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000
FXUS65 KRIW 312142
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
242 PM MST SAT JAN 31 2015

.SHORT TERM...TONIGHT THROUGH SUNDAY

LOW CLOUDS AND FOG TOOK UNTIL EARLY AFTERNOON TO LIFT IN THE CENTRAL
VALLEYS AS WELL AS IN THE STAR VALLEY. OTHERWISE A MOSTLY SUNNY DAY
WITH MILD TEMPS FOR THE MOST PART. A COLD FRONT HAS ENTERED NORTHERN
WY AS OF 19Z. PRECIP IS BREAKING OUT IN SOUTHERN MONTANA AS A
WEATHER SYSTEM DIVES SOUTHEAST THROUGH MONTANA AND HEADS TOWARD WY
FOR THE TONIGHT PERIOD. THIS SYSTEM WILL MAINLY IMPACT THE AREAS
EAST OF THE CONTINENTAL DIVIDE TONIGHT INTO EARLY SUNDAY WITH SOME
SNOW AND WIND AND COLDER TEMPS. THE BEST CHANCE OF SNOW WILL BE FROM
THE BIGHORN MOUNTAINS SOUTH TO CASPER MOUNTAIN...INCLUDING BUFFALO
TO CASPER. HAVE WENT HIGHER WITH THE CHANCE OF SNOW WITH
ACCUMULATIONS AROUND AN INCH IN PLACES. THE BIG HORN BASIN SHOULD
SEE SOME LIGHT SNOW TONIGHT...ENDING BY SUNDAY MORNING. THE WIND
RIVER BASIN SHOULD SEE SOME LIGHT SNOW AT TIMES LATE THIS EVENING TO
AROUND SUNRISE SUNDAY. LESS THAN AN INCH IS EXPECTED FOR THE MOST
PARTS IN THE THOSE BASINS. OUT WEST NOT MUCH EXPECTED ASIDE FROM
SOME MOUNTAIN SNOW SHOWERS OVER THE NORTHWEST MOUNTAINS AND WIND
RIVER MOUNTAINS. WILL HAVE TO DEAL WITH THE FOG AND LOW CLOUDS IN
THE STAR VALLEY AGAIN TONIGHT INTO SUNDAY MORNING. COLDER LOWS EAST
OF THE DIVIDE AS THE BRUNT OF THE COLD AIR WILL REMAIN EAST OF THE
DIVIDE TONIGHT AND SUNDAY. CLOUDS WILL BE ON THE DECREASE SUNDAY
EAST OF THE DIVIDE AS THE SYSTEM DEPARTS. SOME HIGH CLOUDS WILL
FILTER IN SUNDAY PM IN THE NORTHWEST FLOW ALOFT. OUT WEST...SUNDAY
WILL BE DRY FOR MOST OF THE DAY. INCREASING CLOUDS SUNDAY AFTERNOON
WITH SCATTERED LIGHT SNOW FOR THE NORTHWEST WY MOUNTAINS AS MOISTURE
INCREASES IN THE NW FLOW ALOFT. IT SHOULD STAY DRY IN THE WESTERN
VALLEYS THROUGH 00Z MONDAY. HIGHS ON SUNDAY WILL BE 5 TO 10 DEGREES
COLDER THAN SATURDAY EAST OF THE DIVIDE AND SLIGHTLY COLDER WEST OF
THE DIVIDE.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY

THROUGH THE FIRST PORTION OF THE LONG TERM FORECAST...MAINLY THROUGH
TUESDAY...REMAINS OF AN OLD SHOW ON PBS MANY YEARS AGO. THE SHOW IS
UPSTAIRS DOWNSTAIRS. EXPECT...THIS IS THE WEATHER VERSION CALLED
UPSLOPE DOWNSLOPE. IN AREAS WEST OF THE DIVIDE...THEY WILL BE IN THE
UPSLOPE PORTION OF THE FORECAST. THE FIRST SHORTWAVE APPROACHES FROM
THE WEST FOR SUNDAY NIGHT WITH THE FIRST SHOT OF POTENTIAL
ACCUMULATING SNOW. THE NEXT WAVE THEN ARRIVES SOMETIME ON MONDAY.
THE MODELS DO HAVE A FEW TIMING DIFFERENCES WITH THE NAM HAVING A
BIT OF A BREAK ON MONDAY AND THE GFS KEEPING THE PRECIPITATION GOING
THROUGH MUCH OF THE DAY. AT THIS POINT...CONTINUITY LOOKED
REASONABLE SO WE MADE FEW CHANGES. MEANWHILE...EAST OF THE DIVIDE IS
ON THE DOWNSLOPE SIDE. THIS MEANS MAINLY DRY CONDITIONS FOR MOST
LOCATIONS EXPECT FOR THE BIGHORN RANGE AND POSSIBLY THE NORTHERN BIG
HORN BASIN WHERE SOME JET ENERGY COULD BRING SOME LIGHT
PRECIPITATION. WITH THE DOWNSLOPING FLOW...EXPECT TEMPERATURES TO BE
NEAR TO ABOVE NORMAL FOR MOST LOCATIONS. THERE MAY BE THE POTENTIAL
FOR SOME HIGH WINDS...ESPECIALLY MONDAY NIGHT WITH A COUPLE OF
MODELS SHOWING 700 MILLIBAR WINDS AT OR OVER 50 KNOTS...ESPECIALLY
NEAR THE FAVORED AREAS LIKE NEAR CLARK AND PORTIONS OF NATRONA
COUNTY.

THE NEXT DECENT CHANCE FOR PRECIPITATION ACROSS THE AREA WOULD BE
TUESDAY NIGHT INTO WEDNESDAY. BOTH THE GFS AND EUROPEAN SHOW SOME
PRECIPITATION GETTING KICKED ACROSS THE DIVIDE AS A COLD FRONT AND
ASSOCIATED SHORT WAVE DROPS SOUTHWARD OUT OF CANADA AND INTO WYOMING
WITH MAYBE SOME LIGHT UPSLOPE EAST OF THE DIVIDE. AT THIS
POINT...THIS DOES NOT LOOK LIKE A BIG EVENT BUT THERE WILL BE THE
POTENTIAL FOR SOME PRECIPITATION EVERYWHERE. THERE ARE SOME
DIFFERENCES IN THE MODELS TIMING THE SYSTEMS WITH THE GFS MOVING
PRECIPITATION OUT FASTER THAN THE GFS AT THIS POINT.

BOTH THE GFS AND EUROPEAN NOW BUILD RIDGING ACROSS THE AREA FOR LATE
NEXT WEEK WITH MAINLY DRY CONDITIONS DOMINATING FOR THURSDAY AND
EVEN INTO FRIDAY. WE STILL HAVE SOME LIGHT POPS ACROSS THE WEST BUT
FUTURE SHIFTS MAY WANT TO REMOVE IT. WITH THE RIDGING...THE PATTERN
OF ABOVE NORMAL TEMPERATURES WILL CONTINUE WITH SOME 50S POSSIBLE BY
FRIDAY IN WARMER AREAS EAST OF THE DIVIDE. THEN BOTH MODELS SHOW THE
NEXT SYSTEM MOVING IN FOR NEXT WEEKEND.

&&

.AVIATION.../00Z ISSUANCE/

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

CLOUDS WILL LOWER OVER NORTHERN WY WITH AREAS OF LIGHT SNOW
DEVELOPING AROUND 00Z THROUGH 09Z BEFORE IT ENDS AND CONDITIONS
IMPROVE BY 12Z. EXPECT MVFR TO IFR CONDITIONS THROUGH 15Z WITH VFR
CONDITIONS AFTER 15Z SUNDAY. FOR THE CENTRAL AREA FROM KCPR TO
KLND THE LOWER CLOUDS AND AREAS OF LIGHT SNOW WILL OCCUR AROUND
03Z AND CONTINUE THROUGH 12Z. EXPECT MVFR TO IFR CONDITIONS
THROUGH 15Z...THEN CONDITIONS WILL IMPROVE AFTER 15Z WITH VFR
CONDITIONS PREVAILING BY 18Z SUNDAY.

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

SOME FOG AND LOW CLOUDS WILL OCCUR IN THE STAR VALLEY TONIGHT INTO
SUNDAY MORNING WITH IFR CONDITIONS UNTIL 17Z. A COLD FRONT MAY PUSH
LOWER MVFR/IFR CIGS INTO VCNTY KRKS AFTER 07Z TONIGHT. ISOLATED
SNOW SHOWERS ARE EXPECTED OVER THE NORTHWEST MOUNTAINS AND OVER
THE WIND RIVER MOUNTAINS TONIGHT UNTIL 12Z SUNDAY. LOCAL MVFR
CONDITIONS WILL OCCUR IN THESE MOUNTAINS. VFR CONDITIONS WILL
PREVAIL SUNDAY AT THE TERMINAL SITES. SOME LIGHT SNOW FORMS OVER
THE NORTHWEST MOUNTAINS AFTER 20Z SUNDAY WITH SOME MVFR CONDITIONS
DEVELOPING BY 00Z MONDAY IN NW WY.

&&

.FIRE WEATHER...

A WEATHER SYSTEM WILL BRING SOME LIGHT SNOW EAST OF THE DIVIDE
TONIGHT AND SUNDAY MORNING. THEN MOSTLY DRY SUNDAY AFTERNOON
THROUGH MONDAY EAST OF THE DIVIDE. WEST OF THE DIVIDE WILL BE DRY
TONIGHT AND SUNDAY MORNING. LIGHT SNOW DEVELOPS OVER THE NORTHWEST
MOUNTAINS SUNDAY AFTERNOON. PERIODS OF SNOW FOR THE WESTERN
MOUNTAINS AND FAR WEST VALLEYS SUNDAY NIGHT THROUGH MONDAY NIGHT.

&&

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

&&

$$

SHORT TERM...AR
LONG TERM...HATTINGS
AVIATION...AR
FIRE WEATHER...AR







000
FXUS65 KRIW 312142
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
242 PM MST SAT JAN 31 2015

.SHORT TERM...TONIGHT THROUGH SUNDAY

LOW CLOUDS AND FOG TOOK UNTIL EARLY AFTERNOON TO LIFT IN THE CENTRAL
VALLEYS AS WELL AS IN THE STAR VALLEY. OTHERWISE A MOSTLY SUNNY DAY
WITH MILD TEMPS FOR THE MOST PART. A COLD FRONT HAS ENTERED NORTHERN
WY AS OF 19Z. PRECIP IS BREAKING OUT IN SOUTHERN MONTANA AS A
WEATHER SYSTEM DIVES SOUTHEAST THROUGH MONTANA AND HEADS TOWARD WY
FOR THE TONIGHT PERIOD. THIS SYSTEM WILL MAINLY IMPACT THE AREAS
EAST OF THE CONTINENTAL DIVIDE TONIGHT INTO EARLY SUNDAY WITH SOME
SNOW AND WIND AND COLDER TEMPS. THE BEST CHANCE OF SNOW WILL BE FROM
THE BIGHORN MOUNTAINS SOUTH TO CASPER MOUNTAIN...INCLUDING BUFFALO
TO CASPER. HAVE WENT HIGHER WITH THE CHANCE OF SNOW WITH
ACCUMULATIONS AROUND AN INCH IN PLACES. THE BIG HORN BASIN SHOULD
SEE SOME LIGHT SNOW TONIGHT...ENDING BY SUNDAY MORNING. THE WIND
RIVER BASIN SHOULD SEE SOME LIGHT SNOW AT TIMES LATE THIS EVENING TO
AROUND SUNRISE SUNDAY. LESS THAN AN INCH IS EXPECTED FOR THE MOST
PARTS IN THE THOSE BASINS. OUT WEST NOT MUCH EXPECTED ASIDE FROM
SOME MOUNTAIN SNOW SHOWERS OVER THE NORTHWEST MOUNTAINS AND WIND
RIVER MOUNTAINS. WILL HAVE TO DEAL WITH THE FOG AND LOW CLOUDS IN
THE STAR VALLEY AGAIN TONIGHT INTO SUNDAY MORNING. COLDER LOWS EAST
OF THE DIVIDE AS THE BRUNT OF THE COLD AIR WILL REMAIN EAST OF THE
DIVIDE TONIGHT AND SUNDAY. CLOUDS WILL BE ON THE DECREASE SUNDAY
EAST OF THE DIVIDE AS THE SYSTEM DEPARTS. SOME HIGH CLOUDS WILL
FILTER IN SUNDAY PM IN THE NORTHWEST FLOW ALOFT. OUT WEST...SUNDAY
WILL BE DRY FOR MOST OF THE DAY. INCREASING CLOUDS SUNDAY AFTERNOON
WITH SCATTERED LIGHT SNOW FOR THE NORTHWEST WY MOUNTAINS AS MOISTURE
INCREASES IN THE NW FLOW ALOFT. IT SHOULD STAY DRY IN THE WESTERN
VALLEYS THROUGH 00Z MONDAY. HIGHS ON SUNDAY WILL BE 5 TO 10 DEGREES
COLDER THAN SATURDAY EAST OF THE DIVIDE AND SLIGHTLY COLDER WEST OF
THE DIVIDE.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY

THROUGH THE FIRST PORTION OF THE LONG TERM FORECAST...MAINLY THROUGH
TUESDAY...REMAINS OF AN OLD SHOW ON PBS MANY YEARS AGO. THE SHOW IS
UPSTAIRS DOWNSTAIRS. EXPECT...THIS IS THE WEATHER VERSION CALLED
UPSLOPE DOWNSLOPE. IN AREAS WEST OF THE DIVIDE...THEY WILL BE IN THE
UPSLOPE PORTION OF THE FORECAST. THE FIRST SHORTWAVE APPROACHES FROM
THE WEST FOR SUNDAY NIGHT WITH THE FIRST SHOT OF POTENTIAL
ACCUMULATING SNOW. THE NEXT WAVE THEN ARRIVES SOMETIME ON MONDAY.
THE MODELS DO HAVE A FEW TIMING DIFFERENCES WITH THE NAM HAVING A
BIT OF A BREAK ON MONDAY AND THE GFS KEEPING THE PRECIPITATION GOING
THROUGH MUCH OF THE DAY. AT THIS POINT...CONTINUITY LOOKED
REASONABLE SO WE MADE FEW CHANGES. MEANWHILE...EAST OF THE DIVIDE IS
ON THE DOWNSLOPE SIDE. THIS MEANS MAINLY DRY CONDITIONS FOR MOST
LOCATIONS EXPECT FOR THE BIGHORN RANGE AND POSSIBLY THE NORTHERN BIG
HORN BASIN WHERE SOME JET ENERGY COULD BRING SOME LIGHT
PRECIPITATION. WITH THE DOWNSLOPING FLOW...EXPECT TEMPERATURES TO BE
NEAR TO ABOVE NORMAL FOR MOST LOCATIONS. THERE MAY BE THE POTENTIAL
FOR SOME HIGH WINDS...ESPECIALLY MONDAY NIGHT WITH A COUPLE OF
MODELS SHOWING 700 MILLIBAR WINDS AT OR OVER 50 KNOTS...ESPECIALLY
NEAR THE FAVORED AREAS LIKE NEAR CLARK AND PORTIONS OF NATRONA
COUNTY.

THE NEXT DECENT CHANCE FOR PRECIPITATION ACROSS THE AREA WOULD BE
TUESDAY NIGHT INTO WEDNESDAY. BOTH THE GFS AND EUROPEAN SHOW SOME
PRECIPITATION GETTING KICKED ACROSS THE DIVIDE AS A COLD FRONT AND
ASSOCIATED SHORT WAVE DROPS SOUTHWARD OUT OF CANADA AND INTO WYOMING
WITH MAYBE SOME LIGHT UPSLOPE EAST OF THE DIVIDE. AT THIS
POINT...THIS DOES NOT LOOK LIKE A BIG EVENT BUT THERE WILL BE THE
POTENTIAL FOR SOME PRECIPITATION EVERYWHERE. THERE ARE SOME
DIFFERENCES IN THE MODELS TIMING THE SYSTEMS WITH THE GFS MOVING
PRECIPITATION OUT FASTER THAN THE GFS AT THIS POINT.

BOTH THE GFS AND EUROPEAN NOW BUILD RIDGING ACROSS THE AREA FOR LATE
NEXT WEEK WITH MAINLY DRY CONDITIONS DOMINATING FOR THURSDAY AND
EVEN INTO FRIDAY. WE STILL HAVE SOME LIGHT POPS ACROSS THE WEST BUT
FUTURE SHIFTS MAY WANT TO REMOVE IT. WITH THE RIDGING...THE PATTERN
OF ABOVE NORMAL TEMPERATURES WILL CONTINUE WITH SOME 50S POSSIBLE BY
FRIDAY IN WARMER AREAS EAST OF THE DIVIDE. THEN BOTH MODELS SHOW THE
NEXT SYSTEM MOVING IN FOR NEXT WEEKEND.

&&

.AVIATION.../00Z ISSUANCE/

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

CLOUDS WILL LOWER OVER NORTHERN WY WITH AREAS OF LIGHT SNOW
DEVELOPING AROUND 00Z THROUGH 09Z BEFORE IT ENDS AND CONDITIONS
IMPROVE BY 12Z. EXPECT MVFR TO IFR CONDITIONS THROUGH 15Z WITH VFR
CONDITIONS AFTER 15Z SUNDAY. FOR THE CENTRAL AREA FROM KCPR TO
KLND THE LOWER CLOUDS AND AREAS OF LIGHT SNOW WILL OCCUR AROUND
03Z AND CONTINUE THROUGH 12Z. EXPECT MVFR TO IFR CONDITIONS
THROUGH 15Z...THEN CONDITIONS WILL IMPROVE AFTER 15Z WITH VFR
CONDITIONS PREVAILING BY 18Z SUNDAY.

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

SOME FOG AND LOW CLOUDS WILL OCCUR IN THE STAR VALLEY TONIGHT INTO
SUNDAY MORNING WITH IFR CONDITIONS UNTIL 17Z. A COLD FRONT MAY PUSH
LOWER MVFR/IFR CIGS INTO VCNTY KRKS AFTER 07Z TONIGHT. ISOLATED
SNOW SHOWERS ARE EXPECTED OVER THE NORTHWEST MOUNTAINS AND OVER
THE WIND RIVER MOUNTAINS TONIGHT UNTIL 12Z SUNDAY. LOCAL MVFR
CONDITIONS WILL OCCUR IN THESE MOUNTAINS. VFR CONDITIONS WILL
PREVAIL SUNDAY AT THE TERMINAL SITES. SOME LIGHT SNOW FORMS OVER
THE NORTHWEST MOUNTAINS AFTER 20Z SUNDAY WITH SOME MVFR CONDITIONS
DEVELOPING BY 00Z MONDAY IN NW WY.

&&

.FIRE WEATHER...

A WEATHER SYSTEM WILL BRING SOME LIGHT SNOW EAST OF THE DIVIDE
TONIGHT AND SUNDAY MORNING. THEN MOSTLY DRY SUNDAY AFTERNOON
THROUGH MONDAY EAST OF THE DIVIDE. WEST OF THE DIVIDE WILL BE DRY
TONIGHT AND SUNDAY MORNING. LIGHT SNOW DEVELOPS OVER THE NORTHWEST
MOUNTAINS SUNDAY AFTERNOON. PERIODS OF SNOW FOR THE WESTERN
MOUNTAINS AND FAR WEST VALLEYS SUNDAY NIGHT THROUGH MONDAY NIGHT.

&&

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

&&

$$

SHORT TERM...AR
LONG TERM...HATTINGS
AVIATION...AR
FIRE WEATHER...AR






000
FXUS65 KRIW 312142
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
242 PM MST SAT JAN 31 2015

.SHORT TERM...TONIGHT THROUGH SUNDAY

LOW CLOUDS AND FOG TOOK UNTIL EARLY AFTERNOON TO LIFT IN THE CENTRAL
VALLEYS AS WELL AS IN THE STAR VALLEY. OTHERWISE A MOSTLY SUNNY DAY
WITH MILD TEMPS FOR THE MOST PART. A COLD FRONT HAS ENTERED NORTHERN
WY AS OF 19Z. PRECIP IS BREAKING OUT IN SOUTHERN MONTANA AS A
WEATHER SYSTEM DIVES SOUTHEAST THROUGH MONTANA AND HEADS TOWARD WY
FOR THE TONIGHT PERIOD. THIS SYSTEM WILL MAINLY IMPACT THE AREAS
EAST OF THE CONTINENTAL DIVIDE TONIGHT INTO EARLY SUNDAY WITH SOME
SNOW AND WIND AND COLDER TEMPS. THE BEST CHANCE OF SNOW WILL BE FROM
THE BIGHORN MOUNTAINS SOUTH TO CASPER MOUNTAIN...INCLUDING BUFFALO
TO CASPER. HAVE WENT HIGHER WITH THE CHANCE OF SNOW WITH
ACCUMULATIONS AROUND AN INCH IN PLACES. THE BIG HORN BASIN SHOULD
SEE SOME LIGHT SNOW TONIGHT...ENDING BY SUNDAY MORNING. THE WIND
RIVER BASIN SHOULD SEE SOME LIGHT SNOW AT TIMES LATE THIS EVENING TO
AROUND SUNRISE SUNDAY. LESS THAN AN INCH IS EXPECTED FOR THE MOST
PARTS IN THE THOSE BASINS. OUT WEST NOT MUCH EXPECTED ASIDE FROM
SOME MOUNTAIN SNOW SHOWERS OVER THE NORTHWEST MOUNTAINS AND WIND
RIVER MOUNTAINS. WILL HAVE TO DEAL WITH THE FOG AND LOW CLOUDS IN
THE STAR VALLEY AGAIN TONIGHT INTO SUNDAY MORNING. COLDER LOWS EAST
OF THE DIVIDE AS THE BRUNT OF THE COLD AIR WILL REMAIN EAST OF THE
DIVIDE TONIGHT AND SUNDAY. CLOUDS WILL BE ON THE DECREASE SUNDAY
EAST OF THE DIVIDE AS THE SYSTEM DEPARTS. SOME HIGH CLOUDS WILL
FILTER IN SUNDAY PM IN THE NORTHWEST FLOW ALOFT. OUT WEST...SUNDAY
WILL BE DRY FOR MOST OF THE DAY. INCREASING CLOUDS SUNDAY AFTERNOON
WITH SCATTERED LIGHT SNOW FOR THE NORTHWEST WY MOUNTAINS AS MOISTURE
INCREASES IN THE NW FLOW ALOFT. IT SHOULD STAY DRY IN THE WESTERN
VALLEYS THROUGH 00Z MONDAY. HIGHS ON SUNDAY WILL BE 5 TO 10 DEGREES
COLDER THAN SATURDAY EAST OF THE DIVIDE AND SLIGHTLY COLDER WEST OF
THE DIVIDE.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY

THROUGH THE FIRST PORTION OF THE LONG TERM FORECAST...MAINLY THROUGH
TUESDAY...REMAINS OF AN OLD SHOW ON PBS MANY YEARS AGO. THE SHOW IS
UPSTAIRS DOWNSTAIRS. EXPECT...THIS IS THE WEATHER VERSION CALLED
UPSLOPE DOWNSLOPE. IN AREAS WEST OF THE DIVIDE...THEY WILL BE IN THE
UPSLOPE PORTION OF THE FORECAST. THE FIRST SHORTWAVE APPROACHES FROM
THE WEST FOR SUNDAY NIGHT WITH THE FIRST SHOT OF POTENTIAL
ACCUMULATING SNOW. THE NEXT WAVE THEN ARRIVES SOMETIME ON MONDAY.
THE MODELS DO HAVE A FEW TIMING DIFFERENCES WITH THE NAM HAVING A
BIT OF A BREAK ON MONDAY AND THE GFS KEEPING THE PRECIPITATION GOING
THROUGH MUCH OF THE DAY. AT THIS POINT...CONTINUITY LOOKED
REASONABLE SO WE MADE FEW CHANGES. MEANWHILE...EAST OF THE DIVIDE IS
ON THE DOWNSLOPE SIDE. THIS MEANS MAINLY DRY CONDITIONS FOR MOST
LOCATIONS EXPECT FOR THE BIGHORN RANGE AND POSSIBLY THE NORTHERN BIG
HORN BASIN WHERE SOME JET ENERGY COULD BRING SOME LIGHT
PRECIPITATION. WITH THE DOWNSLOPING FLOW...EXPECT TEMPERATURES TO BE
NEAR TO ABOVE NORMAL FOR MOST LOCATIONS. THERE MAY BE THE POTENTIAL
FOR SOME HIGH WINDS...ESPECIALLY MONDAY NIGHT WITH A COUPLE OF
MODELS SHOWING 700 MILLIBAR WINDS AT OR OVER 50 KNOTS...ESPECIALLY
NEAR THE FAVORED AREAS LIKE NEAR CLARK AND PORTIONS OF NATRONA
COUNTY.

