Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 010345
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
944 PM MDT TUE MAR 31 2015

.SHORT TERM...TONIGHT THROUGH WEDNESDAY

A COLD FRONT WILL BRING INCREASING MOUNTAIN SHOWERS WITH ISOLATED
THUNDERSTORMS IN THE NORTH THIS EVENING. SHOWERS WILL LINGER THROUGH
WEDNESDAY. SOME MOUNTAIN AREAS ABOVE 8500 FEET COULD SEE
ACCUMULATIONS OF 1 TO 4 INCHES OF WET HEAVY SNOW. TEMPERATURES WILL
TURN MUCH COLDER BEHIND THE COLD FRONT WITH HIGHER RELATIVE HUMIDITY
AND A WIND SHIFT TO THE NORTHWEST. THE WIND RIVER BASIN AND GREEN
RIVER BASIN AND MAINLY THE NORTHERN BIGHORN BASIN AND NORTHERN
JOHNSON COUNTY SHOULD SEE QUITE STRONG NORTHWEST WINDS ON WEDNESDAY
WITH SOME GUSTS OF 40 TO 50 MPH.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY

WEAK RIPPLE OUT BETWEEN 140W AND 150/46-50N BECOMES OUR NEXT TROUGH
WHICH DIGS INTO NRN CA AT THE START OF THIS PERIOD...THEN INTO THE
SRN UT/4-CORNERS REGION WEDNESDAY NIGHT INTO THURSDAY WITH GOOD COLD
CORE ALOFT MOVING INTO MUCH OF THE AREA. FLOW BEGINS TO BEND OVER TO
A MORE NLY OR BRIEFLY NELY FLOW THURSDAY WITH SOME MODEL DIFFERENCES
ON THE DETAILS. NLY FRONT SAGGING SWD WED NGT WILL HAVE TO BE
WATCHED FOR ANY SNOW SHOWERS ALONG IT...ESPECIALLY ALONG THE CENTRAL
FOOTHILLS FROM CODY SWD. THE NAM IS MORE BULLISH ON THIS SCENARIO.
THE GFS KEEPS THE ACTIVITY GENERALLY IN THE HIGHER TERRAIN WED NGT.
ON THURSDAY...FRONT PUSHES SWD INTO THE RED DESERT/I80 CORRIDOR WITH
POTENTIAL FARSON/RKS CONVERGENCE ZONE WITH NW FLOW UPPER GREEN WINDS
MEETING THE NE FRONTAL WINDS. BUMPED UP POPS SOME ALONG THIS AREA
THURSDAY. OTHERWISE...VERY STEEP LAPSE RATES (8.5C/KM) AND LI`S
AROUND ZERO EXPECTED THURSDAY WITH DEVELOPING HIGHER TERRAIN SNOW
SHOWERS INCREASING AND TRYING TO SPREAD SSEWD OFF THE MOUNTAINS.
GRADUAL IMPROVEMENT LATER THURSDAY NIGHT. COLD START FRIDAY MORNING
WITH TEENS TO LOWER 20S EAST AND SINGLE DIGITS AND SOME TEENS WEST.
SLOW RECOVERY FRIDAY WITH HIGHS IN THE MID 40S TO LOWER 50S EAST AND
30S TO LOWER 40S WEST WITH MID 20S TO MID 30S IN THE HIGH COUNTRY.
FLOW QUICKLY FLATTENS LATE FRIDAY INTO FRIDAY NIGHT FOR INCREASING
MTN WIND WITH POTENTIAL FOR STRONG CODY FOOTHILL WINDS. SHORTWAVE
THEN PASSES BY TO THE NORTH SATURDAY LEADING TO A SHALLOW FRONT
PUSHING SWD ACROSS AREAS EAST OF THE DIVIDE BY SATURDAY NIGHT. LOOKS
DRY BUT THIS MAY BE A BOUNDARY FOR SOME LGT PCPN AS IT LIFTS NWD
SUNDAY AHEAD OF OUR DEVELOPING PACNW TROUGH. ISENTROPIC LIFT/QG
FORCING MAY AID IN SOME LGT PCPN...ESPECIALLY AROUND THE HIGHER
TERRAIN/MTNS IN THE NRN ZONES. DEVELOPING LOW PRESSURE EAST OF THE
DIVIDE AHEAD OF THIS NEXT THROUGH WILL USHER IN STRONG STRONG AND
GUSTY WINDS. FIRST SHORTWAVE SHOOTS EWD OUT OF THE MAIN TROUGH
SUNDAY NIGHT/MON TO OUR NORTH WITH PACIFIC TYPE FRONT PUSHING EWD
ACROSS THE AREA WITH INCREASING WEST WIND. POTENTIALLY HIGH WIND ON
MONDAY FROM THE I80 CORRIDOR TO CASPER WITH QUITE A BIT OF WIND IN
MOST PLACES. GOOD SHOT OF SNOW OUT WEST WITH THIS WAVE ON MON WITH
UNSETTLED CONDITIONS THROUGH TUESDAY AND THE REST OF THE TROUGH
OPENS UP AND PASSES THROUGH. OVERALL...A COLD...WINDY AND UNSETTLED
PERIOD EARLY NEXT WEEK.

