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000
FXAK68 PAFC 300017
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
417 PM AKDT SAT AUG 29 2015

.ANALYSIS AND UPPER LEVELS...
A PATTERN ADJUSTMENT IS UNDERWAY THIS AFTERNOON. AN UPPER LEVEL
TROUGH THAT EXTENDS FROM EASTERN RUSSIA TO THE ROCKIES CONTAINS A
CUT-OFF LOW OVER BARROW THAT IS BEGINNING TO DIVE SOUTHEAST TO THE
GULF. ANOTHER LARGE CUT-OFF LOW IS BETWEEN THE SOUTHERN KAMCHATKA
PENINSULA AND THE WESTERN ALEUTIANS. A NORTH PACIFIC RIDGE IS
STILL POKING INTO THE SOUTHERN BERING. AT THE SURFACE...A BROAD
AREA OF LOW PRESSURE IS OVER THE NORTHERN GULF...WITH ANOTHER LOW
WEST OF ATTU. ANOTHER WEAKENING LOW IS NEAR BARROW. A SURFACE
RIDGE HAS RETREATED INTO THE NORTH PACIFIC WITH ONLY THE EXTREME
NORTHERN QUADRANT STILL NOSING INTO THE BERING...WHILE ANOTHER
HIGH FROM EASTERN RUSSIA IS DIVING INTO THE NORTHERN BERING. A
WEATHER FRONT IS BRINGING SOME RAIN TO PORTIONS OF SOUTHWEST AK
AND KODIAK ISLAND.

&&

.MODEL DISCUSSION...
MODELS REMAIN IN EXCELLENT AGREEMENT AND CONFIRM THE PATTERN
SHIFT. THE UPPER LOW OVER NORTHERN AK WILL DIG INTO THE BASE OF
THE TROUGH BY MON AND TEMPORARILY CONSOLIDATE OVER THE
NORTHEASTERN GULF COAST. THIS DIGGING WILL BE ACCOMPANIED BY TWO
WAVES THAT WILL SEQUENTIALLY TIGHTEN THE SURFACE PRESSURE GRADIENT
ACROSS THE SOUTHERN HALF OF THE STATE. THE FIRST WILL BE TONIGHT
INTO SUN...AND THE SECOND STRONGER WAVE SUN NIGHT INTO MON
MORNING. THE INITIAL WAVE WILL PUSH THE BERING/SOUTHWEST AK FRONT
INTO THE NORTH PACIFIC.

WHILE THIS IS HAPPENING...HIGH PRESSURE NOSING INTO THE SOUTHERN
BERING WILL MERGE WITH THE HIGH MOVING OFF THE RUSSIAN COAST LATER
ON SUN. THIS RIDGE OF HIGH PRESSURE WILL THEN DOMINATE THE EASTERN
BERING AND THEN MOVE INTO SOUTHWEST AK SUN NIGHT INTO MON. BY MON
AFTERNOON THE PRESSURE GRADIENT OVER SOUTHWEST AK WILL WEAKEN...BUT
BE SLIGHTLY MORE PERSISTENT OVER SOUTHCENTRAL...AT LEAST UNTIL
HIGH PRESSURE AND COOLER AIR ON NORTHWEST FLOW BEGIN TO FILTER
ACROSS THE AK RANGE LATER ON MON AND INTO TUE.

IN THE FAR WEST THE KAMCHATKA/ATTU LOW WILL MOVE NORTH AND BRING A
FRONT ACROSS THE WESTERN ALEUTIANS SUN AND THE WESTERN BERING ON
MON. ANY EASTWARD PROGRESSION OF THIS FEATURE WILL BE LIMITED BY
THE STRENGTH OF THE HIGH THAT DEVELOPS OVER THE BERING.

IN ORDER TO BETTER CAPTURE DETAILS OF THE WIND FIELD THE FORECAST
UTILIZES THE HIGHER RESOLUTION NAM IN THE EAST AND GEM/EC IN THE
WEST.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE NORTHERLY OFFSHORE FLOW WILL CONTINUE AS WE HEAD INTO THE
EARLY PART OF NEXT WEEK. WE WILL SEE COOLER TEMPERATURES COMBINED
WITH STRONG GUSTY GAP WINDS ASSOCIATED WITH UPPER LEVEL
DISTURBANCES MOVING THROUGH THE REGION. THE FIRST DISTURBANCE WILL
DROP FROM THE NORTH LATER TONIGHT RESULTING INCREASED PRESSURE
GRADIENTS. BY SUNDAY NIGHT THE NEXT DISTURBANCE WILL FOLLOW THE
SAME TRACK AS THE PREVIOUS AND EXIT THE SOUTHCENTRAL REGION INTO
THE NORTHERN GULF BY MONDAY. THIS SYNOPTIC FEATURE WILL FURTHER
ENHANCE THE STRONG GUSTY NORTHERLY WINDS. LOOK FOR THE SAME
SCENARIO WITH STRONG GAP WINDS THROUGH WHITTIER...SEWARD...VALDEZ
...THOMPSON PASS AND THE COPPER RIVER DELTA THROUGH MONDAY BEFORE
THE WEAKENING OF THE PRESSURE GRADIENT. THE OTHER AREA OF CONCERN
WILL BE THE BARREN ISLANDS AND THE NORTHERN KODIAK ISLAND REGION.
THEY WILL HAVE STRONG GUSTY NORTHWESTERLY WINDS AS THE COLDER AIR
FILTERS INTO THE REGION. THE BARREN ISLANDS ARE EXPECTED TO HAVE
GALE FORCE WINDS BY THE LATE EVENING AS THE SHORTWAVE MOVES
THROUGH AND WILL BE ACCOMPANIED BY THE SHORTWAVE PUSHING THROUGH
THE REGION. KODIAK ISLAND WILL BE IN THE SAME STRONG GUSTY GAP
WIND REGIME BEFORE DIMINISHING BY LATE MONDAY.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
AS THE UPPER LOW OVER THE STATE ELONGATES TO THE SOUTH IT WILL
KEEP NORTH TO NORTHWEST FLOW OVER THE SOUTHWEST THROUGH MONDAY.
THIS REGION WILL ALSO BE SQUEEZED BETWEEN THE LOW AND RIDGING OVER
THE BERING KEEPING GUSTY WINDS...ESPECIALLY THROUGH CHANNELED
TERRAIN AND ALONG THE COAST. THE WINDS WILL THEN WEAKEN MONDAY AS
THE LOW PUSHES OFF TO THE SOUTHEAST. SHORTWAVES CIRCULATING AROUND
THE LOW WILL ALSO KEEP SHOWERS OVER THE SOUTHWEST THAT WILL
DIMINISH AS RIDGING OVER THE BERING PUSHES IN OVER THE AREA INTO
MONDAY.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE MAIN IMPACT FOR THE ALEUTIANS IS THE LOW TO THE SOUTHWEST OF
THE WESTERN ALEUTIANS AND ITS ASSOCIATED FRONT THAT STRETCHES
ACROSS THE CENTRAL ALEUTIANS AND MUCH OF THE SOUTHERN BERING. THE
FRONT WILL CONTINUE ITS SLOW TRACK EAST BRINGING RAIN TO THE
ISLANDS AND THEN DIMINISH AS IT IS BEING HELD UP BY RIDGING TO
THE EAST. THE LOW ITSELF WILL SLOWLY TRACK NORTH AND BRING ANOTHER
SHOT OF RAIN TO THE WESTERN ALEUTIANS SUNDAY AFTERNOON AS IT PASSES.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...TUE THROUGH SAT)...BIGGEST
CHANGE FOR THIS TIME PERIOD FROM THE PREVIOUS DAYS IS THAT IT
LOOKS LIKE THE NORTHERN ENERGY WILL KEEP THE RIDGE SUPPRESSED A
BIT LONGER. RATHER THAN SEEING THE RIDGE BE OVER THE SOUTHWEST AND
SOUTHCENTRAL PORTIONS OF THE STATE ON TUESDAY...THERE WILL STILL
BE SOME PIECES OF ENERGY MOVING THROUGH FROM THE NORTHWEST. THIS
WILL KEEP SOME GUSTY WINDS...ESPECIALLY THROUGH FAVORED AREAS LIKE
SEWARD...WHITTIER...AND THE BARREN ISLANDS. IT WILL ALSO KEEP
TEMPERATURES ON THE COOLER SIDE FOR ANOTHER DAY. PLACES FURTHER
INLAND WHERE THE WINDS DIE OFF FIRST WILL LIKELY BE THE COLDEST
SPOTS ON TUESDAY MORNING. BY WEDNESDAY...MODELS STILL INDICATE
THAT AN EXTENSION OF THE NORTH PACIFIC RIDGE SHOULD BUILD OVER
SOUTHWEST AND SOUTHCENTRAL. THIS WILL RESULT IN ABUNDANT SUNSHINE
AND SHOULD ALLOW TEMPERATURES TO MODERATE A BIT GOING THROUGH THE
WEEK.

