Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 221003
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
303 AM MST MON DEC 22 2014

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT

CONDITIONS CONTINUE TO GENERALLY IMPROVE ACROSS THE AREA AS ALL
HIGHLIGHTS HAVE BEEN REMOVED. PERIODS OF LIGHT SNOWFALL WILL REMAIN
POSSIBLE THROUGH THE DAY ACROSS MUCH OF THE FORECAST AREA...THOUGH
SNOWFALL WILL MOST SIGNIFICANTLY IMPACT THE EASTERN THIRD OF THE
FORECAST AREA BY THIS AFTERNOON. TEMPERATURES ARE EXPECTED TO BE
COOLER TODAY IN RESPONSE TO THIS SYSTEM.

BUILDING HIGH PRESSURE OVER THE AREA WILL HELP TO END SNOWFALL
ACROSS THE WESTERN MOUNTAINS AND VALLEYS OVERNIGHT. SNOWFALL WILL
ALSO WANE ACROSS EASTERN WYOMING AS THE INFLUENCING SYSTEM MOVES
FURTHER INTO THE CENTRAL PLAINS.

HIGH PRESSURE ACROSS THE AREA WILL GENERALLY BE SHORT LIVED...THOUGH
GENERALLY DRY CONDITIONS WILL BE AROUND LATE TUESDAY THROUGH EARLY
WEDNESDAY. SLIGHTLY WARMER TEMPERATURES WILL BE REALIZED ON
WEDNESDAY AHEAD OF THE NEXT APPROACHING SYSTEM. MODELS TRY TO SHOW
SOME WEAK DISTURBANCES WITHIN THE RIDGE THAT WOULD CREATE SOME
SNOWFALL OVER THE NORTHWESTERN MOUNTAINS BY WEDNESDAY AFTERNOON.
COVERAGE DOES NOT APPEAR TO BECOME SIGNIFICANT UNTIL THE LATE
EVENING HOURS AS A TROUGH APPROACHES THE INTERMOUNTAIN WEST.

THIS TROUGH WILL WORK TO SPREAD SNOWFALL ACROSS THE WESTERN THIRD OF
THE FORECAST AREA THROUGH WEDNESDAY NIGHT.

.LONG TERM...CHRISTMAS DAY THURSDAY THROUGH MONDAY

THE MODELS CONTINUE TO ORDER UP A WHITE CHRISTMAS WITH SOME LIGHT
SNOW ACROSS MOST OF THE AREA DURING THE DAY INTO CHRISTMAS NIGHT.
ACCUMULATIONS AT THE LOWER ELEVATIONS 1 TO 3 INCHES AND 2 TO 5
NEW INCHES FOR THE MOUNTAINS. THE GFS AND ECMWF MODELS ARE STILL
TRENDING SLOWER WITH THE ONSET OF SNOW EAST OF THE DIVIDE...NOW
ACTUALLY LOOKING AT CHRISTMAS MORNING TO AS LATE AS MIDDAY. THE MAIN
CHANCE OF SNOW FOR SOME PLACES MAY OCCUR CHRISTMAS EVENING/NIGHT.
LINGERING LIGHT SNOW ON FRIDAY MORNING THEN MOSTLY DRY FRIDAY
AFTERNOON AND NIGHT EAST OF THE DIVIDE. MOUNTAINS COULD SEE LT SNOW
UNTIL LATE FRI PM OVER THE PEAKS AND PASSES. SATURDAY THROUGH
SATURDAY NIGHT LOOKS DRY EAST OF THE DIVIDE. IN THE WEST...SOME
MOISTURE MOVES BACK SATURDAY AFTERNOON AND NIGHT FOR AN INCREASING
CHANCE OF SNOW. THE NEXT WEATHER SYSTEM IS POISED TO MOVE INTO THE
ROCKY MOUNTAIN REGION SUNDAY THROUGH MONDAY. THIS SYSTEM TAPS SOME
ARCTIC AIR AND SENDS IT INTO WY SUNDAY NIGHT THROUGH MONDAY. LIGHT
FLUFFY SNOW WOULD ALSO OCCUR SUNDAY INTO MONDAY. PLENTY OF TIME TO
WATCH HOW MUCH COLD AIR GETS PULLED SOUTH AND ADJUST FORECAST WITH
TIME. BOTTOM LINE...AN UNSETTLED WEATHER PATTERN FROM CHRISTMAS DAY
INTO THE WEEKEND...IMPACTING TRAVEL FROM TIME TO TIME. HIGH TEMPS
WILL BE AT OR BELOW SEASONAL NORMALS THROUGH THE PERIOD.

