Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 012118
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
318 PM MDT WED APR 1 2015

.SHORT TERM...TONIGHT THROUGH THURSDAY

CLOUD COVER WILL CONTINUE TO INCREASE THIS EVENING...ESPECIALLY
OVER WESTERN AND NORTHERN WYOMING. A COLD FRONT CONTINUES TO WORK
ITS WAY THROUGH THE FORECAST AREA...LEAVING COOLER TEMPERATURES IN
ITS WAKE...AS WELL AS SOME GUSTY WINDS AND SOME SHOWER ACTIVITY.

SNOWFALL HAS ALREADY FALLEN OVER SOME WESTERN MOUNTAINS...AND
ACTIVITY WILL CONTINUE THROUGH THURSDAY AFTERNOON. TEMPERATURES
WILL REMAIN COOL ON THURSDAY AFTERNOON IN RESPONSE TO THIS SYSTEM.
CONVECTIVE ACTIVITY IS EXPECTED THROUGH THURSDAY...WITH MODELS
SHOWING DECENT INSTABILITY...ESPECIALLY WEST OF THE CONTINENTAL
DIVIDE. THE CONVECTIVE NATURE OF THIS SYSTEM WILL LEAVE SNOW
AMOUNTS MORE DIFFICULT TO SPECIFY AS SOME STORMS MAY PRODUCE A BIT
MORE THAN OTHERS. WIDESPREAD GENERALLY LIGHT SNOWFALL EXPECTED.


.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY

UPPER TROUGH IS SWINGING SE ACROSS THE AREA TO START THIS PERIOD
WITH STEEP LAPSE RATES AND LI`S AROUND ZERO IN THE SW HALF
PRODUCING QUITE A BIT OF SNOW SHOWERS AROUND AND DOWNWIND OF THE
MOUNTAINS. ANOTHER AREA TO WATCH IS ALONG A POTENTIAL CONVERGENCE
BOUNDARY BETWEEN THE FRONT PUSHING WWD INTO THE RED DESERT/I80
CORRIDOR SETTING UP THE POTENTIAL FARSON TO RKS VICINITY CONVERGENCE
AXIS RESULTING IN ENHANCED SNOW SHOWERS. CONDITIONS GRADUALLY
IMPROVE LATER THURSDAY NIGHT AS SYSTEM MOVES SE AND IS REPLACED BY A
FLAT RIDGE. RIDGE AXIS MOVES OVERHEAD LATE FRIDAY NIGHT OR SATURDAY
WITH A SPEED MAX PASSING BY JUST TO THE NORTH. LEE TROUGHING...RIGHT
FRONT QUAD DYNAMICS AND AT LEAST SOME POTENTIAL GAP FLOW ADDS UP TO
MODERATE TO STRONG WLY WINDS ACROSS THE CODY FOOTHILLS FRIDAY NIGHT
INTO EARLY SATURDAY. MOST OF THE WEEKEND LOOKS DECENT AHEAD OF A
MUCH MORE UNSETTLED EARLY WEEK PERIOD. THE BEGINNINGS OF THIS CHANGE
COMES FROM THE ALEUTIAN LOW WHICH SLOWLY CHUGS EWD. THE FIRST PIECE
OF ENERGY MAY MOVE INTO THE WEST AS EARLY AS SUNDAY WITH THE
MAJORITY OF THE TROUGH SWINGING THROUGH ON MONDAY. TURNING COOLER TO
COLDER WITH MOUNTAIN SNOWFALL AT TIMES AND SOME MIXED PCPN IN THE
LOWER ELEVATIONS OF THE WEST BECOMING MORE SNOW MONDAY. PCPN LOOKS
LIMITED EAST OF THE DIVIDE WITH OPEN WAVE NATURE OF THIS SYSTEM.
TIMING AND DETAILS HAVE CHANGED SINCE YESTERDAY WITH POTENTIAL GAP
BETWEEN THIS MONDAY SYSTEM AND THE NEXT ONE. TUESDAY MAY BE THE
TRANSITION DAY BEFORE NEXT TROUGH DIGS INTO TUE NIGHT INTO
WEDNESDAY. MODELS STRUGGLE ON WHETHER THIS IS MORE ONE TROUGH OR TWO
TROUGHS WITH A BREAK IN BETWEEN. THE GFS SHOWS THIS WED SYSTEM
ORIGINATING FROM ASIA AND BEING THE KICKER FOR THE MONDAY SYSTEM.
THE NEW ECMWF IS MUCH WEAKER WITH THE FIRST SYSTEM AS THE LATE TUE
THROUGH WEDNESDAY SYSTEM BECOMES THE MAIN UPPER TROUGH WITH MINIMAL
IMPACT FROM THE MONDAY SYSTEM. CONFIDENCE REMAINS LOW WITH THE
DETAILS FOR EARLY NEXT WEEK.


