Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 190526
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1026 PM MST TUE NOV 18 2014

.SHORT TERM...TONIGHT THROUGH WEDNESDAY (ISSUED AT 107 PM MST)

NORTH NORTHWEST FLOW ALOFT WILL CONTINUE TO BRING AREAS OF MID AND
UPPER LEVEL CLOUD COVER TO WESTERN AND CENTRAL WYOMING.  AREAS IMPACTED
BY STRONG INVERSIONS ARE GRADUALLY DECREASING WITH STRONG TEMPERATURE
AND WIND GRADIENTS EXISTING BOTH HORIZONTALLY AND VERTICALLY. THE COLDER
TRAPPED AREAS WILL CONTINUE TO SEE AREAS OF LOW STRATUS CLOUDS AND FOG
WITH GENERALLY LIGHT WINDS.  THE MIXED AREAS WILL BE 20 TO 30
DEGREES WARMER THAN THE TRAPPED VALLEYS AND BASINS AT TIMES...WITH
SIGNIFICANTLY LOWER RELATIVE HUMIDITY AND STRONG GUSTY WINDS. THE
NORTHERN MOUNTAINS CAN EXPECT SOME VERY LIGHT SNOW THIS EVENING...
OTHERWISE DRY CONDITIONS WILL PREVAIL THROUGH WEDNESDAY.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY

AN AMPLIFYING RIDGE OF HIGH PRESSURE WILL START OFF THE FORECAST
PERIOD. A WAVE OF LOW PRESSURE WILL MOVE EAST OVER THE PACIFIC
COASTLINE WEDNESDAY...AND MODELS CONTINUE TO INDICATE THAT THIS
SYSTEM WILL SPLIT AS IT ADVANCES TOWARDS THE INTERMOUNTAIN WEST.
THE NORTHERN PORTION OF THIS SYSTEM MAY BRING WEAK AMOUNTS OF
MOISTURE FOR AREAS WEST OF THE CONTINENTAL DIVIDE BY LATE WEDNESDAY
NIGHT AND INTO THURSDAY MORNING. THESE SHOWERS ARE NOT EXPECTED TO
BE SIGNIFICANT.

A STRONGER PUSH OF MOISTURE WILL MOVE OVER THE INTERMOUNTAIN WEST ON
SATURDAY...WITH INCREASING SHOWER ACTIVITY EXPECTED OVER THE WESTERN
MOUNTAINS AND VALLEYS. THE WAVE OF LOW PRESSURE ASSOCIATED WITH THIS
SYSTEM WILL CONTINUE ITS EASTWARD PROGRESSION...AND WILL INCREASE
COVERAGE ACROSS WESTERN WYOMING...WITH SHOWERS SPILLING OVER TO THE
EAST SIDE OF THE DIVIDE BY SATURDAY EVENING.

SHOWERS WILL CONTINUE EVEN AS THIS SYSTEM MOVES EAST OF THE FORECAST
AREA ON SUNDAY. A MOIST NORTHWEST FLOW WILL DEVELOP OVER THE AREA
HIGH PRESSURE ATTEMPTS TO BUILD OVER THE WESTERN HALF OF THE UNITED
STATES. A BRIEF REPRIEVE FROM SHOWERS MAY BE FOUND LATE MONDAY...BUT
WILL BE SHORT LIVED AS ANOTHER...POTENTIALLY POTENT SLUG OF MOISTURE
MOVES INTO THE WEST BY LATE MONDAY NIGHT. THIS MOISTURE WILL AGAIN
SPREAD ACROSS THE FORECAST AREA THROUGH TUESDAY.

A GENERAL WARMING TREND IS ANTICIPATED THROUGH SATURDAY...WITH A
RETURN OF COLDER AIR EXPECTED SUNDAY AND INTO THE EARLY PORTION OF
THE WORK WEEK.

&&

.AVIATION.../06Z ISSUANCE/

VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. LOCAL AREAS OF FOG
OR LOW CLOUDS MAY OCCUR OVERNIGHT INTO WEDNESDAY MORNING IN THE FAR
WEST VALLEYS...INCLUDING THE AFTON AND JACKSON AIRPORTS. THUS AREAS
OF MVFR/IFR CONDITIONS ARE EXPECTED UNTIL 18Z. THE CURRENT JACKSON
TERMINAL FORECAST HAS VCNTY FOG BUT KEEPS VFR CONDITIONS. WILL
MONITOR AND AMEND FORECAST AS NEEDED AT KJAC AIRPORT.

&&

.FIRE WEATHER...

NORTH NORTHWEST FLOW ALOFT WILL CONTINUE TO BRING AREAS OF MID AND
UPPER LEVEL CLOUD COVER TO WESTERN AND CENTRAL WYOMING.  AREAS IMPACTED
BY STRONG INVERSIONS ARE GRADUALLY DECREASING WITH STRONG TEMPERATURE
AND WIND GRADIENTS EXISTING BOTH HORIZONTALLY AND VERTICALLY. THE COLDER
TRAPPED AREAS WILL CONTINUE TO SEE AREAS OF LOW STRATUS CLOUDS AND FOG
WITH GENERALLY LIGHT WINDS AND VERY LOW MIXING HEIGHTS AND POOR
SMOKE DISPERSAL. THE MIXED AREAS WILL BE 20 TO 30 DEGREES WARMER THAN
THE TRAPPED VALLEYS AND BASINS AT TIMES WITH SIGNIFICANTLY LOWER
RELATIVE HUMIDITY AND STRONG GUSTY WINDS. THE NORTHERN MOUNTAINS
CAN EXPECT SOME VERY LIGHT SNOW... OTHERWISE DRY CONDITIONS WILL
PREVAIL.

&&

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

$$

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










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