THE NEXT DECENT CHANCE FOR PRECIPITATION ACROSS THE AREA WOULD BE
TUESDAY NIGHT INTO WEDNESDAY. BOTH THE GFS AND EUROPEAN SHOW SOME
PRECIPITATION GETTING KICKED ACROSS THE DIVIDE AS A COLD FRONT AND
ASSOCIATED SHORT WAVE DROPS SOUTHWARD OUT OF CANADA AND INTO WYOMING
WITH MAYBE SOME LIGHT UPSLOPE EAST OF THE DIVIDE. AT THIS
POINT...THIS DOES NOT LOOK LIKE A BIG EVENT BUT THERE WILL BE THE
POTENTIAL FOR SOME PRECIPITATION EVERYWHERE. THERE ARE SOME
DIFFERENCES IN THE MODELS TIMING THE SYSTEMS WITH THE GFS MOVING
PRECIPITATION OUT FASTER THAN THE GFS AT THIS POINT.

BOTH THE GFS AND EUROPEAN NOW BUILD RIDGING ACROSS THE AREA FOR LATE
NEXT WEEK WITH MAINLY DRY CONDITIONS DOMINATING FOR THURSDAY AND
EVEN INTO FRIDAY. WE STILL HAVE SOME LIGHT POPS ACROSS THE WEST BUT
FUTURE SHIFTS MAY WANT TO REMOVE IT. WITH THE RIDGING...THE PATTERN
OF ABOVE NORMAL TEMPERATURES WILL CONTINUE WITH SOME 50S POSSIBLE BY
FRIDAY IN WARMER AREAS EAST OF THE DIVIDE. THEN BOTH MODELS SHOW THE
NEXT SYSTEM MOVING IN FOR NEXT WEEKEND.

&&

.AVIATION.../00Z ISSUANCE/

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

CLOUDS WILL LOWER OVER NORTHERN WY WITH AREAS OF LIGHT SNOW
DEVELOPING AROUND 00Z THROUGH 09Z BEFORE IT ENDS AND CONDITIONS
IMPROVE BY 12Z. EXPECT MVFR TO IFR CONDITIONS THROUGH 15Z WITH VFR
CONDITIONS AFTER 15Z SUNDAY. FOR THE CENTRAL AREA FROM KCPR TO
KLND THE LOWER CLOUDS AND AREAS OF LIGHT SNOW WILL OCCUR AROUND
03Z AND CONTINUE THROUGH 12Z. EXPECT MVFR TO IFR CONDITIONS
THROUGH 15Z...THEN CONDITIONS WILL IMPROVE AFTER 15Z WITH VFR
CONDITIONS PREVAILING BY 18Z SUNDAY.

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

SOME FOG AND LOW CLOUDS WILL OCCUR IN THE STAR VALLEY TONIGHT INTO
SUNDAY MORNING WITH IFR CONDITIONS UNTIL 17Z. A COLD FRONT MAY PUSH
LOWER MVFR/IFR CIGS INTO VCNTY KRKS AFTER 07Z TONIGHT. ISOLATED
SNOW SHOWERS ARE EXPECTED OVER THE NORTHWEST MOUNTAINS AND OVER
THE WIND RIVER MOUNTAINS TONIGHT UNTIL 12Z SUNDAY. LOCAL MVFR
CONDITIONS WILL OCCUR IN THESE MOUNTAINS. VFR CONDITIONS WILL
PREVAIL SUNDAY AT THE TERMINAL SITES. SOME LIGHT SNOW FORMS OVER
THE NORTHWEST MOUNTAINS AFTER 20Z SUNDAY WITH SOME MVFR CONDITIONS
DEVELOPING BY 00Z MONDAY IN NW WY.

&&

.FIRE WEATHER...

A WEATHER SYSTEM WILL BRING SOME LIGHT SNOW EAST OF THE DIVIDE
TONIGHT AND SUNDAY MORNING. THEN MOSTLY DRY SUNDAY AFTERNOON
THROUGH MONDAY EAST OF THE DIVIDE. WEST OF THE DIVIDE WILL BE DRY
TONIGHT AND SUNDAY MORNING. LIGHT SNOW DEVELOPS OVER THE NORTHWEST
MOUNTAINS SUNDAY AFTERNOON. PERIODS OF SNOW FOR THE WESTERN
MOUNTAINS AND FAR WEST VALLEYS SUNDAY NIGHT THROUGH MONDAY NIGHT.

&&

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

&&

$$

SHORT TERM...AR
LONG TERM...HATTINGS
AVIATION...AR
FIRE WEATHER...AR






000
FXUS65 KRIW 312142
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
242 PM MST SAT JAN 31 2015

.SHORT TERM...TONIGHT THROUGH SUNDAY

LOW CLOUDS AND FOG TOOK UNTIL EARLY AFTERNOON TO LIFT IN THE CENTRAL
VALLEYS AS WELL AS IN THE STAR VALLEY. OTHERWISE A MOSTLY SUNNY DAY
WITH MILD TEMPS FOR THE MOST PART. A COLD FRONT HAS ENTERED NORTHERN
WY AS OF 19Z. PRECIP IS BREAKING OUT IN SOUTHERN MONTANA AS A
WEATHER SYSTEM DIVES SOUTHEAST THROUGH MONTANA AND HEADS TOWARD WY
FOR THE TONIGHT PERIOD. THIS SYSTEM WILL MAINLY IMPACT THE AREAS
EAST OF THE CONTINENTAL DIVIDE TONIGHT INTO EARLY SUNDAY WITH SOME
SNOW AND WIND AND COLDER TEMPS. THE BEST CHANCE OF SNOW WILL BE FROM
THE BIGHORN MOUNTAINS SOUTH TO CASPER MOUNTAIN...INCLUDING BUFFALO
TO CASPER. HAVE WENT HIGHER WITH THE CHANCE OF SNOW WITH
ACCUMULATIONS AROUND AN INCH IN PLACES. THE BIG HORN BASIN SHOULD
SEE SOME LIGHT SNOW TONIGHT...ENDING BY SUNDAY MORNING. THE WIND
RIVER BASIN SHOULD SEE SOME LIGHT SNOW AT TIMES LATE THIS EVENING TO
AROUND SUNRISE SUNDAY. LESS THAN AN INCH IS EXPECTED FOR THE MOST
PARTS IN THE THOSE BASINS. OUT WEST NOT MUCH EXPECTED ASIDE FROM
SOME MOUNTAIN SNOW SHOWERS OVER THE NORTHWEST MOUNTAINS AND WIND
RIVER MOUNTAINS. WILL HAVE TO DEAL WITH THE FOG AND LOW CLOUDS IN
THE STAR VALLEY AGAIN TONIGHT INTO SUNDAY MORNING. COLDER LOWS EAST
OF THE DIVIDE AS THE BRUNT OF THE COLD AIR WILL REMAIN EAST OF THE
DIVIDE TONIGHT AND SUNDAY. CLOUDS WILL BE ON THE DECREASE SUNDAY
EAST OF THE DIVIDE AS THE SYSTEM DEPARTS. SOME HIGH CLOUDS WILL
FILTER IN SUNDAY PM IN THE NORTHWEST FLOW ALOFT. OUT WEST...SUNDAY
WILL BE DRY FOR MOST OF THE DAY. INCREASING CLOUDS SUNDAY AFTERNOON
WITH SCATTERED LIGHT SNOW FOR THE NORTHWEST WY MOUNTAINS AS MOISTURE
INCREASES IN THE NW FLOW ALOFT. IT SHOULD STAY DRY IN THE WESTERN
VALLEYS THROUGH 00Z MONDAY. HIGHS ON SUNDAY WILL BE 5 TO 10 DEGREES
COLDER THAN SATURDAY EAST OF THE DIVIDE AND SLIGHTLY COLDER WEST OF
THE DIVIDE.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY

THROUGH THE FIRST PORTION OF THE LONG TERM FORECAST...MAINLY THROUGH
TUESDAY...REMAINS OF AN OLD SHOW ON PBS MANY YEARS AGO. THE SHOW IS
UPSTAIRS DOWNSTAIRS. EXPECT...THIS IS THE WEATHER VERSION CALLED
UPSLOPE DOWNSLOPE. IN AREAS WEST OF THE DIVIDE...THEY WILL BE IN THE
UPSLOPE PORTION OF THE FORECAST. THE FIRST SHORTWAVE APPROACHES FROM
THE WEST FOR SUNDAY NIGHT WITH THE FIRST SHOT OF POTENTIAL
ACCUMULATING SNOW. THE NEXT WAVE THEN ARRIVES SOMETIME ON MONDAY.
THE MODELS DO HAVE A FEW TIMING DIFFERENCES WITH THE NAM HAVING A
BIT OF A BREAK ON MONDAY AND THE GFS KEEPING THE PRECIPITATION GOING
THROUGH MUCH OF THE DAY. AT THIS POINT...CONTINUITY LOOKED
REASONABLE SO WE MADE FEW CHANGES. MEANWHILE...EAST OF THE DIVIDE IS
ON THE DOWNSLOPE SIDE. THIS MEANS MAINLY DRY CONDITIONS FOR MOST
LOCATIONS EXPECT FOR THE BIGHORN RANGE AND POSSIBLY THE NORTHERN BIG
HORN BASIN WHERE SOME JET ENERGY COULD BRING SOME LIGHT
PRECIPITATION. WITH THE DOWNSLOPING FLOW...EXPECT TEMPERATURES TO BE
NEAR TO ABOVE NORMAL FOR MOST LOCATIONS. THERE MAY BE THE POTENTIAL
FOR SOME HIGH WINDS...ESPECIALLY MONDAY NIGHT WITH A COUPLE OF
MODELS SHOWING 700 MILLIBAR WINDS AT OR OVER 50 KNOTS...ESPECIALLY
NEAR THE FAVORED AREAS LIKE NEAR CLARK AND PORTIONS OF NATRONA
COUNTY.

THE NEXT DECENT CHANCE FOR PRECIPITATION ACROSS THE AREA WOULD BE
TUESDAY NIGHT INTO WEDNESDAY. BOTH THE GFS AND EUROPEAN SHOW SOME
PRECIPITATION GETTING KICKED ACROSS THE DIVIDE AS A COLD FRONT AND
ASSOCIATED SHORT WAVE DROPS SOUTHWARD OUT OF CANADA AND INTO WYOMING
WITH MAYBE SOME LIGHT UPSLOPE EAST OF THE DIVIDE. AT THIS
POINT...THIS DOES NOT LOOK LIKE A BIG EVENT BUT THERE WILL BE THE
POTENTIAL FOR SOME PRECIPITATION EVERYWHERE. THERE ARE SOME
DIFFERENCES IN THE MODELS TIMING THE SYSTEMS WITH THE GFS MOVING
PRECIPITATION OUT FASTER THAN THE GFS AT THIS POINT.

BOTH THE GFS AND EUROPEAN NOW BUILD RIDGING ACROSS THE AREA FOR LATE
NEXT WEEK WITH MAINLY DRY CONDITIONS DOMINATING FOR THURSDAY AND
EVEN INTO FRIDAY. WE STILL HAVE SOME LIGHT POPS ACROSS THE WEST BUT
FUTURE SHIFTS MAY WANT TO REMOVE IT. WITH THE RIDGING...THE PATTERN
OF ABOVE NORMAL TEMPERATURES WILL CONTINUE WITH SOME 50S POSSIBLE BY
FRIDAY IN WARMER AREAS EAST OF THE DIVIDE. THEN BOTH MODELS SHOW THE
NEXT SYSTEM MOVING IN FOR NEXT WEEKEND.

&&

.AVIATION.../00Z ISSUANCE/

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

CLOUDS WILL LOWER OVER NORTHERN WY WITH AREAS OF LIGHT SNOW
DEVELOPING AROUND 00Z THROUGH 09Z BEFORE IT ENDS AND CONDITIONS
IMPROVE BY 12Z. EXPECT MVFR TO IFR CONDITIONS THROUGH 15Z WITH VFR
CONDITIONS AFTER 15Z SUNDAY. FOR THE CENTRAL AREA FROM KCPR TO
KLND THE LOWER CLOUDS AND AREAS OF LIGHT SNOW WILL OCCUR AROUND
03Z AND CONTINUE THROUGH 12Z. EXPECT MVFR TO IFR CONDITIONS
THROUGH 15Z...THEN CONDITIONS WILL IMPROVE AFTER 15Z WITH VFR
CONDITIONS PREVAILING BY 18Z SUNDAY.

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

SOME FOG AND LOW CLOUDS WILL OCCUR IN THE STAR VALLEY TONIGHT INTO
SUNDAY MORNING WITH IFR CONDITIONS UNTIL 17Z. A COLD FRONT MAY PUSH
LOWER MVFR/IFR CIGS INTO VCNTY KRKS AFTER 07Z TONIGHT. ISOLATED
SNOW SHOWERS ARE EXPECTED OVER THE NORTHWEST MOUNTAINS AND OVER
THE WIND RIVER MOUNTAINS TONIGHT UNTIL 12Z SUNDAY. LOCAL MVFR
CONDITIONS WILL OCCUR IN THESE MOUNTAINS. VFR CONDITIONS WILL
PREVAIL SUNDAY AT THE TERMINAL SITES. SOME LIGHT SNOW FORMS OVER
THE NORTHWEST MOUNTAINS AFTER 20Z SUNDAY WITH SOME MVFR CONDITIONS
DEVELOPING BY 00Z MONDAY IN NW WY.

&&

.FIRE WEATHER...

A WEATHER SYSTEM WILL BRING SOME LIGHT SNOW EAST OF THE DIVIDE
TONIGHT AND SUNDAY MORNING. THEN MOSTLY DRY SUNDAY AFTERNOON
THROUGH MONDAY EAST OF THE DIVIDE. WEST OF THE DIVIDE WILL BE DRY
TONIGHT AND SUNDAY MORNING. LIGHT SNOW DEVELOPS OVER THE NORTHWEST
MOUNTAINS SUNDAY AFTERNOON. PERIODS OF SNOW FOR THE WESTERN
MOUNTAINS AND FAR WEST VALLEYS SUNDAY NIGHT THROUGH MONDAY NIGHT.

&&

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

&&

$$

SHORT TERM...AR
LONG TERM...HATTINGS
AVIATION...AR
FIRE WEATHER...AR







000
FXUS65 KRIW 312011
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
111 PM MST SAT JAN 31 2015

.SHORT TERM...TODAY THROUGH MONDAY NIGHT (ISSUED AT 250 AM MST)

ANY LEFT OVER SNOWFALL IN SOUTHERN SWEETWATER COUNTY THIS MORNING
WILL SHUT OFF SHORTLY AFTER SUNRISE AS THE LOW OVER VEGAS PROPAGATES
SOUTH TO OLD MEXICO. THE ASCT HIGH AND MID CLOUDS THAT HAVE BEEN
OVER CENTRAL AND SOUTHERN WY FRIDAY WILL CLEAR OUT OF SWEETWATER AND
NATRONA COUNTIES TO THE SOUTHEAST WITH MOSTLY CLEAR SKIES BY 18Z
TODAY. OTHERWISE EXPECT A MOSTLY SUNNY DAY WITH LIGHT WINDS AND
RELATIVELY MILD TEMPERATURES TODAY. THE NORTHERN STREAM VORT OVER
SOUTHERN BC WILL TRACK ACROSS WY FROM THE NW BY 00Z SAT. THIS
WEATHER FEATURE WILL DELIVER PATCHY LIGHT SNOW TO AREAS NORTH AND
EAST OF THE DIVIDE TONIGHT AS IT DRIVES A COLD FRONT SOUTH AND H7
TEMPS DROP TO -16C IN JOHNSON COUNTY BY 12Z SUNDAY. POST FRONTAL NNW
WINDS WILL INCREASE IN JOHNSON COUNTY LATE TODAY. SUNDAY WILL BE
RELATIVELY CHILLY WITH WARM AIR ADVECTING IN ALOFT FROM THE
SOUTHWEST SO THE COOLER AIR WILL BE SHORT LIVED. NORTHERN AND
WESTERN WY MAY NOT BREAK FREEZING SUNDAY BEFORE WARMING BACK UP
MONDAY. STILL...SEASONABLE TEMPS SLATED FOR THIS TIME OF YEAR
SUNDAY. BY SUNDAY NIGHT THE STEERING FLOW WILL BACK FROM NW TO WEST
AND INCREASE IN SPEED...MORE DIRECTLY OFF THE PACIFIC  UNDER A
FLATTENING RIDGE. A BATCH OF PACIFIC MOISTURE COMBINED WITH A WEAK
VORT EMBEDDED IN THE BACKING FLOW...SNOW WILL INCREASE IN THE WEST
SUNDAY NIGHT. SNOW WILL LESSEN IN INTENSITY MONDAY IN THE FAR WEST.
THEN THE CIRCULATION NOW WELL OFF THE PACIFIC COAST AT 45N/152W WILL
ARRIVE AS A VIGOROUS SHORTWAVE BRINGING ANOTHER SLUG OF PACIFIC
MOISTURE ACROSS MT/WY MONDAY NIGHT WITH SNOWFALL INCREASING ONCE
AGAIN IN THE FAR WEST. WITH FAVORABLE UPSLOPE CONDITIONS FOR THE FAR
WEST SUNDAY NIGHT THROUGH MONDAY NIGHT WITH THESE TWO BACK TO BACK
PACIFIC SYSTEMS...THERE WILL BE A POTENTIAL OF ACCUMULATING SNOWFALL
FOR THE FAR WEST AND WILL HAVE TO BE MONITORED. THERE WILL BE SOME
ISENTROPIC LIFT IN THE FAR WEST MONDAY NIGHT AS WELL WITH THE SECOND
PACIFIC SYSTEM.

.LONG TERM...TUESDAY THROUGH SATURDAY

THE OVERALL BIG PICTURE IS REASONABLY SIMILAR IN THE MODELS TONIGHT
BUT THE TIMING/SPEED VARIES ENOUGH TO MAKE THE FORECAST A CHALLENGE.
OVERALL...IT STILL LOOKS LIKE A COLD SHORTWAVE AND ASSOCIATED COLD
FRONT WILL DROP SOUTH OUT OF CANADA ON TUESDAY INTO TUESDAY NIGHT
WITH POTENTIAL FOR UPSLOPE EAST OF THE DIVIDE...ESPECIALLY IN THE
NORTH. IN THE WEST...A MOIST W-NW FLOW WILL KEEP SNOW FLYING OUT
THERE WITH STRONG W-NW WIND AHEAD OF THE CANADIAN FRONT EAST OF THE
DIVIDE. GFS HAS MORE AMPLIFICATION OF THE UPSTREAM RIDGE WEDNESDAY
WITH A COLDER...CYCLONIC NW FLOW WHILE THE ECMWF PUSHES THE RIDGE
AXIS MORE QUICKLY OFF TO THE EAST WITH LESS AMPLIFICATION. THE GEM
IS MORE OF A COMPROMISE. WILL GRADUALLY PUSH THE POPS SWD INTO
WEDNESDAY TO MAINLY COVER THE WEST AND SOUTH HALF. AS THE RIDGE AXIS
STARTS TO MOVE IN WEDNESDAY NIGHT SOME ISENTROPIC UPGLIDE MAY BE
ENOUGH FOR SOME LIGHT MTN SNOWFALL OUT WEST. DRIEST DAY IS SHAPING
UP TO BE THURSDAY WITH RIDGE AXIS INTO THE WEST. ECMWF KEEPS THE DRY
RIDGE AXIS OVER US THROUGH FRIDAY WHILE THE GFS IS FLATTER AND MORE
MOIST WITH PERSISTENT AT LEAST LIGHT PCPN OUT WEST. DUE TO THE
UNCERTAINTY THIS FAR OUT WILL KEEP JUST SOME POPS OUT WEST.
POTENTIAL FOR VALLEY RAIN OR SNOW AND MOUNTAIN SNOW INCREASING ONCE
AGAIN BY SATURDAY WITH POTENTIAL SHORTWAVE OR TWO SPINNING OFF THE
ERN PACIFIC TROUGH AND MOVING EAST ACROSS THE AREA. OVERALL...THIS
PATTERN COULD KEEP AREAS EAST OF THE DIVIDE MIXED OFF AND ON WITH
MILD TEMPERATURES. WINDY AHEAD OF THE CANADIAN FRONT TUESDAY. BRIEF
COLDER AIR WEDNESDAY WITH DECENT SURFACE HIGH JUST TO THE NE...THEN
WARM AIR ALOFT MOVING IN AGAIN BY THURSDAY THROUGH SATURDAY WITH
POTENTIAL FOR ENOUGH FLOW ALOFT AND PRESSURE GRADIENT TO KEEP
QUITE A FEW AREAS EAST OF THE DIVIDE MIXED...ESPECIALLY FRIDAY AND
SATURDAY. GENERALLY GOING WITH 40S AND SOME 50S EAST OF THE DIVIDE
FOR FRIDAY AND SATURDAY. COOLER IN THE WEST WITH INVERSIONS
HOLDING IN BETWEEN SYSTEMS AND THEN OF COURSE COLD RAIN OR SNOW AT
TIMES WITH EACH SYSTEM. SO MAINLY 30S OUT WEST.

&&

.AVIATION.../18Z ISSUANCE/

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

A COLD FRONT WILL PUSH SOUTH ACROSS NORTHERN WYOMING THIS AFTERNOON.
AREAS OF LOWER MVFR/IFR CIGS AND -SN WILL FOLLOW THE FRONT INTO
NORTHERN WYOMING AFTER 22Z...AND SOUTHWARD TO NEAR A VCNTY KRIW-KCPR
LINE BY 03Z SUNDAY. AREAS OF LOWER MVFR/IFR CIGS...LCL LIFR CIGS/FG
WILL LIKELY REMAIN AGAINST THE EAST SLOPES OF THE DIVIDE THROUGH 12Z
SUNDAY.

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

PATCHY FOG WILL LINGER IN THE STAR VALLEY THIS AFTERNOON AND REFORM
AGAIN AFTER 03Z THIS EVENING...EXPECT MVFR TO LIFR CONDITIONS AROUND
THE AFTON AIRPORT UNTIL 16Z SUNDAY. A COLD FRONT MAY PUSH LOWER
MVFR/IFR CIGS INTO VCNTY KRKS AFTER 06Z SUNDAY. ISOLATED SNOW
SHOWERS ARE POSSIBLE OVER THE NORTHWEST MOUNTAINS AND OVER THE WIND
RIVER MOUNTAINS AFTER 03Z SUNDAY UNTIL 13Z SUNDAY WITH LOCAL MVFR
CONDITIONS.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE TODAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. TODAY WILL SEE IMPROVEMENT
IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST OF THE
DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

&&

$$

SHORT TERM...LIPSON
LONG TERM...PS
AVIATION...AR
FIRE WEATHER...LIPSON













000
FXUS65 KRIW 312011
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
111 PM MST SAT JAN 31 2015

.SHORT TERM...TODAY THROUGH MONDAY NIGHT (ISSUED AT 250 AM MST)

ANY LEFT OVER SNOWFALL IN SOUTHERN SWEETWATER COUNTY THIS MORNING
WILL SHUT OFF SHORTLY AFTER SUNRISE AS THE LOW OVER VEGAS PROPAGATES
SOUTH TO OLD MEXICO. THE ASCT HIGH AND MID CLOUDS THAT HAVE BEEN
OVER CENTRAL AND SOUTHERN WY FRIDAY WILL CLEAR OUT OF SWEETWATER AND
NATRONA COUNTIES TO THE SOUTHEAST WITH MOSTLY CLEAR SKIES BY 18Z
TODAY. OTHERWISE EXPECT A MOSTLY SUNNY DAY WITH LIGHT WINDS AND
RELATIVELY MILD TEMPERATURES TODAY. THE NORTHERN STREAM VORT OVER
SOUTHERN BC WILL TRACK ACROSS WY FROM THE NW BY 00Z SAT. THIS
WEATHER FEATURE WILL DELIVER PATCHY LIGHT SNOW TO AREAS NORTH AND
EAST OF THE DIVIDE TONIGHT AS IT DRIVES A COLD FRONT SOUTH AND H7
TEMPS DROP TO -16C IN JOHNSON COUNTY BY 12Z SUNDAY. POST FRONTAL NNW
WINDS WILL INCREASE IN JOHNSON COUNTY LATE TODAY. SUNDAY WILL BE
RELATIVELY CHILLY WITH WARM AIR ADVECTING IN ALOFT FROM THE
SOUTHWEST SO THE COOLER AIR WILL BE SHORT LIVED. NORTHERN AND
WESTERN WY MAY NOT BREAK FREEZING SUNDAY BEFORE WARMING BACK UP
MONDAY. STILL...SEASONABLE TEMPS SLATED FOR THIS TIME OF YEAR
SUNDAY. BY SUNDAY NIGHT THE STEERING FLOW WILL BACK FROM NW TO WEST
AND INCREASE IN SPEED...MORE DIRECTLY OFF THE PACIFIC  UNDER A
FLATTENING RIDGE. A BATCH OF PACIFIC MOISTURE COMBINED WITH A WEAK
VORT EMBEDDED IN THE BACKING FLOW...SNOW WILL INCREASE IN THE WEST
SUNDAY NIGHT. SNOW WILL LESSEN IN INTENSITY MONDAY IN THE FAR WEST.
THEN THE CIRCULATION NOW WELL OFF THE PACIFIC COAST AT 45N/152W WILL
ARRIVE AS A VIGOROUS SHORTWAVE BRINGING ANOTHER SLUG OF PACIFIC
MOISTURE ACROSS MT/WY MONDAY NIGHT WITH SNOWFALL INCREASING ONCE
AGAIN IN THE FAR WEST. WITH FAVORABLE UPSLOPE CONDITIONS FOR THE FAR
WEST SUNDAY NIGHT THROUGH MONDAY NIGHT WITH THESE TWO BACK TO BACK
PACIFIC SYSTEMS...THERE WILL BE A POTENTIAL OF ACCUMULATING SNOWFALL
FOR THE FAR WEST AND WILL HAVE TO BE MONITORED. THERE WILL BE SOME
ISENTROPIC LIFT IN THE FAR WEST MONDAY NIGHT AS WELL WITH THE SECOND
PACIFIC SYSTEM.