OVER THE BERING...TYPHOON ATSANI REMNANTS WILL STAY ANCHORED IN A
BROAD TROUGH OVER THE WESTERN BERING. THIS WILL KEEP WARM MOIST
AIR FLOWING INTO THE EASTERN ALEUTIANS AND PRIBILOF ISLANDS
LEADING TO WIDESPREAD FOG AND THE CHANCE FOR RAIN. BY
WEDNESDAY...A WEAK SURFACE LOW DEVELOPS OVER THE CENTRAL ALEUTIANS
ALONG AN OLD BOUNDARY. MODELS ARE NOW IN MUCH BETTER AGREEMENT IN
CARRYING THIS LOW QUICKLY NORTHWARD TOWARD THE BERING STRAIT.
WHILE NOT A DEEP LOW BY ANY MEANS...IT COULD BE JUST ENOUGH TO
HELP TO TICK WINDS UP TO THE SMALL CRAFT LEVEL. IT WILL ALSO BRING
A FAIRLY WIDE SWATH OF RAIN FROM THE EASTERN BERING TO THE WEST
COAST BY WEDNESDAY MORNING.

THE LATTER HALF OF THE WEEK WILL FEATURE THE WARM FRONT OVER
SOUTHWEST AK FALLING APART AS IT TRIES TO MAKE IT ACROSS THE AK
RANGE. BUT THE RIDGE AND DRY OVER THE MAINLAND COULD BE ENOUGH TO
KEEP THINGS DRY ACROSS MUCH OF THE AREA. EVEN IF A FEW SHOWERS DO
DEVELOP ACROSS THE KENAI AND CHUGACH MOUNTAINS INTO FRIDAY...NO
ONE SYSTEM LOOKS IMPRESSIVE AT THIS TIME. THE FLOW BECOMES MORE
ZONAL BY NEXT WEEKEND...WHICH COULD OPEN THE DOOR FOR MORE WEAK
SYSTEMS FROM THE BERING.
&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 121 127-138.
FIRE WEATHER...NONE.
&&

$$

SYNOPSIS AND MODEL DISCUSSION...DS
SOUTHCENTRAL ALASKA...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...MO





000
FXAK68 PAFC 300017
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
417 PM AKDT SAT AUG 29 2015

.ANALYSIS AND UPPER LEVELS...
A PATTERN ADJUSTMENT IS UNDERWAY THIS AFTERNOON. AN UPPER LEVEL
TROUGH THAT EXTENDS FROM EASTERN RUSSIA TO THE ROCKIES CONTAINS A
CUT-OFF LOW OVER BARROW THAT IS BEGINNING TO DIVE SOUTHEAST TO THE
GULF. ANOTHER LARGE CUT-OFF LOW IS BETWEEN THE SOUTHERN KAMCHATKA
PENINSULA AND THE WESTERN ALEUTIANS. A NORTH PACIFIC RIDGE IS
STILL POKING INTO THE SOUTHERN BERING. AT THE SURFACE...A BROAD
AREA OF LOW PRESSURE IS OVER THE NORTHERN GULF...WITH ANOTHER LOW
WEST OF ATTU. ANOTHER WEAKENING LOW IS NEAR BARROW. A SURFACE
RIDGE HAS RETREATED INTO THE NORTH PACIFIC WITH ONLY THE EXTREME
NORTHERN QUADRANT STILL NOSING INTO THE BERING...WHILE ANOTHER
HIGH FROM EASTERN RUSSIA IS DIVING INTO THE NORTHERN BERING. A
WEATHER FRONT IS BRINGING SOME RAIN TO PORTIONS OF SOUTHWEST AK
AND KODIAK ISLAND.

&&

.MODEL DISCUSSION...
MODELS REMAIN IN EXCELLENT AGREEMENT AND CONFIRM THE PATTERN
SHIFT. THE UPPER LOW OVER NORTHERN AK WILL DIG INTO THE BASE OF
THE TROUGH BY MON AND TEMPORARILY CONSOLIDATE OVER THE
NORTHEASTERN GULF COAST. THIS DIGGING WILL BE ACCOMPANIED BY TWO
WAVES THAT WILL SEQUENTIALLY TIGHTEN THE SURFACE PRESSURE GRADIENT
ACROSS THE SOUTHERN HALF OF THE STATE. THE FIRST WILL BE TONIGHT
INTO SUN...AND THE SECOND STRONGER WAVE SUN NIGHT INTO MON
MORNING. THE INITIAL WAVE WILL PUSH THE BERING/SOUTHWEST AK FRONT
INTO THE NORTH PACIFIC.

WHILE THIS IS HAPPENING...HIGH PRESSURE NOSING INTO THE SOUTHERN
BERING WILL MERGE WITH THE HIGH MOVING OFF THE RUSSIAN COAST LATER
ON SUN. THIS RIDGE OF HIGH PRESSURE WILL THEN DOMINATE THE EASTERN
BERING AND THEN MOVE INTO SOUTHWEST AK SUN NIGHT INTO MON. BY MON
AFTERNOON THE PRESSURE GRADIENT OVER SOUTHWEST AK WILL WEAKEN...BUT
BE SLIGHTLY MORE PERSISTENT OVER SOUTHCENTRAL...AT LEAST UNTIL
HIGH PRESSURE AND COOLER AIR ON NORTHWEST FLOW BEGIN TO FILTER
ACROSS THE AK RANGE LATER ON MON AND INTO TUE.

IN THE FAR WEST THE KAMCHATKA/ATTU LOW WILL MOVE NORTH AND BRING A
FRONT ACROSS THE WESTERN ALEUTIANS SUN AND THE WESTERN BERING ON
MON. ANY EASTWARD PROGRESSION OF THIS FEATURE WILL BE LIMITED BY
THE STRENGTH OF THE HIGH THAT DEVELOPS OVER THE BERING.

