Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 150536
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1136 PM MDT TUE APR 14 2015

.SHORT TERM...TONIGHT THROUGH WEDNESDAY (ISSUED AT 349 PM MDT)

IN THE WESTERN MOUNTAINS THE SHOWERS WILL TURN TO SNOW WITH STRONG
WINDS CAUSING BLOWING SNOW. THE SNOW WILL SPREAD EAST THROUGH THE
NIGHT MOVING INTO THE WIND RIVER AND ABSAROKA MOUNTAINS BY MIDNIGHT.
THE SNOW WILL THEN SPREAD FROM THE NORTHWEST TO THE SOUTHEAST
THROUGH WEDNESDAY.  THE LOWER ELEVATIONS OF THE BIGHORN BASIN...WIND
RIVER BASIN...NATRONA AND JOHNSON COUNTIES WILL LIKELY SEE THE SNOW
MIX WITH OR CHANGE TO SNOW AT TIMES WEDNESDAY BEFORE THE COLDER AIR
MOVES IN LATER WEDNESDAY AFTERNOON AND EVENING. PLEASE REFER TO THE
RED FLAG WARNING...HIGH WIND WARNING AND WINTER STORM WARNING AND
WINTER WEATHER ADVISORIES FOR MORE DETAILS IN YOUR AREA AS THIS IS A
VERY COMPLEX STORM.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY

THE MOST SIGNIFICANT WEATHER IN THE FORECAST PERIOD WILL OCCUR IN
THE FIRST 24 HOURS...AS THE AREA OF LOW PRESSURE CONTINUES TO MOVE
THROUGH THE STATE. MODELS HAVE SLOWED DOWN THE DEPARTURE OF THE
SYSTEM A BIT...WITH SHOWERS EXPECTED TO LINGER THROUGH THURSDAY
MORNING ACROSS THE SOUTH AND EAST. COOLER TEMPERATURES WILL KEEP
ACTIVITY PREDOMINATELY SNOW...WITH AREAS OF BLOWING SNOW POSSIBLE
WEDNESDAY NIGHT.

BUILDING NORTHERLY FLOW WILL MOVE OVER THE AREA LATE THURSDAY AND
INTO FRIDAY AS A RIDGE OF HIGH PRESSURE WORKS TO MOVE OVER THE
PACIFIC NORTHWEST. THE AXIS OF THE RIDGE WILL REMOVE OFF THE PACIFIC
COASTLINE THROUGH THURSDAY NIGHT. MODELS IN FAIR AGREEMENT THAT
SHOWERS WILL OFFICIALLY DRY OUT FRIDAY MORNING ACROSS THE
AREA...WITH WIDESPREAD BENIGN CONDITIONS.

A WEAK WAVE OF LOW PRESSURE WILL MOVE INTO WESTERN WYOMING BY
SATURDAY AFTERNOON AND EVENING...POTENTIALLY SPREADING SHOWERS OVER
THE NORTHERN HALF OF THE AREA BY SATURDAY EVENING. SCATTERED SHOWERS
WILL LINGER THROUGH SUNDAY ACROSS THE AREA...WITH A RETURNING
NORTHWESTERLY FLOW ANTICIPATED BY MONDAY MORNING. SHOWERS WILL
DISSIPATE ACROSS THE AREA. ANOTHER PUSH OF MOISTURE IS POSSIBLE
TUESDAY...THOUGH MODELS ARE NOT IN FAIR AGREEMENT WITH THE ARRIVAL
OF THIS SYSTEM. THE ECMWF MAINTAINS A WIDELY DRY SOLUTION...WHILE
THE GFS INDICATES PRECIPITATION SPREADING ACROSS THE AREA. TRENDED
THE FORECAST PACKAGE MORE TOWARDS THE ECMWF UNTIL MODEL CONSISTENCY
INCREASES.