&&

.AVIATION.../12Z ISSUANCE/

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

AREAS OF GUSTY NORTHWEST WIND WILL REMAIN...ESPECIALLY VCNTY
KDUB-KRIW AND KBYG...THROUGH THE PERIOD.  -SHSN ACTIVITY WILL REMAIN
MOSTLY ISOLD-WDLY SCT WITH MOST OF THIS ACTIVITY VCNTY AND EAST OF A
KCOD-KWRL-KCPR LINE THROUGH MONDAY MORNING WITH MORE NMRS SHSN
OBSCURING THE SURROUNDING MTNS.  MOISTURE AND INSTABILITY WILL
INCREASE MONDAY AFTERNOON WITH SHSN BECOMING MORE SCT ACROSS THE
CENTRAL BASINS.  SOME WRAPAROUND MOISTURE IS EXPECTED TO PUSH BACK
FROM AN UPPER LOW OVER THE PLAINS INTO EASTERN WYOMING MONDAY
NIGHT...AND THIS MAY BRING MORE WIDESPREAD MVFR/IFR -SN AS FAR WEST
AS THE BIGHORN RANGE TO VCNTY KCPR.

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

A MOIST AND UNSTABLE NW FLOW WILL REMAIN OVER THE AREA THROUGH
MONDAY AFTERNOON.  AN UPPER LEVEL DISTURBANCE IN THIS FLOW IS
EXPECTED TO DIVE SOUTH ALONG THE DIVIDE LATE MONDAY MORNING AND
MONDAY AFTERNOON...EXITING SOUTH OF INTERSTATE 80 MONDAY EVENING.
SNOW SHOWER ACTIVITY WILL INCREASE AHEAD OF THIS SYSTEM FROM NW-SE
MONDAY MORNING WITH IMPROVING CONDITIONS AND GUSTY NW WINDS
FOLLOWING THE DISTURBANCE MONDAY AFTERNOON AND MONDAY EVENING.
CLEARING CONDITIONS AND DIMINISHING WIND WILL FOLLOW OVERNIGHT
MONDAY.

&&

.FIRE WEATHER...

GUSTY WIND WILL REMAIN ACROSS MUCH OF THE FORECAST AREA TODAY...WITH
WIND WEAKENING DURING THE EVENING AND OVERNIGHT HOURS. TEMPERATURES
WILL COOL ACROSS THE AREA TODAY...AND CONTINUE TO COOL TUESDAY
BEFORE EXPERIENCING A SLIGHT WARMING ON WEDNESDAY. SNOWFALL WILL
LINGER ACROSS THE AREA TODAY...WITH MUCH OF ITS IMPACT EXPECTED TO
BE FELT ACROSS THE EASTERN THIRD OF THE FORECAST AREA. HIGH PRESSURE
WILL MOVE IN THIS EVENING AND OVERNIGHT TO HELP END MOST SHOWER
ACTIVITY. THE NEXT APPROACHING TROUGH WILL MOVE INTO NORTHWESTERN
WYOMING WEDNESDAY AFTERNOON AND EVENING...AND WILL SPREAD THROUGH
THE OVERNIGHT HOURS.

&&

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

&&

$$

SHORT TERM...BRANHAM
LONG TERM...AR
AVIATION...AEM
FIRE WEATHER...BRANHAM







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