IN ORDER TO BETTER CAPTURE DETAILS OF THE WIND FIELD THE FORECAST
UTILIZES THE HIGHER RESOLUTION NAM IN THE EAST AND GEM/EC IN THE
WEST.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE NORTHERLY OFFSHORE FLOW WILL CONTINUE AS WE HEAD INTO THE
EARLY PART OF NEXT WEEK. WE WILL SEE COOLER TEMPERATURES COMBINED
WITH STRONG GUSTY GAP WINDS ASSOCIATED WITH UPPER LEVEL
DISTURBANCES MOVING THROUGH THE REGION. THE FIRST DISTURBANCE WILL
DROP FROM THE NORTH LATER TONIGHT RESULTING INCREASED PRESSURE
GRADIENTS. BY SUNDAY NIGHT THE NEXT DISTURBANCE WILL FOLLOW THE
SAME TRACK AS THE PREVIOUS AND EXIT THE SOUTHCENTRAL REGION INTO
THE NORTHERN GULF BY MONDAY. THIS SYNOPTIC FEATURE WILL FURTHER
ENHANCE THE STRONG GUSTY NORTHERLY WINDS. LOOK FOR THE SAME
SCENARIO WITH STRONG GAP WINDS THROUGH WHITTIER...SEWARD...VALDEZ
...THOMPSON PASS AND THE COPPER RIVER DELTA THROUGH MONDAY BEFORE
THE WEAKENING OF THE PRESSURE GRADIENT. THE OTHER AREA OF CONCERN
WILL BE THE BARREN ISLANDS AND THE NORTHERN KODIAK ISLAND REGION.
THEY WILL HAVE STRONG GUSTY NORTHWESTERLY WINDS AS THE COLDER AIR
FILTERS INTO THE REGION. THE BARREN ISLANDS ARE EXPECTED TO HAVE
GALE FORCE WINDS BY THE LATE EVENING AS THE SHORTWAVE MOVES
THROUGH AND WILL BE ACCOMPANIED BY THE SHORTWAVE PUSHING THROUGH
THE REGION. KODIAK ISLAND WILL BE IN THE SAME STRONG GUSTY GAP
WIND REGIME BEFORE DIMINISHING BY LATE MONDAY.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
AS THE UPPER LOW OVER THE STATE ELONGATES TO THE SOUTH IT WILL
KEEP NORTH TO NORTHWEST FLOW OVER THE SOUTHWEST THROUGH MONDAY.
THIS REGION WILL ALSO BE SQUEEZED BETWEEN THE LOW AND RIDGING OVER
THE BERING KEEPING GUSTY WINDS...ESPECIALLY THROUGH CHANNELED
TERRAIN AND ALONG THE COAST. THE WINDS WILL THEN WEAKEN MONDAY AS
THE LOW PUSHES OFF TO THE SOUTHEAST. SHORTWAVES CIRCULATING AROUND
THE LOW WILL ALSO KEEP SHOWERS OVER THE SOUTHWEST THAT WILL
DIMINISH AS RIDGING OVER THE BERING PUSHES IN OVER THE AREA INTO
MONDAY.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE MAIN IMPACT FOR THE ALEUTIANS IS THE LOW TO THE SOUTHWEST OF
THE WESTERN ALEUTIANS AND ITS ASSOCIATED FRONT THAT STRETCHES
ACROSS THE CENTRAL ALEUTIANS AND MUCH OF THE SOUTHERN BERING. THE
FRONT WILL CONTINUE ITS SLOW TRACK EAST BRINGING RAIN TO THE
ISLANDS AND THEN DIMINISH AS IT IS BEING HELD UP BY RIDGING TO
THE EAST. THE LOW ITSELF WILL SLOWLY TRACK NORTH AND BRING ANOTHER
SHOT OF RAIN TO THE WESTERN ALEUTIANS SUNDAY AFTERNOON AS IT PASSES.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...TUE THROUGH SAT)...BIGGEST
CHANGE FOR THIS TIME PERIOD FROM THE PREVIOUS DAYS IS THAT IT
LOOKS LIKE THE NORTHERN ENERGY WILL KEEP THE RIDGE SUPPRESSED A
BIT LONGER. RATHER THAN SEEING THE RIDGE BE OVER THE SOUTHWEST AND
SOUTHCENTRAL PORTIONS OF THE STATE ON TUESDAY...THERE WILL STILL
BE SOME PIECES OF ENERGY MOVING THROUGH FROM THE NORTHWEST. THIS
WILL KEEP SOME GUSTY WINDS...ESPECIALLY THROUGH FAVORED AREAS LIKE
SEWARD...WHITTIER...AND THE BARREN ISLANDS. IT WILL ALSO KEEP
TEMPERATURES ON THE COOLER SIDE FOR ANOTHER DAY. PLACES FURTHER
INLAND WHERE THE WINDS DIE OFF FIRST WILL LIKELY BE THE COLDEST
SPOTS ON TUESDAY MORNING. BY WEDNESDAY...MODELS STILL INDICATE
THAT AN EXTENSION OF THE NORTH PACIFIC RIDGE SHOULD BUILD OVER
SOUTHWEST AND SOUTHCENTRAL. THIS WILL RESULT IN ABUNDANT SUNSHINE
AND SHOULD ALLOW TEMPERATURES TO MODERATE A BIT GOING THROUGH THE
WEEK.

OVER THE BERING...TYPHOON ATSANI REMNANTS WILL STAY ANCHORED IN A
BROAD TROUGH OVER THE WESTERN BERING. THIS WILL KEEP WARM MOIST
AIR FLOWING INTO THE EASTERN ALEUTIANS AND PRIBILOF ISLANDS
LEADING TO WIDESPREAD FOG AND THE CHANCE FOR RAIN. BY
WEDNESDAY...A WEAK SURFACE LOW DEVELOPS OVER THE CENTRAL ALEUTIANS
ALONG AN OLD BOUNDARY. MODELS ARE NOW IN MUCH BETTER AGREEMENT IN
CARRYING THIS LOW QUICKLY NORTHWARD TOWARD THE BERING STRAIT.
WHILE NOT A DEEP LOW BY ANY MEANS...IT COULD BE JUST ENOUGH TO
HELP TO TICK WINDS UP TO THE SMALL CRAFT LEVEL. IT WILL ALSO BRING
A FAIRLY WIDE SWATH OF RAIN FROM THE EASTERN BERING TO THE WEST
COAST BY WEDNESDAY MORNING.

THE LATTER HALF OF THE WEEK WILL FEATURE THE WARM FRONT OVER
SOUTHWEST AK FALLING APART AS IT TRIES TO MAKE IT ACROSS THE AK
RANGE. BUT THE RIDGE AND DRY OVER THE MAINLAND COULD BE ENOUGH TO
KEEP THINGS DRY ACROSS MUCH OF THE AREA. EVEN IF A FEW SHOWERS DO
DEVELOP ACROSS THE KENAI AND CHUGACH MOUNTAINS INTO FRIDAY...NO
ONE SYSTEM LOOKS IMPRESSIVE AT THIS TIME. THE FLOW BECOMES MORE
ZONAL BY NEXT WEEKEND...WHICH COULD OPEN THE DOOR FOR MORE WEAK
SYSTEMS FROM THE BERING.
&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 121 127-138.
FIRE WEATHER...NONE.
&&

$$

SYNOPSIS AND MODEL DISCUSSION...DS
SOUTHCENTRAL ALASKA...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...MO




000
FXAK68 PAFC 300017
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
417 PM AKDT SAT AUG 29 2015

.ANALYSIS AND UPPER LEVELS...
A PATTERN ADJUSTMENT IS UNDERWAY THIS AFTERNOON. AN UPPER LEVEL
TROUGH THAT EXTENDS FROM EASTERN RUSSIA TO THE ROCKIES CONTAINS A
CUT-OFF LOW OVER BARROW THAT IS BEGINNING TO DIVE SOUTHEAST TO THE
GULF. ANOTHER LARGE CUT-OFF LOW IS BETWEEN THE SOUTHERN KAMCHATKA
PENINSULA AND THE WESTERN ALEUTIANS. A NORTH PACIFIC RIDGE IS
STILL POKING INTO THE SOUTHERN BERING. AT THE SURFACE...A BROAD
AREA OF LOW PRESSURE IS OVER THE NORTHERN GULF...WITH ANOTHER LOW
WEST OF ATTU. ANOTHER WEAKENING LOW IS NEAR BARROW. A SURFACE
RIDGE HAS RETREATED INTO THE NORTH PACIFIC WITH ONLY THE EXTREME
NORTHERN QUADRANT STILL NOSING INTO THE BERING...WHILE ANOTHER
HIGH FROM EASTERN RUSSIA IS DIVING INTO THE NORTHERN BERING. A
WEATHER FRONT IS BRINGING SOME RAIN TO PORTIONS OF SOUTHWEST AK
AND KODIAK ISLAND.

&&

.MODEL DISCUSSION...
MODELS REMAIN IN EXCELLENT AGREEMENT AND CONFIRM THE PATTERN
SHIFT. THE UPPER LOW OVER NORTHERN AK WILL DIG INTO THE BASE OF
THE TROUGH BY MON AND TEMPORARILY CONSOLIDATE OVER THE
NORTHEASTERN GULF COAST. THIS DIGGING WILL BE ACCOMPANIED BY TWO
WAVES THAT WILL SEQUENTIALLY TIGHTEN THE SURFACE PRESSURE GRADIENT
ACROSS THE SOUTHERN HALF OF THE STATE. THE FIRST WILL BE TONIGHT
INTO SUN...AND THE SECOND STRONGER WAVE SUN NIGHT INTO MON
MORNING. THE INITIAL WAVE WILL PUSH THE BERING/SOUTHWEST AK FRONT
INTO THE NORTH PACIFIC.

WHILE THIS IS HAPPENING...HIGH PRESSURE NOSING INTO THE SOUTHERN
BERING WILL MERGE WITH THE HIGH MOVING OFF THE RUSSIAN COAST LATER
ON SUN. THIS RIDGE OF HIGH PRESSURE WILL THEN DOMINATE THE EASTERN
BERING AND THEN MOVE INTO SOUTHWEST AK SUN NIGHT INTO MON. BY MON
AFTERNOON THE PRESSURE GRADIENT OVER SOUTHWEST AK WILL WEAKEN...BUT
BE SLIGHTLY MORE PERSISTENT OVER SOUTHCENTRAL...AT LEAST UNTIL
HIGH PRESSURE AND COOLER AIR ON NORTHWEST FLOW BEGIN TO FILTER
ACROSS THE AK RANGE LATER ON MON AND INTO TUE.

IN THE FAR WEST THE KAMCHATKA/ATTU LOW WILL MOVE NORTH AND BRING A
FRONT ACROSS THE WESTERN ALEUTIANS SUN AND THE WESTERN BERING ON
MON. ANY EASTWARD PROGRESSION OF THIS FEATURE WILL BE LIMITED BY
THE STRENGTH OF THE HIGH THAT DEVELOPS OVER THE BERING.