.LONG TERM...TUESDAY THROUGH SATURDAY

THE OVERALL BIG PICTURE IS REASONABLY SIMILAR IN THE MODELS TONIGHT
BUT THE TIMING/SPEED VARIES ENOUGH TO MAKE THE FORECAST A CHALLENGE.
OVERALL...IT STILL LOOKS LIKE A COLD SHORTWAVE AND ASSOCIATED COLD
FRONT WILL DROP SOUTH OUT OF CANADA ON TUESDAY INTO TUESDAY NIGHT
WITH POTENTIAL FOR UPSLOPE EAST OF THE DIVIDE...ESPECIALLY IN THE
NORTH. IN THE WEST...A MOIST W-NW FLOW WILL KEEP SNOW FLYING OUT
THERE WITH STRONG W-NW WIND AHEAD OF THE CANADIAN FRONT EAST OF THE
DIVIDE. GFS HAS MORE AMPLIFICATION OF THE UPSTREAM RIDGE WEDNESDAY
WITH A COLDER...CYCLONIC NW FLOW WHILE THE ECMWF PUSHES THE RIDGE
AXIS MORE QUICKLY OFF TO THE EAST WITH LESS AMPLIFICATION. THE GEM
IS MORE OF A COMPROMISE. WILL GRADUALLY PUSH THE POPS SWD INTO
WEDNESDAY TO MAINLY COVER THE WEST AND SOUTH HALF. AS THE RIDGE AXIS
STARTS TO MOVE IN WEDNESDAY NIGHT SOME ISENTROPIC UPGLIDE MAY BE
ENOUGH FOR SOME LIGHT MTN SNOWFALL OUT WEST. DRIEST DAY IS SHAPING
UP TO BE THURSDAY WITH RIDGE AXIS INTO THE WEST. ECMWF KEEPS THE DRY
RIDGE AXIS OVER US THROUGH FRIDAY WHILE THE GFS IS FLATTER AND MORE
MOIST WITH PERSISTENT AT LEAST LIGHT PCPN OUT WEST. DUE TO THE
UNCERTAINTY THIS FAR OUT WILL KEEP JUST SOME POPS OUT WEST.
POTENTIAL FOR VALLEY RAIN OR SNOW AND MOUNTAIN SNOW INCREASING ONCE
AGAIN BY SATURDAY WITH POTENTIAL SHORTWAVE OR TWO SPINNING OFF THE
ERN PACIFIC TROUGH AND MOVING EAST ACROSS THE AREA. OVERALL...THIS
PATTERN COULD KEEP AREAS EAST OF THE DIVIDE MIXED OFF AND ON WITH
MILD TEMPERATURES. WINDY AHEAD OF THE CANADIAN FRONT TUESDAY. BRIEF
COLDER AIR WEDNESDAY WITH DECENT SURFACE HIGH JUST TO THE NE...THEN
WARM AIR ALOFT MOVING IN AGAIN BY THURSDAY THROUGH SATURDAY WITH
POTENTIAL FOR ENOUGH FLOW ALOFT AND PRESSURE GRADIENT TO KEEP
QUITE A FEW AREAS EAST OF THE DIVIDE MIXED...ESPECIALLY FRIDAY AND
SATURDAY. GENERALLY GOING WITH 40S AND SOME 50S EAST OF THE DIVIDE
FOR FRIDAY AND SATURDAY. COOLER IN THE WEST WITH INVERSIONS
HOLDING IN BETWEEN SYSTEMS AND THEN OF COURSE COLD RAIN OR SNOW AT
TIMES WITH EACH SYSTEM. SO MAINLY 30S OUT WEST.

&&

.AVIATION.../18Z ISSUANCE/

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

A COLD FRONT WILL PUSH SOUTH ACROSS NORTHERN WYOMING THIS AFTERNOON.
AREAS OF LOWER MVFR/IFR CIGS AND -SN WILL FOLLOW THE FRONT INTO
NORTHERN WYOMING AFTER 22Z...AND SOUTHWARD TO NEAR A VCNTY KRIW-KCPR
LINE BY 03Z SUNDAY. AREAS OF LOWER MVFR/IFR CIGS...LCL LIFR CIGS/FG
WILL LIKELY REMAIN AGAINST THE EAST SLOPES OF THE DIVIDE THROUGH 12Z
SUNDAY.

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

PATCHY FOG WILL LINGER IN THE STAR VALLEY THIS AFTERNOON AND REFORM
AGAIN AFTER 03Z THIS EVENING...EXPECT MVFR TO LIFR CONDITIONS AROUND
THE AFTON AIRPORT UNTIL 16Z SUNDAY. A COLD FRONT MAY PUSH LOWER
MVFR/IFR CIGS INTO VCNTY KRKS AFTER 06Z SUNDAY. ISOLATED SNOW
SHOWERS ARE POSSIBLE OVER THE NORTHWEST MOUNTAINS AND OVER THE WIND
RIVER MOUNTAINS AFTER 03Z SUNDAY UNTIL 13Z SUNDAY WITH LOCAL MVFR
CONDITIONS.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE TODAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. TODAY WILL SEE IMPROVEMENT
IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST OF THE
DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

&&

$$

SHORT TERM...LIPSON
LONG TERM...PS
AVIATION...AR
FIRE WEATHER...LIPSON












000
FXUS65 KRIW 310950
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
250 AM MST SAT JAN 31 2015

.SHORT TERM...TODAY THROUGH MONDAY NIGHT

ANY LEFT OVER SNOWFALL IN SOUTHERN SWEETWATER COUNTY THIS MORNING
WILL SHUT OFF SHORTLY AFTER SUNRISE AS THE LOW OVER VEGAS PROPAGATES
SOUTH TO OLD MEXICO. THE ASCT HIGH AND MID CLOUDS THAT HAVE BEEN
OVER CENTRAL AND SOUTHERN WY FRIDAY WILL CLEAR OUT OF SWEETWATER AND
NATRONA COUNTIES TO THE SOUTHEAST WITH MOSTLY CLEAR SKIES BY 18Z
TODAY. OTHERWISE EXPECT A MOSTLY SUNNY DAY WITH LIGHT WINDS AND
RELATIVELY MILD TEMPERATURES TODAY. THE NORTHERN STREAM VORT OVER
SOUTHERN BC WILL TRACK ACROSS WY FROM THE NW BY 00Z SAT. THIS
WEATHER FEATURE WILL DELIVER PATCHY LIGHT SNOW TO AREAS NORTH AND
EAST OF THE DIVIDE TONIGHT AS IT DRIVES A COLD FRONT SOUTH AND H7
TEMPS DROP TO -16C IN JOHNSON COUNTY BY 12Z SUNDAY. POST FRONTAL NNW
WINDS WILL INCREASE IN JOHNSON COUNTY LATE TODAY. SUNDAY WILL BE
RELATIVELY CHILLY WITH WARM AIR ADVECTING IN ALOFT FROM THE
SOUTHWEST SO THE COOLER AIR WILL BE SHORT LIVED. NORTHERN AND
WESTERN WY MAY NOT BREAK FREEZING SUNDAY BEFORE WARMING BACK UP
MONDAY. STILL...SEASONABLE TEMPS SLATED FOR THIS TIME OF YEAR
SUNDAY. BY SUNDAY NIGHT THE STEERING FLOW WILL BACK FROM NW TO WEST
AND INCREASE IN SPEED...MORE DIRECTLY OFF THE PACIFIC  UNDER A
FLATTENING RIDGE. A BATCH OF PACIFIC MOISTURE COMBINED WITH A WEAK
VORT EMBEDDED IN THE BACKING FLOW...SNOW WILL INCREASE IN THE WEST
SUNDAY NIGHT. SNOW WILL LESSEN IN INTENSITY MONDAY IN THE FAR WEST.
THEN THE CIRCULATION NOW WELL OFF THE PACIFIC COAST AT 45N/152W WILL
ARRIVE AS A VIGOROUS SHORTWAVE BRINGING ANOTHER SLUG OF PACIFIC
MOISTURE ACROSS MT/WY MONDAY NIGHT WITH SNOWFALL INCREASING ONCE
AGAIN IN THE FAR WEST. WITH FAVORABLE UPSLOPE CONDITIONS FOR THE FAR
WEST SUNDAY NIGHT THROUGH MONDAY NIGHT WITH THESE TWO BACK TO BACK
PACIFIC SYSTEMS...THERE WILL BE A POTENTIAL OF ACCUMULATING SNOWFALL
FOR THE FAR WEST AND WILL HAVE TO BE MONITORED. THERE WILL BE SOME
ISENTROPIC LIFT IN THE FAR WEST MONDAY NIGHT AS WELL WITH THE SECOND
PACIFIC SYSTEM.

.LONG TERM...TUESDAY THROUGH SATURDAY

THE OVERALL BIG PICTURE IS REASONABLY SIMILAR IN THE MODELS TONIGHT
BUT THE TIMING/SPEED VARIES ENOUGH TO MAKE THE FORECAST A CHALLENGE.
OVERALL...IT STILL LOOKS LIKE A COLD SHORTWAVE AND ASSOCIATED COLD
FRONT WILL DROP SOUTH OUT OF CANADA ON TUESDAY INTO TUESDAY NIGHT
WITH POTENTIAL FOR UPSLOPE EAST OF THE DIVIDE...ESPECIALLY IN THE
NORTH. IN THE WEST...A MOIST W-NW FLOW WILL KEEP SNOW FLYING OUT
THERE WITH STRONG W-NW WIND AHEAD OF THE CANADIAN FRONT EAST OF THE
DIVIDE. GFS HAS MORE AMPLIFICATION OF THE UPSTREAM RIDGE WEDNESDAY
WITH A COLDER...CYCLONIC NW FLOW WHILE THE ECMWF PUSHES THE RIDGE
AXIS MORE QUICKLY OFF TO THE EAST WITH LESS AMPLIFICATION. THE GEM
IS MORE OF A COMPROMISE. WILL GRADUALLY PUSH THE POPS SWD INTO
WEDNESDAY TO MAINLY COVER THE WEST AND SOUTH HALF. AS THE RIDGE AXIS
STARTS TO MOVE IN WEDNESDAY NIGHT SOME ISENTROPIC UPGLIDE MAY BE
ENOUGH FOR SOME LIGHT MTN SNOWFALL OUT WEST. DRIEST DAY IS SHAPING
UP TO BE THURSDAY WITH RIDGE AXIS INTO THE WEST. ECMWF KEEPS THE DRY
RIDGE AXIS OVER US THROUGH FRIDAY WHILE THE GFS IS FLATTER AND MORE
MOIST WITH PERSISTENT AT LEAST LIGHT PCPN OUT WEST. DUE TO THE
UNCERTAINTY THIS FAR OUT WILL KEEP JUST SOME POPS OUT WEST.
POTENTIAL FOR VALLEY RAIN OR SNOW AND MOUNTAIN SNOW INCREASING ONCE
AGAIN BY SATURDAY WITH POTENTIAL SHORTWAVE OR TWO SPINNING OFF THE
ERN PACIFIC TROUGH AND MOVING EAST ACROSS THE AREA. OVERALL...THIS
PATTERN COULD KEEP AREAS EAST OF THE DIVIDE MIXED OFF AND ON WITH
MILD TEMPERATURES. WINDY AHEAD OF THE CANADIAN FRONT TUESDAY. BRIEF
COLDER AIR WEDNESDAY WITH DECENT SURFACE HIGH JUST TO THE NE...THEN
WARM AIR ALOFT MOVING IN AGAIN BY THURSDAY THROUGH SATURDAY WITH
POTENTIAL FOR ENOUGH FLOW ALOFT AND PRESSURE GRADIENT TO KEEP
QUITE A FEW AREAS EAST OF THE DIVIDE MIXED...ESPECIALLY FRIDAY AND
SATURDAY. GENERALLY GOING WITH 40S AND SOME 50S EAST OF THE DIVIDE
FOR FRIDAY AND SATURDAY. COOLER IN THE WEST WITH INVERSIONS
HOLDING IN BETWEEN SYSTEMS AND THEN OF COURSE COLD RAIN OR SNOW AT
TIMES WITH EACH SYSTEM. SO MAINLY 30S OUT WEST.

&&

.AVIATION.../12Z ISSUANCE/

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

AREAS OF FOG WILL OBSCURE TERRAIN ACROSS THE LOWER BIGHORN BASIN
THROUGH 14Z...VCNTY KGEY-KWRL.  A COLD FRONT WILL PUSH SOUTH ACROSS
NORTHERN WYOMING LATE THIS MORNING...LIKELY SCOURING OUT ANY
LINGERING FOG. HOWEVER...AREAS OF LOWER MVFR/IFR CIGS AND -SN WILL
FOLLOW THE FRONT INTO NORTHERN WYOMING AFTER 20Z...AND SOUTHWARD
TO NEAR A VCNTY KRIW-KCPR LINE BY 00Z SUNDAY. AREAS OF LOWER
MVFR/IFR CIGS...LCL LIFR CIGS/FG WILL LIKELY REMAIN AGAINST THE
EAST SLOPES OF THE DIVIDE THROUGH 12Z SUNDAY.

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

AREAS OF IFR/MVFR CIGS AND -SN WILL GRADUALLY DECREASE ACROSS THE
INTERSTATE 80 CORRIDOR THROUGH 14Z...BUT PATCHY FOG MAY LINGER IN
THIS AREA THROUGH THE MORNING.  OTHERWISE...VFR CONDITIONS WILL
PREVAIL ACROSS THE AREA 15Z TODAY-03Z SUNDAY. A COLD FRONT WILL
PLUNGE DOWN THE EAST SLOPES OF THE DIVIDE LATE THIS MORNING
THROUGH THIS AFTERNOON WITH SOME MTN OBSCURATIONS POSSIBLE ALONG
THE DIVIDE. THIS FRONT MAY PUSH LOWER MVFR/IFR CIGS INTO VCNTY
KRKS AFTER 06Z SUNDAY. FURTHER OUT FROM THE FRONT....LOWER
MVFR/IFR CIGS FROM EASTERN IDAHO MAY PUSH INTO THE FAR
WEST...VCNTY KJAC-KAFO AFTER 03Z SUNDAY.

&&

.FIRE WEATHER...
FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE TODAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. TODAY WILL SEE IMPROVEMENT
IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST OF THE
DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

&&

$$

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









000
FXUS65 KRIW 310654
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1154 PM MST FRI JAN 30 2015

UPDATE...ADDED 06Z AVIATION DISCUSSION.

.SHORT TERM...TONIGHT THROUGH SATURDAY (ISSUED AT 230 PM MST)

A WARM PACIFIC LOW OVER THE FOUR CORNERS AREA THIS
AFTERNOON...CONTINUES TO STREAM HIGH CLOUDS ACROSS THE COWBOY
STATE. LOW CLOUDS HAVE MADE THEIR WAY INTO THE I-80 CORRIDOR NEAR
KRKS...WHILE THE RAIN SHOWERS REMAIN WELL TO THE SOUTH IN NE
UT/NW CO. THESE SHOWERS WILL SLOWLY MAKE THEIR WAY NORTHWARD THIS
EVENING. TEMPERATURES ARE EXPECTED TO BE AT OR BELOW FREEZING BY
THIS TIME...PRODUCING LIGHT SNOW SHOWERS ACROSS SWEETWATER COUNTY.
ACCUMULATIONS ARE EXPECTED TO REMAIN LIGHT THROUGH MID MORNING
SATURDAY.

FOG CONTINUES TO HOLD ON OVER NORTHERN PORTIONS OF THE BIGHORN
BASIN...DESPITE THE CLOUDS ALOFT. FOG WILL BEGIN TO FILL IN
FURTHER SOUTH TOWARD KWRL DURING THE OVERNIGHT HOURS. FOG SHOULD
LIFT OUT BY MID MORNING...AS SKIES BEGIN TO CLEAR ACROSS THE AREA.

A COLD FRONT WILL BEGIN TO IMPACT NORTHERN PORTIONS LATE SATURDAY
AFTERNOON...BRINGING LOW CLOUDS AND GUSTY WINDS TO JOHNSON COUNTY.
LIGHT SNOW SHOWERS WILL BE POSSIBLE IN THE BIGHORNS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY NIGHT

THE SHORTWAVE MOVING THROUGH NORTHEASTERN WYOMING SATURDAY NIGHT
WILL HAVE SOME IMPACT OVER THE EASTERN PORTION OF THE FORECAST AREA
THROUGH SUNDAY MORNING. LIGHT SHOWER ACTIVITY IS EXPECTED.

BUILDING NORTHWEST FLOW THEN EXPECTED SUNDAY AFTERNOON AND EVENING
AS A RIDGE OF HIGH PRESSURE BUILDS OFF THE PACIFIC COAST. THIS
SYSTEM WILL BRING SOME MOISTURE INTO NORTHWESTERN WYOMING EARLY
MONDAY MORNING...MAINLY IMPACTING WESTERN AND NORTHERN WYOMING.

ANOTHER...MORE SIGNIFICANT PUSH OF MOISTURE WILL FOLLOW THAT SYSTEM
QUICKLY...WITH PRECIPITATION SPREADING INTO WESTERN WYOMING MONDAY
EVENING. ACTIVITY FROM THIS SYSTEM WILL LINGER THROUGH WEDNESDAY AS
ANOTHER PUSH COMES DOWN FROM THE NORTH AS WELL. THE ACTIVITY WILL
SPREAD TO INCLUDE MUCH OF THE FORECAST AREA. MODELS HAVE SOME
VARIATIONS ON THIS SYSTEM...WITH THE GFS REMAINING THE MOST
AGGRESSIVE MODEL. HOWEVER...ALL MODELS ARE IN FAIR AGREEMENT THAT
COVERAGE WILL INCREASE THROUGH WEDNESDAY MORNING.

CONDITIONS TO IMPROVE WEDNESDAY AFTERNOON AND EVENING. A BUILDING
RIDGE WILL HELP TO CLEAR OUT ACTIVITY...THOUGH SOME VERY LIGHT
ACTIVITY MAY REMAIN POSSIBLE ACROSS THE NORTHWEST THROUGH THURSDAY
AFTERNOON. DRY CONDITIONS EXPECTED BY FRIDAY MORNING...WHICH MAY NOT
LAST LONG.

&&

.AVIATION.../06Z ISSUANCE

AREAS OF FOG WILL OBSCURE TERRAIN ACROSS THE LOWER BIGHORN BASIN
THROUGH 14Z...VCNTY KGEY-KWRL.  A COLD FRONT WILL PUSH SOUTH ACROSS
NORTHERN WYOMING LATE SATURDAY MORNING...LIKELY SCOURING OUT ANY
LINGERING FOG.  HOWEVER...AREAS OF LOWER MVFR/IFR CIGS AND -SN WILL
FOLLOW THE FRONT INTO NORTHERN WYOMING AFTER 20Z...AND SOUTHWARD TO
NEAR A VCNTY KRIW-KCPR LINE BY 00Z SUNDAY.  AREAS OF LOWER MVFR/IFR
CIGS...LCL LIFR CIGS/FG WILL LIKELY REMAIN AGAINST THE EAST SLOPES
OF THE DIVIDE THROUGH 12Z SUNDAY.

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

AREAS OF IFR/MVFR CIGS AND -SN WILL GRADUALLY DECREASE ACROSS THE
INTERSTATE 80 CORRIDOR THROUGH 14Z...BUT PATCHY FOG MAY LINGER IN
THIS AREA THROUGH THE MORNING.  OTHERWISE...VFR CONDITIONS WILL
PREVAIL ACROSS THE AREA 15Z SAT-03Z SUNDAY.  A COLD FRONT WILL
PLUNGE DOWN THE EAST SLOPES OF THE DIVIDE LATE SATURDAY MORNING
THROUGH SATURDAY AFTERNOON WITH SOME MTN OBSCURATIONS POSSIBLE ALONG
THE DIVIDE.  THIS FRONT MAY PUSH LOWER MVFR/IFR CIGS INTO VCNTY KRKS
AFTER 06Z SUNDAY.  FURTHER OUT FROM THE FRONT....LOWER MVFR/IFR CIGS
FROM EASTERN IDAHO MAY PUSH INTO THE FAR WEST...VCNTY KJAC-KAFO
AFTER 03Z SUNDAY.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SATURDAY WILL SEE
IMPROVEMENT IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY
EAST OF THE DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

$$

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










000
FXUS65 KRIW 310654
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1154 PM MST FRI JAN 30 2015

UPDATE...ADDED 06Z AVIATION DISCUSSION.

.SHORT TERM...TONIGHT THROUGH SATURDAY (ISSUED AT 230 PM MST)

A WARM PACIFIC LOW OVER THE FOUR CORNERS AREA THIS
AFTERNOON...CONTINUES TO STREAM HIGH CLOUDS ACROSS THE COWBOY
STATE. LOW CLOUDS HAVE MADE THEIR WAY INTO THE I-80 CORRIDOR NEAR
KRKS...WHILE THE RAIN SHOWERS REMAIN WELL TO THE SOUTH IN NE
UT/NW CO. THESE SHOWERS WILL SLOWLY MAKE THEIR WAY NORTHWARD THIS
EVENING. TEMPERATURES ARE EXPECTED TO BE AT OR BELOW FREEZING BY
THIS TIME...PRODUCING LIGHT SNOW SHOWERS ACROSS SWEETWATER COUNTY.
ACCUMULATIONS ARE EXPECTED TO REMAIN LIGHT THROUGH MID MORNING
SATURDAY.

FOG CONTINUES TO HOLD ON OVER NORTHERN PORTIONS OF THE BIGHORN
BASIN...DESPITE THE CLOUDS ALOFT. FOG WILL BEGIN TO FILL IN
FURTHER SOUTH TOWARD KWRL DURING THE OVERNIGHT HOURS. FOG SHOULD
LIFT OUT BY MID MORNING...AS SKIES BEGIN TO CLEAR ACROSS THE AREA.

A COLD FRONT WILL BEGIN TO IMPACT NORTHERN PORTIONS LATE SATURDAY
AFTERNOON...BRINGING LOW CLOUDS AND GUSTY WINDS TO JOHNSON COUNTY.
LIGHT SNOW SHOWERS WILL BE POSSIBLE IN THE BIGHORNS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY NIGHT

THE SHORTWAVE MOVING THROUGH NORTHEASTERN WYOMING SATURDAY NIGHT
WILL HAVE SOME IMPACT OVER THE EASTERN PORTION OF THE FORECAST AREA
THROUGH SUNDAY MORNING. LIGHT SHOWER ACTIVITY IS EXPECTED.

BUILDING NORTHWEST FLOW THEN EXPECTED SUNDAY AFTERNOON AND EVENING
AS A RIDGE OF HIGH PRESSURE BUILDS OFF THE PACIFIC COAST. THIS
SYSTEM WILL BRING SOME MOISTURE INTO NORTHWESTERN WYOMING EARLY
MONDAY MORNING...MAINLY IMPACTING WESTERN AND NORTHERN WYOMING.

