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000
FXUS65 KRIW 061808
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1108 AM MST THU MAR 6 2014

.UPDATE...
SOME VERY LOCALIZED HIGH WIND GUSTS NOTED WEST OF CLARK ALMOST
ADJACENT TO THE ABSAROKA RANGE. OTHER NEARBY OBSERVATION POINTS
COMING IN WITH SUB-40MPH WIND. THIS INFORMATION COUPLED WITH
EXPECTED DECREASE IN 700MB WINDS THROUGH THE AFTERNOON HAS LED US
TO LET THE HIGH WIND WARNING FOR ZONE 3 EXPIRE.

&&

.SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT

FEW MOUNTAIN SHOWERS THIS EVENING...WILL BEGIN TO INCREASE OVERNIGHT
AS A RIDGE RIDING SW BUMPS INTO THE WESTERN MOUNTAINS BY 08Z. TEMPS
THIS MORNING WILL BRING A VARIETY OF LIQUID/FROZEN AND MIXED PRECIP.
TOUGH CALL IN PLACES LIKE JACKSON WITH H7 TEMPS AROUND -3 TO -4 BUT
S TO SW SFC WINDS TRYING TO WARM THINGS A BIT DOWN LOW.
ADDITIONALLY...WINDS WILL PICK OVERNIGHT TO NEAR OR ABOVE WARNING
CRITERIA IN ZONE 03 - THE CODY FOOTHILLS AS TIGHT P AND T GRADS FROM
SFC TO MID LVLS DEVELOP AND H7 WINDS INCREASE TO 50-60KTS.
ADDITIONALLY...OMEGA FIELDS IN THE DRY ATMOSPHERE CONTINUE TO
INDICATE HIGH WIND POTENTIAL AND THE ABILITY TO BRING DOWN SOME OF
THE UPR FLOW WITH MOUNTAIN WAVE DEVELOPMENT. LEE BREAKING WAVE
CLOUDS ARE NOW JUST STARTING TO SHOW UP IN SAT IMAGERY. SEVERAL
SPOTS IN THE CODY FOOTHILLS HAVE STARTED TO GUST BETWEEN 45 AND 55
MPH AND SHOULD INCREASE THROUGH THE MORNING...MOST LIKELY PEAKING BY
MID MORNING. HIGH WIND WARNING FOR CODY FOOTHILLS HAS FOLLOWED THE
WATCH AND STRETCHES FROM 03Z TONIGHT UNTIL 18Z THIS MORNING. WINDS
ARE ALSO PICKING UP AND GUSTING 40-50 MPH ACROSS THE SE WIND
CORRIDOR OF ZONES 19 AND 20 AND ALSO 15 AND 16.

THROUGH THE SHORT TERM...THE STRONGEST UPR LVL SUPPORT WILL ARRIVE
IN A FEW HOURS AS STATED ABOVE...WITH DECENT AMOUNTS OF PAC MOISTURE
IN TOW. HOWEVER...THIS WILL BE A HARD BUT ALSO RATHER QUICK
HITTER...AS EVEN THE MAIN WAVE AXIS WILL BE THRU THE CWA BY FRI
MORNING. STAYING AHEAD OF THIS WAVE... AN IMMATURE FRONT WILL ALSO
ROLL THRU THE REGION BY THIS EVENING...BECOMING MUCH BETTER
ORGANIZED ONCE IT GETS TO OUR SOUTH. THIS AFTERNOON MUCH OF THE
ACTIVITY WILL LIKELY BECOME CONVECTIVE AND MORE SCATTERED...AND
REMAIN SO UNTIL AFTER THE MAIN TROF AXIS PASSES. OVERALL...THE
MOUNTAINS OF THE WEST WILL MAKE OUT WELL. HOWEVER...NOW IT NOW LOOKS
TO BE A SYSTEM THAT REMAINS AOB ADVISORY LEVEL IN THE WRN
MOUNTAINS...WITH THE BULK OF STRONGER ACTIVITY COMING BETWEEN
SUNRISE AND NOON IN PARK AND TETON COUNTIES AND THE WESTERN WIND
RIVER MOUNTAINS...SHIFTING SWD INTO LINCOLN COUNTY THIS AFTERNOON.
GENERAL SNOWFALL AMOUNTS SHOULD TOTAL OUT BY THIS EVENING AT BETWEEN
3 AND 6 INCHES WITH LOCALIZED HIGHER AMOUNTS FROM 7 TO 10 INCHES IN
THE TETONS N INTO THE SRN PORTION OF YELLOWSTONE. THEN... POST
FRONTAL LIGHT CONVECTIVE PRECIP WILL LINGER THROUGH TONIGHT NIGHT
AND FRIDAY WITH LITTLE ADDITIONAL ACCUMULATING SNOW. TODAY MAY END
UP BEING THE WARMEST DAY OF THE WEEK ACROSS MUCH OF THE
CWA...PARTICULARLY E OF THE DIVIDE...WITH TEMPS CLIMBING INTO THE
50S AND LOWER LOWER 60S IN THE BASINS AND OVR THE ERN HIGH PLAINS
OF JOHNSON AND NATRONA COUNTIES.

