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000
FXUS65 KRIW 110028
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
628 PM MDT MON MAR 10 2014

.UPDATE...

DECIDED TO INCLUDE NORTHERN JOHNSON...BUFFALO...INTO THE WINTER WX
ADVISORY BEGINNING AT 10 PM TONIGHT THRU 4 PM. KEPT HIGH WIND
WARNING ONGOING ACROSS NORTHERN JOHNSON. USUALLY THIS WOULD RESULT
IN A BLIZZARD WARNING. HOWEVER...CURRENT THINKING IS THAT WIND
/SUSTAINED 35+ MPH/ AND VSBY CRITERIA /1/4SM OR LESS/ TOGETHER WILL
NOT BE MET FOR 3+ HOURS.

ENDED THE BUFFALO ADVISORY AT 4 PM...BUT ALL OF THE NORTHERN ZONES
COULD ACTUALLY SEE MUCH OF THE SNOW END BY LATE MORNING OR MIDDAY
TUESDAY. HOWEVER TO KEEP TIMING THE SAME AS THE ALREADY ISSUED
WINTER WX ADVISORY.

ALSO ALLOWED THE HIGH WIND WARNING FOR THE ABSAROKA AND CODY
FOOTHILLS EXPIRE AT 6 PM.

NO OTHER CHANGES AT THIS TIME.

&&

.PREV DISCUSSION... /ISSUED 243 PM MDT MON MAR 10 2014/

SHORT TERM...TONIGHT THROUGH TUESDAY

A COMPLEX WINTER TROUGH WILL PASS THROUGH THE AREA THROUGH THE
SHORT TERM BRINGING SNOW...LOCALLY HEAVY IN THE MOUNTAINS AND
ALONG NORTH AND EAST FACING SLOPES EAST OF THE CONTINENTAL DIVIDE.
THE LOWER ELEVATIONS SHOULD SEE RAIN INITIALLY AND THEN TURN TO
SNOW. AS THE COLD FRONT MOVES SOUTH FROM MONTANA...HIGH WINDS WILL
DEVELOP ACROSS THE LOWER ELEVATIONS OF THE NORTH THEN SPREAD INTO
CENTRAL AREAS LATER TONIGHT. HIT THE WINDS THE HARDEST WHERE HIGH
WINDS WILL DOMINATE THE WEATHER STORY AND WENT WITH WINTER WEATHER
ADVISORIES WHERE THE SNOW AND BLOWING SNOW IS EXPECTED TO BE THE PRIME
WEATHER STORY. BY MID AFTERNOON SNOW SHOULD BE ALL BUT OVER WITH
DIMINISHING WINDS AS THE SYSTEM MOVES SOUTH AND EAST OUT OF THE
AREA.

ICE JAM FLOODING CONTINUES TO BE A PROBLEM IN THE EASTERN BIG HORN
BASIN ALONG THE BIG HORN AND NOWOOD RIVERS IN NORTHERN WASHAKIE
COUNTY AND BIG HORN COUNTY. THE WORST IS AROUND GREYBULL AND
MANDERSON. LOCAL SNOW MELT FLOODING WILL REMAIN A THREAT...AND MAY
BE INCREASED BY RAINFALL IN THE STAR VALLEY AND JACKSON HOLE AS WELL
AS PARTS OF YELLOWSTONE NATIONAL PARK BELOW 7500 FEET.  SOME FLOODING
CONTINUES TO BE REPORTED ALONG CASPER CREEK NORTHWEST OF THE CITY
OF CASPER.

LONG TERM...TUESDAY NIGHT THROUGH MONDAY

CHANCES FOR PRECIPITATION WILL QUICKLY DIMINISH BETWEEN 00Z AND 06Z
WEDNESDAY...AS THE STORM SYSTEM MOVES INTO COLORADO/UTAH. MOST OF
THIS ACTIVITY WILL BE CONFINED ACROSS THE WIND RIVER MOUNTAINS AND
SALT AND WYOMING RANGES. TEMPERATURES WILL BE COLD WEDNESDAY
MORNING...WITH MOST LOCATIONS DROPPING INTO THE SINGLE DIGITS AND
TEENS. LOWER TO MIDDLE 20S WILL OCCUR IN THE NORTHERN BIG HORN
BASIN...JOHNSON COUNTY...AND ISOLATED POCKETS OF WESTERN SWEETWATER
COUNTY.