ANOTHER...MORE SIGNIFICANT PUSH OF MOISTURE WILL FOLLOW THAT SYSTEM
QUICKLY...WITH PRECIPITATION SPREADING INTO WESTERN WYOMING MONDAY
EVENING. ACTIVITY FROM THIS SYSTEM WILL LINGER THROUGH WEDNESDAY AS
ANOTHER PUSH COMES DOWN FROM THE NORTH AS WELL. THE ACTIVITY WILL
SPREAD TO INCLUDE MUCH OF THE FORECAST AREA. MODELS HAVE SOME
VARIATIONS ON THIS SYSTEM...WITH THE GFS REMAINING THE MOST
AGGRESSIVE MODEL. HOWEVER...ALL MODELS ARE IN FAIR AGREEMENT THAT
COVERAGE WILL INCREASE THROUGH WEDNESDAY MORNING.

CONDITIONS TO IMPROVE WEDNESDAY AFTERNOON AND EVENING. A BUILDING
RIDGE WILL HELP TO CLEAR OUT ACTIVITY...THOUGH SOME VERY LIGHT
ACTIVITY MAY REMAIN POSSIBLE ACROSS THE NORTHWEST THROUGH THURSDAY
AFTERNOON. DRY CONDITIONS EXPECTED BY FRIDAY MORNING...WHICH MAY NOT
LAST LONG.

&&

.AVIATION.../06Z ISSUANCE

AREAS OF FOG WILL OBSCURE TERRAIN ACROSS THE LOWER BIGHORN BASIN
THROUGH 14Z...VCNTY KGEY-KWRL.  A COLD FRONT WILL PUSH SOUTH ACROSS
NORTHERN WYOMING LATE SATURDAY MORNING...LIKELY SCOURING OUT ANY
LINGERING FOG.  HOWEVER...AREAS OF LOWER MVFR/IFR CIGS AND -SN WILL
FOLLOW THE FRONT INTO NORTHERN WYOMING AFTER 20Z...AND SOUTHWARD TO
NEAR A VCNTY KRIW-KCPR LINE BY 00Z SUNDAY.  AREAS OF LOWER MVFR/IFR
CIGS...LCL LIFR CIGS/FG WILL LIKELY REMAIN AGAINST THE EAST SLOPES
OF THE DIVIDE THROUGH 12Z SUNDAY.

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

AREAS OF IFR/MVFR CIGS AND -SN WILL GRADUALLY DECREASE ACROSS THE
INTERSTATE 80 CORRIDOR THROUGH 14Z...BUT PATCHY FOG MAY LINGER IN
THIS AREA THROUGH THE MORNING.  OTHERWISE...VFR CONDITIONS WILL
PREVAIL ACROSS THE AREA 15Z SAT-03Z SUNDAY.  A COLD FRONT WILL
PLUNGE DOWN THE EAST SLOPES OF THE DIVIDE LATE SATURDAY MORNING
THROUGH SATURDAY AFTERNOON WITH SOME MTN OBSCURATIONS POSSIBLE ALONG
THE DIVIDE.  THIS FRONT MAY PUSH LOWER MVFR/IFR CIGS INTO VCNTY KRKS
AFTER 06Z SUNDAY.  FURTHER OUT FROM THE FRONT....LOWER MVFR/IFR CIGS
FROM EASTERN IDAHO MAY PUSH INTO THE FAR WEST...VCNTY KJAC-KAFO
AFTER 03Z SUNDAY.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SATURDAY WILL SEE
IMPROVEMENT IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY
EAST OF THE DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

$$

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











000
FXUS65 KRIW 302130
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
230 PM MST FRI JAN 30 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

A WARM PACIFIC LOW OVER THE FOUR CORNERS AREA THIS
AFTERNOON...CONTINUES TO STREAM HIGH CLOUDS ACROSS THE COWBOY
STATE. LOW CLOUDS HAVE MADE THEIR WAY INTO THE I-80 CORRIDOR NEAR
KRKS...WHILE THE RAIN SHOWERS REMAIN WELL TO THE SOUTH IN NE
UT/NW CO. THESE SHOWERS WILL SLOWLY MAKE THEIR WAY NORTHWARD THIS
EVENING. TEMPERATURES ARE EXPECTED TO BE AT OR BELOW FREEZING BY
THIS TIME...PRODUCING LIGHT SNOW SHOWERS ACROSS SWEETWATER COUNTY.
ACCUMULATIONS ARE EXPECTED TO REMAIN LIGHT THROUGH MID MORNING
SATURDAY.

FOG CONTINUES TO HOLD ON OVER NORTHERN PORTIONS OF THE BIGHORN
BASIN...DESPITE THE CLOUDS ALOFT. FOG WILL BEGIN TO FILL IN
FURTHER SOUTH TOWARD KWRL DURING THE OVERNIGHT HOURS. FOG SHOULD
LIFT OUT BY MID MORNING...AS SKIES BEGIN TO CLEAR ACROSS THE AREA.

A COLD FRONT WILL BEGIN TO IMPACT NORTHERN PORTIONS LATE SATURDAY
AFTERNOON...BRINGING LOW CLOUDS AND GUSTY WINDS TO JOHNSON COUNTY.
LIGHT SNOW SHOWERS WILL BE POSSIBLE IN THE BIGHORNS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY NIGHT

THE SHORTWAVE MOVING THROUGH NORTHEASTERN WYOMING SATURDAY NIGHT
WILL HAVE SOME IMPACT OVER THE EASTERN PORTION OF THE FORECAST AREA
THROUGH SUNDAY MORNING. LIGHT SHOWER ACTIVITY IS EXPECTED.

BUILDING NORTHWEST FLOW THEN EXPECTED SUNDAY AFTERNOON AND EVENING
AS A RIDGE OF HIGH PRESSURE BUILDS OFF THE PACIFIC COAST. THIS
SYSTEM WILL BRING SOME MOISTURE INTO NORTHWESTERN WYOMING EARLY
MONDAY MORNING...MAINLY IMPACTING WESTERN AND NORTHERN WYOMING.

ANOTHER...MORE SIGNIFICANT PUSH OF MOISTURE WILL FOLLOW THAT SYSTEM
QUICKLY...WITH PRECIPITATION SPREADING INTO WESTERN WYOMING MONDAY
EVENING. ACTIVITY FROM THIS SYSTEM WILL LINGER THROUGH WEDNESDAY AS
ANOTHER PUSH COMES DOWN FROM THE NORTH AS WELL. THE ACTIVITY WILL
SPREAD TO INCLUDE MUCH OF THE FORECAST AREA. MODELS HAVE SOME
VARIATIONS ON THIS SYSTEM...WITH THE GFS REMAINING THE MOST
AGGRESSIVE MODEL. HOWEVER...ALL MODELS ARE IN FAIR AGREEMENT THAT
COVERAGE WILL INCREASE THROUGH WEDNESDAY MORNING.

CONDITIONS TO IMPROVE WEDNESDAY AFTERNOON AND EVENING. A BUILDING
RIDGE WILL HELP TO CLEAR OUT ACTIVITY...THOUGH SOME VERY LIGHT
ACTIVITY MAY REMAIN POSSIBLE ACROSS THE NORTHWEST THROUGH THURSDAY
AFTERNOON. DRY CONDITIONS EXPECTED BY FRIDAY MORNING...WHICH MAY NOT
LAST LONG.

&&

.AVIATION.../00Z ISSUANCE/

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

VFR CONDITIONS WILL PREVAIL THIS EVENING...WITH FOG LINGERING IN
THE BIGHORN BASIN NEAR KGEY. FOG WILL SPREAD THROUGHOUT THE
NIGHT...REACHING KWRL BY 10Z SATURDAY. N-NE SFC WINDS WILL
PREVAIL ACROSS THE AREA...WITH SOME LOWER CIGS EXPECTED ALONG THE
EAST SLOPES OF THE DIVIDE AND OTHER UPSLOPE FAVORED AREAS. MOST OF
THESE CIGS ARE EXPECTED TO REMAIN VFR...OBSCURING HIGHER MTNS.
CLEARING IS EXPECTED AFTER 12Z SATURDAY...WITH IMPROVING
CONDITIONS FROM NORTH TO SOUTH THROUGH THE DAY. THIS WILL BE
SHORT-LIVED...AS A COLD FRONT BEGINS TO IMPACT KCOD-KWRL WITH MVFR
CONDITIONS BY 23Z SATURDAY.

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

AN UPPER LEVEL LOW PRESSURE SYSTEM OVER THE FOUR CORNERS...WILL
CONTINUE TO PUSH UP MOISTURE INTO SOUTHERN WYOMING THROUGH THE
PERIOD...WITH CIGS EXPECTED TO GRADUALLY LOWER VCNTY AND SOUTH OF
INTERSTATE 80...WITH SOME ISOLD TO SCT -SHSN MOVING IN EARLY THIS
EVENING ALONG WITH LOCAL MVFR/IFR CONDITIONS. MVFR/IFR CONDITIONS ARE
EXPECTED TO BECOME MORE PREVALENT IN THIS AREA AFTER 00Z SATURDAY.
VFR CONDITIONS WILL RETURN TO THESE AREAS AFTER 15Z
SATURDAY...WITH INCREASING WESTERLY WINDS OF 15 TO 25 MPH BY 21Z.

NORTH OF INTERSTATE 80...VFR CONDITIONS WILL PREVAIL THROUGH THE
PERIOD.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SATURDAY WILL SEE
IMPROVEMENT IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY
EAST OF THE DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

$$

SHORT TERM...LAVOIE
LONG TERM...BRANHAM
AVIATION...LAVOIE
FIRE WEATHER...LAVOIE







000
FXUS65 KRIW 302130
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
230 PM MST FRI JAN 30 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

A WARM PACIFIC LOW OVER THE FOUR CORNERS AREA THIS
AFTERNOON...CONTINUES TO STREAM HIGH CLOUDS ACROSS THE COWBOY
STATE. LOW CLOUDS HAVE MADE THEIR WAY INTO THE I-80 CORRIDOR NEAR
KRKS...WHILE THE RAIN SHOWERS REMAIN WELL TO THE SOUTH IN NE
UT/NW CO. THESE SHOWERS WILL SLOWLY MAKE THEIR WAY NORTHWARD THIS
EVENING. TEMPERATURES ARE EXPECTED TO BE AT OR BELOW FREEZING BY
THIS TIME...PRODUCING LIGHT SNOW SHOWERS ACROSS SWEETWATER COUNTY.
ACCUMULATIONS ARE EXPECTED TO REMAIN LIGHT THROUGH MID MORNING
SATURDAY.

FOG CONTINUES TO HOLD ON OVER NORTHERN PORTIONS OF THE BIGHORN
BASIN...DESPITE THE CLOUDS ALOFT. FOG WILL BEGIN TO FILL IN
FURTHER SOUTH TOWARD KWRL DURING THE OVERNIGHT HOURS. FOG SHOULD
LIFT OUT BY MID MORNING...AS SKIES BEGIN TO CLEAR ACROSS THE AREA.

A COLD FRONT WILL BEGIN TO IMPACT NORTHERN PORTIONS LATE SATURDAY
AFTERNOON...BRINGING LOW CLOUDS AND GUSTY WINDS TO JOHNSON COUNTY.
LIGHT SNOW SHOWERS WILL BE POSSIBLE IN THE BIGHORNS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY NIGHT

THE SHORTWAVE MOVING THROUGH NORTHEASTERN WYOMING SATURDAY NIGHT
WILL HAVE SOME IMPACT OVER THE EASTERN PORTION OF THE FORECAST AREA
THROUGH SUNDAY MORNING. LIGHT SHOWER ACTIVITY IS EXPECTED.

BUILDING NORTHWEST FLOW THEN EXPECTED SUNDAY AFTERNOON AND EVENING
AS A RIDGE OF HIGH PRESSURE BUILDS OFF THE PACIFIC COAST. THIS
SYSTEM WILL BRING SOME MOISTURE INTO NORTHWESTERN WYOMING EARLY
MONDAY MORNING...MAINLY IMPACTING WESTERN AND NORTHERN WYOMING.

ANOTHER...MORE SIGNIFICANT PUSH OF MOISTURE WILL FOLLOW THAT SYSTEM
QUICKLY...WITH PRECIPITATION SPREADING INTO WESTERN WYOMING MONDAY
EVENING. ACTIVITY FROM THIS SYSTEM WILL LINGER THROUGH WEDNESDAY AS
ANOTHER PUSH COMES DOWN FROM THE NORTH AS WELL. THE ACTIVITY WILL
SPREAD TO INCLUDE MUCH OF THE FORECAST AREA. MODELS HAVE SOME
VARIATIONS ON THIS SYSTEM...WITH THE GFS REMAINING THE MOST
AGGRESSIVE MODEL. HOWEVER...ALL MODELS ARE IN FAIR AGREEMENT THAT
COVERAGE WILL INCREASE THROUGH WEDNESDAY MORNING.

CONDITIONS TO IMPROVE WEDNESDAY AFTERNOON AND EVENING. A BUILDING
RIDGE WILL HELP TO CLEAR OUT ACTIVITY...THOUGH SOME VERY LIGHT
ACTIVITY MAY REMAIN POSSIBLE ACROSS THE NORTHWEST THROUGH THURSDAY
AFTERNOON. DRY CONDITIONS EXPECTED BY FRIDAY MORNING...WHICH MAY NOT
LAST LONG.

&&

.AVIATION.../00Z ISSUANCE/

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

VFR CONDITIONS WILL PREVAIL THIS EVENING...WITH FOG LINGERING IN
THE BIGHORN BASIN NEAR KGEY. FOG WILL SPREAD THROUGHOUT THE
NIGHT...REACHING KWRL BY 10Z SATURDAY. N-NE SFC WINDS WILL
PREVAIL ACROSS THE AREA...WITH SOME LOWER CIGS EXPECTED ALONG THE
EAST SLOPES OF THE DIVIDE AND OTHER UPSLOPE FAVORED AREAS. MOST OF
THESE CIGS ARE EXPECTED TO REMAIN VFR...OBSCURING HIGHER MTNS.
CLEARING IS EXPECTED AFTER 12Z SATURDAY...WITH IMPROVING
CONDITIONS FROM NORTH TO SOUTH THROUGH THE DAY. THIS WILL BE
SHORT-LIVED...AS A COLD FRONT BEGINS TO IMPACT KCOD-KWRL WITH MVFR
CONDITIONS BY 23Z SATURDAY.

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

AN UPPER LEVEL LOW PRESSURE SYSTEM OVER THE FOUR CORNERS...WILL
CONTINUE TO PUSH UP MOISTURE INTO SOUTHERN WYOMING THROUGH THE
PERIOD...WITH CIGS EXPECTED TO GRADUALLY LOWER VCNTY AND SOUTH OF
INTERSTATE 80...WITH SOME ISOLD TO SCT -SHSN MOVING IN EARLY THIS
EVENING ALONG WITH LOCAL MVFR/IFR CONDITIONS. MVFR/IFR CONDITIONS ARE
EXPECTED TO BECOME MORE PREVALENT IN THIS AREA AFTER 00Z SATURDAY.
VFR CONDITIONS WILL RETURN TO THESE AREAS AFTER 15Z
SATURDAY...WITH INCREASING WESTERLY WINDS OF 15 TO 25 MPH BY 21Z.

NORTH OF INTERSTATE 80...VFR CONDITIONS WILL PREVAIL THROUGH THE
PERIOD.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SATURDAY WILL SEE
IMPROVEMENT IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY
EAST OF THE DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

$$

SHORT TERM...LAVOIE
LONG TERM...BRANHAM
AVIATION...LAVOIE
FIRE WEATHER...LAVOIE








000
FXUS65 KRIW 301740
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1040 AM MST FRI JAN 30 2015

.UPDATE...ADDED 18Z AVIATION DISCUSSION BELOW


SHORT TERM...TODAY THROUGH SUNDAY NIGHT (ISSUED AT 323 AM MST)

EXCEPT FOR GEY...SO FAR VERY LITTLE FOG HAS BEEN DETECTED ACROSS
THE CWA IN RESPONSE TO THE HIGH CLOUDS MOVING IN FROM THE
SOUTHWEST. KEPT PATCHY FOG IN THE FORECAST HOWEVER AS IT IS ONLY
PATCHY AND NOCTURNAL INVERSIONS WILL PERSIST TO A LESSER EXTENT
OVER THE BASINS AND VALLEY THROUGH THIS MORNING. TOOK FOG OUT OF
GEY FOR THIS AFTERNOON. THE INCREASING HIGH CLOUDS ARE ASSOCIATED
WITH THE SOUTHERN STREAM CIRCULATION ALONG THE SOUTHERN CA/BAJA CA
COAST WHICH IS ANTICIPATED TO CONTINUE TO CLOSE OFF SOUTHWEST AND
SOUTH OF VEGAS TODAY AND TONIGHT. WITH THE MAIN ENERGY REMAINING
WELL TO OUR SOUTH...THE NORTHEAST EXTENT OF THIS CIRRUS SHIELD
WILL REMAIN ACROSS SOUTHERN WY TODAY WITH THE NORTHERN EXTENSION
CONTINUING TO DISSIPATE AS FAST AS IT MOVES NORTH. ANY MIXED
PRECIP THAT FALLS FROM THIS FEATURE WILL REMAIN ALONG AND SOUTH OF
INTERSTATE 80 TODAY AND TONIGHT. THIS WEATHER SYSTEM WILL PULL
AWAY INTO OLD MEXICO SATURDAY AND TAKE ITS CLOUDS AND PRECIP WITH
IT WELL TO OUR SOUTH. IN THE MEANTIME...A NORTHERN STREAM BRITISH
COLUMBIA CLIPPER WILL TRACK SOUTHEAST ACROSS MT/NE WY/NORTHERN AND
CENTRAL PLAINS SATURDAY NIGHT. THIS WX SYSTEM WILL BRING LIGHT
SNOW TO AREAS EAST OF THE DIVIDE...MAINLY IN THE MTNS AND IN
JOHNSON/NATRONA COUNTIES. THERE IS A CHANCE THAT A BAND OF LIGHT
PRECIP MAY LEAK THROUGH THE OWL CREEK/BRIDGER MTNS FROM THE BIG
HORN BASIN AND INTO THE WIND RIVER BASIN AS A SOUTHBOUND BAND OF
PRECIP ASSOCIATED WITH THE COLD FRONT MOVES SOUTH...ONLY AFFECTING
AREAS EAST OF THE DIVIDE THROUGH SUNDAY MORNING. H7 TEMPS WILL
BOTTOM OUT AT -16C IN NE JOHNSON COUNTY ON SUNDAY. H7 TEMPS WILL
REMAIN UNCHANGED WEST OF THE DIVIDE. THE FOLD OVER RIDGE NORTH OF
THE MEXICAN LOW WILL FLATTEN AND BACK THE FLOW MORE DIRECTLY OFF
THE PACIFIC THUS INCREASING THE LIKELIHOOD OF SNOW IN THE FAR WEST
BY SUNDAY NIGHT. AS FOR TEMPS...EXPECT SEASONABLY MILD TEMPS TODAY
AND SATURDAY. JOHNSON COUNTY SHOULD SEE THE BIGGEST COOL DOWN
SUNDAY WITH SUB 30 TEMPS. TEMPS QUICKLY WARM BACK UP MONDAY WITH
THE ZONAL FLOW.

LONG TERM...MONDAY THROUGH FRIDAY

A RELATIVELY MOIST WEST OR NORTHWEST FLOW WITH EMBEDDED SHORTWAVES
MONDAY THROUGH WEDNESDAY WILL RESULT IN PERIODS OF SNOWFALL OVER THE
WEST/NORTHWEST. TIMING AND SNOW AMOUNTS CONTINUE FLUCTUATE QUITE A
BIT...BUT THERE IS A GOOD CHANCE THAT THE FAR WESTERN MOUNTAINS AND
VALLEYS WILL SEE ONE OR TWO PERIODS WITH LIGHT TO MODERATE AMOUNTS
OF SNOWFALL IN THE MONDAY THROUGH WEDNESDAY TIME FRAME. RIGHT
NOW...MODELS ARE GENERALLY SHOWING THE HEAVIEST SNOWFALL OCCURRING
MONDAY NIGHT AND THEN AGAIN TUESDAY NIGHT.

00Z MODELS HAVE TRENDED WITH MORE OF A WESTERLY FLOW ALOFT. THIS
KEEPS THE BULK OF AN ARCTIC AIR MASS MAINLY NORTH AND EAST OF THE
FORECAST AREA THROUGH TUESDAY...BEFORE BRIEFLY PUSHING INTO THE AREA
TUESDAY NIGHT/WEDNESDAY. WITHOUT THIS ARCTIC FRONT TO FOCUS
PRECIPITATION...AREAS EAST OF THE DIVIDE SHOULD REMAIN MAINLY DRY
DUE TO DOWNSLOPING CONDITIONS MONDAY AND TUESDAY. THE ECMWF
CONTINUES TO BE THE MOST BULLISH IN PRECIPITATION EAST OF THE DIVIDE
WEDNESDAY. ALSO...WINDY CONDITIONS ARE EXPECTED IN THE ROCK SPRINGS
TO CASPER WIND CORRIDOR MONDAY AND TUESDAY...AND AT TIMES IN THE
CODY FOOTHILLS AND DUBOIS AREA.

GLOBAL MODELS SHOW AN UPPER RIDGE BUILDING INTO THE AREA THURSDAY
AND FRIDAY WITH MAINLY DRY AND MILD EARLY FEBRUARY TEMPERATURES. IF
THE ARCTIC AIR MASS CAN SETTLE INTO THE BASINS EAST OF THE DIVIDE
TUESDAY NIGHT/WEDNESDAY...TEMPERATURES WILL STRUGGLE TO WARM UP IN
THOSE TRAPPED BASIN...DESPITE WARMING TEMPERATURES ALOFT.

AVIATION.../18Z ISSUANCE/

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

VFR CONDITIONS WILL PREVAIL THE REST OF THIS AFTERNOON...WITH FOG
LINGERING IN THE BIGHORN BASIN NEAR KGEY. N-NE SFC WINDS WILL
PREVAIL ACROSS THE AREA...WITH SOME LOWER CIGS EXPECTED TO FORM
ALONG THE EAST SLOPES OF THE DIVIDE AND OTHER UPSLOPE FAVORED
AREAS INCLUDING VCNTY KCPR. MOST OF THESE CIGS ARE EXPECTED TO
REMAIN VFR OBSCURING HIGHER MTNS. CLEARING IS EXPECTED AFTER 06Z
SATURDAY WITH PATCHY FOG REFORMING MAINLY IN THE LOWER CENTRAL
BASINS...OR VCNTY KGEY-KWRL.

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

AN UPPER LEVEL LOW PRESSURE SYSTEM OVER THE FOUR CORNERS...WILL
CONTINUE TO PUSH UP MOISTURE INTO SOUTHERN WYOMING THROUGH THE
PERIOD...WITH CIGS EXPECTED TO GRADUALLY LOWER VCNTY AND SOUTH OF
INTERSTATE 80...WITH SOME ISOLD TO SCT -SHSN MOVING IN EARLY THIS
EVENING ALONG WITH LOCAL MVFR/IFR CONDITIONS. MVFR/IFR CONDITIONS ARE
EXPECTED TO BECOME MORE PREVALENT IN THIS AREA AFTER 00Z SATURDAY.

NORTH OF INTERSTATE 80...VFR CONDITIONS WILL PREVAIL THROUGH THE
PERIOD.

FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SMOKE DISPERSION WILL BE POOR
ACROSS MOST OF THE REGION TODAY. SATURDAY WILL SEE IMPROVEMENT IN
BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST OF THE DIVIDE
AND ACROSS THE SOUTHERN ZONES.

