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000
FXUS65 KRIW 111751
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1151 AM MDT TUE MAR 11 2014

.UPDATE...HIGH WIND WARNING FOR JOHNSON COUNTY HAS EXPIRED.
WINTER WEATHER ADVISORIES HAVE EXPIRED.

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT

SNOW CONTINUES IN THE WESTERN MOUNTAINS AND RAIN HAS TURNED TO
SNOW IN THE WESTERN VALLEYS. MEANWHILE THE COLD FRONT APPEARS TO
BE DRAPED FROM JUST SOUTH OF RIVERTON TO JUST NORTH OF CASPER. THE
SECOND SURGE IS COMING THROUGH GEY ATTM AND SHOULD BE PLOWING
THROUGH WORLAND MOMENTARILY WHERE AREAS OF SNOW AND FOG ARE
OCCURRING ALONG AND BEHIND IT WITH AN INCREASING NORTH WIND. THE
COLD FRONT SHOULD REACH RKS BY 18Z. AREAS LIKE CPR AND LND ARE
EXPERIENCING HIGHER TEMPS NOW THEN THE PROJECTED DAYTIME HIGHS FOR
TODAY.3 HOUR POST FRONTAL SURFACE PRESSURE RISES ARE PROGGED TO BE
AROUND 8MB AS REFLECTED BY THE INCREASING NORTH WINDS...ESPECIALLY
IN JOHNSON COUNTY AND THROUGH THE WIND RIVER CANYON AND INTO THE
WIND RIVER BASIN. HIGH WIND HAS NOT YET BEEN REACHED HOWEVER. Q
VECTOR FORCING ASSOCIATED WITH THE UPPER TROUGH THAT SLUNG THE
COLD FRONT SOUTH ACROSS WYOMING WILL AID IN LIFT WITH THESE
DYNAMICS AIDING IN SEEDING THE LOWER DECK OF UPSLOPE INDUCED SNOW
CLOUDS BEHIND THE FRONT EAST OF THE DIVIDE. WINTER WEATHER
ADVISORIES STILL LOOK APPROPRIATE FOR THE AREAS EAST AND WEST OF
THE DIVIDE THAT ARE CURRENTLY IN EFFECT. HOWEVER...WITH DRIER AIR
AND A 1028MB SFC HIGH MOVING IN FROM THE NORTH...IT APPEARS THAT
THE HILITES CAN END AT 18Z TODAY. ACTUALLY...AREAS LIKE RIVERTON
SHOULD SEE A QUICK BURST OF SNOW WITH THE FRONT EARLY THIS MORNING
WITH STRONG DOWNSLOPE WINDS COMING OFF THE OWL CREEK MTNS PUTTING
AN EARLY END TO THE SNOW. THIS SAME NORTHERLY WIND TRAJECTORY WILL
AID IN UPSLOPE INDUCED SNOWFALL FROM LANDER TO CASPER. SKIES WILL
CLEAR TUESDAY NIGHT. WITH WARM AIR ADVECTING IN ALOFT FROM THE
NORTH BY 12Z WEDNESDAY...FRESH SNOW COVER IN PLACE AND CLEARED
SKIES...THIS SPELLS IDEAL CONDITIONS FOR FOG FORMATION IN THE
VALLEYS AND BASINS. WITH THE INCREASING SUN ANGLE THIS TIME OF
YEAR...DO NOT EXPECT THE BASINS TO STAY TRAPPED WHICH WOULD BE
MORE THE CASE FOR DEC-FEB. TEMPS SHOULD BEGIN TO RECOVER QUITE
QUICKLY WED AFTERNOON AFTER A CHILLY MORNING WEDNESDAY WITH LOWS
IN THE SINGLE DIGITS AT SOME FAR WEST LOCATIONS. THE WARMING TREND
WILL CONTINUE THROUGH THE REST OF THE WEEK WITH HIGHS BACK UP INTO
THE 50S EXPECTED BY THURSDAY AT THE LOWER ELEVATIONS EAST OF THE
DIVIDE. THE ONLY OTHER FLY IN THE OINTMENT IS A WEAK CLIPPER TYPE
SYSTEM THAT WILL BRUSH OUR AREA TO THE NORTHEAST ON THURSDAY. ANY
MOISTURE WITH THIS FEATURE WILL REMAIN TO THE NORTH AND EAST OF
THE CWA. AREAS FROM THE BIG HORN BASIN TO JOHNSON COUNTY TO
NATRONA COUNTY WILL NOTICE A SUBTLE COOL DOWN ON THURSDAY NIGHT.
ICE JAM FLOODING REMAINS A THREAT IN SOUTH CENTRAL BIG HORN COUNTY
AS DOES FLOODING FROM MELTING SNOW IN THE FAR WEST VALLEYS THROUGH
MID AFTERNOON TUESDAY.

