Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 260215
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
715 PM MST TUE NOV 25 2014

.UPDATE...WITH THE WINDS DECREASING IN THE SOUTH WE HAVE CANCELLED
THE HIGH WIND WARNING. WE ALSO CANCELLED IN DUBOIS SINCE THE HIGH
WINDS HAVE NOT MATERIALIZED. ALL OTHER ADVSIORIES AND WARNING REMAIN
AS IS.

.SHORT TERM...TONIGHT THROUGH WEDNESDAY

MODERATE TO HEAVY SNOW CONTINUES MUCH OF THE WEST AND NORTH THIS
AFTERNOON. WARMER TEMPERATURES HAVE NOT MATERIALIZED...ESPECIALLY
IN THE LOWER ELEVATIONS AND HAS SERIOUSLY IMPACTED THE SNOW FORECAST.
STILL HANGING IN AT 32 AT AFO WITH SNOW.  MID DAY REPORT OF 7 INCHES
AT ALPINE. ALSO IN THE NORTH IN BIGHORN COUNTY 4-6 INCHES OF SNOW
WITH TEMPS 32 TO 31 POWELL...GREYBULL...WORLAND...COWLEY AND CODY.
HIGH WINDS DEVELOPED AND HAVE BEEN SUSTAINING AT KEMMERER AIRPORT
FRO THE PAST FEW HOURS. OTHER AREAS ALONG I 80 HAVE OCCASIONALLY HIT
HIGH WIND. UPGRADED ALL THE MOUNTAINS TO WINTER STORM WARNING WITH
MANY AREAS ALREADY IN THE 8 TO 11 INCH RANGE. ISSUED WINTER STORM
WARNING FOR BIGHORN COUNTY WITH WINTER WEATHER ADVISORIES FOR THE
REST OF THE BIGHORN BASIN AND EASTERN JOHNSON COUNTY. UPGRADED
JACKSON HOLE AND STAR VALLEY TO WINTER STORM WARNING. STAR VALLEY
UNTIL 07Z WITH 12Z TERMINATION IN JACKSON HOLE. WINTER WEATHER
ADVISORY FOR UPPER GREEN RIVER BASIN. HIGH WIND WARNING FOR THE
SOUTHWEST AND DUBOIS ZONES GO THROUGH 06Z. NATRONA COUNTY AND WIND
RIVER BASIN WILL SEE SOME SNOW BUT ARE EXPECTED TO BE BELOW ADVISORY
AMOUNTS AND NOT WINDY ENOUGH FOR HIGH WIND. CONDITIONS ARE EXPECTED
TO IMPROVE SLOWLY THROUGH LATE MORNING THEN IMPROVEMENT SHOULD
ACCELERATE. COOLED TEMPERATURES MOST AREAS TONIGHT AND WEDNESDAY.
THE SOUTHWEST WILL HAVE THE LEAST CHANGE IN TEMPERATURES AND WILL BE
VERY WELL MIXED.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY

ON WEDNESDAY NIGHT THE AREA OF LINGERING SNOWFALL IN NORTHWEST WY
WILL BE PERPETUATED BY THE CONTINUED STREAM OF PACIFIC MOISTURE FROM
THE NORTHWEST BUT WILL CONTINUE TO DIMINISH AS THE DYNAMICS MOVE OFF
TO THE EAST WITH THE EXITING WEATHER SYSTEM AS THE FLATTENING HIGH
PRESSURE RIDGE...NOW A STRONG RIDGE JUST OFF THE PACIFIC
COAST...BUILDS INTO WYOMING FROM THE WEST. THE STRONG FLOW FROM THE
NORTHWEST WHICH WILL BACK TO THE WEST BY FRIDAY WILL CONTINUE WITHIN
THE FLATTENING RIDGE KEEPING THE WINDS BLOWING IN THE MTNS WITHOUT A
LET UP WED NT THROUGH SATURDAY WITH THE SOUTHWEST WINDS INCREASING
IN SPEED ALONG THE SOUTHERN WIND CORRIDOR KICKING IN BY FRIDAY. AS
THIS RIDGE BUILDS IN...ALMOST ALL AREAS WILL MIX OUT WITH HIGHS IN
THE LOW TO MID 50S EXPECTED IN THE WIND RIVER BASIN...THE LOWER
ELEVATIONS OF JOHNSON AND NATRONA COUNTIES...THE WESTERN PORTION OF
THE BIG HORN BASIN AS WELL AS ACROSS PORTIONS OF SWEETWATER COUNTY
THURSDAY AND FRIDAY MAKING FOR A PLEASANT THANKSGIVING DAY MOST
AREAS. OTHER LOWER ELEVATIONS WILL HAVE HIGHS IN THE 40S WITH 30S TO
LOW 40S IN THE FAR WEST VALLEYS. HIGHS WILL ONLY BE IN THE 40S
ACROSS THE EASTERN BIG HORN BASIN THU/FRI WITH FRESH SNOW COVER IN
PLACE THERE. ONLY ISOLATED SHOWERS ARE EXPECTED IN THE NW MTNS WITH
THE CONTINUED NW TO WEST FLOW DURING THIS TIME FRAME. THEN BY
SATURDAY...SNOWFALL IN THE WEST WITH SOME RAIN MIXED IN WITH THE
SNOW IN THE WESTERN VALLEYS...IS EXPECTED AS THE NEXT NORTHERN
PACIFIC TROUGH BEING DRIVEN BY THE SPINNING POLAR VORTEX SWINGS BY
JUST TO OUR NORTH WITH NORTHERN WY BEING CONSIDERABLY COLDER THEN
CENTRAL AND SOUTHERN WY ON SUNDAY. THE SNOW WILL CONTINUE ON
SATURDAY NIGHT IN THE WEST. DRYING IS EXPECTED SUNDAY. TEMPS WILL
WARM UP MONDAY BEFORE COOLING EVERYWHERE TUE BUT NOT TO THE EXTENT
THAT IS DOES SUNDAY IN THE NORTH AS THE NEXT SPLITTING PACIFIC
TROUGH APPROACHES FROM THE WEST AND WE CAPTURE THE NORTHERN STREAM
ENERGY. THE GFS AND THE EURO ARE IN FAIRLY GOOD AGREEMENT WITH THIS.
KEPT MORE SNOW IN THE FORECAST FOR WESTERN WY MONDAY NIGHT AND
TUESDAY WITH THIS NEXT TROUGH.

&&

.AVIATION.../00Z ISSUANCE/

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

OVER THE MOUNTAINS AND NORTH IFR TO MVFR CEILINGS AND VISIBILITIES
REDUCED IN SNOW AND BLOWING SNOW WILL BE WIDESPREAD THROUGH 12Z
WEDNESDAY...THEN DECREASE THROUGH 00Z THURSDAY.  TO THE SOUTH VFR
CONDITIONS ARE EXPECTED IN THE WIND RIVER BASIN AND SOUTHERN
NATRONA COUNTIES UNTIL 02Z THEN IFR/MVFR CONDITIONS WILL SPREAD
SOUTH BEHIND THE COLD FRONT UP TO THE CONTINENTAL DIVIDE BY 05Z.
STRONG WEST WINDS 30 TO 40 KTS WITH GUSTS TO 60KTS ARE EXPECTED
ALONG AND NEAR THE EAST SLOPES OF THE MOUNTAINS UNTIL 06Z. WINDS
WILL SHIFT TO THE NORTH AS A COLD FRONT MOVES SOUTH.

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

IFR TO LOCAL MVFR CEILINGS AND VISIBILITIES REDUCED IN SNOW AND
BLOWING SNOW WILL BE ACROSS THE EAST THROUGH 15Z WEDNESDAY WITH
GRADUAL IMPROVEMENT FROM 15Z TO 18Z. STRONG WEST WINDS 30 TO 40
KTS WITH GUSTS TO 60KTS ARE EXPECTED ALONG AND NEAR THE EAST
SLOPES OF THE MOUNTAINS UNTIL 06Z THEN WILL GRADUALLY DIMINISH.

&&

.FIRE WEATHER...

COLD SNOWY WINTER WEATHER WITH STRONG WINDS AND LOW MIXING HEIGHTS
WILL PERSIST. VARIOUS WARNINGS AND ADVISORIES ARE IN EFFECT TONIGHT
FOR WIND AND SNOW. HEAVY SNOW ACCUMULATION IS POSSIBLE IN THE
NORTHERN AND WESTERN MOUNTAINS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...

WINTER WEATHER ADVISORY UNTIL 5 AM MST WEDNESDAY
WYZ003-005>007-010-011-025.

WINTER STORM WARNING UNTIL 5 AM MST WEDNESDAY
WYZ001-002-004-008-009-012>015-024.

WINTER STORM WARNING UNTIL MIDNIGHT MST TONIGHT WYZ023.

&&

$$

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










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