&&

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

$$

SHORT TERM...LIPSON
LONG TERM...WM
AVIATION...AEM
FIRE WEATHER...LIPSON








000
FXUS65 KRIW 301023
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
323 AM MST FRI JAN 30 2015

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT

EXCEPT FOR GEY...SO FAR VERY LITTLE FOG HAS BEEN DETECTED ACROSS
THE CWA IN RESPONSE TO THE HIGH CLOUDS MOVING IN FROM THE
SOUTHWEST. KEPT PATCHY FOG IN THE FORECAST HOWEVER AS IT IS ONLY
PATCHY AND NOCTURNAL INVERSIONS WILL PERSIST TO A LESSER EXTENT
OVER THE BASINS AND VALLEY THROUGH THIS MORNING. TOOK FOG OUT OF
GEY FOR THIS AFTERNOON. THE INCREASING HIGH CLOUDS ARE ASSOCIATED
WITH THE SOUTHERN STREAM CIRCULATION ALONG THE SOUTHERN CA/BAJA CA
COAST WHICH IS ANTICIPATED TO CONTINUE TO CLOSE OFF SOUTHWEST AND
SOUTH OF VEGAS TODAY AND TONIGHT. WITH THE MAIN ENERGY REMAINING
WELL TO OUR SOUTH...THE NORTHEAST EXTENT OF THIS CIRRUS SHIELD
WILL REMAIN ACROSS SOUTHERN WY TODAY WITH THE NORTHERN EXTENSION
CONTINUING TO DISSIPATE AS FAST AS IT MOVES NORTH. ANY MIXED
PRECIP THAT FALLS FROM THIS FEATURE WILL REMAIN ALONG AND SOUTH OF
INTERSTATE 80 TODAY AND TONIGHT. THIS WEATHER SYSTEM WILL PULL
AWAY INTO OLD MEXICO SATURDAY AND TAKE ITS CLOUDS AND PRECIP WITH
IT WELL TO OUR SOUTH. IN THE MEANTIME...A NORTHERN STREAM BRITISH
COLUMBIA CLIPPER WILL TRACK SOUTHEAST ACROSS MT/NE WY/NORTHERN AND
CENTRAL PLAINS SATURDAY NIGHT. THIS WX SYSTEM WILL BRING LIGHT
SNOW TO AREAS EAST OF THE DIVIDE...MAINLY IN THE MTNS AND IN
JOHNSON/NATRONA COUNTIES. THERE IS A CHANCE THAT A BAND OF LIGHT
PRECIP MAY LEAK THROUGH THE OWL CREEK/BRIDGER MTNS FROM THE BIG
HORN BASIN AND INTO THE WIND RIVER BASIN AS A SOUTHBOUND BAND OF
PRECIP ASCT WITH AN ASCT COLD FRONT MOVES SOUTH...ONLY AFFECTING
AREAS EAST OF THE DIVIDE THROUGH SUNDAY MORNING. H7 TEMPS WILL
BOTTOM OUT AT -16C IN NE JOHNSON COUNTY ON SUNDAY. H7 TEMPS WILL
REMAIN UNCHANGED WEST OF THE DIVIDE. THE FOLD OVER RIDGE NORTH OF
THE MEXICAN LOW WILL FLATTEN AND BACK THE FLOW MORE DIRECTLY OFF
THE PACIFIC THUS INCREASING THE LIKELIHOOD OF SNOW IN THE FAR WEST
BY SUNDAY NIGHT. AS FOR TEMPS...EXPECT SEASONABLY MILD TEMPS TODAY
AND SATURDAY. JOHNSON COUNTY SHOULD SEE THE BIGGEST COOL DOWN
SUNDAY WITH SUB 30 TEMPS. TEMPS QUICKLY WARM BACK UP MONDAY WITH
THE ZONAL FLOW.

.LONG TERM...MONDAY THROUGH FRIDAY

A RELATIVELY MOIST WEST OR NORTHWEST FLOW WITH EMBEDDED SHORTWAVES
MONDAY THROUGH WEDNESDAY WILL RESULT IN PERIODS OF SNOWFALL OVER THE
WEST/NORTHWEST. TIMING AND SNOW AMOUNTS CONTINUE FLUCTUATE QUITE A
BIT...BUT THERE IS A GOOD CHANCE THAT THE FAR WESTERN MOUNTAINS AND
VALLEYS WILL SEE ONE OR TWO PERIODS WITH LIGHT TO MODERATE AMOUNTS
OF SNOWFALL IN THE MONDAY THROUGH WEDNESDAY TIME FRAME. RIGHT
NOW...MODELS ARE GENERALLY SHOWING THE HEAVIEST SNOWFALL OCCURRING
MONDAY NIGHT AND THEN AGAIN TUESDAY NIGHT.

00Z MODELS HAVE TRENDED WITH MORE OF A WESTERLY FLOW ALOFT. THIS
KEEPS THE BULK OF AN ARCTIC AIR MASS MAINLY NORTH AND EAST OF THE
FORECAST AREA THROUGH TUESDAY...BEFORE BRIEFLY PUSHING INTO THE AREA
TUESDAY NIGHT/WEDNESDAY. WITHOUT THIS ARCTIC FRONT TO FOCUS
PRECIPITATION...AREAS EAST OF THE DIVIDE SHOULD REMAIN MAINLY DRY
DUE TO DOWNSLOPING CONDITIONS MONDAY AND TUESDAY. THE ECMWF
CONTINUES TO BE THE MOST BULLISH IN PRECIPITATION EAST OF THE DIVIDE
WEDNESDAY. ALSO...WINDY CONDITIONS ARE EXPECTED IN THE ROCK SPRINGS
TO CASPER WIND CORRIDOR MONDAY AND TUESDAY...AND AT TIMES IN THE
CODY FOOTHILLS AND DUBOIS AREA.

GLOBAL MODELS SHOW AN UPPER RIDGE BUILDING INTO THE AREA THURSDAY
AND FRIDAY WITH MAINLY DRY AND MILD EARLY FEBRUARY TEMPERATURES. IF
THE ARCTIC AIR MASS CAN SETTLE INTO THE BASINS EAST OF THE DIVIDE
TUESDAY NIGHT/WEDNESDAY...TEMPERATURES WILL STRUGGLE TO WARM UP IN
THOSE TRAPPED BASIN...DESPITE WARMING TEMPERATURES ALOFT.

&&

.AVIATION.../12Z ISSUANCE/

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

VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD WITH PATCHY MORNING
FOG PARTIALLY OBSCURING TERRAIN.  N-NE SFC WINDS WILL PREVAIL ACROSS
THE AREA AFTER 18Z TODAY WITH SOME LOWER CIGS EXPECTED TO FORM
ALONG THE EAST SLOPES OF THE DIVIDE AND OTHER UPSLOPE FAVORED
AREAS INCLUDING VCNTY KCPR. MOST OF THESE CIGS ARE EXPECTED TO
REMAIN VFR OBSCURING HIGHER MTNS...BUT LOCAL MVFR CIGS WILL BE
POSSIBLE. CLEARING IS EXPECTED AFTER 06Z SATURDAY WITH PATCHY FOG
REFORMING MAINLY IN THE LOWER CENTRAL BASINS...OR VCNTY KGEY-KRIW.

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

AN UPPER LEVEL LOW PRESSURE SYSTEM OVER SOUTHERN CALIFORNIA WILL
CONTINUE TO PUSH UP MOISTURE INTO SOUTHERN WYOMING THROUGH THE
PERIOD WITH CIGS EXPECTED TO GRADUALLY LOWER VCNTY AND SOUTH OF
INTERSTATE 80 WITH SOME ISOLD TO SCT -SHSN MOVING IN EARLY THIS
MORNING ALONG WITH LCL MVFR/IFR CONDITIONS.  MVFR/IFR CONDITIONS
ARE EXPECTED TO BECOME MORE PREVALENT IN THIS AREA AFTER 00Z SATURDAY.

NORTH OF INTERSTATE 80...VFR CONDITIONS WILL PREVAIL THROUGH THE
PERIOD WITH SOME PATCHY MORNING FOG PARTIALLY OBSCURING TERRAIN.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SMOKE DISPERSION WILL BE POOR
ACROSS MOST OF THE REGION TODAY. SATURDAY WILL SEE IMPROVEMENT IN
BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST OF THE DIVIDE
AND ACROSS THE SOUTHERN ZONES.

&&

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

&&

$$

SHORT TERM...LIPSON
LONG TERM...WM
AVIATION...AEM
FIRE WEATHER...LIPSON











000
FXUS65 KRIW 301023
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
323 AM MST FRI JAN 30 2015

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT

EXCEPT FOR GEY...SO FAR VERY LITTLE FOG HAS BEEN DETECTED ACROSS
THE CWA IN RESPONSE TO THE HIGH CLOUDS MOVING IN FROM THE
SOUTHWEST. KEPT PATCHY FOG IN THE FORECAST HOWEVER AS IT IS ONLY
PATCHY AND NOCTURNAL INVERSIONS WILL PERSIST TO A LESSER EXTENT
OVER THE BASINS AND VALLEY THROUGH THIS MORNING. TOOK FOG OUT OF
GEY FOR THIS AFTERNOON. THE INCREASING HIGH CLOUDS ARE ASSOCIATED
WITH THE SOUTHERN STREAM CIRCULATION ALONG THE SOUTHERN CA/BAJA CA
COAST WHICH IS ANTICIPATED TO CONTINUE TO CLOSE OFF SOUTHWEST AND
SOUTH OF VEGAS TODAY AND TONIGHT. WITH THE MAIN ENERGY REMAINING
WELL TO OUR SOUTH...THE NORTHEAST EXTENT OF THIS CIRRUS SHIELD
WILL REMAIN ACROSS SOUTHERN WY TODAY WITH THE NORTHERN EXTENSION
CONTINUING TO DISSIPATE AS FAST AS IT MOVES NORTH. ANY MIXED
PRECIP THAT FALLS FROM THIS FEATURE WILL REMAIN ALONG AND SOUTH OF
INTERSTATE 80 TODAY AND TONIGHT. THIS WEATHER SYSTEM WILL PULL
AWAY INTO OLD MEXICO SATURDAY AND TAKE ITS CLOUDS AND PRECIP WITH
IT WELL TO OUR SOUTH. IN THE MEANTIME...A NORTHERN STREAM BRITISH
COLUMBIA CLIPPER WILL TRACK SOUTHEAST ACROSS MT/NE WY/NORTHERN AND
CENTRAL PLAINS SATURDAY NIGHT. THIS WX SYSTEM WILL BRING LIGHT
SNOW TO AREAS EAST OF THE DIVIDE...MAINLY IN THE MTNS AND IN
JOHNSON/NATRONA COUNTIES. THERE IS A CHANCE THAT A BAND OF LIGHT
PRECIP MAY LEAK THROUGH THE OWL CREEK/BRIDGER MTNS FROM THE BIG
HORN BASIN AND INTO THE WIND RIVER BASIN AS A SOUTHBOUND BAND OF
PRECIP ASCT WITH AN ASCT COLD FRONT MOVES SOUTH...ONLY AFFECTING
AREAS EAST OF THE DIVIDE THROUGH SUNDAY MORNING. H7 TEMPS WILL
BOTTOM OUT AT -16C IN NE JOHNSON COUNTY ON SUNDAY. H7 TEMPS WILL
REMAIN UNCHANGED WEST OF THE DIVIDE. THE FOLD OVER RIDGE NORTH OF
THE MEXICAN LOW WILL FLATTEN AND BACK THE FLOW MORE DIRECTLY OFF
THE PACIFIC THUS INCREASING THE LIKELIHOOD OF SNOW IN THE FAR WEST
BY SUNDAY NIGHT. AS FOR TEMPS...EXPECT SEASONABLY MILD TEMPS TODAY
AND SATURDAY. JOHNSON COUNTY SHOULD SEE THE BIGGEST COOL DOWN
SUNDAY WITH SUB 30 TEMPS. TEMPS QUICKLY WARM BACK UP MONDAY WITH
THE ZONAL FLOW.

.LONG TERM...MONDAY THROUGH FRIDAY

A RELATIVELY MOIST WEST OR NORTHWEST FLOW WITH EMBEDDED SHORTWAVES
MONDAY THROUGH WEDNESDAY WILL RESULT IN PERIODS OF SNOWFALL OVER THE
WEST/NORTHWEST. TIMING AND SNOW AMOUNTS CONTINUE FLUCTUATE QUITE A
BIT...BUT THERE IS A GOOD CHANCE THAT THE FAR WESTERN MOUNTAINS AND
VALLEYS WILL SEE ONE OR TWO PERIODS WITH LIGHT TO MODERATE AMOUNTS
OF SNOWFALL IN THE MONDAY THROUGH WEDNESDAY TIME FRAME. RIGHT
NOW...MODELS ARE GENERALLY SHOWING THE HEAVIEST SNOWFALL OCCURRING
MONDAY NIGHT AND THEN AGAIN TUESDAY NIGHT.

00Z MODELS HAVE TRENDED WITH MORE OF A WESTERLY FLOW ALOFT. THIS
KEEPS THE BULK OF AN ARCTIC AIR MASS MAINLY NORTH AND EAST OF THE
FORECAST AREA THROUGH TUESDAY...BEFORE BRIEFLY PUSHING INTO THE AREA
TUESDAY NIGHT/WEDNESDAY. WITHOUT THIS ARCTIC FRONT TO FOCUS
PRECIPITATION...AREAS EAST OF THE DIVIDE SHOULD REMAIN MAINLY DRY
DUE TO DOWNSLOPING CONDITIONS MONDAY AND TUESDAY. THE ECMWF
CONTINUES TO BE THE MOST BULLISH IN PRECIPITATION EAST OF THE DIVIDE
WEDNESDAY. ALSO...WINDY CONDITIONS ARE EXPECTED IN THE ROCK SPRINGS
TO CASPER WIND CORRIDOR MONDAY AND TUESDAY...AND AT TIMES IN THE
CODY FOOTHILLS AND DUBOIS AREA.

GLOBAL MODELS SHOW AN UPPER RIDGE BUILDING INTO THE AREA THURSDAY
AND FRIDAY WITH MAINLY DRY AND MILD EARLY FEBRUARY TEMPERATURES. IF
THE ARCTIC AIR MASS CAN SETTLE INTO THE BASINS EAST OF THE DIVIDE
TUESDAY NIGHT/WEDNESDAY...TEMPERATURES WILL STRUGGLE TO WARM UP IN
THOSE TRAPPED BASIN...DESPITE WARMING TEMPERATURES ALOFT.

&&

.AVIATION.../12Z ISSUANCE/

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

VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD WITH PATCHY MORNING
FOG PARTIALLY OBSCURING TERRAIN.  N-NE SFC WINDS WILL PREVAIL ACROSS
THE AREA AFTER 18Z TODAY WITH SOME LOWER CIGS EXPECTED TO FORM
ALONG THE EAST SLOPES OF THE DIVIDE AND OTHER UPSLOPE FAVORED
AREAS INCLUDING VCNTY KCPR. MOST OF THESE CIGS ARE EXPECTED TO
REMAIN VFR OBSCURING HIGHER MTNS...BUT LOCAL MVFR CIGS WILL BE
POSSIBLE. CLEARING IS EXPECTED AFTER 06Z SATURDAY WITH PATCHY FOG
REFORMING MAINLY IN THE LOWER CENTRAL BASINS...OR VCNTY KGEY-KRIW.

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

AN UPPER LEVEL LOW PRESSURE SYSTEM OVER SOUTHERN CALIFORNIA WILL
CONTINUE TO PUSH UP MOISTURE INTO SOUTHERN WYOMING THROUGH THE
PERIOD WITH CIGS EXPECTED TO GRADUALLY LOWER VCNTY AND SOUTH OF
INTERSTATE 80 WITH SOME ISOLD TO SCT -SHSN MOVING IN EARLY THIS
MORNING ALONG WITH LCL MVFR/IFR CONDITIONS.  MVFR/IFR CONDITIONS
ARE EXPECTED TO BECOME MORE PREVALENT IN THIS AREA AFTER 00Z SATURDAY.

NORTH OF INTERSTATE 80...VFR CONDITIONS WILL PREVAIL THROUGH THE
PERIOD WITH SOME PATCHY MORNING FOG PARTIALLY OBSCURING TERRAIN.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SMOKE DISPERSION WILL BE POOR
ACROSS MOST OF THE REGION TODAY. SATURDAY WILL SEE IMPROVEMENT IN
BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST OF THE DIVIDE
AND ACROSS THE SOUTHERN ZONES.

&&

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

&&

$$

SHORT TERM...LIPSON
LONG TERM...WM
AVIATION...AEM
FIRE WEATHER...LIPSON










000
FXUS65 KRIW 300601
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1059 PM MST THU JAN 29 2015

UPDATE...ADDED 06Z AVIATION DISCUSSION BELOW.


.SHORT TERM...TONGIHT THROUGH FRIDAY (ISSUED AT 159 PM MST)

FOG HAS FINALLY BEGUN TO DISSIPATE NEAR ROCK SPRINGS AND SOUTHERN
LINCOLN COUNTY...BUT CONTINUES TO LINGER NEAR GREYBULL. THIS
PORTION OF THE BIGHORN BASIN WILL REMAIN FOGGY THROUGH FRIDAY
MORNING...AND WILL SPREAD TOWARD WORLAND DURING THE OVERNIGHT
HOURS. FOG IS ALSO EXPECTED TO RETURN IN THE UPPER GREEN RIVER
BASIN AND JACKSON HOLE. AS AREAS...EXCEPT NEAR GREYBULL...SHOULD
DISSIPATE LATE FRIDAY MORNING...AS H7 TEMPS COOL AND UPPER LEVEL
CLOUDS SPREAD ACROSS THE AREA.

THE FORECAST AREA WILL REMAIN DRY THROUGH FRIDAY...EXCEPT SOUTHERN
PORTIONS OF SWEETWATER COUNTY. A MOIST CUT OFF LOW...MOVING INTO
THE FOUR CORNERS AREA...WILL BRING MID TO HIGH CLOUDS ACROSS THE
SOUTHWESTERN HALF OF THE FORECAST AREA. THIS SYSTEM WILL ALSO
BRING AN INFLUX OF MOISTURE INTO SOUTHERN WYOMING. RAIN AND SNOW
SHOWERS WILL BE POSSIBLE THROUGH THE DAY ON FRIDAY. ANY SNOW
ACCUMULATION WILL BE LITTLE TO NONE.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY NIGHT

A LOW PRESSURE SYSTEM MOVING UP INTO THE FOUR CORNERS REGION WILL
EVENTUALLY BE PUSHED BACK TO THE SOUTH BY A SYSTEM MOVING SOUTHEAST
OUT OF CANADA EARLY IN THE PERIOD. MOISTURE WRAPPING AROUND THE LOW
COULD RESULT IN A FEW SHOWERS ACROSS OUR AREA AS FAR NORTH AS FARSON
ON FRIDAY NIGHT BUT MOST OF THE ENERGY FROM THIS SYSTEM WILL REMAIN
WELL TO OUR SOUTH. THE SECOND PIECE OF ENERGY MOVING OUT OF THE
NORTH WILL ALSO PROVIDE A GLANCING BLOW TO OUR FAR NORTHEASTERN
ZONES. THE MODELS HAVE BEEN TRENDING FURTHER AND FURTHER EAST WITH
THIS SYSTEM...WHICH WOULD KEEP MOST OF THE PRECIP OUT OF OUR AREA.
HOWEVER...THERE IS A DECENT COLD POOL WITH THIS ONE THAT COULD
ENCOURAGE SOME SNOW BANDING IN ADDITION TO A CHANCE FOR SOME
MEASURABLE SNOW ALONG THE COLD FRONT AS IT DROPS SOUTH ON
SATURDAY NIGHT. AT THIS TIME...IT LOOKS LIKE MOST OF THE
PRECIPITATION WILL BE FROM THE BIGHORNS EAST...WITH A SLIGHT
CHANCE AS FAR SOUTH AS CASPER. GIVEN ITS ORIGINS...NOT MUCH
MOISTURE WILL COME ALONG WITH THIS SYSTEM WITH NO SECONDARY
MOISTURE FEED TO WORK WITH...NOT MUCH SNOW IS EXPECTED.

SWIFT NORTHWEST FLOW SETS UP BEHIND THE SYSTEM ON SATURDAY. THERE
WILL BE A SERIES OF DISTURBANCES MOVING THROUGH THE END OF THE
PERIOD. OVERALL...THERE WILL BE BREEZY PERIODS THROUGHOUT THE LONG
TERM PERIOD WITH OCCASIONAL CHANCES FOR RAIN AND SNOW WITH EACH
DISTURBANCE. THE BEST CHANCE FOR SNOW WILL BE IN THE WESTERN
MOUNTAINS AND IN THE BIGHORNS BUT THERE COULD BE A FEW DROPS AND
FLAKES THAT MAKE IT EAST OF THE DIVIDE POTENTIALLY ON TUESDAY...AS
A MORE ROBUST WAVE MOVES THROUGH WITH ENOUGH DYNAMIC FORCING TO
HELP SOME MOISTURE MAKE IT EAST OF THE DIVIDE.

TOWARD THE END OF THE PERIOD...GLOBAL MODELS ARE BUILDING A RIDGE
ACROSS THE WEST WITH A TROUGH OVER THE MIDWEST. THERE ARE SOME
DIFFERENCES AS TO HOW STRONG THE RIDGE IS BUT THE OVERALL PATTERN
WOULD SUGGEST A MILD AND DRY END TO THE WEEK NEXT WEEK.

&&

.AVIATION.../06Z ISSUANCE/

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

VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD WITH PATCHY MORNING
FOG PARTIALLY OBSCURING TERRAIN.  N-NE SFC WINDS WILL PREVAIL ACROSS
THE AREA AFTER 18Z FRIDAY WITH SOME LOWER CIGS EXPECTED TO FORM
ALONG THE EAST SLOPES OF THE DIVIDE AND OTHER UPSLOPE FAVORED AREAS
INCLUDING VCNTY KCPR.  MOST OF THESE CIGS ARE EXPECTED TO REMAIN VFR
OBSCURING HIGHER MTNS...BUT LOCAL MVFR CIGS WILL BE POSSIBLE.
CLEARING IS EXPECTED AFTER 06Z SATURDAY WITH PATCHY FOG REFORMING
MAINLY IN THE LOWER CENTRAL BASINS...OR VCNTY KGEY-KRIW.

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

AN UPPER LEVEL LOW PRESSURE SYSTEM OVER SOUTHERN CALIFORNIA WILL
CONTINUE TO PUSH UP MOISTURE INTO SOUTHERN WYOMING THROUGH THE
PERIOD WITH CIGS EXPECTED TO GRADUALLY LOWER VCNTY AND SOUTH OF
INTERSTATE 80 WITH SOME ISOLD TO SCT -SHSN MOVING IN AFTER 09Z ALONG
WITH LCL MVFR/IFR CONDITIONS.  MVFR/IFR CONDITIONS WITH ARE EXPECTED
TO BECOME MORE PREVALENT IN THIS AREA AFTER 00Z SATURDAY.

NORTH OF INTERSTATE 80...VFR CONDITIONS WILL PREVAIL THROUGH THE
PERIOD WITH SOME PATCHY MORNING FOG PARTIALLY OBSCURING TERRAIN.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SMOKE DISPERSION WILL BE POOR
ACROSS MOST OF THE REGION FRIDAY. SATURDAY WILL SEE IMPROVEMENT
IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST OF THE
DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

$$

SHORT TERM...LAVOIE
LONG TERM...ALLEN
AVIATION...AEM
FIRE WEATHER...LAVOIE











000
FXUS65 KRIW 300601
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1059 PM MST THU JAN 29 2015

UPDATE...ADDED 06Z AVIATION DISCUSSION BELOW.


.SHORT TERM...TONGIHT THROUGH FRIDAY (ISSUED AT 159 PM MST)

FOG HAS FINALLY BEGUN TO DISSIPATE NEAR ROCK SPRINGS AND SOUTHERN
LINCOLN COUNTY...BUT CONTINUES TO LINGER NEAR GREYBULL. THIS
PORTION OF THE BIGHORN BASIN WILL REMAIN FOGGY THROUGH FRIDAY
MORNING...AND WILL SPREAD TOWARD WORLAND DURING THE OVERNIGHT
HOURS. FOG IS ALSO EXPECTED TO RETURN IN THE UPPER GREEN RIVER
BASIN AND JACKSON HOLE. AS AREAS...EXCEPT NEAR GREYBULL...SHOULD
DISSIPATE LATE FRIDAY MORNING...AS H7 TEMPS COOL AND UPPER LEVEL
CLOUDS SPREAD ACROSS THE AREA.