FROM FRI NIGHT ON THROUGH SUN MORNING...IT DRIES OUT STATE WIDE WITH
BRIGHT SUN BREAKING OUT EVERYWHERE WITH HIGH TEMPS CLIMBING BACK
INTO THE UPPER 40S AND 50S E OF THE DIVIDE AND MOSTLY 40S WEST. SAT
NIGHT...W TO SW WINDS WILL ALSO BEGIN TO INCREASE OVR AND IN THE LEE
OF THE ABSAROKA MOUNTAINS...POSSIBLY GETTING DOWN INTO THE CODY
FOOTHILL REGION.

.LONG TERM...SUNDAY THROUGH THURSDAY

FAIRLY LARGE DISCREPANCIES BETWEEN THE OPERATIONAL GFS AND ECMWF
MODELS TONIGHT. THE OP ECMWF IS FASTER THAN THE OP GFS WITH OUR
NEXT POTENTIAL WEATHER MAKER MONDAY AND TUESDAY. SUNDAY IS DRY
WITH THE FLOW GENERALLY FLATTENING WITH INCREASING WIND AND MILD
TEMPERATURES FOR MUCH OF THE AREA AS H7 TEMPERATURES GET TO NEAR
0C AT H7 OR POSSIBLY WARMER. AFTER THAT...THE GFS HAS A LEAD
SHORTWAVE THAT PRODUCES A QUICK SHOT OF SNOW OUT WEST WEDNESDAY
WITH A COLD FRONT DROPPING SOUTH ACROSS THE NORTH WITH RAIN
POTENTIALLY CHANGING TO SNOW MONDAY NIGHT. THE GFS THEN HAS THE
MAIN TROUGH MOVING IN FROM THE WEST TUESDAY INTO TUESDAY NIGHT
POTENTIALLY CLOSING OFF OVER SRN IDAHO BEFORE IT TRACKS ACROSS SRN
WYOMING TUESDAY NIGHT FOR A POTENTIAL SIGNIFICANT SNOWSTORM FOR
CENTRAL WYOMING. THE OP ECMWF HAS THE RIDGE AXIS DEVELOPING
SLIGHTLY FURTHER EWD AND HAS MOST OF THE ENERGY WITH THE FIRST
SHORTWAVE LATE MONDAY INTO MONDAY NIGHT AND TUESDAY MORNING. THIS
SOLUTION WOULD RESULT IN RAIN CHANGING TO SNOW OUT WEST BY MONDAY
AFTERNOON INTO MONDAY EVENING WITH SNOW DEVELOPING AND DROPPING
SOUTH ACROSS CENTRAL WYOMING MONDAY NIGHT AND TUESDAY WITH THE
SECONDARY SHORTWAVE DROPPING DOWN FROM THE NORTH TUESDAY AFTERNOON
AND EVENING. THE ECMWF ENSEMBLE HAVE THE RIDGE AXIS SLIGHTLY
FURTHER WEST LIKE THE GFS. TOUGH TO PICK THE BETTER SOLUTION RIGHT
NOW AS THEY ARE BOTH POSSIBLE WITH ONLY SUBTLE SHIFTS IN THE
PATTERN MAKING ONE RIGHT OR WRONG. BOTTOM LINE INDICATES AN
UNSETTLED PERIOD FOR THE FIRST HALF OF THE WEEK WITH A POTENTIAL
DECENT SNOW EVENT FOR ESPECIALLY CENTRAL WYOMING AS EARLY AS
MONDAY NIGHT OR AS LATE AS TUESDAY NIGHT. HOWEVER...BOTH HAVE TWO
SYSTEMS INVOLVED WITH A CHANCE OF RAIN/SNOW EITHER AT THE
BEGINNING OR END OF THE PERIOD. GENERALLY HAVE LIKELY POPS OUT
WEST MONDAY WITH CHANCE POPS EAST OF THE DIVIDE MUCH OF THE PERIOD
MONDAY NIGHT THROUGH TUESDAY NIGHT WITH FALLING TEMPERATURES. GFS
DRIES US OUT WEDNESDAY NIGHT AND THURSDAY WHILE THE OP ECMWF HAS A
SYSTEM MOVING IN FROM THE WEST THURSDAY AND THURSDAY NIGHT WITH A
DECENT SHOT OF RAIN AND SNOW ACROSS THE AREA. THE ECMWF ENSEMBLES
SUPPORT MORE OF THE GFS IDEA OF BUILDING HEIGHTS TO THE WEST WITH
A DRY END OF THE MEDIUM RANGE PERIOD AND THIS WAS FOLLOWED.