&&

.AVIATION.../00Z ISSUANCE/

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

WIDESPREAD VFR CONDITIONS EXPECTED THROUGH 12Z THURSDAY...THOUGH
SOME GUSTY WIND WILL REMAIN POSSIBLE THROUGH 03Z FOR THE IMPACTED
CENTRAL TERMINALS INCLUDING KRIW...KLND...AND KCOD. A FEW SHOWERS
MAY BE POSSIBLE ACROSS NORTH-CENTRAL WYOMING BRINGING BRIEF PERIODS
OF MVFR CONDITIONS. CLOUD COVER WILL CONTINUE TO INCREASE OVERNIGHT
IN RESPONSE TO THE FRONTAL PASSAGE. SHOWER COVERAGE WILL INCREASE
AFTER 18Z THURSDAY TO INCLUDE MORE PORTIONS OF CENTRAL AND EASTERN
WYOMING. VCSH HAS BEEN INCLUDED AT MANY OF THE TERMINALS AS TIMING
IS DIFFICULT TO PIN DOWN. SOME GUSTY WIND WILL ALSO RETURN AFTER
18Z...THOUGH NOT AS STRONG AS IN PAST DAYS.

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

INCREASING CLOUD COVER EXPECTED OVER THE AREA IN RESPONSE TO THE
COLD FRONTAL PASSAGE. GUSTY WIND WILL REMAIN...ALONG WITH SOME
SHOWER ACTIVITY THROUGH THE OVERNIGHT HOURS. SOME MVFR CONDITIONS
POSSIBLE IN SHOWER ACTIVITY. MOUNTAIN OBSCURATIONS WILL BE
POSSIBLE DURING THE FORECAST PERIOD...WITH INCREASED TURBULENCE
ALSO POSSIBLE. NORTHWESTERN WYOMING WILL BEGIN TO SEE SOME
CLEARING AFTER 12Z THURSDAY...THOUGH CONVECTIVE SHOWERS WILL
RETURN AFTER 18Z THURSDAY. ANY SHOWER DEVELOPMENT MAY RESULT
ADDITIONAL PERIODS OF MVFR CONDITIONS THROUGH 00Z FRIDAY.

&&

.FIRE WEATHER...

THE PASSAGE OF A COLD FRONT IS KEEPING GUSTY WIND ACROSS MUCH OF
CENTRAL AND SOUTHERN WYOMING THIS EVENING. SHOWER ACTIVITY WILL
ALSO REMAIN FROM THIS SYSTEM....AND WILL SPREAD TO INCLUDE THE
MAJORITY OF THE FORECAST AREA FOR THURSDAY AFTERNOON. COOLER
TEMPERATURES AND INCREASED HUMIDITY WILL BE EXPECTED WITH THIS
SYSTEM...WITH HIGH PRESSURE EXPECTED TO BEGIN BUILDING BACK OVER
THE AREA BY FRIDAY MORNING.

&&

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

$$

SHORT TERM...BRANHAM
LONG TERM...SKRBAC
AVIATION...BRANHAM
FIRE WEATHER...BRANHAM





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