THE FORECAST AREA WILL REMAIN DRY THROUGH FRIDAY...EXCEPT SOUTHERN
PORTIONS OF SWEETWATER COUNTY. A MOIST CUT OFF LOW...MOVING INTO
THE FOUR CORNERS AREA...WILL BRING MID TO HIGH CLOUDS ACROSS THE
SOUTHWESTERN HALF OF THE FORECAST AREA. THIS SYSTEM WILL ALSO
BRING AN INFLUX OF MOISTURE INTO SOUTHERN WYOMING. RAIN AND SNOW
SHOWERS WILL BE POSSIBLE THROUGH THE DAY ON FRIDAY. ANY SNOW
ACCUMULATION WILL BE LITTLE TO NONE.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY NIGHT

A LOW PRESSURE SYSTEM MOVING UP INTO THE FOUR CORNERS REGION WILL
EVENTUALLY BE PUSHED BACK TO THE SOUTH BY A SYSTEM MOVING SOUTHEAST
OUT OF CANADA EARLY IN THE PERIOD. MOISTURE WRAPPING AROUND THE LOW
COULD RESULT IN A FEW SHOWERS ACROSS OUR AREA AS FAR NORTH AS FARSON
ON FRIDAY NIGHT BUT MOST OF THE ENERGY FROM THIS SYSTEM WILL REMAIN
WELL TO OUR SOUTH. THE SECOND PIECE OF ENERGY MOVING OUT OF THE
NORTH WILL ALSO PROVIDE A GLANCING BLOW TO OUR FAR NORTHEASTERN
ZONES. THE MODELS HAVE BEEN TRENDING FURTHER AND FURTHER EAST WITH
THIS SYSTEM...WHICH WOULD KEEP MOST OF THE PRECIP OUT OF OUR AREA.
HOWEVER...THERE IS A DECENT COLD POOL WITH THIS ONE THAT COULD
ENCOURAGE SOME SNOW BANDING IN ADDITION TO A CHANCE FOR SOME
MEASURABLE SNOW ALONG THE COLD FRONT AS IT DROPS SOUTH ON
SATURDAY NIGHT. AT THIS TIME...IT LOOKS LIKE MOST OF THE
PRECIPITATION WILL BE FROM THE BIGHORNS EAST...WITH A SLIGHT
CHANCE AS FAR SOUTH AS CASPER. GIVEN ITS ORIGINS...NOT MUCH
MOISTURE WILL COME ALONG WITH THIS SYSTEM WITH NO SECONDARY
MOISTURE FEED TO WORK WITH...NOT MUCH SNOW IS EXPECTED.

SWIFT NORTHWEST FLOW SETS UP BEHIND THE SYSTEM ON SATURDAY. THERE
WILL BE A SERIES OF DISTURBANCES MOVING THROUGH THE END OF THE
PERIOD. OVERALL...THERE WILL BE BREEZY PERIODS THROUGHOUT THE LONG
TERM PERIOD WITH OCCASIONAL CHANCES FOR RAIN AND SNOW WITH EACH
DISTURBANCE. THE BEST CHANCE FOR SNOW WILL BE IN THE WESTERN
MOUNTAINS AND IN THE BIGHORNS BUT THERE COULD BE A FEW DROPS AND
FLAKES THAT MAKE IT EAST OF THE DIVIDE POTENTIALLY ON TUESDAY...AS
A MORE ROBUST WAVE MOVES THROUGH WITH ENOUGH DYNAMIC FORCING TO
HELP SOME MOISTURE MAKE IT EAST OF THE DIVIDE.

TOWARD THE END OF THE PERIOD...GLOBAL MODELS ARE BUILDING A RIDGE
ACROSS THE WEST WITH A TROUGH OVER THE MIDWEST. THERE ARE SOME
DIFFERENCES AS TO HOW STRONG THE RIDGE IS BUT THE OVERALL PATTERN
WOULD SUGGEST A MILD AND DRY END TO THE WEEK NEXT WEEK.

&&

.AVIATION.../06Z ISSUANCE/

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

VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD WITH PATCHY MORNING
FOG PARTIALLY OBSCURING TERRAIN.  N-NE SFC WINDS WILL PREVAIL ACROSS
THE AREA AFTER 18Z FRIDAY WITH SOME LOWER CIGS EXPECTED TO FORM
ALONG THE EAST SLOPES OF THE DIVIDE AND OTHER UPSLOPE FAVORED AREAS
INCLUDING VCNTY KCPR.  MOST OF THESE CIGS ARE EXPECTED TO REMAIN VFR
OBSCURING HIGHER MTNS...BUT LOCAL MVFR CIGS WILL BE POSSIBLE.
CLEARING IS EXPECTED AFTER 06Z SATURDAY WITH PATCHY FOG REFORMING
MAINLY IN THE LOWER CENTRAL BASINS...OR VCNTY KGEY-KRIW.

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

AN UPPER LEVEL LOW PRESSURE SYSTEM OVER SOUTHERN CALIFORNIA WILL
CONTINUE TO PUSH UP MOISTURE INTO SOUTHERN WYOMING THROUGH THE
PERIOD WITH CIGS EXPECTED TO GRADUALLY LOWER VCNTY AND SOUTH OF
INTERSTATE 80 WITH SOME ISOLD TO SCT -SHSN MOVING IN AFTER 09Z ALONG
WITH LCL MVFR/IFR CONDITIONS.  MVFR/IFR CONDITIONS WITH ARE EXPECTED
TO BECOME MORE PREVALENT IN THIS AREA AFTER 00Z SATURDAY.

NORTH OF INTERSTATE 80...VFR CONDITIONS WILL PREVAIL THROUGH THE
PERIOD WITH SOME PATCHY MORNING FOG PARTIALLY OBSCURING TERRAIN.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SMOKE DISPERSION WILL BE POOR
ACROSS MOST OF THE REGION FRIDAY. SATURDAY WILL SEE IMPROVEMENT
IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST OF THE
DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

$$

SHORT TERM...LAVOIE
LONG TERM...ALLEN
AVIATION...AEM
FIRE WEATHER...LAVOIE










000
FXUS65 KRIW 292059
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
159 PM MST THU JAN 29 2015

.SHORT TERM...TONGIHT THROUGH FRIDAY

FOG HAS FINALLY BEGUN TO DISSIPATE NEAR ROCK SPRINGS AND SOUTHERN
LINCOLN COUNTY...BUT CONTINUES TO LINGER NEAR GREYBULL. THIS
PORTION OF THE BIGHORN BASIN WILL REMAIN FOGGY THROUGH FRIDAY
MORNING...AND WILL SPREAD TOWARD WORLAND DURING THE OVERNIGHT
HOURS. FOG IS ALSO EXPECTED TO RETURN IN THE UPPER GREEN RIVER
BASIN AND JACKSON HOLE. AS AREAS...EXCEPT NEAR GREYBULL...SHOULD
DISSIPATE LATE FRIDAY MORNING...AS H7 TEMPS COOL AND UPPER LEVEL
CLOUDS SPREAD ACROSS THE AREA.

THE FORECAST AREA WILL REMAIN DRY THROUGH FRIDAY...EXCEPT SOUTHERN
PORTIONS OF SWEETWATER COUNTY. A MOIST CUT OFF LOW...MOVING INTO
THE FOUR CORNERS AREA...WILL BRING MID TO HIGH CLOUDS ACROSS THE
SOUTHWESTERN HALF OF THE FORECAST AREA. THIS SYSTEM WILL ALSO
BRING AN INFLUX OF MOISTURE INTO SOUTHERN WYOMING. RAIN AND SNOW
SHOWERS WILL BE POSSIBLE THROUGH THE DAY ON FRIDAY. ANY SNOW
ACCUMULATION WILL BE LITTLE TO NONE.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY NIGHT

A LOW PRESSURE SYSTEM MOVING UP INTO THE FOUR CORNERS REGION WILL
EVENTUALLY BE PUSHED BACK TO THE SOUTH BY A SYSTEM MOVING SOUTHEAST
OUT OF CANADA EARLY IN THE PERIOD. MOISTURE WRAPPING AROUND THE LOW
COULD RESULT IN A FEW SHOWERS ACROSS OUR AREA AS FAR NORTH AS FARSON
ON FRIDAY NIGHT BUT MOST OF THE ENERGY FROM THIS SYSTEM WILL REMAIN
WELL TO OUR SOUTH. THE SECOND PIECE OF ENERGY MOVING OUT OF THE
NORTH WILL ALSO PROVIDE A GLANCING BLOW TO OUR FAR NORTHEASTERN
ZONES. THE MODELS HAVE BEEN TRENDING FURTHER AND FURTHER EAST WITH
THIS SYSTEM...WHICH WOULD KEEP MOST OF THE PRECIP OUT OF OUR AREA.
HOWEVER...THERE IS A DECENT COLD POOL WITH THIS ONE THAT COULD
ENCOURAGE SOME SNOW BANDING IN ADDITION TO A CHANCE FOR SOME
MEASURABLE SNOW ALONG THE COLD FRONT AS IT DROPS SOUTH ON
SATURDAY NIGHT. AT THIS TIME...IT LOOKS LIKE MOST OF THE
PRECIPITATION WILL BE FROM THE BIGHORNS EAST...WITH A SLIGHT
CHANCE AS FAR SOUTH AS CASPER. GIVEN ITS ORIGINS...NOT MUCH
MOISTURE WILL COME ALONG WITH THIS SYSTEM WITH NO SECONDARY
MOISTURE FEED TO WORK WITH...NOT MUCH SNOW IS EXPECTED.

SWIFT NORTHWEST FLOW SETS UP BEHIND THE SYSTEM ON SATURDAY. THERE
WILL BE A SERIES OF DISTURBANCES MOVING THROUGH THE END OF THE
PERIOD. OVERALL...THERE WILL BE BREEZY PERIODS THROUGHOUT THE LONG
TERM PERIOD WITH OCCASIONAL CHANCES FOR RAIN AND SNOW WITH EACH
DISTURBANCE. THE BEST CHANCE FOR SNOW WILL BE IN THE WESTERN
MOUNTAINS AND IN THE BIGHORNS BUT THERE COULD BE A FEW DROPS AND
FLAKES THAT MAKE IT EAST OF THE DIVIDE POTENTIALLY ON TUESDAY...AS
A MORE ROBUST WAVE MOVES THROUGH WITH ENOUGH DYNAMIC FORCING TO
HELP SOME MOISTURE MAKE IT EAST OF THE DIVIDE.

TOWARD THE END OF THE PERIOD...GLOBAL MODELS ARE BUILDING A RIDGE
ACROSS THE WEST WITH A TROUGH OVER THE MIDWEST. THERE ARE SOME
DIFFERENCES AS TO HOW STRONG THE RIDGE IS BUT THE OVERALL PATTERN
WOULD SUGGEST A MILD AND DRY END TO THE WEEK NEXT WEEK.

&&

.AVIATION.../00Z ISSUANCE/

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

DRY AIR AND MOSTLY CLEAR SKIES WILL REMAIN ACROSS THE AREA THIS
EVENING. MID TO HIGH CLOUDS WILL BEGIN TO MOVE ACROSS THE AREA
THROUGH THE OVERNIGHT HOURS. FOG WILL CONTINUE NEAR KGEY THROUGH
THE REST OF THE NIGHT...INTO FRIDAY MORNING...AND MOVE THROUGH THE
REST OF THE BIGHORN BASIN TOWARD KWRL AFTER MIDNIGHT.
PATCHY FOG WILL ALSO BE POSSIBLE IN THE LOWER BASINS.

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

LOW IFR/LIFR CIGS OR FOG WILL RETURN LATER TONIGHT BY 10Z FOR
KBPI/KPNA AND 11Z FOR KJAC. AN UPPER LEVEL DISTURBANCE WILL
SPREAD MID TO HIGH LEVEL CLOUDS FOR MUCH OF THE AREA TONIGHT AS
WELL. ISOLD TO WDLY SCT -SHRASN WILL ALSO BE POSSIBLE NEAR KRKS AFTER
12Z FRIDAY WITH MOST OF THIS ACTIVITY EXPECTED TO STAY VCNTY
INTERSTATE 80 AND SOUTH.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SMOKE DISPERSION WILL BE POOR
ACROSS MOST OF THE REGION FRIDAY. SATURDAY WILL SEE IMPROVEMENT
IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST OF THE
DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

$$

SHORT TERM...LAVOIE
LONG TERM...ALLEN
AVIATION...LAVOIE
FIRE WEATHER...LAVOIE








000
FXUS65 KRIW 292059
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
159 PM MST THU JAN 29 2015

.SHORT TERM...TONGIHT THROUGH FRIDAY

FOG HAS FINALLY BEGUN TO DISSIPATE NEAR ROCK SPRINGS AND SOUTHERN
LINCOLN COUNTY...BUT CONTINUES TO LINGER NEAR GREYBULL. THIS
PORTION OF THE BIGHORN BASIN WILL REMAIN FOGGY THROUGH FRIDAY
MORNING...AND WILL SPREAD TOWARD WORLAND DURING THE OVERNIGHT
HOURS. FOG IS ALSO EXPECTED TO RETURN IN THE UPPER GREEN RIVER
BASIN AND JACKSON HOLE. AS AREAS...EXCEPT NEAR GREYBULL...SHOULD
DISSIPATE LATE FRIDAY MORNING...AS H7 TEMPS COOL AND UPPER LEVEL
CLOUDS SPREAD ACROSS THE AREA.

THE FORECAST AREA WILL REMAIN DRY THROUGH FRIDAY...EXCEPT SOUTHERN
PORTIONS OF SWEETWATER COUNTY. A MOIST CUT OFF LOW...MOVING INTO
THE FOUR CORNERS AREA...WILL BRING MID TO HIGH CLOUDS ACROSS THE
SOUTHWESTERN HALF OF THE FORECAST AREA. THIS SYSTEM WILL ALSO
BRING AN INFLUX OF MOISTURE INTO SOUTHERN WYOMING. RAIN AND SNOW
SHOWERS WILL BE POSSIBLE THROUGH THE DAY ON FRIDAY. ANY SNOW
ACCUMULATION WILL BE LITTLE TO NONE.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY NIGHT

A LOW PRESSURE SYSTEM MOVING UP INTO THE FOUR CORNERS REGION WILL
EVENTUALLY BE PUSHED BACK TO THE SOUTH BY A SYSTEM MOVING SOUTHEAST
OUT OF CANADA EARLY IN THE PERIOD. MOISTURE WRAPPING AROUND THE LOW
COULD RESULT IN A FEW SHOWERS ACROSS OUR AREA AS FAR NORTH AS FARSON
ON FRIDAY NIGHT BUT MOST OF THE ENERGY FROM THIS SYSTEM WILL REMAIN
WELL TO OUR SOUTH. THE SECOND PIECE OF ENERGY MOVING OUT OF THE
NORTH WILL ALSO PROVIDE A GLANCING BLOW TO OUR FAR NORTHEASTERN
ZONES. THE MODELS HAVE BEEN TRENDING FURTHER AND FURTHER EAST WITH
THIS SYSTEM...WHICH WOULD KEEP MOST OF THE PRECIP OUT OF OUR AREA.
HOWEVER...THERE IS A DECENT COLD POOL WITH THIS ONE THAT COULD
ENCOURAGE SOME SNOW BANDING IN ADDITION TO A CHANCE FOR SOME
MEASURABLE SNOW ALONG THE COLD FRONT AS IT DROPS SOUTH ON
SATURDAY NIGHT. AT THIS TIME...IT LOOKS LIKE MOST OF THE
PRECIPITATION WILL BE FROM THE BIGHORNS EAST...WITH A SLIGHT
CHANCE AS FAR SOUTH AS CASPER. GIVEN ITS ORIGINS...NOT MUCH
MOISTURE WILL COME ALONG WITH THIS SYSTEM WITH NO SECONDARY
MOISTURE FEED TO WORK WITH...NOT MUCH SNOW IS EXPECTED.

SWIFT NORTHWEST FLOW SETS UP BEHIND THE SYSTEM ON SATURDAY. THERE
WILL BE A SERIES OF DISTURBANCES MOVING THROUGH THE END OF THE
PERIOD. OVERALL...THERE WILL BE BREEZY PERIODS THROUGHOUT THE LONG
TERM PERIOD WITH OCCASIONAL CHANCES FOR RAIN AND SNOW WITH EACH
DISTURBANCE. THE BEST CHANCE FOR SNOW WILL BE IN THE WESTERN
MOUNTAINS AND IN THE BIGHORNS BUT THERE COULD BE A FEW DROPS AND
FLAKES THAT MAKE IT EAST OF THE DIVIDE POTENTIALLY ON TUESDAY...AS
A MORE ROBUST WAVE MOVES THROUGH WITH ENOUGH DYNAMIC FORCING TO
HELP SOME MOISTURE MAKE IT EAST OF THE DIVIDE.

TOWARD THE END OF THE PERIOD...GLOBAL MODELS ARE BUILDING A RIDGE
ACROSS THE WEST WITH A TROUGH OVER THE MIDWEST. THERE ARE SOME
DIFFERENCES AS TO HOW STRONG THE RIDGE IS BUT THE OVERALL PATTERN
WOULD SUGGEST A MILD AND DRY END TO THE WEEK NEXT WEEK.

&&

.AVIATION.../00Z ISSUANCE/

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

DRY AIR AND MOSTLY CLEAR SKIES WILL REMAIN ACROSS THE AREA THIS
EVENING. MID TO HIGH CLOUDS WILL BEGIN TO MOVE ACROSS THE AREA
THROUGH THE OVERNIGHT HOURS. FOG WILL CONTINUE NEAR KGEY THROUGH
THE REST OF THE NIGHT...INTO FRIDAY MORNING...AND MOVE THROUGH THE
REST OF THE BIGHORN BASIN TOWARD KWRL AFTER MIDNIGHT.
PATCHY FOG WILL ALSO BE POSSIBLE IN THE LOWER BASINS.

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

LOW IFR/LIFR CIGS OR FOG WILL RETURN LATER TONIGHT BY 10Z FOR
KBPI/KPNA AND 11Z FOR KJAC. AN UPPER LEVEL DISTURBANCE WILL
SPREAD MID TO HIGH LEVEL CLOUDS FOR MUCH OF THE AREA TONIGHT AS
WELL. ISOLD TO WDLY SCT -SHRASN WILL ALSO BE POSSIBLE NEAR KRKS AFTER
12Z FRIDAY WITH MOST OF THIS ACTIVITY EXPECTED TO STAY VCNTY
INTERSTATE 80 AND SOUTH.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK. MEASURABLE PRECIPITATION WILL NOT FALL ACROSS THE FORECAST
AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE DIVIDE.
FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SMOKE DISPERSION WILL BE POOR
ACROSS MOST OF THE REGION FRIDAY. SATURDAY WILL SEE IMPROVEMENT
IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST OF THE
DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

$$

SHORT TERM...LAVOIE
LONG TERM...ALLEN
AVIATION...LAVOIE
FIRE WEATHER...LAVOIE







000
FXUS65 KRIW 291743
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1043 AM MST THU JAN 29 2015

.UPDATE...ADDED 18Z AVIATION DISCUSSION

SHORT TERM...TODAY THROUGH SATURDAY NIGHT (ISSUED AT 257 SM MST)

IMAGERY SHOWING RIDGE OVR LOW ACROSS THE WRN CONUS WITH WY UNDER NW FLOW
ONCE AGAIN. EXTREME WEST SIDE OF THE SW TROF THAT PASSED THRU THE FA
TODAY NOW MOVING OUT OF THE ERN PORTION OF THE STATE THIS
MORNING...TAKING LIGHT PRECIP WITH IT AND LEAVING DEVELOPING AREAS
OF PATCHY FOG AROUND THE CWA. YELLOWSTONE AND THE NRN BIGHORN BASIN
CURRENTLY HAVE THE MOST FOG IN THE VALLEYS AND BASIN BOTTOMS.

BEGINNING OF FCST...FOG IS EXPECTED TO HAVE TO HAVE DEVELOPED AND
PERSIST INTO THE MORNING HRS OVR MOST BASINS...MANY WRN
VALLEYS...AND THE LOWER ELEVATIONS OF JOHNSON AND NATRONA COUNTIES.
ALTHOUGH CURRENTLY FCSTING THE FOG TO LIFT BY LATE MORNING...IT
COULD PERSIST OVR SOME AREAS INTO THE AFTERNOON...WITH ANOTHER ROUND
OF FOG SCHEDULED ACROSS MANY OF THE SAME AREAS OVERNIGHT TONIGHT AND
INTO FRI MORNING.

WE WILL BE LARGELY DEVOID OF PRECIP UNTIL LATE SATURDAY...EXCEPT FOR
AN EVER SO SLIGHT POSSIBILITY OF A SPRINKLE OR TWO ACROSS THE SRN
BORDER AREA ON FRIDAY DUE TO THE DEVELOPMENT OF A LARGE CLOSED LOW
SYSTEM ACROSS THE DESERT SW OUT OF WHAT IS CURRENTLY THE WEAK TROF
UNDER THE RIDGE AS MENTIONED ABOVE. JET PHASING OF THE SRN BRANCH
AND CYCLOGENESIS SHOULD OCCUR BY FRI NIGHT NEAR THE NRN BAJA REGION.
HOWEVER THE STRENGTH AND POSITION OF THE SRN BRANCH OF THE JET WILL
KEEP THE TRACK FOR THIS WET STORM SYSTEM WELL SOUTH OF THE FA THIS
TIME AROUND...ONLY SCRAPING THE SRN BORDER OF WY WITH MODEST
MOISTURE THRU SAT MORNING.

OTHERWISE...WELL UPSTREAM AND CURRENTLY OVR THE GULF OF AK...A
PORTION OF THE NRN BRANCH OF THE JET WILL MOVE AROUND THE RIDGE OVR
THE EPAC/WRN CONUS...EVENTUALLY MAKING ITS WAY INTO THE NRN CWA BY
LATE SAT...PUSHING A DEVELOPING LOW AND FRONT THRU MT THEN WY BY
LATE AFTERNOON/EVE. POST FRONTAL POP CHANCES WILL INCREASE MAINLY
ACROSS THE NRN AND ERN ZONES...E OF THE DIVIDE...BEHIND THIS CLIPPER
LIKE FRONT. THE PREVIOUS DAYS RELATIVELY DRY ATMOSPHERE ALONG WITH
THE PROJECTED TRAJECTORY WILL KEEP MOISTURE AT A PREMIUM...SO ONLY
EXPECTING RELATIVELY LIGHT PRECIP EAST OF THE DIVIDE OVERNIGHT
SAT...BUT ALL AS SNOW...AS OPPOSED TO THE MOST RECENT WEATHER
SYSTEM. THIS WILL USHER IN THE BEGINNINGS OF A WEEK`S WORTH OF
SEVERAL UPR LVL DISTURBANCES THAT WILL MOVE QUICKLY THRU THE
PERSISTENT UPR LVL NW FLOW...BRINGING INCREASED CHANCES FOR SNOWFALL
ACROSS THE WEST AND NORTH.

LONG TERM...SUNDAY THROUGH THURSDAY

IN WAKE OF THE SYSTEM SATURDAY/SATURDAY NIGHT...A MAINLY DRY
NORTHWEST FLOW IS EXPECTED SUNDAY. WOULD STILL EXPECT THE
POSSIBILITY FOR SOME MOUNTAIN SNOW SHOWERS OVER THE NORTHWEST AND
NORTH. MEDIUM RANGE MODELS CONTINUE TO SHOW A PACIFIC SHORTWAVE
TROUGH BRIEFLY FLATTENING OUT THE WEST COAST RIDGE AS IT PUSHES INTO
THE PACIFIC NORTHWEST SUNDAY NIGHT. THIS SHORTWAVE TROUGH IS THEN
PROJECTED TO PUSH ACROSS THE NORTHERN ROCKIES IN THE MONDAY/MONDAY
NIGHT TIME FRAME. THIS SHOULD RESULT IN A GOOD CHANCE OF SNOWFALL
OVER THE FAR WEST/NORTHWEST AND BIGHORN MTS...WITH BREEZY TO WINDY
CONDITIONS IN THE WIND CORRIDOR. IN WAKE OF THIS SYSTEM...THE
WESTERN UPPER RIDGE BUILDS BACK...WITH MODELS SHOWING A RELATIVELY
MOIST NORTHWEST FLOW OVER THE FORECAST AREA...WITH PERHAPS A
DISTURBANCE OR TWO TUESDAY AND WEDNESDAY. THIS WILL KEEP CHANCES OF
SNOWFALL IN THE FORECAST...ESPECIALLY OVER THE NORTHWEST/NORTHERN
MOUNTAINS...POSSIBLY SPILLING INTO THE LOWER ELEVATIONS EAST OF THE
DIVIDE AT TIMES. MODELS HAVE CONTINUED TO STRUGGLE WITH THE
PLACEMENT/TIMING OF AN ARCTIC COLD FRONT IN THE TUESDAY/WEDNESDAY
TIME FRAME. THE GFS KEEPS THE ARCTIC AIR MASS NORTH AND EAST OF THE
AREA...WHILE THE ECMWF AND GEM ARE SHOWING THIS COLD AIR MASS
IMPACTING THE AREAS EAST OF THE DIVIDE TUESDAY AND WEDNESDAY. MODELS
ARE HINTING AT THE WESTERN RIDGE SHIFTING A BIT OVER THE ROCKIES
THURSDAY WITH MILDER AND MAINLY DRY CONDITIONS.

