Weather Service Report


285 
FXUS65 KRIW 230922
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
322 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.../12Z 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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