Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 262145
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
245 PM MST WED NOV 26 2014

.SHORT TERM...TONIGHT THROUGH THURSDAY

LIGHT SNOW WILL DECREASE OVER THE NORTHERN MOUNTAINS...THE
NORTHERN BIGHORN BASIN AND NORTHERN JOHNSON COUNTY TONIGHT WITH
WIDELY SCATTERED SHOWERS LINGERING OVER THE NORTHWEST THROUGH
THURSDAY. TEMPERATURES WILL WARM AS WEST WINDS INCREASE ACROSS THE
AREA. HIGH WINDS WILL BECOME A THREAT EAST OF THE CONTINENTAL
DIVIDE...ESPECIALLY IN THE ABSAROKA MOUNTAINS INTO THE CODY
FOOTHILLS. PLEASE REFER TO THE HIGH WIND WATCH FOR MORE DETAILS.
IN THE VALLEYS AND BASINS ALONG RIVERS AND LAKES... AREAS OF FOG
MAY DEVELOP TONIGHT AND REMAIN INTO THURSDAY MORNING BEFORE
DISSIPATING.

.LONG TERM...THURSDDAY NIGHT THROUGH WEDNESDAY

BEGINNING OF FCST...WRN CONUS UPR LVL RIDGE PUSHING INTO AND
FLATTENING ACROSS THE FA. SFC SHOWS GENERAL HI P WEST WITH LOWERING
PRESSURE EAST OF THE BIGHORN MOUNTAINS ACROSS ERN WY. TIGHTENING
THERMAL AND PRESSURE GRAD ALONG/OVR/NEAR ABSAROKA MOUNTAINS IN
ADDITION TO INCREASING WINDS ALOFT BECOMING MORE FAVORABLY ORIENTED
IN ALL DIRECTIONS WITH RESPECT TO THE MOUNTAIN RIDGELINES FOR
EXCELLENT MOUNTAIN WAVE PRODUCTION...GIVING AN EXTENDED PERIOD OF
STRONG...POSSIBLY DAMAGING...WINDS ACROSS THE ABSAROKAS AND ADJACENT
CODY FOOTHILLS. THIS SET-UP WILL LAST FROM LATER IN THE DAY
THANKSGIVING THRU THE DAY ON SATURDAY. AN NPW FOR A HIGH WIND WATCH
HAS BEEN ISSUED.

THE RIDGE CONTINUES TO FLATTEN THROUGH THE DAY ON FRIDAY WITH THE
APPROACH OF THE NEXT SW TROF AND ASSOCIATED JET. A SRN STREAM OF
MODEST MOISTURE WILL CONTINUE TO STREAM INTO NWRN WY THRU THE DAY ON
FRIDAY OFFERING LOW END CHCS FOR OROGRAPHICALLY FORCED SNOW ACROSS
THE MOUNTAINS OF MAINLY YELLOWSTONE THE WAY IT LOOKS ATTM.
HOWEVER...FCST EPV FIELDS SHOW MAJOR CYCLO/FRONTO-GENESIS ALSO
BEGINNING DURING THE DAY OVR THE NWRN CONUS...CONTINUING INTO THE NRN
ROCKIES THRU THE REST OF THE DAY AND BECOMING A MAJOR PLAYER ACROSS
THE WRN FA BY SAT AS MORE PAC MOISTURE ALSO SINKS INTO THE REGION
BEGINNING LATER FRI NIGHT. THROUGH THE DAY SAT...STRONG SFC TO UPR LVL
FORCING WILL COME TOGETHER ALONG WITH THE INCREASING AVAILABLE
MOISTURE AND TERRAIN FORCING TO GIVE A GOOD PERIOD...18 TO 24
HRS...OF MODERATE TO HEAVY SNOWFALL OVR THE WRN MOUNTAINS. WITH
SNOWFALL RATES INCREASING AND FCST TO AVG AROUND AN INCH/HR AT
TIMES...TOTAL SNOW FALL OF 12 -16 INCHES IN THE MOUNTAINS WILL NOT
BE OUT OF THE ORDINARY...WITH 4 TO 8 ACROSS THE VALLEYS. WILL WATCH
THE EVOLUTION OF THE STORM FOR CONSISTENCY WITH RESPECT TO POSITION
AND INTENSITY OVR THE NEXT 24 HRS BEFORE DECIDING THE EXACT
HIGHLIGHTS NEEDED OUT WEST. THEN...IT DOES LOOK LIKE THIS STORM WILL
AFFECT MOST OF THE REST OF THE CWA ON SUNDAY AS...WHAT LOOKS TO BE A
WELL FORMED FRONT PUSHES SOUTH ACROSS THE FA GIVING AT LEAST A SHORT
PERIOD OF DECENT UPSLOPE FLOW OVR THE CNTRL BASINS AS WELL THE ERN
ZONES. BEST OVERALL FORCING E OF THE DIVIDE LOOKS TO SET-UP FROM
JOHNSON AND NATRONA COUNTIES...TO ERN FREMONT AND TOWARD THE SOUTH
PASS AREA. THIS SITUATION COULD PRODUCE GOOD AMOUNTS OF SNOW
PARTICULARLY ACROSS THE SRN HALF OF NATRONA COUNTY WHERE DEEP
FORCING AND MOISTURE WILL BE MAXIMIZED FOR A 6 TO 9 HR PERIOD. WILL
CONTINUE TO MONITOR THIS AREA FOR FUTURE HIGHLIGHTS.

THE FRONT PASSES THRU THE CWA MON NIGHT WITH MOSTLY FAIR/COLD
CONDITIONS MON AHEAD OF ANOTHER GOOD UPR LVL SITUATION LEADING FROM
LEE TROFFING TO EVENTUALLY LEE SIDE CYCLOGENESIS ACROSS THE HIGH
PLAINS OF WY/CO THRU THE DAY TUE. BY LATER MON NIGHT...TERRAIN
FORCED SNOW LOOKS PROMISING ONCE AGAIN IN THE NW MOUNTAINS BEFORE
WRAP-AROUND FORCING FROM THE LEE CYCLOGENESIS ALLOWS FOR INCREASING
POPS ACROSS THE SRN HALF OF THE FA FROM WEST TO EAST LATER TUE INTO
WED.

&&

.AVIATION.../00Z ISSUANCE/

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

AREAS OF MVFR TO IFR CEILINGS AND VISIBILITIES REDUCED IN LIGHT
SNOW AND FOG WILL GRADUALLY DECREASE THROUGH 15Z ACROSS THE NORTH
IMPACTING VICINITY KCOD...KWRL...KGEY...KPOY AND KBYG AT TIMES.
TO THE SOUTH AREAS OF FOG MAY DEVELOP ALONG THE RIVERS AND RESERVOIRS
ACROSS THE BIGHORN BASIN AND WIND RIVER BASIN AND MAY PRODUCE PERIODS
OF IFR CEILINGS AND VISIBILITIES REDUCED IN FOG VICINITY KTHP...KRIW
AND KLND. ALONG AND EAST OF THE CONTINENTAL DIVIDE STRONG WEST
WINDS WILL INCREASE WITH AREAS OF 35 TO 45 KTS GUSTING TO 65 KTS
ALONG THE EAST SLOPES OF THE ABSAROKA MOUNTAINS AFT 18Z.

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

AREAS OF MVFR TO IFR CEILINGS AND VISIBILITIES REDUCED IN LIGHT
SNOW AND FOG WILL GRADUALLY DECREASE THROUGH 15Z ACROSS THE NORTHERN
MOUNTAINS. TO THE SOUTH AREAS OF FOG MAY DEVELOP ALONG THE RIVERS
AND RESERVOIRS IN THE VALLEYS AND MAY PRODUCE PERIODS OF IFR
CEILINGS AND VISIBILITIES REDUCED IN FOG VICINITY KJAC...KAFO...
KBPI AND KPNA. OVER THE HIGHER MOUNTAINS AND EAST TO THE
CONTINENTAL DIVIDE...STRONG WEST WINDS WILL INCREASE WITH AREAS
OF 35 TO 45 KTS GUSTING TO 65 KTS AFT 18Z.

&&

.FIRE WEATHER...

LIGHT SNOW WILL DECREASE OVER THE NORTHERN MOUNTAINS...THE
NORTHERN BIGHORN BASIN AND NORTHERN JOHNSON COUNTY TONIGHT WITH
WIDELY SCATTERED SHOWERS LINGERING OVER THE NORTHWEST THROUGH
THURSDAY. TEMPERATURES WILL WARM AS WEST WINDS INCREASE ACROSS THE
AREA. HIGH WINDS WILL BECOME A THREAT EAST OF THE CONTINENTAL
DIVIDE...ESPECIALLY IN THE ABSAROKA MOUNTAINS INTO THE CODY
FOOTHILLS. IN THE VALLEYS AND BASINS ALONG RIVERS AND LAKES...
AREAS OF FOG MAY DEVELOP TONIGHT AND REMAIN INTO THURSDAY MORNING
BEFORE DISSIPATING. SNOW COVER WILL REMAIN WIDESPREAD OVER MOST OF
THE AREA WITH LOW FIRE WEATHER CONCERNS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM THURSDAY AFTERNOON THROUGH SATURDAY
AFTERNOON WYZ002-003.

&&

$$

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









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