AVIATION.../18Z ISSUANCE/

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

DRIER AIR HAS MOVED INTO THE AREA THIS MORNING...WITH CLEAR
SKIES. FOG HAS DISSIPATED ACROSS MOST AREAS...EXCEPT NORTHERN
PORTIONS OF THE BIGHORN BASIN...NEAR KGEY. THIS AREA IS EXPECTED
TO REMAIN TRAPPED UNDER AN INVERSION...KEEPING CHANCES FOR THE FOG
TO REMAIN HIGH. VFR CONDITIONS WILL PREVAIL FOR THE REST OF THE
AREA THIS AFTERNOON...THROUGH THURSDAY NIGHT WITH FOG MORE PATCHY
AND MAINLY OVER THE LOWER BASINS...VCNTY KRIW AND KWRL THURSDAY
NIGHT.

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

LOW IFR/LIFR CIGS OR FOG CONTINUE LATE THIS MORNING OVER THE
WESTERN VALLEYS AND SOUTHWEST. MOST OF THE FOG OR LOWER CIGS WILL
ERODE BY EARLY THIS AFTERNOON. AN UPPER LEVEL DISTURBANCE WILL
SPREAD IN ISOLD TO WDLY SCT -SHRASN INTO THE SOUTHWEST AFTER 06Z
FRIDAY WITH MOST OF THIS ACTIVITY EXPECTED TO STAY VCNTY
INTERSTATE 80 AND SOUTH. LOWER IFR/LIFR CIGS WILL BE POSSIBLE
AGAIN THURSDAY NIGHT FOR KBPI AND KPNA.

FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK AS. MEASURABLE PRECIPITATION WILL NOT FALL AGAIN ACROSS THE
FORECAST AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE
DIVIDE. FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SMOKE DISPERSION WILL BE POOR
ACROSS MOST OF THE REGION TODAY AND AGAIN FRIDAY. SATURDAY WILL SEE
IMPROVEMENT IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST
OF THE DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

$$

SHORT TERM...BRAUN
LONG TERM...WM
AVIATION...LAVOIE
FIRE WEATHER...BRAUN







000
FXUS65 KRIW 291743
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1043 AM MST THU JAN 29 2015

.UPDATE...ADDED 18Z AVIATION DISCUSSION

SHORT TERM...TODAY THROUGH SATURDAY NIGHT (ISSUED AT 257 SM MST)

IMAGERY SHOWING RIDGE OVR LOW ACROSS THE WRN CONUS WITH WY UNDER NW FLOW
ONCE AGAIN. EXTREME WEST SIDE OF THE SW TROF THAT PASSED THRU THE FA
TODAY NOW MOVING OUT OF THE ERN PORTION OF THE STATE THIS
MORNING...TAKING LIGHT PRECIP WITH IT AND LEAVING DEVELOPING AREAS
OF PATCHY FOG AROUND THE CWA. YELLOWSTONE AND THE NRN BIGHORN BASIN
CURRENTLY HAVE THE MOST FOG IN THE VALLEYS AND BASIN BOTTOMS.

BEGINNING OF FCST...FOG IS EXPECTED TO HAVE TO HAVE DEVELOPED AND
PERSIST INTO THE MORNING HRS OVR MOST BASINS...MANY WRN
VALLEYS...AND THE LOWER ELEVATIONS OF JOHNSON AND NATRONA COUNTIES.
ALTHOUGH CURRENTLY FCSTING THE FOG TO LIFT BY LATE MORNING...IT
COULD PERSIST OVR SOME AREAS INTO THE AFTERNOON...WITH ANOTHER ROUND
OF FOG SCHEDULED ACROSS MANY OF THE SAME AREAS OVERNIGHT TONIGHT AND
INTO FRI MORNING.

WE WILL BE LARGELY DEVOID OF PRECIP UNTIL LATE SATURDAY...EXCEPT FOR
AN EVER SO SLIGHT POSSIBILITY OF A SPRINKLE OR TWO ACROSS THE SRN
BORDER AREA ON FRIDAY DUE TO THE DEVELOPMENT OF A LARGE CLOSED LOW
SYSTEM ACROSS THE DESERT SW OUT OF WHAT IS CURRENTLY THE WEAK TROF
UNDER THE RIDGE AS MENTIONED ABOVE. JET PHASING OF THE SRN BRANCH
AND CYCLOGENESIS SHOULD OCCUR BY FRI NIGHT NEAR THE NRN BAJA REGION.
HOWEVER THE STRENGTH AND POSITION OF THE SRN BRANCH OF THE JET WILL
KEEP THE TRACK FOR THIS WET STORM SYSTEM WELL SOUTH OF THE FA THIS
TIME AROUND...ONLY SCRAPING THE SRN BORDER OF WY WITH MODEST
MOISTURE THRU SAT MORNING.

OTHERWISE...WELL UPSTREAM AND CURRENTLY OVR THE GULF OF AK...A
PORTION OF THE NRN BRANCH OF THE JET WILL MOVE AROUND THE RIDGE OVR
THE EPAC/WRN CONUS...EVENTUALLY MAKING ITS WAY INTO THE NRN CWA BY
LATE SAT...PUSHING A DEVELOPING LOW AND FRONT THRU MT THEN WY BY
LATE AFTERNOON/EVE. POST FRONTAL POP CHANCES WILL INCREASE MAINLY
ACROSS THE NRN AND ERN ZONES...E OF THE DIVIDE...BEHIND THIS CLIPPER
LIKE FRONT. THE PREVIOUS DAYS RELATIVELY DRY ATMOSPHERE ALONG WITH
THE PROJECTED TRAJECTORY WILL KEEP MOISTURE AT A PREMIUM...SO ONLY
EXPECTING RELATIVELY LIGHT PRECIP EAST OF THE DIVIDE OVERNIGHT
SAT...BUT ALL AS SNOW...AS OPPOSED TO THE MOST RECENT WEATHER
SYSTEM. THIS WILL USHER IN THE BEGINNINGS OF A WEEK`S WORTH OF
SEVERAL UPR LVL DISTURBANCES THAT WILL MOVE QUICKLY THRU THE
PERSISTENT UPR LVL NW FLOW...BRINGING INCREASED CHANCES FOR SNOWFALL
ACROSS THE WEST AND NORTH.

LONG TERM...SUNDAY THROUGH THURSDAY

IN WAKE OF THE SYSTEM SATURDAY/SATURDAY NIGHT...A MAINLY DRY
NORTHWEST FLOW IS EXPECTED SUNDAY. WOULD STILL EXPECT THE
POSSIBILITY FOR SOME MOUNTAIN SNOW SHOWERS OVER THE NORTHWEST AND
NORTH. MEDIUM RANGE MODELS CONTINUE TO SHOW A PACIFIC SHORTWAVE
TROUGH BRIEFLY FLATTENING OUT THE WEST COAST RIDGE AS IT PUSHES INTO
THE PACIFIC NORTHWEST SUNDAY NIGHT. THIS SHORTWAVE TROUGH IS THEN
PROJECTED TO PUSH ACROSS THE NORTHERN ROCKIES IN THE MONDAY/MONDAY
NIGHT TIME FRAME. THIS SHOULD RESULT IN A GOOD CHANCE OF SNOWFALL
OVER THE FAR WEST/NORTHWEST AND BIGHORN MTS...WITH BREEZY TO WINDY
CONDITIONS IN THE WIND CORRIDOR. IN WAKE OF THIS SYSTEM...THE
WESTERN UPPER RIDGE BUILDS BACK...WITH MODELS SHOWING A RELATIVELY
MOIST NORTHWEST FLOW OVER THE FORECAST AREA...WITH PERHAPS A
DISTURBANCE OR TWO TUESDAY AND WEDNESDAY. THIS WILL KEEP CHANCES OF
SNOWFALL IN THE FORECAST...ESPECIALLY OVER THE NORTHWEST/NORTHERN
MOUNTAINS...POSSIBLY SPILLING INTO THE LOWER ELEVATIONS EAST OF THE
DIVIDE AT TIMES. MODELS HAVE CONTINUED TO STRUGGLE WITH THE
PLACEMENT/TIMING OF AN ARCTIC COLD FRONT IN THE TUESDAY/WEDNESDAY
TIME FRAME. THE GFS KEEPS THE ARCTIC AIR MASS NORTH AND EAST OF THE
AREA...WHILE THE ECMWF AND GEM ARE SHOWING THIS COLD AIR MASS
IMPACTING THE AREAS EAST OF THE DIVIDE TUESDAY AND WEDNESDAY. MODELS
ARE HINTING AT THE WESTERN RIDGE SHIFTING A BIT OVER THE ROCKIES
THURSDAY WITH MILDER AND MAINLY DRY CONDITIONS.

AVIATION.../18Z ISSUANCE/

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

DRIER AIR HAS MOVED INTO THE AREA THIS MORNING...WITH CLEAR
SKIES. FOG HAS DISSIPATED ACROSS MOST AREAS...EXCEPT NORTHERN
PORTIONS OF THE BIGHORN BASIN...NEAR KGEY. THIS AREA IS EXPECTED
TO REMAIN TRAPPED UNDER AN INVERSION...KEEPING CHANCES FOR THE FOG
TO REMAIN HIGH. VFR CONDITIONS WILL PREVAIL FOR THE REST OF THE
AREA THIS AFTERNOON...THROUGH THURSDAY NIGHT WITH FOG MORE PATCHY
AND MAINLY OVER THE LOWER BASINS...VCNTY KRIW AND KWRL THURSDAY
NIGHT.

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

LOW IFR/LIFR CIGS OR FOG CONTINUE LATE THIS MORNING OVER THE
WESTERN VALLEYS AND SOUTHWEST. MOST OF THE FOG OR LOWER CIGS WILL
ERODE BY EARLY THIS AFTERNOON. AN UPPER LEVEL DISTURBANCE WILL
SPREAD IN ISOLD TO WDLY SCT -SHRASN INTO THE SOUTHWEST AFTER 06Z
FRIDAY WITH MOST OF THIS ACTIVITY EXPECTED TO STAY VCNTY
INTERSTATE 80 AND SOUTH. LOWER IFR/LIFR CIGS WILL BE POSSIBLE
AGAIN THURSDAY NIGHT FOR KBPI AND KPNA.

FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK AS. MEASURABLE PRECIPITATION WILL NOT FALL AGAIN ACROSS THE
FORECAST AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE
DIVIDE. FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SMOKE DISPERSION WILL BE POOR
ACROSS MOST OF THE REGION TODAY AND AGAIN FRIDAY. SATURDAY WILL SEE
IMPROVEMENT IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST
OF THE DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

$$

SHORT TERM...BRAUN
LONG TERM...WM
AVIATION...LAVOIE
FIRE WEATHER...BRAUN








000
FXUS65 KRIW 290957
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
257 AM MST THU JAN 29 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT

IMAGERY SHOWING RIDGE OVR LOW ACROSS THE WRN CONUS WITH WY UNDER NW FLOW
ONCE AGAIN. EXTREME WEST SIDE OF THE SW TROF THAT PASSED THRU THE FA
TODAY NOW MOVING OUT OF THE ERN PORTION OF THE STATE THIS
MORNING...TAKING LIGHT PRECIP WITH IT AND LEAVING DEVELOPING AREAS
OF PATCHY FOG AROUND THE CWA. YELLOWSTONE AND THE NRN BIGHORN BASIN
CURRENTLY HAVE THE MOST FOG IN THE VALLEYS AND BASIN BOTTOMS.

BEGINNING OF FCST...FOG IS EXPECTED TO HAVE TO HAVE DEVELOPED AND
PERSIST INTO THE MORNING HRS OVR MOST BASINS...MANY WRN
VALLEYS...AND THE LOWER ELEVATIONS OF JOHNSON AND NATRONA COUNTIES.
ALTHOUGH CURRENTLY FCSTING THE FOG TO LIFT BY LATE MORNING...IT
COULD PERSIST OVR SOME AREAS INTO THE AFTERNOON...WITH ANOTHER ROUND
OF FOG SCHEDULED ACROSS MANY OF THE SAME AREAS OVERNIGHT TONIGHT AND
INTO FRI MORNING.

WE WILL BE LARGELY DEVOID OF PRECIP UNTIL LATE SATURDAY...EXCEPT FOR
AN EVER SO SLIGHT POSSIBILITY OF A SPRINKLE OR TWO ACROSS THE SRN
BORDER AREA ON FRIDAY DUE TO THE DEVELOPMENT OF A LARGE CLOSED LOW
SYSTEM ACROSS THE DESERT SW OUT OF WHAT IS CURRENTLY THE WEAK TROF
UNDER THE RIDGE AS MENTIONED ABOVE. JET PHASING OF THE SRN BRANCH
AND CYCLOGENESIS SHOULD OCCUR BY FRI NIGHT NEAR THE NRN BAJA REGION.
HOWEVER THE STRENGTH AND POSITION OF THE SRN BRANCH OF THE JET WILL
KEEP THE TRACK FOR THIS WET STORM SYSTEM WELL SOUTH OF THE FA THIS
TIME AROUND...ONLY SCRAPING THE SRN BORDER OF WY WITH MODEST
MOISTURE THRU SAT MORNING.

OTHERWISE...WELL UPSTREAM AND CURRENTLY OVR THE GULF OF AK...A
PORTION OF THE NRN BRANCH OF THE JET WILL MOVE AROUND THE RIDGE OVR
THE EPAC/WRN CONUS...EVENTUALLY MAKING ITS WAY INTO THE NRN CWA BY
LATE SAT...PUSHING A DEVELOPING LOW AND FRONT THRU MT THEN WY BY
LATE AFTERNOON/EVE. POST FRONTAL POP CHANCES WILL INCREASE MAINLY
ACROSS THE NRN AND ERN ZONES...E OF THE DIVIDE...BEHIND THIS CLIPPER
LIKE FRONT. THE PREVIOUS DAYS RELATIVELY DRY ATMOSPHERE ALONG WITH
THE PROJECTED TRAJECTORY WILL KEEP MOISTURE AT A PREMIUM...SO ONLY
EXPECTING RELATIVELY LIGHT PRECIP EAST OF THE DIVIDE OVERNIGHT
SAT...BUT ALL AS SNOW...AS OPPOSED TO THE MOST RECENT WEATHER
SYSTEM. THIS WILL USHER IN THE BEGINNINGS OF A WEEK`S WORTH OF
SEVERAL UPR LVL DISTURBANCES THAT WILL MOVE QUICKLY THRU THE
PERSISTENT UPR LVL NW FLOW...BRINGING INCREASED CHANCES FOR SNOWFALL
ACROSS THE WEST AND NORTH.

.LONG TERM...SUNDAY THROUGH THURSDAY

IN WAKE OF THE SYSTEM SATURDAY/SATURDAY NIGHT...A MAINLY DRY
NORTHWEST FLOW IS EXPECTED SUNDAY. WOULD STILL EXPECT THE
POSSIBILITY FOR SOME MOUNTAIN SNOW SHOWERS OVER THE NORTHWEST AND
NORTH. MEDIUM RANGE MODELS CONTINUE TO SHOW A PACIFIC SHORTWAVE
TROUGH BRIEFLY FLATTENING OUT THE WEST COAST RIDGE AS IT PUSHES INTO
THE PACIFIC NORTHWEST SUNDAY NIGHT. THIS SHORTWAVE TROUGH IS THEN
PROJECTED TO PUSH ACROSS THE NORTHERN ROCKIES IN THE MONDAY/MONDAY
NIGHT TIME FRAME. THIS SHOULD RESULT IN A GOOD CHANCE OF SNOWFALL
OVER THE FAR WEST/NORTHWEST AND BIGHORN MTS...WITH BREEZY TO WINDY
CONDITIONS IN THE WIND CORRIDOR. IN WAKE OF THIS SYSTEM...THE
WESTERN UPPER RIDGE BUILDS BACK...WITH MODELS SHOWING A RELATIVELY
MOIST NORTHWEST FLOW OVER THE FORECAST AREA...WITH PERHAPS A
DISTURBANCE OR TWO TUESDAY AND WEDNESDAY. THIS WILL KEEP CHANCES OF
SNOWFALL IN THE FORECAST...ESPECIALLY OVER THE NORTHWEST/NORTHERN
MOUNTAINS...POSSIBLY SPILLING INTO THE LOWER ELEVATIONS EAST OF THE
DIVIDE AT TIMES. MODELS HAVE CONTINUED TO STRUGGLE WITH THE
PLACEMENT/TIMING OF AN ARCTIC COLD FRONT IN THE TUESDAY/WEDNESDAY
TIME FRAME. THE GFS KEEPS THE ARCTIC AIR MASS NORTH AND EAST OF THE
AREA...WHILE THE ECMWF AND GEM ARE SHOWING THIS COLD AIR MASS
IMPACTING THE AREAS EAST OF THE DIVIDE TUESDAY AND WEDNESDAY. MODELS
ARE HINTING AT THE WESTERN RIDGE SHIFTING A BIT OVER THE ROCKIES
THURSDAY WITH MILDER AND MAINLY DRY CONDITIONS.

&&

.AVIATION.../12Z ISSUANCE/

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

DRIER AIR PUSHING IN EARLY THIS MORNING WILL RESULT IN CLEARING MID
LEVEL CLOUD DECKS THROUGH 12Z WITH AREAS OF FOG OR IFR/LIFR CIGS
LIKELY FORMING AND PERSISTING THROUGH 19Z.  THE WIND RIVER BASIN AND
BIGHORN BASIN...VCNTY KRIW-KWRL-KGEY...STAND THE BEST CHANCE OF THE
MOST WIDESPREAD...PERSISTENT FOG INTO THE EARLY AFTERNOON...BUT FOG
MAY ALSO BECOME FAIRLY WIDESPREAD FURTHER EAST...VCNTY KRIW-KCPR
THROUGH THE MORNING.  MOST FOG SHOULD DISSIPATE BY EARLY THURSDAY
AFTERNOON.  VFR CONDITIONS WILL PREVAIL AFTERWARDS...THROUGH
THURSDAY NIGHT WITH FOG MORE PATCHY AND MAINLY OVER THE LOWER
BASINS...VCNTY KRIW AND KWRL THURSDAY NIGHT.

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

SOME CLEARING OF MID-LEVEL CLOUD DECKS WILL OCCUR EARLY THIS MORNING
RESULTING IN FORMATION OF LOWER IFR/LIFR CIGS OR FOG OVER THE
WESTERN VALLEYS AND SOUTHWEST THROUGH THURSDAY MORNING.  MOST OF THE
FOG OR LOWER CIGS WILL ERODE BY EARLY THURSDAY AFTERNOON. AN UPPER
LEVEL DISTURBANCE WILL SPREAD IN ISOLD TO WDLY SCT -SHRASN INTO THE
SOUTHWEST AFTER 06Z FRIDAY WITH MOST OF THIS ACTIVITY EXPECTED TO
STAY VCNTY INTERSTATE 80 AND SOUTH.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK AS. MEASURABLE PRECIPITATION WILL NOT FALL AGAIN ACROSS THE
FORECAST AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE
DIVIDE. FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SMOKE DISPERSION WILL BE POOR
ACROSS MOST OF THE REGION TODAY AND AGAIN FRIDAY. SATURDAY WILL SEE
IMPROVEMENT IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST
OF THE DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

&&

$$

SHORT TERM...BRAUN
LONG TERM...WM
AVIATION...AEM
FIRE WEATHER...BRAUN








000
FXUS65 KRIW 290957
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
257 AM MST THU JAN 29 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT

IMAGERY SHOWING RIDGE OVR LOW ACROSS THE WRN CONUS WITH WY UNDER NW FLOW
ONCE AGAIN. EXTREME WEST SIDE OF THE SW TROF THAT PASSED THRU THE FA
TODAY NOW MOVING OUT OF THE ERN PORTION OF THE STATE THIS
MORNING...TAKING LIGHT PRECIP WITH IT AND LEAVING DEVELOPING AREAS
OF PATCHY FOG AROUND THE CWA. YELLOWSTONE AND THE NRN BIGHORN BASIN
CURRENTLY HAVE THE MOST FOG IN THE VALLEYS AND BASIN BOTTOMS.

BEGINNING OF FCST...FOG IS EXPECTED TO HAVE TO HAVE DEVELOPED AND
PERSIST INTO THE MORNING HRS OVR MOST BASINS...MANY WRN
VALLEYS...AND THE LOWER ELEVATIONS OF JOHNSON AND NATRONA COUNTIES.
ALTHOUGH CURRENTLY FCSTING THE FOG TO LIFT BY LATE MORNING...IT
COULD PERSIST OVR SOME AREAS INTO THE AFTERNOON...WITH ANOTHER ROUND
OF FOG SCHEDULED ACROSS MANY OF THE SAME AREAS OVERNIGHT TONIGHT AND
INTO FRI MORNING.

WE WILL BE LARGELY DEVOID OF PRECIP UNTIL LATE SATURDAY...EXCEPT FOR
AN EVER SO SLIGHT POSSIBILITY OF A SPRINKLE OR TWO ACROSS THE SRN
BORDER AREA ON FRIDAY DUE TO THE DEVELOPMENT OF A LARGE CLOSED LOW
SYSTEM ACROSS THE DESERT SW OUT OF WHAT IS CURRENTLY THE WEAK TROF
UNDER THE RIDGE AS MENTIONED ABOVE. JET PHASING OF THE SRN BRANCH
AND CYCLOGENESIS SHOULD OCCUR BY FRI NIGHT NEAR THE NRN BAJA REGION.
HOWEVER THE STRENGTH AND POSITION OF THE SRN BRANCH OF THE JET WILL
KEEP THE TRACK FOR THIS WET STORM SYSTEM WELL SOUTH OF THE FA THIS
TIME AROUND...ONLY SCRAPING THE SRN BORDER OF WY WITH MODEST
MOISTURE THRU SAT MORNING.

OTHERWISE...WELL UPSTREAM AND CURRENTLY OVR THE GULF OF AK...A
PORTION OF THE NRN BRANCH OF THE JET WILL MOVE AROUND THE RIDGE OVR
THE EPAC/WRN CONUS...EVENTUALLY MAKING ITS WAY INTO THE NRN CWA BY
LATE SAT...PUSHING A DEVELOPING LOW AND FRONT THRU MT THEN WY BY
LATE AFTERNOON/EVE. POST FRONTAL POP CHANCES WILL INCREASE MAINLY
ACROSS THE NRN AND ERN ZONES...E OF THE DIVIDE...BEHIND THIS CLIPPER
LIKE FRONT. THE PREVIOUS DAYS RELATIVELY DRY ATMOSPHERE ALONG WITH
THE PROJECTED TRAJECTORY WILL KEEP MOISTURE AT A PREMIUM...SO ONLY
EXPECTING RELATIVELY LIGHT PRECIP EAST OF THE DIVIDE OVERNIGHT
SAT...BUT ALL AS SNOW...AS OPPOSED TO THE MOST RECENT WEATHER
SYSTEM. THIS WILL USHER IN THE BEGINNINGS OF A WEEK`S WORTH OF
SEVERAL UPR LVL DISTURBANCES THAT WILL MOVE QUICKLY THRU THE
PERSISTENT UPR LVL NW FLOW...BRINGING INCREASED CHANCES FOR SNOWFALL
ACROSS THE WEST AND NORTH.

