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000
FXUS65 KRIW 090534
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1034 PM MST SAT MAR 8 2014

.SHORT TERM...TONIGHT THROUGH SUNDAY (ISSUED AT 236 PM MST)

HAVE ISSUED HIGH WIND WARNING FOR ABSAROKA MOUNTAINS AND CODY
FOOTHILLS IN PARK COUNTY FROM 7 PM THROUGH EARLY SUNDAY MORNING...AND
FOR NATRONA COUNTY AND SOUTHERN FREMONT COUNTY FROM MIDNIGHT
THROUGH LATE SUNDAY MORNING.  AS A LEE SIDE TROUGH DEEPENS AND STRONG
SURFACE PRESSURE AND TEMPERATURE GRADIENT WILL DEVELOP.
CONDITIONS WILL BE DRY WITH INCREASING TEMPERATURES THROUGH SUNDAY.
THIS WILL CONTINUE TO MELT LOW LEVEL SNOW PACK INCREASING RUN OFF
AND ALSO MELT ICE COVER IN THE RIVERS CONTINUING THE THREAT OF ICE
JAM FLOODING. WILL EXTEND AREAL FLOOD ADVISORIES THROUGH SUNDAY
AFTERNOON.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY

ANOTHER STORM SYSTEM APPROACHES ON SUNDAY NIGHT...GIVING THE
MOISTURE FROM THE EASTERN PACIFIC SOMETHING TO WORK WITH AS THE FLOW
FLATTENS AND THE JET BEGINS TO AGITATE AN APPROACHING WAVE. MOST OF
THE PRECIPITATION WILL REMAIN IN THE NORTHWEST SUNDAY NIGHT WITH
SOME RAIN CHANGING TO SNOW IN THE VALLEYS BELOW 7000 FEET. RAIN AND
SNOW WILL SPREAD SOUTH AND EAST EARLY IN THE MORNING...BRINGING SOME
MORE RAIN TO STAR VALLEY AND LINCOLN COUNTY AROUND SUNRISE...AS THE
MORNING GOES ON...THE UPPER LEVELS BECOME MORE AND MORE DIVERGENT AS
A STRONG TROF CONTINUES TO DIG TO OUR WEST...BRINGING THE RAIN OVER
THE WYOMING AND SALT RANGES AND INTO THE UPPER GREEN RIVER BASIN.

OVERALL...THE MOST ROBUST FORCING FOR ASCENT ARRIVING MONDAY NIGHT
AND THE PRECIP WILL BECOME MORE WIDESPREAD MONDAY NIGHT AND TUES. SFC
FRONT WILL ALSO DROP INTO THE NORTHERN PORTION OF THE FORECAST AREA
MONDAY NIGHT INTO TUE MORNING BRINGING INCREASINGLY GOOD CHANCES FOR
BASIN PRECIP E OF THE DIVIDE BY MIDNIGHT. IN THE BIGHORN
MOUNTAINS...SNOW LVLS WILL START AROUND 8000 FT...BUT WILL ALSO
QUICKLY FALL TO BELOW 4000 FEET POST FRONTAL AND AFTER MIDNIGHT IN
THE ERN PORTIONS OF JOHNSON COUNTY. OVERALL...SNOW WILL BE MORE
PLENTIFUL IN THE WRN MOUNTAINS OVR THE 36 HR PERIOD ENDING TUE
MORNING...WITH THE BIG HORNS LOOKING TO GET ABOUT HALF. JOHNSON
COUNTY AND THE CODY FOOTHILLS LOOK TO MAKE OUT BEST AT THE LOWER
ELEVATIONS WITH WHAT MAY BE LOW END ADVISORY AMOUNTS.

CONCERNING THE FLOOD SITUATION...THE STORM ON SUNDAY NIGHT AND
MONDAY HAS THE POTENTIAL TO DROP ONE QUARTER TO ONE HALF INCH OF
RAIN IN THE WESTERN VALLEYS BEFORE IT CHANGES TO SNOW MONDAY NIGHT.
THIS INCLUDES STAR VALLEY...JACKSON VALLEY AND THE UPPER GREEN RIVER
BASIN. THE SNOW LEVELS WILL START OUT QUITE HIGH...WITH THE HIGHEST
SNOW LEVELS EXPECTED AS YOU HEAD FURTHER SOUTH AND EAST. SO ANY RAIN
THAT DOES OCCUR ON THE LOWER ELEVATION SNOW PACK ON MONDAY COULD ADD
A SIGNIFICANT AMOUNT OF WATER TO THE WATERSHED AS THERE IS A
SIGNIFICANT AMOUNT OF LIQUID MOISTURE STILL CONTAINED IN THIS LOW
ELEVATION SNOW. THE GOOD NEWS FOR THE BIGHORN BASIN...WIND RIVER
BASIN...NATRONA AND JOHNSON COUNTIES IS THAT THE RAINFALL WILL NOT
LAST TOO LONG AS MOST OF THE PRECIPITATION EXPECTED IN THESE AREAS
WILL BE ASSOCIATED WITH THE COLD FRONT...TEMPERATURES ARE COLD
ENOUGH BEHIND THE FRONT TO QUICKLY CHANGE THE RAIN TO SNOW.

