Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 130952
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
252 AM MST SAT FEB 13 2016

.SHORT TERM...TODAY THROUGH MONDAY NIGHT

AN APPROACHING WAVE AND ASSOCIATED COLD FRONT WILL APPROACH THE AREA
THIS MORNING...AND MOVE THROUGH THE AREA THIS AFTERNOON AND EVENING.
ADDITIONAL MOISTURE WILL BE FOUND WITHIN THIS SYSTEM TO PRODUCE
SNOWFALL OVER THE WESTERN MOUNTAINS AND INTO THE VALLEYS THROUGH THE
DAY. AS THE WAVE MOVES THROUGH THE AREA...IT IS ANTICIPATED TO BRING
SOME PRECIPITATION ACROSS AREAS EAST OF THE CONTINENTAL DIVIDE...BUT
TEMPERATURES ACROSS THE AREA WILL HELP TO KEEP THE LOWER ELEVATIONS
PRECIPITATION AS RAIN DURING THE AFTERNOON AND EARLY EVENING. AS
TEMPERATURES LOWER...CONVERSION TO SNOWFALL WILL BE POSSIBLE.

OTHER THAN PRECIPITATION...THE FRONT WILL RESULT IN GUSTY WIND
ACROSS THE AREA. THE CENTRAL MOUNTAINS AND BASINS LOOK TO EXPERIENCE
THE STRONGEST WINDS OUT OF THIS APPROACHING SYSTEM. AS THE FRONT
MOVES THROUGH THE AREA THIS EVENING IT WILL HELP WIND TO RELAX.

MOISTURE WILL CONTINUE TO MOVE ALONG THE NORTHWEST FLOW TO KEEP
SNOWFALL OVER THE NORTHWESTERN MOUNTAINS AND VALLEYS FOR THE NEXT
COUPLE OF DAYS. MOISTURE HAS A DECENT PUSH SUNDAY AND INTO
MONDAY...WITH SOME INCREASED ACCUMULATION ANTICIPATED ACROSS THE
WESTERN MOUNTAINS. BY MONDAY MORNING NEW SNOWFALL ACCUMULATIONS OF 3
TO 5 INCHES WILL BE WIDESPREAD ACROSS THE WESTERN MOUNTAINS...WITH 6
TO 7 INCHES POSSIBLE OVER THE TETON AND GROS VENTRE RANGES. THE
WESTERN VALLEYS WILL SEE POSSIBLE NEW ACCUMULATIONS OF 1 TO 3
INCHES. THIS MOISTURE PUSH WILL BE EVALUATED WITH UPCOMING MODEL
SOLUTIONS TO SEE IF ANY WINTER RELATED HIGHLIGHTS WILL BE NECESSARY.

.LONG TERM...TUESDAY THROUGH SATURDAY
RIDGE AXIS TO THE WEST GRADUALLY SHIFTS EWD TUE INTO WED. BY
00Z...THU BOTH THE ECMWF AND GFS HAVE THE AXIS CENTERED RIGHT
OVER CENTRAL WYO ALONG WITH THE H7 THERMAL RIDGE. TEMPS WILL
CONTINUE TO WARM TUESDAY INTO WEDNESDAY. WEATHER BEGINS TO CHANGE
THURSDAY AS SYSTEM APPROACHING THE KAMCHATKA AREA RIGHT NOW MOVES
ACROSS THE PACIFIC AND INTO WESTERN WYOMING EARLY THURSDAY AND
THEN MOVING EAST ACROSS THE REST OF THE AREA LATER THURSDAY INTO
THURSDAY NIGHT. SYSTEM IS STILL MOVING THROUGH THE MEAN RIDGE SO
IT MAY WEAKEN/OR SPLIT MORE THAN SHOWN BUT STILL PRODUCE SNOW FOR
THE WEST ESPECIALLY AND WIND FOR THE MTNS AND CENTRAL WYOMING.
KEEPING THE IDEA OF INCREASING WINDS WED NGT...PEAKING ON THURSDAY
WITH POTENTIAL FOR HIGH WINDS IN CENTRAL WYOMING DEPENDING ON HOW
MUCH WEAKENING OCCURS WITH THIS SYSTEM AS IT HITS THE RIDGE. TEMPS
EACH OF THE DIVIDE COULD BE TRICKY THURSDAY DEPENDING ON THE
TIMING OF THIS TROUGH. COULD STILL BE QUITE WARM...ESPECIALLY ERN
HALF. SYSTEM EXITS QUICKLY WITH HEIGHTS REBUILDING FRIDAY INTO
SATURDAY WITH VALLEY/BASIN INVERSIONS REDEVELOPING. NOT AS STRONG
AS PAST WEEKS...ESPECIALLY EAST OF THE DIVIDE WITH MOST OF THE
SNOW GONE BY THEN AFTER ANOTHER WEEK OF WELL ABOVE NORMAL TEMPS.
MODELS DIVERGE ON A SYSTEM RIGHT AT THE END OF THE MEDIUM RANGE
PERIOD WITH THE GFS KEEPING MOST OF THE ENERGY SOUTH AND THE ECMWF
SHOWING A SYSTEM RACING ACROSS MONTANA ON SATURDAY. STRENGTH OF
LONGWAVE RIDGE AND ITS PROXIMITY WILL LIKELY KEEP THIS SYSTEM FROM
HAVING A HUGE IMPACT ON OUR AREA SO WE ONLY HAVE SLGT CHANCES IN
THE WRN MTNS. TEMPS IN THE MIXED AREAS WILL COOL A LITTLE WITH
THIS SYSTEM WHILE THE BASINS/VALLEYS MAY NOT SEE A BIG CHANGE AS
THEY MIX OUT MORE BUT ALSO HAVE LIMITED WARMING POTENTIAL WITH
COOLER AIR ASSOCIATED WITH THE TROUGH. OVERALL...ONE MAIN SHOT OF
SNOW OUT WEST THURSDAY WITH MOST AREAS CONTINUING TO SEE ABOVE
NORMAL TEMPS THROUGH THE PERIOD WITH WEDNESDAY BEING THE PEAK WHEN
50S AND EVEN A FEW 60S ARE POSSIBLE EAST OF THE DIVIDE WITH MAINLY
UPPER 30S TO NEAR 50 WEST. AS NOTED LAST NIGHT...H7 TEMPS ARE
FORECAST TO BE IN THE +3 TO +4 AT H7 IN CENTRAL WYO WED
AFTN...SIMILAR TO WHAT WE SAW FRIDAY BUT WITH LESS SNOW COVER.