OTHERWISE...FORECAST REMAINS ON TRACK THROUGH THE REST OF THE WEEK
AS HAS BEEN DEPICTED THROUGH THE LAST SEVERAL MODEL RUNS. NO CHANGES
THROUGH THE EXTENDED PERIOD...AS HIGH PRESSURE CONTINUES TO REMAIN
IN CONTROL THROUGH FRIDAY EVENING. MOSTLY CLEAR SKIES AND DRY
CONDITIONS WILL BE THE NORM THROUGH THIS TIME...AS A WARMING TREND
RETURNS ON WEDNESDAY. AFTERNOON TEMPERATURES ON WEDNESDAY WILL RANGE
FROM THE MIDDLE 30S ACROSS WESTERN PORTIONS...TO THE UPPER 40S AND
ISOLATED LOWER 50S EAST OF THE DIVIDE. DAYTIME TEMPERATURES WILL
RANGE FROM THE LOWER 40S TO LOWER 50S ACROSS THE AREA THURSDAY AND
FRIDAY. OVERNIGHT TEMPERATURES WILL DROP BELOW FREEZING THROUGH THIS
PERIOD...DUE TO MOSTLY CLEAR SKIES. FLOODING CONCERNS WILL RETURN
DUE TO THESE CONDITIONS...ESPECIALLY FOR LOCATIONS WHERE APPRECIABLE
SNOW IS A FOOT OR MORE IN DEPTH. THESE LOCATIONS WOULD
INCLUDE...AROUND YELLOWSTONE...JACKSON HOLE...AND STAR VALLEY. ICE
JAM FLOODING IS NOT EXPECTED TO BE AS MUCH OF A THREAT...NOW THAT
RIVERS HAVE STARTED TO THAW.

THE GFS AND ECMWF STILL HAVE NOT COME IN LINE WITH EACH OTHER...WITH
RESPECT TO THE QUICK HITTING DISTURBANCE EXPECTED ON SATURDAY. THE
ECMWF HAS NOW BECOME THE MORE BULLISH MODEL...SLOWLY DIGGING THIS
SYSTEM INTO THE SOUTHERN ROCKIES EARLY SUNDAY MORNING...WHILE THE
GFS QUICKLY MOVES IT INTO THE MIDDLE MISSISSIPPI VALLEY DURING THE
SAME TIME. EVEN WITH THE ECMWF SOLUTION...IMPACTS APPEAR TO BE
MINIMAL AT THIS TIME. ANY PRECIPITATION DOES NOT LOOK TO HASTEN ANY
FLOODING EFFECTS. IF ANYTHING...TEMPERATURES SHOULD COOL A
BIT...WHICH SHOULD SLOW DOWN ANY MELTING WE GET FROM WEDNESDAY
THROUGH FRIDAY.

A HIGH PRESSURE RIDGE QUICKLY BUILDS BACK OVER THE AREA SUNDAY AND
MONDAY...WITH ANOTHER WEAK DISTURBANCE IMPACTING NORTHERN PORTIONS
BY TUESDAY MORNING. WINDS MAY BE AN ISSUE ACROSS THE FORECAST AREA
MONDAY...WITH H7 WINDS OF 40 TO 50 KTS FROM THE WEST. ATMOSPHERE
ALSO LOOKS TO BE WELL MIXED AS THE RIDGE AXIS BEGINS TO
COLLAPSE...IN ADVANCE OF THE NEXT DISTURBANCE MOVING SOUTHWARD FROM
CANADA.