.LONG TERM...FRIDAY THROUGH TUESDAY

FRIDAY LOOKS DRY FOR THE REGION WITH BREEZY AREAS AND MILD HIGH
TEMPS. THE NEXT WEATHER SYSTEM SPREADS MOISTURE INTO NW WY FRIDAY
EVENING AND THIS WILL BEGIN SOME SNOW FOR THE MOUNTAINS. BY 12Z
SATURDAY THE NORTHERN MOUNTAINS WILL BE SNOWING WITH THE LOWER
ELEVATIONS OF THE NORTH SEEING RAIN OR SNOW. THE WEATHER SYSTEM
MOVES THROUGH THE AREA ON SATURDAY BRINGING SCATTERED RAIN AND SNOW
TO THE LOWER ELEVATIONS EAST OF THE DIVIDE WITH SNOW FOR THE
MOUNTAINS. PRECIP IN THE SOUTHWEST LOOKS TO BE LIGHT TO NONE AT THIS
POINT. HIGHS TO BE COOLER SATURDAY AND MAY NEED TO LOWER HIGHS MORE
EAST OF THE DIVIDE IF THIS SYSTEM DOES INDEED BRING AS MUCH COLD
AIR WITH IT AS INDICATED AT 700MB. SUNDAY LOOKS DRY AND WARMER
FOR THE REGION. THE NEXT WEATHER SYSTEM IS HANDLED DIFFERENTLY BY
THE GFS AND ECMWF. THE GFS HAS THE TROUGH SPLITTING AS IT MOVES
TOWARD THE ROCKIES WITH ONLY A GLANCING BLOW FOR THE NORTH. THE
ECMWF BRINGS THE SYSTEM INTO THE GREAT BASIN MONDAY AND DOES NOT
SPLIT THE ENERGY. THIS WOULD LEAD TO A BETTER CHANCE OF PRECIP
MONDAY. LEANING TOWARD THE ECMWF FOR NOW AND HAVE A LOW CHANCE OF
PRECIP ACROSS THE REGION MONDAY INTO MONDAY EVENING. COOLER HIGHS
FOR MONDAY. NEXT TUESDAY LOOKS DRY AND MILDER.

.AVIATION.../18Z ISSUANCE/

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

IN WAKE OF A COLD FRONT LAST NIGHT...WIDESPREAD MVFR CEILINGS WITH
AREAS OF SNOWFALL WITH IFR/LIFR CONDITIONS WILL BE TAPERING OFF
FROM NORTH TO SOUTH DURING THE DAY. SKIES OVER THE BIG HORN BASIN
AND JOHNSON COUNTY SHOULD LIFT TO VFR AND OR SCATTER OUT BETWEEN
18Z AND 20Z...WHILE THE WIND RIVER BASIN AND NATRONA COUNTY
SHOULD DO THE SAME BETWEEN 21Z AND 23Z. WINDY NORTHERLY WIND WILL
CONTINUE THROUGH THE DAY. TONIGHT...MAINLY SKC CONDITIONS ARE
EXPECTED WITH WINDS BECOMING LIGHT DURING THE EVENING...WHICH
COULD LEAD TO SOME FOG IN VALLEYS/BASINS.  AREAS OF IFR CEILINGS
IN LOW STRATUS AND VISIBILITIES REDUCED IN FOG WILL DEVELOP AFTER
06Z IN THE LOWER ELEVATIONS OF THE VALLEYS AND BASINS AND MAY
IMPACT KWRL...KLND...KRIW...KGEY...KCPR AND KBYG.


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

IN WAKE OF A COLD FRONT LAST NIGHT...WIDESPREAD MVFR CEILINGS WITH
AREAS OF SNOWFALL WITH IFR/LIFR CONDITIONS WILL BE TAPERING OFF
FROM NORTH TO SOUTH DURING THE DAY. SKIES OVER THE NORTHWEST MOUNTAINS
SHOULD LIFT TO VFR AND OR SCATTER OUT BETWEEN 18Z AND 20Z...WHILE
TETON...LINCOLN AND SUBLETTE COUNTIES SHOULD DO THE SAME BETWEEN
21Z AND 23Z. WINDY NORTHERLY WIND WILL CONTINUE THROUGH THE DAY.
TONIGHT...MAINLY SKC CONDITIONS ARE EXPECTED WITH WINDS BECOMING
LIGHT DURING THE EVENING...WHICH COULD LEAD TO SOME FOG IN
VALLEYS/BASINS. AREAS OF IFR CEILINGS IN LOW STRATUS AND
VISIBILITIES REDUCED IN FOG WILL DEVELOP AFTER 06Z IN THE LOWER
ELEVATIONS OF THE VALLEYS AND BASINS AND MAY IMPACT KJAC...KAFO...
KEMM..KBPI...KPNA AND KRKS.

.FIRE WEATHER...

SIGNIFICANT SNOWFALL IS EXPECTED EAST AND WEST OF THE DIVIDE
THROUGH 12 NOON TUESDAY. VERY STRONG POST FRONTAL NORTHERLY WINDS
ARE EXPECTED THIS MORNING EAST OF THE DIVIDE. SKIES WILL CLEAR
TONIGHT. STRONG TEMPERATURE INVERSIONS WILL DEVELOP BY 12Z WED
ALONG WITH FOG AND POOR SMOKE DISPERSAL IN THE VALLEYS AND BASINS.
A WARM UP CAN BE EXPECTED FOR THE REMAINDER OF THE WEEK. A SUBTLE
COOL DOWN IS EXPECTED FROM THE BIG HORN BASIN TO JOHNSON COUNTY TO
NATRONA COUNTY FRIDAY BEHIND A WEAK WEATHER DISTURBANCE BUT EVEN
THESE AREAS WILL WARM UP AGAIN SATURDAY.

&&

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

$$

UPDATE...C.BAKER
SHORT TERM...LIPSON
LONG TERM...AR
AVIATION...C.BAKER
FIRE WEATHER...LIPSON