&&

.AVIATION.../12Z ISSUANCE/

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

FOG WILL NOT BE AS EXTENSIVE AS THE LAST FEW NIGHTS...BUT PATCHY FOG
MAY PARTIALLY OBSCURE TERRAIN IN THE WESTERN VALLEYS THROUGH 15Z SAT.

A COLD FRONT WILL PUSH ACROSS THE AREA 16Z-20Z BRINGING NMRS MTN
SHSN AND FQT MTN OBSCURATIONS VCNTY AND NORTH OF A KJAC-KDUB LINE
WITH MAINLY SCT MVFR SHSN OVER THE WESTERN VALLEYS AND FURTHER SOUTH
ALONG THE DIVIDE.  AREAS OF LLWS WILL ALSO ACCOMPANY THE COLD FRONT
VCNTY KJAC WHERE SFC WINDS WILL REMAIN SW WHILE W-NW SFC WINDS
INCREASE TO 20-30KTS AT OTHER TERMINALS.

AN INCREASINGLY MOIST NW FLOW WILL BRING WIDESPREAD MVFR/IFR -SN
INTO FAR WEST...VCNTY KJAC-KAFO 06Z-12Z SUNDAY WITH MTNS ALONG AND
WEST OF THE DIVIDE BECOMING MOSTLY OBSCURED.

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

VFR CONDITIONS WITH MAINLY SOME SCT-BKN MID AND HIGH CLOUDS WILL
PREVAIL THROUGH SATURDAY MORNING.  A COLD FRONT WILL PUSH ACROSS THE
AREA 19Z-22Z SATURDAY BRINGING SCT-NMRS MVFR/IFR SHSN VCNTY AND
NORTH OF A KBYG-KPOY LINE ALONG WITH THE BIGHORN AND ABSAROKA RANGES
BECOMING MOSTLY OBSCURED.  AREAS OF SFC NW WINDS AT 20-30KTS WITH
GUSTS NEAR 40KTS WILL FOLLOW THE FRONT...WITH THE STRONGEST WINDS
EXPECTED VCNTY KDUB-KRIW AND KSHR-KBYG THROUGH EARLY SATURDAY
EVENING.  WINDS WILL DIMINISH AFTER 02Z SUNDAY ALONG WITH SHSN
ENDING ACROSS NORTHERN WYOMING.  INCREASING MOISTURE IN WESTERLY
FLOW WILL RESULT IN THE HIGHER PEAKS OF THE WIND RIVER AND ABSAROKA
RANGE BECOMING MOSTLY OBSCURED AFTER 06Z SUNDAY.

&&

.FIRE WEATHER...

PERIODS SNOWFALL IS EXPECTED OVER THE WESTERN MOUNTAINS AND VALLEYS
FOR THE NEXT FEW DAYS. A COLD FRONT WILL MOVE THROUGH THE AREA
TODAY...WITH WIND SHIFTS ANTICIPATED AS WELL AS PERIODS OF GUSTY TO
BREEZY WIND.  SUNDAY AND INTO MONDAY LOOKS TO PRODUCE THE MOST
ACCUMULATION...WITH SOME ACTIVITY ANTICIPATED TO MOVE EAST OF THE
DIVIDE...MAINLY ACROSS NORTHERN WYOMING. DAYTIME TEMPERATURES WILL
KEEP ACTIVITY AS RAIN THROUGH THE EARLY EVENING...WITH CONVERSION TO
SNOWFALL POSSIBLE WITH DROPPING OVERNIGHT TEMPERATURES. LIGHT
SNOWFALL WILL CONTINUE THROUGH MONDAY....MAINLY OVER THE WESTERN
MOUNTAINS AND VALLEYS.

&&

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

&&

$$

SHORT TERM...BRANHAM
LONG TERM...PS
AVIATION...AEM
FIRE WEATHER...BRANHAM


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