IN ORDER TO BETTER CAPTURE DETAILS OF THE WIND FIELD THE FORECAST
UTILIZES THE HIGHER RESOLUTION NAM IN THE EAST AND GEM/EC IN THE
WEST.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE NORTHERLY OFFSHORE FLOW WILL CONTINUE AS WE HEAD INTO THE
EARLY PART OF NEXT WEEK. WE WILL SEE COOLER TEMPERATURES COMBINED
WITH STRONG GUSTY GAP WINDS ASSOCIATED WITH UPPER LEVEL
DISTURBANCES MOVING THROUGH THE REGION. THE FIRST DISTURBANCE WILL
DROP FROM THE NORTH LATER TONIGHT RESULTING INCREASED PRESSURE
GRADIENTS. BY SUNDAY NIGHT THE NEXT DISTURBANCE WILL FOLLOW THE
SAME TRACK AS THE PREVIOUS AND EXIT THE SOUTHCENTRAL REGION INTO
THE NORTHERN GULF BY MONDAY. THIS SYNOPTIC FEATURE WILL FURTHER
ENHANCE THE STRONG GUSTY NORTHERLY WINDS. LOOK FOR THE SAME
SCENARIO WITH STRONG GAP WINDS THROUGH WHITTIER...SEWARD...VALDEZ
...THOMPSON PASS AND THE COPPER RIVER DELTA THROUGH MONDAY BEFORE
THE WEAKENING OF THE PRESSURE GRADIENT. THE OTHER AREA OF CONCERN
WILL BE THE BARREN ISLANDS AND THE NORTHERN KODIAK ISLAND REGION.
THEY WILL HAVE STRONG GUSTY NORTHWESTERLY WINDS AS THE COLDER AIR
FILTERS INTO THE REGION. THE BARREN ISLANDS ARE EXPECTED TO HAVE
GALE FORCE WINDS BY THE LATE EVENING AS THE SHORTWAVE MOVES
THROUGH AND WILL BE ACCOMPANIED BY THE SHORTWAVE PUSHING THROUGH
THE REGION. KODIAK ISLAND WILL BE IN THE SAME STRONG GUSTY GAP
WIND REGIME BEFORE DIMINISHING BY LATE MONDAY.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
AS THE UPPER LOW OVER THE STATE ELONGATES TO THE SOUTH IT WILL
KEEP NORTH TO NORTHWEST FLOW OVER THE SOUTHWEST THROUGH MONDAY.
THIS REGION WILL ALSO BE SQUEEZED BETWEEN THE LOW AND RIDGING OVER
THE BERING KEEPING GUSTY WINDS...ESPECIALLY THROUGH CHANNELED
TERRAIN AND ALONG THE COAST. THE WINDS WILL THEN WEAKEN MONDAY AS
THE LOW PUSHES OFF TO THE SOUTHEAST. SHORTWAVES CIRCULATING AROUND
THE LOW WILL ALSO KEEP SHOWERS OVER THE SOUTHWEST THAT WILL
DIMINISH AS RIDGING OVER THE BERING PUSHES IN OVER THE AREA INTO
MONDAY.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE MAIN IMPACT FOR THE ALEUTIANS IS THE LOW TO THE SOUTHWEST OF
THE WESTERN ALEUTIANS AND ITS ASSOCIATED FRONT THAT STRETCHES
ACROSS THE CENTRAL ALEUTIANS AND MUCH OF THE SOUTHERN BERING. THE
FRONT WILL CONTINUE ITS SLOW TRACK EAST BRINGING RAIN TO THE
ISLANDS AND THEN DIMINISH AS IT IS BEING HELD UP BY RIDGING TO
THE EAST. THE LOW ITSELF WILL SLOWLY TRACK NORTH AND BRING ANOTHER
SHOT OF RAIN TO THE WESTERN ALEUTIANS SUNDAY AFTERNOON AS IT PASSES.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...TUE THROUGH SAT)...BIGGEST
CHANGE FOR THIS TIME PERIOD FROM THE PREVIOUS DAYS IS THAT IT
LOOKS LIKE THE NORTHERN ENERGY WILL KEEP THE RIDGE SUPPRESSED A
BIT LONGER. RATHER THAN SEEING THE RIDGE BE OVER THE SOUTHWEST AND
SOUTHCENTRAL PORTIONS OF THE STATE ON TUESDAY...THERE WILL STILL
BE SOME PIECES OF ENERGY MOVING THROUGH FROM THE NORTHWEST. THIS
WILL KEEP SOME GUSTY WINDS...ESPECIALLY THROUGH FAVORED AREAS LIKE
SEWARD...WHITTIER...AND THE BARREN ISLANDS. IT WILL ALSO KEEP
TEMPERATURES ON THE COOLER SIDE FOR ANOTHER DAY. PLACES FURTHER
INLAND WHERE THE WINDS DIE OFF FIRST WILL LIKELY BE THE COLDEST
SPOTS ON TUESDAY MORNING. BY WEDNESDAY...MODELS STILL INDICATE
THAT AN EXTENSION OF THE NORTH PACIFIC RIDGE SHOULD BUILD OVER
SOUTHWEST AND SOUTHCENTRAL. THIS WILL RESULT IN ABUNDANT SUNSHINE
AND SHOULD ALLOW TEMPERATURES TO MODERATE A BIT GOING THROUGH THE
WEEK.

OVER THE BERING...TYPHOON ATSANI REMNANTS WILL STAY ANCHORED IN A
BROAD TROUGH OVER THE WESTERN BERING. THIS WILL KEEP WARM MOIST
AIR FLOWING INTO THE EASTERN ALEUTIANS AND PRIBILOF ISLANDS
LEADING TO WIDESPREAD FOG AND THE CHANCE FOR RAIN. BY
WEDNESDAY...A WEAK SURFACE LOW DEVELOPS OVER THE CENTRAL ALEUTIANS
ALONG AN OLD BOUNDARY. MODELS ARE NOW IN MUCH BETTER AGREEMENT IN
CARRYING THIS LOW QUICKLY NORTHWARD TOWARD THE BERING STRAIT.
WHILE NOT A DEEP LOW BY ANY MEANS...IT COULD BE JUST ENOUGH TO
HELP TO TICK WINDS UP TO THE SMALL CRAFT LEVEL. IT WILL ALSO BRING
A FAIRLY WIDE SWATH OF RAIN FROM THE EASTERN BERING TO THE WEST
COAST BY WEDNESDAY MORNING.

THE LATTER HALF OF THE WEEK WILL FEATURE THE WARM FRONT OVER
SOUTHWEST AK FALLING APART AS IT TRIES TO MAKE IT ACROSS THE AK
RANGE. BUT THE RIDGE AND DRY OVER THE MAINLAND COULD BE ENOUGH TO
KEEP THINGS DRY ACROSS MUCH OF THE AREA. EVEN IF A FEW SHOWERS DO
DEVELOP ACROSS THE KENAI AND CHUGACH MOUNTAINS INTO FRIDAY...NO
ONE SYSTEM LOOKS IMPRESSIVE AT THIS TIME. THE FLOW BECOMES MORE
ZONAL BY NEXT WEEKEND...WHICH COULD OPEN THE DOOR FOR MORE WEAK
SYSTEMS FROM THE BERING.
&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 121 127-138.
FIRE WEATHER...NONE.
&&

$$

SYNOPSIS AND MODEL DISCUSSION...DS
SOUTHCENTRAL ALASKA...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...MO





000
FXAK68 PAFC 300017
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
417 PM AKDT SAT AUG 29 2015

.ANALYSIS AND UPPER LEVELS...
A PATTERN ADJUSTMENT IS UNDERWAY THIS AFTERNOON. AN UPPER LEVEL
TROUGH THAT EXTENDS FROM EASTERN RUSSIA TO THE ROCKIES CONTAINS A
CUT-OFF LOW OVER BARROW THAT IS BEGINNING TO DIVE SOUTHEAST TO THE
GULF. ANOTHER LARGE CUT-OFF LOW IS BETWEEN THE SOUTHERN KAMCHATKA
PENINSULA AND THE WESTERN ALEUTIANS. A NORTH PACIFIC RIDGE IS
STILL POKING INTO THE SOUTHERN BERING. AT THE SURFACE...A BROAD
AREA OF LOW PRESSURE IS OVER THE NORTHERN GULF...WITH ANOTHER LOW
WEST OF ATTU. ANOTHER WEAKENING LOW IS NEAR BARROW. A SURFACE
RIDGE HAS RETREATED INTO THE NORTH PACIFIC WITH ONLY THE EXTREME
NORTHERN QUADRANT STILL NOSING INTO THE BERING...WHILE ANOTHER
HIGH FROM EASTERN RUSSIA IS DIVING INTO THE NORTHERN BERING. A
WEATHER FRONT IS BRINGING SOME RAIN TO PORTIONS OF SOUTHWEST AK
AND KODIAK ISLAND.

