Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 180559
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1157 PM MDT FRI APR 17 2015

UPDATE...ADDED 06Z AVIATION DISCUSSION.

.SHORT TERM...TONIGHT THROUGH SATURDAY (ISSUED AT 323 PM MDT)

THE SOUTH AND EAST WILL BE COLD WITH WIDESPREAD SHOWERS OF RAIN
AND SNOW. NORTHEAST WINDS WILL SLOWLY DIMINISH THROUGH SATURDAY WITH
WIDESPREAD LOW CLOUDS. MOUNTAIN AREAS ABOVE 7500 FEET WILL HAVE THE
BEST CHANCE FOR SNOW ACCUMULATION WITH AREAS RECEIVING UP TO 6
INCHES OF SNOW...ESPECIALLY ON CASPER MOUNTAIN AND THE SOUTHEAST
WIND RIVER MOUNTAINS AROUND SOUTH PASS.

A PACIFIC TROUGH WILL APPROACH THE WEST THROUGH THE AFTERNOON WITH
CONVECTION DEVELOPING OVER THE WEST AND NORTH MOUNTAINS.
TEMPERATURES WILL BE WARMING OVERALL.  CLOUDS WILL INCREASE
THROUGH THE MORNING WITH AREAS OF SHOWERS AND ISOLATED
THUNDERSTORMS DEVELOPING. AREAS OF HEAVIER PRECIPITATION WILL OCCUR
OVER THE HIGHER MOUNTAINS. SMALL HAIL AND STRONG WIND GUSTS WILL
ACCOMPANY THE THUNDERSTORMS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

A SHORT WAVE DROPPING SOUTHEAST FROM FROM CANADA WILL FINALLY KICK
OUR RESIDENT CLOSED LOW OUT INTO THE PLAINS. THIS SYSTEM WILL
ENCOURAGE SOME SHOWER DEVELOPMENT ACROSS THE FORECAST AREA TO REMAIN
INTO THE EARLY EVENING ON SATURDAY. THE MID LEVEL COLD POOL MOVES IN
LATE IN THE NIGHT...LIKELY KEEPING A FEW SHOWERS GOING THROUGH
SUNDAY MORNING. THE GUSTY NORTH WINDS BEHIND THE COLD FRONT WILL
ALSO BEGIN TO TAPER OFF ON SUNDAY...WITH PERHAPS A FEW GUSTY
NORTHWEST WINDS REMAINING IN NORTHERN JOHNSON COUNTY SUNDAY
AFTERNOON.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. OVERALL THE FORECAST LOOKS RATHER MESSY...COOL AND
UNSETTLED WITH SIGNIFICANT DIFFERENCES IN THE MODEL SOLUTIONS FROM
RUN TO RUN AND BETWEEN ONE ANOTHER REGARDING THE NEXT SYSTEM. WAS
PRETTY GENEROUS WITH THE SLIGHT CHANCE POPS LATE IN THE PERIOD AS
BOTH GLOBAL MODELS BRING SOMETHING THROUGH AND KEEP IT AROUND FOR
A WHILE.

&&

.AVIATION.../06Z ISSUANCE/

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

AREAS OF MVFR/IFR -RASN BR WILL CONTINUE VCNTY AND SOUTH OF A
KCPR-KRKS LINE THROUGH 15Z.  A COLD FRONT WILL PUSH SOUTH ACROSS THE
MONTANA/WYOMING BORDER AROUND 15Z SATURDAY AND ACROSS THE AREA BY
EARLY SATURDAY AFTERNOON.  SCT MVFR/IFR -SHRASN WILL FOLLOW THE
FRONT WITH MORE NMRS -SHSN OVER THE MTNS WITH MTNS BECOMING FQTLY
OBSCURED THROUGH SATURDAY AFTN.  THE FRONT WILL ALSO PRODUCE UPSLOPE
IFR RASN VCNTY KCPR THROUGH THE AFTERNOON INTO SATURDAY EVENING.
DRIER AIR WILL WRAP INTO NORTHEAST WYOMING SATURDAY NIGHT...BUT
AREAS OF MVFR/IFR CIGS ARE EXPECTED TO BANK UP AGAINST THE EAST
SLOPES OF THE DIVIDE...VCNTY KCOD-KLND.

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

WRAPAROUND MOISTURE FROM AN UPPER LEVEL LOW PRESSURE SYSTEM WILL
CONTINUE TO PRODUCE OCNL MVFR/IFR CONDITIONS IN -RASN BR VCNTY AND
EAST OF KRKS THROUGH 15Z.  A COLD FRONT WILL PUSH SOUTH ALONG THE
DIVIDE SATURDAY AFTERNOON WITH SCT-NMRS SHSN RESULTING IN FQT MTN
OBSCURATIONS AFTER 20Z.  THIS ACTIVITY IS EXPECTED TO BE MORE WDLY
SCT OVER THE VALLEYS WITH POSSIBLE BRIEF MVFR/IFR CONDITIONS AT ALL
TERMINALS THROUGH SATURDAY EVENING.  MOST OF THIS ACTIVITY WILL
SHIFT ALONG AND EAST OF THE CONTINENTAL DIVIDE AFTER 06Z SUNDAY.

&&

.FIRE WEATHER...

THE SOUTH AND EAST WILL BE COLD WITH WIDESPREAD SHOWERS OF RAIN
AND SNOW.  NORTHEAST WINDS WILL SLOWLY DIMINISH THROUGH SATURDAY.
WITH WIDESPREAD LOW CLOUDS THE MIXING HEIGHTS WILL BE LOW WITH
POOR SMOKE DISPERSAL..ESPECIALLY IN AREAS OF PRECIPITATION.

A PACIFIC TROUGH WILL APPROACH THE WEST THROUGH THE AFTERNOON WITH
CONVECTION DEVELOPING OVER THE WEST AND NORTH MOUNTAINS.  CLOUDS
WILL INCREASE THROUGH THE MORNING WITH AREAS OF SHOWERS AND ISOLATED
THUNDERSTORMS DEVELOPING. TEMPERATURES WILL BE WARMER IN THE NORTH
AND WEST. MIXING HEIGHTS WILL INCREASE WITH THE CONVECTIVE LIFT
WITH GOOD SMOKE DISPERSAL OR BETTER EXPECTED IN THE AFTERNOON.
AREAS OF HEAVIER PRECIPITATION OVER THE HIGHER MOUNTAINS WILL LOCALLY
CAUSE LOWER MIXING HEIGHTS AND DEVELOPING POOR SMOKE DISPERSAL.

&&

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

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...AEM
FIRE WEATHER...C.BAKER












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