&&

.AVIATION.../06Z ISSUANCE/

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

CLOUDS WILL LOWER OVER THE EAST OVERNIGHT AND RAIN AND SNOW DEVELOPS
OVER MANY LOCATIONS. A MIX OF RAIN AND SNOW MAY OCCUR IN THE BIGHORN
BASIN INCLUDING AROUND KWRL THROUGH THE DAY WEDNESDAY. THE OTHER
TERMINAL SITES WILL SEE RAIN CHANGE TO SNOW BY 12Z AND THEN SNOW
WILL PREVAIL THROUGH 06Z THURS. EXPECT MVFR TO IFR CONDITIONS TO
PREVAIL BY 12Z IN THE NORTH AND THEN ALL AREAS BY 15Z. AFTER 01Z
CONDITIONS IN THE NORTH WILL IMPROVE SOME WITH VFR CONDITIONS
PREVAILING BY 06Z THURS. MOUNTAINS WILL BE FREQUENTLY OBSCURED.
PLEASE SEE INDIVIDUAL TERMINAL SITES FOR MORE DETAILS.

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

VFR CONDITIONS WILL TURN TO MVFR/IFR CONDITIONS OVERNIGHT AS SNOW
DEVELOPS OVER MOST OF THE AREA. EXPECT SNOW TO OCCUR THROUGH MOST OF
WEDNESDAY...DECREASING WEDNESDAY NIGHT. MOUNTAINS WILL BE FREQUENTLY
OBSCURED THROUGH WEDNESDAY EVENING. VFR CONDITIONS WILL BEGIN TO
OCCUR AT SOME OF THE WESTERN TERMINAL SITES AFTER 00Z THURS. PLEASE
SEE INDIVIDUAL TERMINAL SITES FOR MORE DETAILS.

&&

.FIRE WEATHER...

RED FLAG WARNINGS WILL REMAIN IN EFFECT FOR STRONG WINDS AND LOW
RELATIVE HUMIDITY FOR MUCH OF THE LOWER ELEVATIONS EAST OF THE
CONTINENTAL DIVIDE UNTIL 10 PM MDT. THE SOUTH AND AREAS ALONG AND
NEAR THE EAST SLOPES OF THE MOUNTAINS WILL EXPERIENCE HIGH WINDS
UNTIL 10 PM MDT THIS EVENING.  WEST OF THE CONTINENTAL DIVIDE
RAIN AND SNOW SHOWERS WILL TURN TO SNOW AND BECOME WIDESPREAD
TONIGHT.  THE SNOW WILL SPREAD FROM NORTHWEST TO SOUTHEAST ACROSS
THE AREA TONIGHT THROUGH WEDNESDAY. STRONG NORTH WINDS WILL BECOME
WIDESPREAD WEDNESDAY.  SOME LOWER ELEVATION AREAS IN THE BIGHORN
BASIN...JOHNSON COUNTY...NATRONA COUNTY AND THE WIND RIVER BASIN
MAY SEE SNOW CHANGE TO RAIN OR MIX WITH RAIN DURING THE DAY
WEDNESDAY. THE SNOW WILL START ENDING IN THE NORTHWEST WEDNESDAY
EVENING CONTINUING ON IN THE EAST UNTIL THURSDAY MORNING.
TEMPERATURES WILL BECOME MUCH COLDER WITH SIGNIFICANT INCREASE
IN RELATIVE HUMIDITY.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...

WINTER WEATHER ADVISORY FROM 6 AM WEDNESDAY TO 6 AM MDT THURSDAY
WYZ008-009-019.

WINTER WEATHER ADVISORY FROM 3 AM WEDNESDAY TO 6 AM MDT THURSDAY
WYZ016>018.

WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM MDT
WEDNESDAY WYZ012.

WINTER WEATHER ADVISORY FROM NOON WEDNESDAY TO 6 AM MDT THURSDAY
WYZ010-011-020-022.

WINTER STORM WARNING FROM 3 AM WEDNESDAY TO 6 AM MDT THURSDAY
WYZ014-015.

WINTER WEATHER ADVISORY FROM 3 AM WEDNESDAY TO MIDNIGHT MDT
WEDNESDAY NIGHT WYZ005>007.

WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT MDT
WEDNESDAY NIGHT WYZ002-003.

&&

$$

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





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