&&

.MODEL DISCUSSION...
MODELS REMAIN IN EXCELLENT AGREEMENT AND CONFIRM THE PATTERN
SHIFT. THE UPPER LOW OVER NORTHERN AK WILL DIG INTO THE BASE OF
THE TROUGH BY MON AND TEMPORARILY CONSOLIDATE OVER THE
NORTHEASTERN GULF COAST. THIS DIGGING WILL BE ACCOMPANIED BY TWO
WAVES THAT WILL SEQUENTIALLY TIGHTEN THE SURFACE PRESSURE GRADIENT
ACROSS THE SOUTHERN HALF OF THE STATE. THE FIRST WILL BE TONIGHT
INTO SUN...AND THE SECOND STRONGER WAVE SUN NIGHT INTO MON
MORNING. THE INITIAL WAVE WILL PUSH THE BERING/SOUTHWEST AK FRONT
INTO THE NORTH PACIFIC.

WHILE THIS IS HAPPENING...HIGH PRESSURE NOSING INTO THE SOUTHERN
BERING WILL MERGE WITH THE HIGH MOVING OFF THE RUSSIAN COAST LATER
ON SUN. THIS RIDGE OF HIGH PRESSURE WILL THEN DOMINATE THE EASTERN
BERING AND THEN MOVE INTO SOUTHWEST AK SUN NIGHT INTO MON. BY MON
AFTERNOON THE PRESSURE GRADIENT OVER SOUTHWEST AK WILL WEAKEN...BUT
BE SLIGHTLY MORE PERSISTENT OVER SOUTHCENTRAL...AT LEAST UNTIL
HIGH PRESSURE AND COOLER AIR ON NORTHWEST FLOW BEGIN TO FILTER
ACROSS THE AK RANGE LATER ON MON AND INTO TUE.

IN THE FAR WEST THE KAMCHATKA/ATTU LOW WILL MOVE NORTH AND BRING A
FRONT ACROSS THE WESTERN ALEUTIANS SUN AND THE WESTERN BERING ON
MON. ANY EASTWARD PROGRESSION OF THIS FEATURE WILL BE LIMITED BY
THE STRENGTH OF THE HIGH THAT DEVELOPS OVER THE BERING.

IN ORDER TO BETTER CAPTURE DETAILS OF THE WIND FIELD THE FORECAST
UTILIZES THE HIGHER RESOLUTION NAM IN THE EAST AND GEM/EC IN THE
WEST.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE NORTHERLY OFFSHORE FLOW WILL CONTINUE AS WE HEAD INTO THE
EARLY PART OF NEXT WEEK. WE WILL SEE COOLER TEMPERATURES COMBINED
WITH STRONG GUSTY GAP WINDS ASSOCIATED WITH UPPER LEVEL
DISTURBANCES MOVING THROUGH THE REGION. THE FIRST DISTURBANCE WILL
DROP FROM THE NORTH LATER TONIGHT RESULTING INCREASED PRESSURE
GRADIENTS. BY SUNDAY NIGHT THE NEXT DISTURBANCE WILL FOLLOW THE
SAME TRACK AS THE PREVIOUS AND EXIT THE SOUTHCENTRAL REGION INTO
THE NORTHERN GULF BY MONDAY. THIS SYNOPTIC FEATURE WILL FURTHER
ENHANCE THE STRONG GUSTY NORTHERLY WINDS. LOOK FOR THE SAME
SCENARIO WITH STRONG GAP WINDS THROUGH WHITTIER...SEWARD...VALDEZ
...THOMPSON PASS AND THE COPPER RIVER DELTA THROUGH MONDAY BEFORE
THE WEAKENING OF THE PRESSURE GRADIENT. THE OTHER AREA OF CONCERN
WILL BE THE BARREN ISLANDS AND THE NORTHERN KODIAK ISLAND REGION.
THEY WILL HAVE STRONG GUSTY NORTHWESTERLY WINDS AS THE COLDER AIR
FILTERS INTO THE REGION. THE BARREN ISLANDS ARE EXPECTED TO HAVE
GALE FORCE WINDS BY THE LATE EVENING AS THE SHORTWAVE MOVES
THROUGH AND WILL BE ACCOMPANIED BY THE SHORTWAVE PUSHING THROUGH
THE REGION. KODIAK ISLAND WILL BE IN THE SAME STRONG GUSTY GAP
WIND REGIME BEFORE DIMINISHING BY LATE MONDAY.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
AS THE UPPER LOW OVER THE STATE ELONGATES TO THE SOUTH IT WILL
KEEP NORTH TO NORTHWEST FLOW OVER THE SOUTHWEST THROUGH MONDAY.
THIS REGION WILL ALSO BE SQUEEZED BETWEEN THE LOW AND RIDGING OVER
THE BERING KEEPING GUSTY WINDS...ESPECIALLY THROUGH CHANNELED
TERRAIN AND ALONG THE COAST. THE WINDS WILL THEN WEAKEN MONDAY AS
THE LOW PUSHES OFF TO THE SOUTHEAST. SHORTWAVES CIRCULATING AROUND
THE LOW WILL ALSO KEEP SHOWERS OVER THE SOUTHWEST THAT WILL
DIMINISH AS RIDGING OVER THE BERING PUSHES IN OVER THE AREA INTO
MONDAY.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE MAIN IMPACT FOR THE ALEUTIANS IS THE LOW TO THE SOUTHWEST OF
THE WESTERN ALEUTIANS AND ITS ASSOCIATED FRONT THAT STRETCHES
ACROSS THE CENTRAL ALEUTIANS AND MUCH OF THE SOUTHERN BERING. THE
FRONT WILL CONTINUE ITS SLOW TRACK EAST BRINGING RAIN TO THE
ISLANDS AND THEN DIMINISH AS IT IS BEING HELD UP BY RIDGING TO
THE EAST. THE LOW ITSELF WILL SLOWLY TRACK NORTH AND BRING ANOTHER
SHOT OF RAIN TO THE WESTERN ALEUTIANS SUNDAY AFTERNOON AS IT PASSES.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...TUE THROUGH SAT)...BIGGEST
CHANGE FOR THIS TIME PERIOD FROM THE PREVIOUS DAYS IS THAT IT
LOOKS LIKE THE NORTHERN ENERGY WILL KEEP THE RIDGE SUPPRESSED A
BIT LONGER. RATHER THAN SEEING THE RIDGE BE OVER THE SOUTHWEST AND
SOUTHCENTRAL PORTIONS OF THE STATE ON TUESDAY...THERE WILL STILL
BE SOME PIECES OF ENERGY MOVING THROUGH FROM THE NORTHWEST. THIS
WILL KEEP SOME GUSTY WINDS...ESPECIALLY THROUGH FAVORED AREAS LIKE
SEWARD...WHITTIER...AND THE BARREN ISLANDS. IT WILL ALSO KEEP
TEMPERATURES ON THE COOLER SIDE FOR ANOTHER DAY. PLACES FURTHER
INLAND WHERE THE WINDS DIE OFF FIRST WILL LIKELY BE THE COLDEST
SPOTS ON TUESDAY MORNING. BY WEDNESDAY...MODELS STILL INDICATE
THAT AN EXTENSION OF THE NORTH PACIFIC RIDGE SHOULD BUILD OVER
SOUTHWEST AND SOUTHCENTRAL. THIS WILL RESULT IN ABUNDANT SUNSHINE
AND SHOULD ALLOW TEMPERATURES TO MODERATE A BIT GOING THROUGH THE
WEEK.