&&

.AVIATION.../00Z ISSUANCE/

VFR CONDITIONS WILL PREVAIL AT THE TERMINAL SITES THROUGH 06Z
WEDNESDAY AHEAD OF AN UPPER LEVEL DISTURBANCE AND SURFACE FRONT
THAT WILL RACE THROUGH OVERNIGHT. THIS SYSTEM WILL PRODUCE RAIN
AND SNOW SHOWERS AND ISOLATED THUNDERSTORMS MAINLY WEST OF THE
CONTINENTAL DIVIDE AND THE NORTH.  OVER THE NORTHERN AND WESTERN
MOUNTAINS MVFR TO IFR CEILINGS AND VISIBILITY REDUCED IN HEAVIER
SNOW SHOWERS WILL OBSCURE TERRAIN.  MOST TERMINALS EXCEPT FOR
KBPI...KRIW...AND KRKS...WILL CARRY VCSH THROUGH THE END OF THE
FORECAST PERIOD. ANY SHOWERS REACHING THE TERMINALS MAY BRING
BRIEF PERIODS OF MVFR CONDITIONS. PARTIAL CLEARING IS EXPECTED
20Z WEDNESDAY THROUGH 00Z THURSDAY.

&&

.FIRE WEATHER...

THE WIND RIVER BASIN...SWEETWATER...LINCOLN AND SUBLETTE COUNTIES
WILL EXPERIENCE GUSTY WINDS AND LOW RELATIVE HUMIDITYAGAIN
TODAY...HOWEVER FIRE DANGER VALUES SHOULD REMAIN JUST ABOVE CRITICAL
FOR MOST LOCATIONS.

A COLD FRONT WILL BRING INCREASING MOUNTAIN SHOWERS WITH ISOLATED
THUNDERSTORMS IN THE NORTH THIS EVENING. SHOWERS WILL LINGER
THROUGH WEDNESDAY. SOME MOUNTAIN AREAS ABOVE 8500 FEET COULD SEE
ACCUMULATIONS OF 1 TO 4 INCHES OF WET HEAVY SNOW. TEMPERATURES
WILL TURN MUCH COLDER BEHIND THE COLD FRONT WITH HIGHER RELATIVE
HUMIDITY AND A WIND SHIFT TO THE NORTHWEST. THE WIND RIVER BASIN
AND GREEN RIVER BASIN AND MAINLY THE NORTHERN BIGHORN BASIN AND
NORTHERN JOHNSON COUNTY SHOULD SEE QUITE STRONG NORTHWEST WINDS ON
WEDNESDAY WITH SOME GUSTS OF 40 TO 50 MPH. STRONG MIXING CAN BE
EXPECTED WITH THE FRONTAL INVERSION LIMITING THE DEPTH OF THE
MIXING BUT MOST AREAS WILL HAVE FAIR TO GOOD SMOKE DISPERSAL.

&&

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


&&

$$

SHORT TERM...C.BAKER
LONG TERM...SKRBAC
AVIATION...BRAUN
FIRE WEATHER...BRAUN










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