.LONG TERM...SUNDAY THROUGH THURSDAY

IN WAKE OF THE SYSTEM SATURDAY/SATURDAY NIGHT...A MAINLY DRY
NORTHWEST FLOW IS EXPECTED SUNDAY. WOULD STILL EXPECT THE
POSSIBILITY FOR SOME MOUNTAIN SNOW SHOWERS OVER THE NORTHWEST AND
NORTH. MEDIUM RANGE MODELS CONTINUE TO SHOW A PACIFIC SHORTWAVE
TROUGH BRIEFLY FLATTENING OUT THE WEST COAST RIDGE AS IT PUSHES INTO
THE PACIFIC NORTHWEST SUNDAY NIGHT. THIS SHORTWAVE TROUGH IS THEN
PROJECTED TO PUSH ACROSS THE NORTHERN ROCKIES IN THE MONDAY/MONDAY
NIGHT TIME FRAME. THIS SHOULD RESULT IN A GOOD CHANCE OF SNOWFALL
OVER THE FAR WEST/NORTHWEST AND BIGHORN MTS...WITH BREEZY TO WINDY
CONDITIONS IN THE WIND CORRIDOR. IN WAKE OF THIS SYSTEM...THE
WESTERN UPPER RIDGE BUILDS BACK...WITH MODELS SHOWING A RELATIVELY
MOIST NORTHWEST FLOW OVER THE FORECAST AREA...WITH PERHAPS A
DISTURBANCE OR TWO TUESDAY AND WEDNESDAY. THIS WILL KEEP CHANCES OF
SNOWFALL IN THE FORECAST...ESPECIALLY OVER THE NORTHWEST/NORTHERN
MOUNTAINS...POSSIBLY SPILLING INTO THE LOWER ELEVATIONS EAST OF THE
DIVIDE AT TIMES. MODELS HAVE CONTINUED TO STRUGGLE WITH THE
PLACEMENT/TIMING OF AN ARCTIC COLD FRONT IN THE TUESDAY/WEDNESDAY
TIME FRAME. THE GFS KEEPS THE ARCTIC AIR MASS NORTH AND EAST OF THE
AREA...WHILE THE ECMWF AND GEM ARE SHOWING THIS COLD AIR MASS
IMPACTING THE AREAS EAST OF THE DIVIDE TUESDAY AND WEDNESDAY. MODELS
ARE HINTING AT THE WESTERN RIDGE SHIFTING A BIT OVER THE ROCKIES
THURSDAY WITH MILDER AND MAINLY DRY CONDITIONS.

&&

.AVIATION.../12Z ISSUANCE/

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

DRIER AIR PUSHING IN EARLY THIS MORNING WILL RESULT IN CLEARING MID
LEVEL CLOUD DECKS THROUGH 12Z WITH AREAS OF FOG OR IFR/LIFR CIGS
LIKELY FORMING AND PERSISTING THROUGH 19Z.  THE WIND RIVER BASIN AND
BIGHORN BASIN...VCNTY KRIW-KWRL-KGEY...STAND THE BEST CHANCE OF THE
MOST WIDESPREAD...PERSISTENT FOG INTO THE EARLY AFTERNOON...BUT FOG
MAY ALSO BECOME FAIRLY WIDESPREAD FURTHER EAST...VCNTY KRIW-KCPR
THROUGH THE MORNING.  MOST FOG SHOULD DISSIPATE BY EARLY THURSDAY
AFTERNOON.  VFR CONDITIONS WILL PREVAIL AFTERWARDS...THROUGH
THURSDAY NIGHT WITH FOG MORE PATCHY AND MAINLY OVER THE LOWER
BASINS...VCNTY KRIW AND KWRL THURSDAY NIGHT.

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

SOME CLEARING OF MID-LEVEL CLOUD DECKS WILL OCCUR EARLY THIS MORNING
RESULTING IN FORMATION OF LOWER IFR/LIFR CIGS OR FOG OVER THE
WESTERN VALLEYS AND SOUTHWEST THROUGH THURSDAY MORNING.  MOST OF THE
FOG OR LOWER CIGS WILL ERODE BY EARLY THURSDAY AFTERNOON. AN UPPER
LEVEL DISTURBANCE WILL SPREAD IN ISOLD TO WDLY SCT -SHRASN INTO THE
SOUTHWEST AFTER 06Z FRIDAY WITH MOST OF THIS ACTIVITY EXPECTED TO
STAY VCNTY INTERSTATE 80 AND SOUTH.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW FOR ALL AREAS...AND WILL REMAIN SO THROUGH NEXT
WEEK AS. MEASURABLE PRECIPITATION WILL NOT FALL AGAIN ACROSS THE
FORECAST AREA UNTIL LATE SATURDAY INTO SUNDAY MORNING EAST OF THE
DIVIDE. FROM SUNDAY NIGHT THROUGH THE NEXT WORK WEEK...A SERIES OF
DISTURBANCES WILL RIDE THROUGH THE REGION...AFFECTING MAINLY THE
WESTERN AND NORTHERN DISPATCH ZONES. SMOKE DISPERSION WILL BE POOR
ACROSS MOST OF THE REGION TODAY AND AGAIN FRIDAY. SATURDAY WILL SEE
IMPROVEMENT IN BOTH MIXING ABILITY AND DISPERSION...ESPECIALLY EAST
OF THE DIVIDE AND ACROSS THE SOUTHERN ZONES.

&&

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

&&

$$

SHORT TERM...BRAUN
LONG TERM...WM
AVIATION...AEM
FIRE WEATHER...BRAUN









000
FXUS65 KRIW 290545
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1045 PM MST WED JAN 28 2015

UPDATE...ADDED 06Z AVIATION DISCUSSION

.SHORT TERM...TONIGHT THROUGH THURSDAY (ISSUED AT 214 PM MST)

IMPROVING CONDITIONS EXPECTED THROUGH THE EVENING WITH LINGERING
SHOWERS TAPERING OFF. SKIES WILL CLEAR ACROSS MUCH OF THE FORECAST
AREA OVERNIGHT WITH HIGH PRESSURE BUILDING OVER WESTERN AND CENTRAL
WYOMING.

THESE CLEARING SKIES AND REMNANT MOISTURE FROM THE EARLIER SHOWER
ACTIVITY WILL PROMOTE THE DEVELOPMENT OF PATCHY FOG AROUND MIDNIGHT.
FOG MAY PERSIST THROUGH THE MID TO LATE MORNING HOURS FOR SOME
AREAS...THOUGH SHOULD GENERALLY HAVE LIFTED BY THE AFTERNOON.

BENIGN CONDITIONS WILL THEN BE FOUND THROUGH THE AFTERNOON ACROSS
THE AREA.

.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY

THIS PERIOD STARTS WITH OUR CURRENT UPPER LOW OFF THE SRN CA WHICH
IS FORECAST TO MOVE SLOWLY TOWARDS SRN CA/NRN BAJA ON FRIDAY...THEN
IT LOOKS LIKE IT WILL MOVE SLOWLY INTO AZ ON SATURDAY BEFORE SAGGING
SOUTH AGAIN INTO MEXICO AS THE NRN BRANCH BEGINS TO TAKE OVER. A
COUPLE SHORTWAVES THEN LOOK LIKE THEY`LL HAVE VARYING AMOUNTS OF
IMPACT OVER US OVER THE WEEKEND AS WE`LL HAVE TO CONTEND WITH TWO
POTENTIAL COLD FRONTS ALONG AND EAST OF THE DIVIDE MAINLY. ALTHOUGH
THE 12Z RUNS TODAY HAVE KEPT THE MAIN IMPACT WITH THESE FRONT OVER
THE FAR NERN ZONES. EARLY NEXT WEEK...IT STILL LOOKS LIKE THE FLOW
WILL FLATTEN EARLY NEXT WEEK LEADING TO AN INCREASED CHANCE OF SNOW
IN THE WEST. BUT THEN BY WEDNESDAY...THE FLOW IS EXPECTED TO SHARPEN
AGAIN WITH BUILDING HEIGHTS ALONG THE WEST COAST AND ANOTHER
POTENTIAL SYSTEM DROPPING DOWN FROM THE NNW.

THE FIRST SYSTEM WELL TO OUR SOUTH LOOKS LIKE IT WILL REMAIN WELL TO
THE SOUTH WITH THE LEADING EDGE OF THE MOISTURE EDGING CLOSE TO THE
AREA WITH CLOUDS BUT MOST IF NOT ALL THE PCPN WILL STAY SOUTH OF THE
AREA. THERE IS A SMALL CHANCE THAT AS THE JET TO THE SOUTH PULLS OFF
TO THE EAST LATE FRI/FRI EVE...WE GET IN THE RIGHT ENTRANCE REGION OVER
SRN SWEETWATER COUNTY AND THAT COULD BE JUST ENOUGH TO HELP WHAT
CLOUD SHIELD MAY BE DOWN THERE TO GET A FEW LIGHT SHOWERS GOING.
HAVE SOME SLIGHT CHANCES IN FOR THAT REASON. WILL PROBABLY HAVE SOME
CONTINUED AT LEAST PATCHY FOG/LOW CLOUDS FRIDAY INTO SATURDAY
MORNING AHEAD OF THIS FIRST WEEKEND SYSTEM. THE FIRST SHORTWAVE TO
DROP SOUTH ORIGINATES FROM THE ERN PACIFIC UPPER LOW WITH A
SHORTWAVE SHOOTING OUT OF THAT AND MOVING THROUGH THE DEVELOPING
WEST COAST RIDGE AND THEN DOWN THE FRONT SIDE. 12Z RUNS HAVE BACKED
OFF ON HOW MUCH OF AN IMPACT THIS SATURDAY FRONT WILL HAVE WITH FLOW
ALOFT A LITTLE MORE NW AND SHOWING THE FRONT HAVING THE GREATEST
IMPACT OVER THE NERN ZONES WITH A CHANCE OF SNOW LATE SAT OR SAT
EVE. THE FRONT STILL LOOKS LIKE IT MAY MAKE IT TO MOST AREAS EAST OF
THE DIVIDE BUT MOST OF THE ENERGY WITH THIS STORM IS FORECAST TO
STAY JUST TO THE NE OF MOST OF THE AREA. THE 12Z NAM IS EVEN FURTHER
TO THE NE WITH THE FRONT. NEXT SHORTWAVE ORIGINATES IN THE
DEVELOPING CROSS POLAR FLOW. THIS SYSTEM HAS ITS ORIGINS WEST OF
ALASKA AND NORTH OF THE ARCTIC CIRCLE. THIS FRONT WILL LIKELY
CONTAIN VERY COLD AIR BUT AT THE SAME TIME...THE CROSS POLAR FLOW IS
BEING SHUNTED SLIGHTLY TO THE EAST AS THE RIDGE TRIES TO NOSE INTO
THE WEST. TOUGH CALL AS JUST A SLIGHTLY FURTHER WWD MOVEMENT WOULD
GIVE AT LEAST PARTS OF OUR NRN OR ERN ZONES A VERY COLD ARCTIC
FRONTAL PASSAGE. 12Z MODEL RUNS ARE GENERALLY KEEPING THE FRONT NE
OR JUST INTO ABOUT JOHNSON COUNT SUNDAY BUT WE`LL NEED TO WATCH IT
CLOSELY AS THERE IS SOME VERY COLD -40 TO -55 BELOW ZERO SFC AIR UP
IN THE FAR NORTH OF ALASKA AND THE NORTHWEST TERRITORIES WHERE THIS
SYSTEM WILL MOVE THROUGH. THE FLOW THEN FLATTENS QUICKLY WITH THE
POTENTIAL FOR A MAJOR SNOWSTORM IN THE WEST AS EARLY AS LATER SUNDAY
NIGHT AND THEN CONTINUING MONDAY INTO TUESDAY. IT`LL START IN A
FAVORABLE WARM ADVECTION PATTERN THEN DYNAMICS INCREASE AHEAD OF A
EWD MOVING DISTURBANCE AND ACTIVE JET MONDAY NIGHT INTO TUESDAY
MORNING. AMPLIFYING FLOW BEHIND THIS SYSTEM WILL LIKELY LEAD TO A
COLD...CYCLONIC... UNSTABLE NW FLOW TUESDAY NIGHT THROUGH WEDNESDAY
NIGHT WITH SOME LIGHT MOUNTAIN SNOWFALL AND A CHANCE
ELSEWHERE...ESPECIALLY EAST OF THE DIVIDE. ALTHOUGH THE ECMWF SHOWS
JUST A BRIEF BREAK AND THEN RELOADS OUR WARM...MOIST NW FLOW FOR
MORE SIGNIFICANT SNOWFALL POTENTIAL IN THE ESPECIALLY THE WRN MTN
WED AND WED NGT. ACTIVE MEDIUM RANGE PERIOD SHAPING UP WITH SEVERAL
THINGS TO WATCH CLOSELY OVER THE NEXT COUPLE DAYS.


&&

.AVIATION.../06Z ISSUANCE/

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

SCT MAINLY LOW VFR -SHSNRA WITH LCL MVFR CONDITIONS WILL DECREASE IN
COVERAGE FROM VCNTY KCPR-KRIW THROUGH 09Z.  DRIER AIR WILL RESULT IN
CLEARING MID LEVEL CLOUD DECKS THROUGH 12Z WITH AREAS OF FOG OR
IFR/LIFR CIGS LIKELY FORMING BY 12Z AND PERSISTING THROUGH 19Z.  THE
WIND RIVER BASIN AND BIGHORN BASIN...VCNTY KRIW-KWRL-KGEY...STAND
THE BEST CHANCE OF THE MOST WIDESPREAD...PERSISTENT FOG INTO THE
EARLY AFTERNOON...BUT FOG MAY ALSO BECOME FAIRLY WIDESPREAD FURTHER
EAST...VCNTY KRIW-KCPR THROUGH THE MORNING.  MOST FOG SHOULD
DISSIPATE BY EARLY THURSDAY AFTERNOON.  VFR CONDITIONS WILL PREVAIL
AFTERWARDS...THROUGH THURSDAY NIGHT WITH FOG MORE PATCHY AND MAINLY
OVER THE LOWER BASINS...VCNTY KRIW AND KWRL THURSDAY NIGHT.


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

SOME CLEARING OF MID-LEVEL CLOUD DECKS WILL OCCUR OVERNIGHT
RESULTING IN FORMATION OF LOWER IFR/LIFR CIGS OR FOG OVER THE
WESTERN VALLEYS AND SOUTHWEST THROUGH THURSDAY MORNING.  MOST OF THE
FOG OR LOWER CIGS WILL ERODE BY EARLY THURSDAY AFTERNOON. AN UPPER
LEVEL DISTURBANCE WILL SPREAD IN ISOLD TO WDLY SCT -SHRASN INTO THE
SOUTHWEST AFTER 06Z FRIDAY WITH MOST OF THIS ACTIVITY EXPECTED TO
STAY VCNTY INTERSTATE 80 AND SOUTH.


&&

.FIRE WEATHER...

FIRE CONCERNS WILL BE LOW FOR THE NEXT FEW DAYS. GENERALLY DRY
CONDITIONS EXPECTED TONIGHT THROUGH THURSDAY...THOUGH MORNING
INVERSIONS WILL BE PRESENT. IN ADDITION TO THE NORMAL IMPACTS OF
MORNING INVERSIONS...SOME PATCHY FOG WILL BE POSSIBLE. DRY
CONDITIONS WITH THE PATCHY FOG WILL PERSIST FOR THE NEXT FEW DAYS
WITH FAIRLY CONSISTENT DAYTIME TEMPERATURES. A BIT OF COOLING WILL
BE POSSIBLE INTO THE EARLY PORTION OF THE WEEKEND.

&&

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

$$

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










000
FXUS65 KRIW 290545
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1045 PM MST WED JAN 28 2015

UPDATE...ADDED 06Z AVIATION DISCUSSION

.SHORT TERM...TONIGHT THROUGH THURSDAY (ISSUED AT 214 PM MST)

IMPROVING CONDITIONS EXPECTED THROUGH THE EVENING WITH LINGERING
SHOWERS TAPERING OFF. SKIES WILL CLEAR ACROSS MUCH OF THE FORECAST
AREA OVERNIGHT WITH HIGH PRESSURE BUILDING OVER WESTERN AND CENTRAL
WYOMING.

THESE CLEARING SKIES AND REMNANT MOISTURE FROM THE EARLIER SHOWER
ACTIVITY WILL PROMOTE THE DEVELOPMENT OF PATCHY FOG AROUND MIDNIGHT.
FOG MAY PERSIST THROUGH THE MID TO LATE MORNING HOURS FOR SOME
AREAS...THOUGH SHOULD GENERALLY HAVE LIFTED BY THE AFTERNOON.

BENIGN CONDITIONS WILL THEN BE FOUND THROUGH THE AFTERNOON ACROSS
THE AREA.

.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY

THIS PERIOD STARTS WITH OUR CURRENT UPPER LOW OFF THE SRN CA WHICH
IS FORECAST TO MOVE SLOWLY TOWARDS SRN CA/NRN BAJA ON FRIDAY...THEN
IT LOOKS LIKE IT WILL MOVE SLOWLY INTO AZ ON SATURDAY BEFORE SAGGING
SOUTH AGAIN INTO MEXICO AS THE NRN BRANCH BEGINS TO TAKE OVER. A
COUPLE SHORTWAVES THEN LOOK LIKE THEY`LL HAVE VARYING AMOUNTS OF
IMPACT OVER US OVER THE WEEKEND AS WE`LL HAVE TO CONTEND WITH TWO
POTENTIAL COLD FRONTS ALONG AND EAST OF THE DIVIDE MAINLY. ALTHOUGH
THE 12Z RUNS TODAY HAVE KEPT THE MAIN IMPACT WITH THESE FRONT OVER
THE FAR NERN ZONES. EARLY NEXT WEEK...IT STILL LOOKS LIKE THE FLOW
WILL FLATTEN EARLY NEXT WEEK LEADING TO AN INCREASED CHANCE OF SNOW
IN THE WEST. BUT THEN BY WEDNESDAY...THE FLOW IS EXPECTED TO SHARPEN
AGAIN WITH BUILDING HEIGHTS ALONG THE WEST COAST AND ANOTHER
POTENTIAL SYSTEM DROPPING DOWN FROM THE NNW.

THE FIRST SYSTEM WELL TO OUR SOUTH LOOKS LIKE IT WILL REMAIN WELL TO
THE SOUTH WITH THE LEADING EDGE OF THE MOISTURE EDGING CLOSE TO THE
AREA WITH CLOUDS BUT MOST IF NOT ALL THE PCPN WILL STAY SOUTH OF THE
AREA. THERE IS A SMALL CHANCE THAT AS THE JET TO THE SOUTH PULLS OFF
TO THE EAST LATE FRI/FRI EVE...WE GET IN THE RIGHT ENTRANCE REGION OVER
SRN SWEETWATER COUNTY AND THAT COULD BE JUST ENOUGH TO HELP WHAT
CLOUD SHIELD MAY BE DOWN THERE TO GET A FEW LIGHT SHOWERS GOING.
HAVE SOME SLIGHT CHANCES IN FOR THAT REASON. WILL PROBABLY HAVE SOME
CONTINUED AT LEAST PATCHY FOG/LOW CLOUDS FRIDAY INTO SATURDAY
MORNING AHEAD OF THIS FIRST WEEKEND SYSTEM. THE FIRST SHORTWAVE TO
DROP SOUTH ORIGINATES FROM THE ERN PACIFIC UPPER LOW WITH A
SHORTWAVE SHOOTING OUT OF THAT AND MOVING THROUGH THE DEVELOPING
WEST COAST RIDGE AND THEN DOWN THE FRONT SIDE. 12Z RUNS HAVE BACKED
OFF ON HOW MUCH OF AN IMPACT THIS SATURDAY FRONT WILL HAVE WITH FLOW
ALOFT A LITTLE MORE NW AND SHOWING THE FRONT HAVING THE GREATEST
IMPACT OVER THE NERN ZONES WITH A CHANCE OF SNOW LATE SAT OR SAT
EVE. THE FRONT STILL LOOKS LIKE IT MAY MAKE IT TO MOST AREAS EAST OF
THE DIVIDE BUT MOST OF THE ENERGY WITH THIS STORM IS FORECAST TO
STAY JUST TO THE NE OF MOST OF THE AREA. THE 12Z NAM IS EVEN FURTHER
TO THE NE WITH THE FRONT. NEXT SHORTWAVE ORIGINATES IN THE
DEVELOPING CROSS POLAR FLOW. THIS SYSTEM HAS ITS ORIGINS WEST OF
ALASKA AND NORTH OF THE ARCTIC CIRCLE. THIS FRONT WILL LIKELY
CONTAIN VERY COLD AIR BUT AT THE SAME TIME...THE CROSS POLAR FLOW IS
BEING SHUNTED SLIGHTLY TO THE EAST AS THE RIDGE TRIES TO NOSE INTO
THE WEST. TOUGH CALL AS JUST A SLIGHTLY FURTHER WWD MOVEMENT WOULD
GIVE AT LEAST PARTS OF OUR NRN OR ERN ZONES A VERY COLD ARCTIC
FRONTAL PASSAGE. 12Z MODEL RUNS ARE GENERALLY KEEPING THE FRONT NE
OR JUST INTO ABOUT JOHNSON COUNT SUNDAY BUT WE`LL NEED TO WATCH IT
CLOSELY AS THERE IS SOME VERY COLD -40 TO -55 BELOW ZERO SFC AIR UP
IN THE FAR NORTH OF ALASKA AND THE NORTHWEST TERRITORIES WHERE THIS
SYSTEM WILL MOVE THROUGH. THE FLOW THEN FLATTENS QUICKLY WITH THE
POTENTIAL FOR A MAJOR SNOWSTORM IN THE WEST AS EARLY AS LATER SUNDAY
NIGHT AND THEN CONTINUING MONDAY INTO TUESDAY. IT`LL START IN A
FAVORABLE WARM ADVECTION PATTERN THEN DYNAMICS INCREASE AHEAD OF A
EWD MOVING DISTURBANCE AND ACTIVE JET MONDAY NIGHT INTO TUESDAY
MORNING. AMPLIFYING FLOW BEHIND THIS SYSTEM WILL LIKELY LEAD TO A
COLD...CYCLONIC... UNSTABLE NW FLOW TUESDAY NIGHT THROUGH WEDNESDAY
NIGHT WITH SOME LIGHT MOUNTAIN SNOWFALL AND A CHANCE
ELSEWHERE...ESPECIALLY EAST OF THE DIVIDE. ALTHOUGH THE ECMWF SHOWS
JUST A BRIEF BREAK AND THEN RELOADS OUR WARM...MOIST NW FLOW FOR
MORE SIGNIFICANT SNOWFALL POTENTIAL IN THE ESPECIALLY THE WRN MTN
WED AND WED NGT. ACTIVE MEDIUM RANGE PERIOD SHAPING UP WITH SEVERAL
THINGS TO WATCH CLOSELY OVER THE NEXT COUPLE DAYS.


&&

.AVIATION.../06Z ISSUANCE/

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

SCT MAINLY LOW VFR -SHSNRA WITH LCL MVFR CONDITIONS WILL DECREASE IN
COVERAGE FROM VCNTY KCPR-KRIW THROUGH 09Z.  DRIER AIR WILL RESULT IN
CLEARING MID LEVEL CLOUD DECKS THROUGH 12Z WITH AREAS OF FOG OR
IFR/LIFR CIGS LIKELY FORMING BY 12Z AND PERSISTING THROUGH 19Z.  THE
WIND RIVER BASIN AND BIGHORN BASIN...VCNTY KRIW-KWRL-KGEY...STAND
THE BEST CHANCE OF THE MOST WIDESPREAD...PERSISTENT FOG INTO THE
EARLY AFTERNOON...BUT FOG MAY ALSO BECOME FAIRLY WIDESPREAD FURTHER
EAST...VCNTY KRIW-KCPR THROUGH THE MORNING.  MOST FOG SHOULD
DISSIPATE BY EARLY THURSDAY AFTERNOON.  VFR CONDITIONS WILL PREVAIL
AFTERWARDS...THROUGH THURSDAY NIGHT WITH FOG MORE PATCHY AND MAINLY
OVER THE LOWER BASINS...VCNTY KRIW AND KWRL THURSDAY NIGHT.


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

SOME CLEARING OF MID-LEVEL CLOUD DECKS WILL OCCUR OVERNIGHT
RESULTING IN FORMATION OF LOWER IFR/LIFR CIGS OR FOG OVER THE
WESTERN VALLEYS AND SOUTHWEST THROUGH THURSDAY MORNING.  MOST OF THE
FOG OR LOWER CIGS WILL ERODE BY EARLY THURSDAY AFTERNOON. AN UPPER
LEVEL DISTURBANCE WILL SPREAD IN ISOLD TO WDLY SCT -SHRASN INTO THE
SOUTHWEST AFTER 06Z FRIDAY WITH MOST OF THIS ACTIVITY EXPECTED TO
STAY VCNTY INTERSTATE 80 AND SOUTH.


&&

.FIRE WEATHER...

FIRE CONCERNS WILL BE LOW FOR THE NEXT FEW DAYS. GENERALLY DRY
CONDITIONS EXPECTED TONIGHT THROUGH THURSDAY...THOUGH MORNING
INVERSIONS WILL BE PRESENT. IN ADDITION TO THE NORMAL IMPACTS OF
MORNING INVERSIONS...SOME PATCHY FOG WILL BE POSSIBLE. DRY
CONDITIONS WITH THE PATCHY FOG WILL PERSIST FOR THE NEXT FEW DAYS
WITH FAIRLY CONSISTENT DAYTIME TEMPERATURES. A BIT OF COOLING WILL
BE POSSIBLE INTO THE EARLY PORTION OF THE WEEKEND.

&&

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

$$

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









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