OVER THE BERING...TYPHOON ATSANI REMNANTS WILL STAY ANCHORED IN A
BROAD TROUGH OVER THE WESTERN BERING. THIS WILL KEEP WARM MOIST
AIR FLOWING INTO THE EASTERN ALEUTIANS AND PRIBILOF ISLANDS
LEADING TO WIDESPREAD FOG AND THE CHANCE FOR RAIN. BY
WEDNESDAY...A WEAK SURFACE LOW DEVELOPS OVER THE CENTRAL ALEUTIANS
ALONG AN OLD BOUNDARY. MODELS ARE NOW IN MUCH BETTER AGREEMENT IN
CARRYING THIS LOW QUICKLY NORTHWARD TOWARD THE BERING STRAIT.
WHILE NOT A DEEP LOW BY ANY MEANS...IT COULD BE JUST ENOUGH TO
HELP TO TICK WINDS UP TO THE SMALL CRAFT LEVEL. IT WILL ALSO BRING
A FAIRLY WIDE SWATH OF RAIN FROM THE EASTERN BERING TO THE WEST
COAST BY WEDNESDAY MORNING.

THE LATTER HALF OF THE WEEK WILL FEATURE THE WARM FRONT OVER
SOUTHWEST AK FALLING APART AS IT TRIES TO MAKE IT ACROSS THE AK
RANGE. BUT THE RIDGE AND DRY OVER THE MAINLAND COULD BE ENOUGH TO
KEEP THINGS DRY ACROSS MUCH OF THE AREA. EVEN IF A FEW SHOWERS DO
DEVELOP ACROSS THE KENAI AND CHUGACH MOUNTAINS INTO FRIDAY...NO
ONE SYSTEM LOOKS IMPRESSIVE AT THIS TIME. THE FLOW BECOMES MORE
ZONAL BY NEXT WEEKEND...WHICH COULD OPEN THE DOOR FOR MORE WEAK
SYSTEMS FROM THE BERING.
&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 121 127-138.
FIRE WEATHER...NONE.
&&

$$

SYNOPSIS AND MODEL DISCUSSION...DS
SOUTHCENTRAL ALASKA...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...MO




000
FXAK68 PAFC 291257
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
457 AM AKDT SAT AUG 29 2015

.ANALYSIS AND UPPER LEVELS...

AN AMPLIFIED UPPER TROUGH OVER THE MAINLAND HAS TWO LOW CENTERS...ONE
AT THE BASE SPINNING OVER THE EASTERN GULF AND THE OTHER IS
SPINNING JUST NORTH OF BARROW. TO THE WEST...A STREAM OF MOISTURE
IS BEING PUMPED NORTH INTO THE BERING BETWEEN THE STRONG RIDGE
CENTERED SOUTH OF THE CENTRAL ALEUTIANS AND A CLOSED LOW SOUTH OF
THE KAMCHATKA PENINSULA. AT THE SURFACE...RAIN CONTINUES TO
DEVELOP ALONG A FRONTAL BOUNDARY THAT IS STRETCHED ALONG THE
NORTHERN WATERS OF THE BERING THROUGH THE SOUTHWEST COAST.
SOUTHCENTRAL AND THE MUCH OF THE GULF STAYED DRY OVERNIGHT WITH
NORTHERLY FLOW BEGINNING TO TAPER OFF THIS MORNING BEHIND THE
FRONT THAT MOVED THROUGH ON FRIDAY.

&&

.MODEL DISCUSSION...

MODELS ARE RELATIVELY IN GOOD AGREEMENT WITH THE SYNOPTIC PATTERN
FOR THE UPCOMING WEEKEND AND THEREFORE ONLY MINOR CHANGES WERE
MADE USING THE HIGHER RESOLUTION MODELS OF THE ECMWF...NAM AND
GEM. THE CHALLENGES FOR THE FORECAST THIS WEEKEND ARE GUSTY WINDS
AND OVERNIGHT LOW TEMPERATURES WHICH ARE DIFFICULT TO RESOLVE
SINCE MODELS HAVE SLIGHT VARIANCES IN THE TIMING OF SHORTWAVES AND
MOISTURE FIELDS. THE OVERALL TREND TODAY IS FOR THE FRONT ACROSS
THE CENTRAL BERING AND SOUTHWEST TO SLIDE SOUTH TO THE SOUTHERN
BERING AND WESTERN GULF AND THEN DISSIPATE THIS AFTERNOON. A COLD
DENSE AIR MASS ACROSS THE BERING STRAIT DIVES SOUTH LATE TODAY
BRINGING GUSTY WINDS BACK ACROSS THE SOUTHERN MAINLAND AND
SURROUNDING WATERS WITH GUSTS CONTINUING THROUGH SUNDAY BEFORE
TAPERING OFF. TO THE WEST...THE RIDGE STARTS TO LOOSE HOLD OVER
THE BERING AS THE ARCTIC LOW AND A LOW NEAR THE WESTERN ALEUTIANS
FORCE A PATTERN CHANGE.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE BIG STORY FOR SOUTHCENTRAL IS THAT THE COOL AND WINDY PATTERN
WILL PERSIST. A SERIES OF UPPER LEVEL SHORT-WAVES DROPPING OUT OF
THE ARCTIC WILL RATCHET WINDS BACK UP AREA-WIDE OVERNIGHT TONIGHT
INTO SUNDAY. WINDS WILL THEN INCREASE FURTHER SUNDAY NIGHT INTO
MONDAY AS AN UPPER LEVEL LOW FORMS AND DROPS THROUGH SOUTHCENTRAL
AND INTO THE GULF. ANOTHER POLAR JET STREAK WILL ENHANCE SUBSIDENCE
HELPING TO MIX DOWN STRONGER WINDS FROM ALOFT DOWN TO THE SURFACE.
THIS UPCOMING WINDSTORM DOES NOT LOOK QUITE AS STRONG AS THE ONE
WHICH JUST OCCURRED (THURSDAY THROUGH FRIDAY)...BUT IT WILL NOT
BE VERY FAR OFF.

A SURFACE LOW MOVING OVER TOP OF THE NORTH PACIFIC/BERING SEA
RIDGE WILL TRACK RIGHT ACROSS KODIAK ISLAND THIS MORNING. WITH
ABUNDANT TROPICAL MOISTURE EXPECT A DECENT RAIN ON THE WEST SIDE
OF THE ISLAND...WITH LOWER AMOUNTS ON THE EAST SIDE DUE TO
WESTERLY FLOW. DRIER CONDITIONS AND STRONG WINDS WILL THEN RETURN
BEHIND THIS. MEANWHILE...THE SHORT-WAVES TRACKING THROUGH
SOUTHCENTRAL THE NEXT COUPLE DAYS WILL ROTATE IN FROM THE WEST AS
THEY MOVE THROUGH. LIFT OUT AHEAD OF THESE COMBINED WITH
INCREASING INSTABILITY AS THE AIR ALOFT PROGRESSIVELY COOLS WILL
LEAD TO SOME SHOWERS...ESPECIALLY ALONG THE MOUNTAINS. SNOW LEVELS
WILL FLUCTUATE BUT WILL SHOW A GENERAL DOWNWARD TREND...SO CHANCES
ARE THE TOPS OF THE MOUNTAINS WILL BE COVERED WITH A LITTLE SNOW
BY EARLY NEXT WEEK.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 THROUGH 3)...
A FRONTAL SYSTEM AND SURFACE LOW TRACKING ALONG THE SOUTHWEST
ALASKA COAST WILL CONTINUE TO BRING RAIN TO MUCH OF SOUTHWEST
ALASKA THIS MORNING. THE SURFACE LOW WILL CROSS OVER THE ALEUTIAN
RANGE LATE MORNING WITH BREEZY NORTHWESTERLY WINDS PUSHING IN
BEHIND IT AND RAIN CHANGING OVER TO SCATTERED SHOWERS. A COLD
UPPER LEVEL LOW OVER INTERIOR ALASKA WITH A SERIES OF SHORTWAVES
SWINGING THROUGH WILL KEEP SOUTHWEST ALASKA WELL SUPPLIED WITH
COOL AIR THROUGH THE WEEKEND AND SCATTERED TO NUMEROUS SHOWERS
ALONG THE MOUNTAINS. SHOWERS IN SOUTHWEST ALASKA WILL TAPER OFF
MONDAY AS AN UPPER LEVEL RIDGE BUILDS OVER THE ALASKA PENINSULA
WHILE AN ALEUTIAN FRONTAL SYSTEM BEGINS TO GRADUALLY PUSH OVER THE
WESTERN PENINSULA MONDAY AND MONDAY NIGHT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 THROUGH 3)...
THE UPPER LEVEL RIDGE OVER THE CENTRAL ALEUTIANS WILL GRADUALLY
FLATTEN AND SINK SOUTH TONIGHT AND SUNDAY ALLOWING THE FRONTAL
SYSTEM IN THE BERING TO SAG SOUTH OVER THE ALEUTIANS. A VERTICALLY
STACKED SURFACE LOW OFF OF THE KAMCHATKA PENINSULA WILL GRADUALLY
DRIFT TOWARDS SHEMYA THROUGH MONDAY. A LOW FROM THE NORTHERN
PACIFIC AND ASSOCIATED FRONTAL SYSTEM WILL LIFT NORTH OVER THE
CENTRAL AND EASTERN ALEUTIANS SUNDAY NIGHT THROUGH MONDAY NIGHT.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...MON THROUGH FRI)...MODELS
ARE IN FAIRLY GOOD AGREEMENT FOR THE EARLY PART OF NEXT WEEK. SO
FOR THE TIME BEING...FORECAST CONFIDENCE IS RELATIVELY HIGH. THE
HIGHLIGHT OF THIS PERIOD WILL BE THE TRANSITION FROM FAIRLY
STRONG...COOL NORTHWEST FLOW THROUGH MUCH OF SOUTH CENTRAL TO A
CALMER AND SLIGHTLY WARMER PATTERN. THE AREA OF THE LOW PRESSURE
IN THE NORTHEAST GULF WILL WORK IN COMBINATION WITH A DEVELOPING
HIGH OVER THE BRISTOL BAY AREA ON MONDAY TO KEEP THE PRESSURE
GRADIENT TIGHT. BUT AS THIS LOW PULLS FURTHER TO THE SOUTH AND
EAST ON TUESDAY...HIGHER PRESSURE WILL BUILD OVER SOUTHWEST
ALASKA. THIS WILL KEEP THINGS DRY ACROSS JUST ABOUT ALL OF THE
SOUTHERN HALF OF THE MAINLAND THROUGH TUESDAY. TEMPERATURES SHOULD
BE ABLE TO REBOUND TO A FEW DEGREES AS WELL WITH THE FLOW BECOMING
MORE WESTERLY AND 850 MB TEMPERATURES CLIMBING 5 TO 6 DEGREES
CELSIUS.

