVERDONE AT THIS POINT...BUT WILL LEAVE
THEM IN AND SEE HOW THINGS LOOK TONIGHT. SEASONAL HIGH TEMPS NEXT
THURSDAY.

&&

.AVIATION.../18Z ISSUANCE/

THE MAIN CONCERN THROUGH THE TAF VALID PERIOD WILL BE CONSIDERABLE
MOUNTAIN TURBULENCE...AS WELL AS LLWS ESPECIALLY ON THE LEE SIDE OF
THE ABSAROKA AND WIND RIVER MOUNTAINS INCLUDING COD AND LND
TERMINALS. VFR AND DRY CONDITIONS WILL OCCUR AT AREA TERMINALS WITH
ONLY MID/HIGH LEVEL CLOUDINESS EXPECTED TODAY. THERE COULD BE SOME
CONVECTION TONIGHT NW OF A KJAC-KCOD LINE...BUT THIS ACTIVITY IS
EXPECTED TO BE LIGHT AND REMAIN AWAY FROM THE TERMINALS.

PLEASE SEE THE AVIATION WEATHER CENTER FOR THE LATEST INFORMATION ON
TURBULENCE FORECASTS.

&&

.FIRE WEATHER...

WARMER AND DRY TODAY BUT IT WILL BE ANOTHER BREEZY DAY IN SPOTS WITH
SOUTHWEST WINDS OF 15 TO 25 MPH COMMON BETWEEN ROCK SPRINGS AND
CASPER AND OVER THE HIGHER ELEVATIONS. STRONG WINDS POSSIBLE ALONG
THE NORTH ZONE OF THE SHOSHONE AND IN THE CODY FOOTHILLS THIS
EVENING WITH SUDDEN 50 TO 60MPH WIND GUSTS POSSIBLE. SOUTHWEST FLOW
RETURNS ON FRIDAY WITH DRIER AND WARMER CONDITIONS REMAINING. THERE
COULD BE A FEW GUSTS OVER 25 MPH IN THE AFTERNOON BETWEEN RAWLINS
AND SOUTHERN CASPER DISPATCH BUT MOST AREAS WILL HAVE RELATIVELY
LIGHT WINDS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...

HIGH WIND WATCH FROM THIS EVENING THROUGH FRIDAY MORNING WYZ003.

&&

$$

SHORT TERM...ALLEN
LONG TERM...AR
AVIATION...WM
FIRE WEATHER...ALLEN








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