SNOW WILL BE ENDING WEDNESDAY MORNING ACROSS THE HIGHER ELEVATIONS
OF SOUTHWESTERN WYOMING...AS THE PACIFIC STORM SYSTEM EXITS THE AREA
SOUTHWARD. PATCHY FOG WILL BE POSSIBLE ACROSS THE UPPER GREEN RIVER
BASIN...WIND RIVER BASIN OVER TO PORTIONS OF NATRONA COUNTY...AND
THE BIG HORN BASIN. HIGH PRESSURE WILL QUICKLY BUILD INTO THE AREA
IN THE WAKE OF THIS SYSTEM...AND RESIDUAL MOISTURE WILL BE AMPLE
ENOUGH FOR FOG FORMATION IN THESE LOCATIONS.

OTHERWISE...CLEAR AND DRY CONDITIONS WILL PREVAIL THROUGH THE REST
OF THE WEEK INTO THE WEEKEND. THE WARMING TREND WILL RETURN WITH
THIS PATTERN...WHICH WILL AID IN SNOW MELTING IN THE LOWER
ELEVATIONS. FLOODING WILL BE THE MAIN CONCERN THROUGH THIS
PERIOD...ESPECIALLY FOR AREAS NEAR RIVERS AND STREAMS. WESTERN
PORTIONS WILL CONTINUE TO BE AFFECTED...AS SNOW DEPTHS REMAIN
SIGNIFICANT IN STAR VALLEY...NEAR JACKSON...MOOSE...AND MORAN. A
WEAK...DRY COLD FRONT WILL MOVE THROUGH ON FRIDAY...WHICH WILL BRING
PARTLY TO MOSTLY CLOUDY SKIES TO NORTHWEST AND NORTH-CENTRAL
PORTIONS OF THE FORECAST AREA. HIGH CLOUDS COULD ALSO REMAIN ACROSS
THESE AREAS ON SATURDAY...WHICH WILL HELP MODERATE THE MELTING
SNOW.

&&

.AVIATION.../06Z ISSUANCE/

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

VFR CONDITIONS WILL OCCUR THROUGH 06Z MONDAY. GUSTY WIND CONDITIONS
AROUND THE KCOD AND KCPR TERMINAL SITE THROUGH MOST OF THE PERIOD.
STRONG MID LEVEL WIND SPEEDS WILL OCCUR WHICH WILL CAUSE SOME WIND
SHEAR AT TIMES OVER THE NEAR THE MOUNTAINS.

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

PATCHY FOG MAY OCCUR IN THE VALLEYS UNTIL 16Z WITH LOCAL MVFR TO IFR
CONDITIONS. OTHERWISE VFR CONDITIONS WILL OCCUR AT MOST TERMINAL
SITES THROUGH THE PERIOD. AT THE KJAC TERMINAL SITE CLOUDS WILL BE
LOWERING BY 00Z AS RAIN AND SNOW DEVELOPS IN THE NW MOUNTAINS AFTER
22Z. SNOW WILL OCCUR IN THE NW MOUNTAINS AFTER 01Z THROUGH 06Z
MONDAY. CONDITIONS AT KJAC TERMINAL SITE WILL LOWER TO MVFR BY 06Z
MONDAY AS SNOW DEVELOPS...WITH POSSIBLE IFR CONDITIONS.

&&

.FIRE WEATHER...

STRONG DOWNSLOPE WINDS ALONG AND NEAR THE EAST SLOPES OF THE MOUNTAINS...
MAINLY EAST OF THE CONTINENTAL DIVIDE ARE EXPECTED TONIGHT AND SUNDAY...
ESPECIALLY IN THE MORNING. SOME PATCHY FOG WILL DEVELOP IN THE VALLEYS
AND BASINS ALONG THE RIVERS TONIGHT LASTING INTO SUNDAY MORNING.
LIGHT SNOW AND CLOUDS WILL WORK INTO THE WESTERN MOUNTAINS SUNDAY
AFTERNOON AND INCREASE SUNDAY NIGHT AND MONDAY. RAIN TO A RAIN
SNOW MIXED IS EXPECTED IN THE WESTERN VALLEYS DURING THIS TIME PERIOD.
GENERALLY RELATIVE HUMIDITY WILL BE FAVORABLE EXCEPT IN THE
WINDIER AREAS. MIXING HEIGHTS WILL BE LOW TONIGHT WITH POOR SMOKE
DISPERSAL.  MIXING HEIGHTS WILL INCREASE SUNDAY AFTERNOON WITH
FAIR TO GOOD SMOKE DISPERSAL. TEMPERATURES WILL WARM SUNDAY AND MONDAY
AHEAD OF THE SNOW.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...

HIGH WIND WARNING FROM 7 PM MST THIS EVENING TO 9 AM MDT SUNDAY
WYZ002-003.

HIGH WIND WARNING FROM MIDNIGHT MST TONIGHT TO NOON MDT SUNDAY
WYZ019-020.

&&

$$

SHORT TERM...C.BAKER
LONG TERM...LAVOIE
AVIATION...AR
FIRE WEATHER...C.BAKER