THE MORE ACTIVE WEATHER WILL BE OVER THE BERING SEA TO START THE
WEEK. THE REMNANTS OF TYPHOON ATSANI WILL CONTINUE TO DRIFT OVER
THE FAR WESTERN BERING. WHILE WINDS SHOULD ALL BE BELOW SMALL
CRAFT LEVEL...IT WILL KEEP A CHANCE FOR RAIN IN THE FORECAST. IT
WILL ALSO LEAVE A DECAYING WARM FRONT ALONG THE CENTRAL AND
EASTERN ALEUTIANS. A WEAK WAVE TRIES TO DEVELOP ALONG THIS
BOUNDARY AS WE GET TO WEDNESDAY. THIS IS WHERE MODELS START TO
DIFFER WITH THE GFS BEING RATHER AGGRESSIVE WITH THIS WAVE AND
SWINGING ANOTHER STORM THROUGH THE BERING STRAIT. MEANWHILE...THE
EC IS MUCH WEAKER AND ONLY BRINGS LIGHT RAIN TO THE SOUTHWEST.
BOTH GLOBAL MODELS SHOW SIGNS OF CYCLOGENESIS IN THE GULF BY THE
LATTER HALF OF THE WEEK WHICH WOULD MEAN A RETURN TO COOLER AND
WETTER WEATHER FOR MUCH OF THE MAINLAND.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 130 131 132 136 137 138 150 155 160 165.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...KH
SOUTHCENTRAL ALASKA...SB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
LONG TERM...MO




000
FXAK68 PAFC 291257
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
457 AM AKDT SAT AUG 29 2015

.ANALYSIS AND UPPER LEVELS...

AN AMPLIFIED UPPER TROUGH OVER THE MAINLAND HAS TWO LOW CENTERS...ONE
AT THE BASE SPINNING OVER THE EASTERN GULF AND THE OTHER IS
SPINNING JUST NORTH OF BARROW. TO THE WEST...A STREAM OF MOISTURE
IS BEING PUMPED NORTH INTO THE BERING BETWEEN THE STRONG RIDGE
CENTERED SOUTH OF THE CENTRAL ALEUTIANS AND A CLOSED LOW SOUTH OF
THE KAMCHATKA PENINSULA. AT THE SURFACE...RAIN CONTINUES TO
DEVELOP ALONG A FRONTAL BOUNDARY THAT IS STRETCHED ALONG THE
NORTHERN WATERS OF THE BERING THROUGH THE SOUTHWEST COAST.
SOUTHCENTRAL AND THE MUCH OF THE GULF STAYED DRY OVERNIGHT WITH
NORTHERLY FLOW BEGINNING TO TAPER OFF THIS MORNING BEHIND THE
FRONT THAT MOVED THROUGH ON FRIDAY.

&&

.MODEL DISCUSSION...

MODELS ARE RELATIVELY IN GOOD AGREEMENT WITH THE SYNOPTIC PATTERN
FOR THE UPCOMING WEEKEND AND THEREFORE ONLY MINOR CHANGES WERE
MADE USING THE HIGHER RESOLUTION MODELS OF THE ECMWF...NAM AND
GEM. THE CHALLENGES FOR THE FORECAST THIS WEEKEND ARE GUSTY WINDS
AND OVERNIGHT LOW TEMPERATURES WHICH ARE DIFFICULT TO RESOLVE
SINCE MODELS HAVE SLIGHT VARIANCES IN THE TIMING OF SHORTWAVES AND
MOISTURE FIELDS. THE OVERALL TREND TODAY IS FOR THE FRONT ACROSS
THE CENTRAL BERING AND SOUTHWEST TO SLIDE SOUTH TO THE SOUTHERN
BERING AND WESTERN GULF AND THEN DISSIPATE THIS AFTERNOON. A COLD
DENSE AIR MASS ACROSS THE BERING STRAIT DIVES SOUTH LATE TODAY
BRINGING GUSTY WINDS BACK ACROSS THE SOUTHERN MAINLAND AND
SURROUNDING WATERS WITH GUSTS CONTINUING THROUGH SUNDAY BEFORE
TAPERING OFF. TO THE WEST...THE RIDGE STARTS TO LOOSE HOLD OVER
THE BERING AS THE ARCTIC LOW AND A LOW NEAR THE WESTERN ALEUTIANS
FORCE A PATTERN CHANGE.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE BIG STORY FOR SOUTHCENTRAL IS THAT THE COOL AND WINDY PATTERN
WILL PERSIST. A SERIES OF UPPER LEVEL SHORT-WAVES DROPPING OUT OF
THE ARCTIC WILL RATCHET WINDS BACK UP AREA-WIDE OVERNIGHT TONIGHT
INTO SUNDAY. WINDS WILL THEN INCREASE FURTHER SUNDAY NIGHT INTO
MONDAY AS AN UPPER LEVEL LOW FORMS AND DROPS THROUGH SOUTHCENTRAL
AND INTO THE GULF. ANOTHER POLAR JET STREAK WILL ENHANCE SUBSIDENCE
HELPING TO MIX DOWN STRONGER WINDS FROM ALOFT DOWN TO THE SURFACE.
THIS UPCOMING WINDSTORM DOES NOT LOOK QUITE AS STRONG AS THE ONE
WHICH JUST OCCURRED (THURSDAY THROUGH FRIDAY)...BUT IT WILL NOT
BE VERY FAR OFF.