AVIATION.../00Z ISSUANCE/

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

SNOW WILL OCCUR IN ABSAROKA...AND BIGHORN MOUNTAINS AND EAST
SLOPE OF THE WIND RIVER MOUNTAINS THROUGH 21Z TUESDAY...EXPECT
MVFR TO IFR CEILINGS AND VISIBILITIES REDUCED IN SNOW AND BLOWING
SNOW. VFR CONDITIONS WILL OCCUR THROUGH 06Z TUESDAY AT THE SOUTHERN
TERMINAL SITES. OVER THE NORTH A COLD FRONT WILL PUSH SOUTH FROM
MONTANA AND SNOW WILL DEVELOP OVER THE NORTH AND SPREAD SOUTH INTO
CENTRAL WYOMING FROM KLND TO KCPR AFTER 06Z. THE COLD FRONT WILL
MOVE THROUGH THE SOUTH WITH SNOW DEVELOPING AROUND 09Z. THIS WILL
LEAD TO MVFR TO IFR CEILINGS AND VISIBILITIES REDUCED IN SNOW AND
BLOWING SNOW. VERY STRONG NORTH WINDS WILL DEVELOP ALONG AND
BEHIND THE COLD FRONT IMPACTING ALL OF THE AIRPORTS.

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

VALLEY RAIN AND MOUNTAIN SNOW WILL OCCUR OVER WESTERN WYOMING.
THEN RAIN WILL CHANGE TO SNOW IN THE VALLEYS AFTER 06Z . THE KJAC
TERMINAL SITE WILL BE IMPACTED BY THE SNOW.  MVFR TO IFR CEILINGS
AND VISIBILITIES REDUCED IN SNOW...BLOWING SNOW AND FOG WILL
PREVAIL IN NW WY THROUGH THE PERIOD.  RAIN AND SNOW WILL SPREAD
OVER ALL OF THE WESTERN MOUNTAINS AS WELL AS THE STAR VALLEY.
EXPECT MVFR TO IFR CONDITIONS TO OCCUR. SOME RAIN AND SNOW WILL
IMPACT THE KBPI AND KPNA TERMINALS THROUGH 03Z TUE...WITH ALL
SNOW AFTER 03Z UNTIL AROUND 21Z. THE KRKS TERMINAL SITE WILL HAVE
VFR CONDITIONS UNTIL 02Z THEN EXPERIENCE PERIODS OF MVFR TO IFR
CONDITIONS WITH A GUSTY WINDS.

FIRE WEATHER...

SNOW WITH SOME LOWER ELEVATION RAINS WILL SPREAD EAST AND SOUTH
TONIGHT THROUGH TUESDAY.  VARIOUS WINTER WEATHER ADVISORIES AND HIGH
WIND WARNINGS ARE IN EFFECT SO REFER TO THESE PRODUCTS FOR DETAILS.
MOST OF THE AREA WILL GET SNOWFALL WITH LOCALLY HEAVY AMOUNTS IN THE
MOUNTAINS AND ALONG NORTH AND EAST FACING SLOPES EAST OF THE
CONTINENTAL DIVIDE. TEMPERATURES WILL BECOME MUCH COLDER WITH
GENERALLY ELEVATED RELATIVE HUMIDITY. MIXING HEIGHTS WILL BE LOW
WITH POOR SMOKE DISPERSAL. PARTIAL CLEARING WILL OCCUR TUESDAY
NIGHT WITH FOG DEVELOPING IN THE VALLEYS. WEDNESDAY MORNING WILL
BE COLD AND THEN A DRY AND WARMING PERIOD BEGINS AND EXTENDS
THROUGH THE WEEK.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 11 PM MDT THIS EVENING WYZ019-020.

WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 4 PM MDT
TUESDAY WYZ015-018>020-022.

WINTER WEATHER ADVISORY UNTIL 4 PM MDT TUESDAY
WYZ001-008-009-012-014-024.

HIGH WIND WARNING FROM 10 PM THIS EVENING TO 9 AM MDT TUESDAY
WYZ004>006-010-011-017.

WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 4 PM MDT
TUESDAY WYZ010.

WINTER WEATHER ADVISORY UNTIL 4 PM MDT TUESDAY WYZ002-003-007.

&&

$$

UPDATE...WM
SHORT TERM...C.BAKER
LONG TERM...LAVOIE
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER