Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 102148
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
348 PM MDT WED SEP 10 2014

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT

THE FIRST OF TWO WINTRY PUNCHES IS CURRENTLY UNDERWAY ACROSS
NORTHEASTERN WYOMING. PORTIONS OF THE BIGHORN MOUNTAINS ARE
EXPERIENCING SNOWFALL...WHICH IS EXPECTED TO PERSIST THIS AFTERNOON.
THE LOWER ELEVATIONS OF JOHNSON COUNTY HAVE RECEIVED RAINFALL FOR
THE BETTER PART OF THE DAY.

THE SECOND...MORE POTENT PUNCH OF WINTRY WEATHER WILL OCCUR THIS
EVENING. A STRONGER AND COLDER PUSH OF MOISTURE WILL MOVE ACROSS
NORTHEASTERN WYOMING. THIS SYSTEM WILL BRING THE POTENTIAL FOR
SIGNIFICANT SNOWFALL ACROSS NORTHEASTERN WYOMING...ESPECIALLY OVER
THE BIGHORN MOUNTAINS AND NORTHERN JOHNSON COUNTY. THE NORTHERN
THIRD OF THE ABSAROKA MOUNTAINS WILL ALSO SEE SIGNIFICANT ADVERSE
IMPACTS FROM THIS SYSTEM. SNOWFALL OF 6 TO 10 INCHES WILL BE
ANTICIPATED OVER THE NORTHERN PORTION OF THE ABSAROKA
MOUNTAINS...WITH 7 TO 12 INCHES OVER THE NORTHERN BIGHORN
MOUNTAINS...AND 3 TO 7 INCHES OVER NORTHERN JOHNSON COUNTY.
TEMPERATURES OVER THE LOWER ELEVATIONS WILL KEEP SNOWFALL FROM
ACCUMULATING VERY SIGNIFICANTLY ON ROADWAYS...BUT THE PERIODS OF
MODERATE SNOWFALL WILL IMPACT TRAVEL AND VEGETATION ACROSS THE AREA.
WINTER STORM WARNINGS HAVE BEEN ISSUED FOR NORTHERN JOHNSON
COUNTY...THE BIGHORN MOUNTAINS...AND THE ABSAROKA MOUNTAINS.

TO A LESSER EXTENT...MODERATE IMPACTS MAY BE SEEN OVER THE CODY
FOOTHILLS AND SOUTHERN JOHNSON COUNTY. SNOWFALL IS ANTICIPATED OVER
THESE AREAS...BUT ACCUMULATION IS NOT EXPECTED TO HAVE AS MUCH
IMPACT AS THE PREVIOUSLY DISCUSSED AREAS. REGARDLESS...TRAVEL ROUTES
WILL BE IMPACTED ALONG WITH VEGETATION...LEADING TO WINTER WEATHER
ADVISORIES FOR THESE LOCATIONS. FOR SPECIFIC DETAILS ON
TIMING...PLEASE REFER TO OUR WINTER WEATHER HIGHLIGHTS.

.LONG TERM...FRIDAY THROUGH WEDNESDAY NIGHT

A MUCH QUIETER PERIOD IS EXPECTED AS COMPARED TO MY ESTEEMED SHORT
TERM COLLEAGUE. THE ONE CONCERN IS FOR THE POTENTIAL FOR A FREEZE WHERE
SNOW DOES NOT OCCUR. WITH A RATHER COLD AIR MASS MOVING IN THE SKY
EXPECTED TO CLEAR LATE AT NIGHT...MANY AREAS WILL FALL DOWN INTO THE
20S FOR LOW TEMPERATURES FRIDAY MORNING. AS A RESULT... WE WILL
HOIST FREEZE WATCHES FOR THE LOWER ELEVATIONS EAST OF THE DIVIDE ANY
TRACES OF THE STORM WILL HAVE EXITED TO THE SOUTH AND EAST BY
FRIDAY MORNING. WE DID ADD SOME PATCHY FOG ACROSS AREAS WITH GREATER
THAN 1 INCH OR SNOWFALL ACCUMULATION WITH SOME MELTING EXPECTED DUE
TO WARM GROUND TEMPERATURES AND CLEARING LATE THURSDAY NIGHT.
OTHERWISE...EXPECT TRANQUIL WEATHER THROUGH FRIDAY INTO SATURDAY.
FLOW BECOMES ZONAL TO EVENTUALLY SOME RIDGING THAT WILL BRING MORE
SUNSHINE ALONG WITH GRADUALLY WARMING TEMPERATURES WARMING BACK TO
THE 60S FOR MANY LOWER ELEVATION LOCATIONS BY SATURDAY...WHICH WILL
MAKE QUICK WORK OF ANY LEFTOVER SNOW ACCUMULATION. SUNDAY LOOKS
MAINLY DRY FOR MOST AREAS. ONE FLY IN THE OINTMENT IS THE EUROPEAN
WHICH BRINGS A WEAK SHORTWAVE THROUGH THE FLOW AND BRUSHES THE
NORTHEASTERN AREAS WITH SOME QPF BUT UNTIL THERE IS MORE
CONSISTENCY WE KEEP THINGS DRY. BY MONDAY TEMPERATURES LOOK TO BE
NEAR TO ABOVE NORMAL FOR MOST LOCATIONS ONCE AGAIN. THE EUROPEAN
TRIES TO CREEP SOME MONSOONAL MOISTURE BACK NORTHWARD INTO
SWEETWATER COUNTY BUT THE OTHER MODELS ARE DRY SO AGAIN WE KEPT
THINGS DRY. THE GENERAL PATTERN FOR EARLY NEXT WEEK LOOKS LIKE AN
AMPLIFYING RIDGE OVER THE ROCKIES THAT WILL BRING ABOVE NORMAL
TEMPERATURES. A WEAK SHORTWAVE MAY DROP TO MOVE INTO WESTERN AREAS
FOR TUESDAY BUT AT THIS POINT IT APPEARS MOISTURE STARVED SO AGAIN
WE LEFT THE FORECAST MAINLY DRY.

&&

.AVIATION.../00Z ISSUANCE/

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

THE AVIATION COMMUNITY WILL SEE RAPIDLY DETERIORATING CONDITIONS
TONIGHT ACROSS NORTHERN WYOMING. A STRONG WINTER-LIKE SYSTEM WILL IMPACT
THE AREA...SPREADING MIXES OF RAIN AND SNOW NORTH AND EAST OF A LINE
FROM KCOD-KRIW-KCPR. SOME TERMINALS WILL SEE PREVAILING SNOWFALL
AFTER 09Z TONIGHT...AND POSSIBLY TO 18Z THURSDAY MORNING. WITH THE
EXCEPTION OF KCOD...NONE OF THESE TERMINALS ARE TAF RECEIVING. KBYG
WILL BE ONE OF THE MOST IMPACTED AIRPORTS THAT WILL RECEIVE SNOW
TONIGHT INTO THURSDAY MORNING. PERIODS OF MVFR CONDITIONS ARE
ANTICIPATED WITH THIS SYSTEM... WITH INSTANCES OF IFR CONDITIONS.
THE WORST CONDITIONS WILL BE BETWEEN 03Z AND 18Z THURSDAY...AS
PRECIPITATION AND COLD TEMPERATURES SPREAD SOUTH THROUGH THE AREA.
SNOW...REDUCED VISIBILITIES...LOW CEILINGS...AND ICING CONDITIONS
WILL ALL BE POSSIBLE DURING THIS TIME FRAME. MOUNTAIN AVIATION
PASSES WILL ALSO BECOME HAZARDOUS DURING THIS SYSTEM...WITH
INCREASED ICING AND TURBULENCE....AND MOUNTAIN OBSCURATION.

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

THIS EVENING WILL SEE A FEW CLOUDS...ALONG WITH SOME GUSTY
WINDS...FOR AREAS WEST OF THE DIVIDE. GUSTY WINDS WILL MOSTLY BE
SEEN ACROSS SOUTHERN WYOMING...ESPECIALLY AT KRKS. AS A SYSTEM
PUSHES THROUGH NORTHEASTERN WYOMING ON THURSDAY A RETURN OF GUSTY
WIND WILL BEGIN AFTER 15Z THURSDAY. INCREASED CLOUD COVER WILL BE
POSSIBLE OVER THE NORTHERN AND CENTRAL MOUNTAINS....WHICH MAY RESULT
IN SOME MOUNTAIN OBSCURATION BETWEEN 00Z AND 06Z THIS EVENING.
OTHERWISE...GENERALLY VFR CONDITIONS ANTICIPATED AT AIRPORTS.

&&

.FIRE WEATHER...

WINTRY SYSTEMS WILL IMPACT THE NORTHEASTERN HALF OF THE FORECAST
AREA THROUGH THURSDAY EVENING. THIS WILL BRING COLDER
TEMPERATURES...ALONG WITH SNOWFALL. SOME SNOWFALL MAY BE
SIGNIFICANT...ESPECIALLY OVER THE ABSAROKA AND BIGHORN MOUNTAINS AND
NORTHERN JOHNSON COUNTY AND A LESSER EXTEND OVER SOUTHERN JOHNSON
AND THE CODY FOOTHILLS. THE SOUTHWESTERN HALF OF THE AREA WILL SEE
MORE BENIGN CONDITIONS...WITH PARTLY CLOUD SKIES AND COOLER
TEMPERATURES. SOME PERIODS OF GUSTY WIND WILL BE FOUND ACROSS THE
SOUTH. OVERALL FIRE WEATHER CONCERNS ARE VERY LOW OVER THE NEXT
COUPLE DAYS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM MDT THURSDAY
WYZ002-008-009.

FREEZE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING
WYZ004>006-017-018-020.

WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM MDT
THURSDAY WYZ003-011.

WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM MDT THURSDAY
WYZ010.

&&

$$

SHORT TERM...BRANHAM
LONG TERM...HATTINGS
AVIATION...ANGLIN
FIRE WEATHER...BRANHAM




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