&&

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

VFR CONDITIONS TO PREVAIL THROUGH THE FORECAST PERIOD AT ALL
TERMINALS EXCEPT KCPR. FRONTAL BOUNDARY WILL PUSH THROUGH KCPR AROUND
09Z-10Z/FRI AND BRING JUST ENOUGH UPSLOPE AND INCREASED MOISTURE TO
GENERATE A BRIEF PERIOD OF IFR/MVFR PRIOR TO 14Z/FRI. OTHERWISE...
MID AND HIGH CLOUD DECKS WILL BE THE RULE ALONG WITH GUSTY WESTERLY
SURFACE WIND AT KCPR AND KCOD THROUGH THIS AFTERNOON. SOME MOUNTAIN
OBSCURATIONS LATE TONIGHT AND EARLY FRIDAY ALONG THE BIGHORNS AND
CASPER MOUNTAIN. CONDITIONS WILL BEGIN TO IMPROVE AFTER 15Z/FRI IN
THAT CORRIDOR.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

MOISTURE CONTINUES TO POUR INTO THE WEST LATE THIS MORNING. LIGHT
SNOW AND MVFR TO PREVAIL AT KJAC WITH POSSIBLE PERIOD OF IFR EARLY
THIS AFTERNOON. COOLER CLOUD TOPS NOTED OVER NORTHERN UTAH WILL
SLIDE INTO SOUTHWEST WYOMING THIS AFTERNOON AND INCREASE RAIN/SNOW
CHANCES AT KPNA AND KBPI TERMINALS. BEST CHANCE OF IFR/MVFR
CONDITIONS SHOULD BE FROM ABOUT 19Z-23Z/THU. FOCUS WILL THEN SHIFT
TOWARD KRKS TERMINAL WHERE CONVECTIVE RAIN SHOWERS WILL GRADUALLY
MIX WITH AND CHANGE TO LIGHT SNOW AFTER 03Z/FRI. LOOKS LIKE THERE
COULD BE A PERIOD OF MVFR CONDITIONS IN LIGHT SNOW AT KRKS CENTERED
AROUND 06Z/FRI. MODEL DIV-Q FIELDS INDICATE SHORT-LIVED PERIOD OF
LIFT DURING THAT TIME ALONG WITH SOME BRIEF JET COUPLING. TROUGH
PASSAGE WILL BRING INCREASING WEST-NORTHWEST FLOW TO KBPI...KPNA...
AND KRKS TOWARD 12Z/FRI. AN UNSETTLED DAY ACROSS THE WEST ON
FRIDAY BUT NO PROLONGED PERIODS OF MVFR CONDITIONS EXCEPT AT KJAC
WHERE CEILINGS WILL REMAIN AROUND BKN030. MOUNTAIN OBSCURATIONS
WILL BE WIDESPREAD THROUGH ABOUT 18Z/FRI.

&&

.FIRE WEATHER...

NO FIRE WEATHER CONCERNS THROUGH THE REST OF THE WEEK. HOWEVER...DRY
AND WARMER WEATHER CONTINUES TODAY EAST THE DIVIDE WITH HIGH
TEMPERATURES AT THE LOWER ELEVATIONS REACHING INTO THE 50S AND LOWER
60S. OTHERWISE...WEST TO SOUTHWEST WINDS OF 20 TO 30 MPH WITH GUSTS
NEAR 50 CAN BE EXPECTED THROUGH THIS MORNING ACROSS THE SOUTHEASTERN
DISPATCH ZONES. STRONG WEST WINDS WITH GUSTS OVER 60 MPH AT TIMES
WILL ALSO BLOW IN THE CODY FOOT HILLS THROUGH THIS MORNING UNTIL
AFTER A WEAK COLD FRONT PASSES BY. ADDITIONALLY...THE NEXT IN A
SERIES OF UPPER LEVEL DISTURBANCES COMBINING WITH PACIFIC MOISTURE
HAS PUSHED INTO THE WESTERN ZONES THIS MORNING WITH PRECIPITATION
INCREASING. GENERALLY...3 TO 6 INCHES OF NEW SNOWFALL CAN BE
EXPECTED ABOVE 6500 FEET WITH SOME LOCALIZED FAVORED AREAS
RECEIVING UP TO 10 INCHES OF NEW SNOW BY SUNDOWN TONIGHT. TONIGHT
THROUGH FRIDAY...WIDESPREAD LIGHT SHOWER ACTIVITY WILL CONTINUE
ACROSS THE WESTERN DISPATCH ZONES...BUT WITH ONLY A FEW INCHES OF
ADDITIONAL SNOWFALL BY THE END OF THE DAY FRIDAY.

&&

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

$$

SHORT TERM...BRAUN
LONG TERM...SKRBAC
AVIATION...CNJ
FIRE WEATHER...BRAUN