A SURFACE LOW MOVING OVER TOP OF THE NORTH PACIFIC/BERING SEA
RIDGE WILL TRACK RIGHT ACROSS KODIAK ISLAND THIS MORNING. WITH
ABUNDANT TROPICAL MOISTURE EXPECT A DECENT RAIN ON THE WEST SIDE
OF THE ISLAND...WITH LOWER AMOUNTS ON THE EAST SIDE DUE TO
WESTERLY FLOW. DRIER CONDITIONS AND STRONG WINDS WILL THEN RETURN
BEHIND THIS. MEANWHILE...THE SHORT-WAVES TRACKING THROUGH
SOUTHCENTRAL THE NEXT COUPLE DAYS WILL ROTATE IN FROM THE WEST AS
THEY MOVE THROUGH. LIFT OUT AHEAD OF THESE COMBINED WITH
INCREASING INSTABILITY AS THE AIR ALOFT PROGRESSIVELY COOLS WILL
LEAD TO SOME SHOWERS...ESPECIALLY ALONG THE MOUNTAINS. SNOW LEVELS
WILL FLUCTUATE BUT WILL SHOW A GENERAL DOWNWARD TREND...SO CHANCES
ARE THE TOPS OF THE MOUNTAINS WILL BE COVERED WITH A LITTLE SNOW
BY EARLY NEXT WEEK.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 THROUGH 3)...
A FRONTAL SYSTEM AND SURFACE LOW TRACKING ALONG THE SOUTHWEST
ALASKA COAST WILL CONTINUE TO BRING RAIN TO MUCH OF SOUTHWEST
ALASKA THIS MORNING. THE SURFACE LOW WILL CROSS OVER THE ALEUTIAN
RANGE LATE MORNING WITH BREEZY NORTHWESTERLY WINDS PUSHING IN
BEHIND IT AND RAIN CHANGING OVER TO SCATTERED SHOWERS. A COLD
UPPER LEVEL LOW OVER INTERIOR ALASKA WITH A SERIES OF SHORTWAVES
SWINGING THROUGH WILL KEEP SOUTHWEST ALASKA WELL SUPPLIED WITH
COOL AIR THROUGH THE WEEKEND AND SCATTERED TO NUMEROUS SHOWERS
ALONG THE MOUNTAINS. SHOWERS IN SOUTHWEST ALASKA WILL TAPER OFF
MONDAY AS AN UPPER LEVEL RIDGE BUILDS OVER THE ALASKA PENINSULA
WHILE AN ALEUTIAN FRONTAL SYSTEM BEGINS TO GRADUALLY PUSH OVER THE
WESTERN PENINSULA MONDAY AND MONDAY NIGHT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 THROUGH 3)...
THE UPPER LEVEL RIDGE OVER THE CENTRAL ALEUTIANS WILL GRADUALLY
FLATTEN AND SINK SOUTH TONIGHT AND SUNDAY ALLOWING THE FRONTAL
SYSTEM IN THE BERING TO SAG SOUTH OVER THE ALEUTIANS. A VERTICALLY
STACKED SURFACE LOW OFF OF THE KAMCHATKA PENINSULA WILL GRADUALLY
DRIFT TOWARDS SHEMYA THROUGH MONDAY. A LOW FROM THE NORTHERN
PACIFIC AND ASSOCIATED FRONTAL SYSTEM WILL LIFT NORTH OVER THE
CENTRAL AND EASTERN ALEUTIANS SUNDAY NIGHT THROUGH MONDAY NIGHT.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...MON THROUGH FRI)...MODELS
ARE IN FAIRLY GOOD AGREEMENT FOR THE EARLY PART OF NEXT WEEK. SO
FOR THE TIME BEING...FORECAST CONFIDENCE IS RELATIVELY HIGH. THE
HIGHLIGHT OF THIS PERIOD WILL BE THE TRANSITION FROM FAIRLY
STRONG...COOL NORTHWEST FLOW THROUGH MUCH OF SOUTH CENTRAL TO A
CALMER AND SLIGHTLY WARMER PATTERN. THE AREA OF THE LOW PRESSURE
IN THE NORTHEAST GULF WILL WORK IN COMBINATION WITH A DEVELOPING
HIGH OVER THE BRISTOL BAY AREA ON MONDAY TO KEEP THE PRESSURE
GRADIENT TIGHT. BUT AS THIS LOW PULLS FURTHER TO THE SOUTH AND
EAST ON TUESDAY...HIGHER PRESSURE WILL BUILD OVER SOUTHWEST
ALASKA. THIS WILL KEEP THINGS DRY ACROSS JUST ABOUT ALL OF THE
SOUTHERN HALF OF THE MAINLAND THROUGH TUESDAY. TEMPERATURES SHOULD
BE ABLE TO REBOUND TO A FEW DEGREES AS WELL WITH THE FLOW BECOMING
MORE WESTERLY AND 850 MB TEMPERATURES CLIMBING 5 TO 6 DEGREES
CELSIUS.

THE MORE ACTIVE WEATHER WILL BE OVER THE BERING SEA TO START THE
WEEK. THE REMNANTS OF TYPHOON ATSANI WILL CONTINUE TO DRIFT OVER
THE FAR WESTERN BERING. WHILE WINDS SHOULD ALL BE BELOW SMALL
CRAFT LEVEL...IT WILL KEEP A CHANCE FOR RAIN IN THE FORECAST. IT
WILL ALSO LEAVE A DECAYING WARM FRONT ALONG THE CENTRAL AND
EASTERN ALEUTIANS. A WEAK WAVE TRIES TO DEVELOP ALONG THIS
BOUNDARY AS WE GET TO WEDNESDAY. THIS IS WHERE MODELS START TO
DIFFER WITH THE GFS BEING RATHER AGGRESSIVE WITH THIS WAVE AND
SWINGING ANOTHER STORM THROUGH THE BERING STRAIT. MEANWHILE...THE
EC IS MUCH WEAKER AND ONLY BRINGS LIGHT RAIN TO THE SOUTHWEST.
BOTH GLOBAL MODELS SHOW SIGNS OF CYCLOGENESIS IN THE GULF BY THE
LATTER HALF OF THE WEEK WHICH WOULD MEAN A RETURN TO COOLER AND
WETTER WEATHER FOR MUCH OF THE MAINLAND.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 130 131 132 136 137 138 150 155 160 165.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...KH
SOUTHCENTRAL ALASKA...SB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
LONG TERM...MO





000
FXAK68 PAFC 291257
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
457 AM AKDT SAT AUG 29 2015

.ANALYSIS AND UPPER LEVELS...

AN AMPLIFIED UPPER TROUGH OVER THE MAINLAND HAS TWO LOW CENTERS...ONE
AT THE BASE SPINNING OVER THE EASTERN GULF AND THE OTHER IS
SPINNING JUST NORTH OF BARROW. TO THE WEST...A STREAM OF MOISTURE
IS BEING PUMPED NORTH INTO THE BERING BETWEEN THE STRONG RIDGE
CENTERED SOUTH OF THE CENTRAL ALEUTIANS AND A CLOSED LOW SOUTH OF
THE KAMCHATKA PENINSULA. AT THE SURFACE...RAIN CONTINUES TO
DEVELOP ALONG A FRONTAL BOUNDARY THAT IS STRETCHED ALONG THE
NORTHERN WATERS OF THE BERING THROUGH THE SOUTHWEST COAST.
SOUTHCENTRAL AND THE MUCH OF THE GULF STAYED DRY OVERNIGHT WITH
NORTHERLY FLOW BEGINNING TO TAPER OFF THIS MORNING BEHIND THE
FRONT THAT MOVED THROUGH ON FRIDAY.

&&

.MODEL DISCUSSION...

MODELS ARE RELATIVELY IN GOOD AGREEMENT WITH THE SYNOPTIC PATTERN
FOR THE UPCOMING WEEKEND AND THEREFORE ONLY MINOR CHANGES WERE
MADE USING THE HIGHER RESOLUTION MODELS OF THE ECMWF...NAM AND
GEM. THE CHALLENGES FOR THE FORECAST THIS WEEKEND ARE GUSTY WINDS
AND OVERNIGHT LOW TEMPERATURES WHICH ARE DIFFICULT TO RESOLVE
SINCE MODELS HAVE SLIGHT VARIANCES IN THE TIMING OF SHORTWAVES AND
MOISTURE FIELDS. THE OVERALL TREND TODAY IS FOR THE FRONT ACROSS
THE CENTRAL BERING AND SOUTHWEST TO SLIDE SOUTH TO THE SOUTHERN
BERING AND WESTERN GULF AND THEN DISSIPATE THIS AFTERNOON. A COLD
DENSE AIR MASS ACROSS THE BERING STRAIT DIVES SOUTH LATE TODAY
BRINGING GUSTY WINDS BACK ACROSS THE SOUTHERN MAINLAND AND
SURROUNDING WATERS WITH GUSTS CONTINUING THROUGH SUNDAY BEFORE
TAPERING OFF. TO THE WEST...THE RIDGE STARTS TO LOOSE HOLD OVER
THE BERING AS THE ARCTIC LOW AND A LOW NEAR THE WESTERN ALEUTIANS
FORCE A PATTERN CHANGE.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE BIG STORY FOR SOUTHCENTRAL IS THAT THE COOL AND WINDY PATTERN
WILL PERSIST. A SERIES OF UPPER LEVEL SHORT-WAVES DROPPING OUT OF
THE ARCTIC WILL RATCHET WINDS BACK UP AREA-WIDE OVERNIGHT TONIGHT
INTO SUNDAY. WINDS WILL THEN INCREASE FURTHER SUNDAY NIGHT INTO
MONDAY AS AN UPPER LEVEL LOW FORMS AND DROPS THROUGH SOUTHCENTRAL
AND INTO THE GULF. ANOTHER POLAR JET STREAK WILL ENHANCE SUBSIDENCE
HELPING TO MIX DOWN STRONGER WINDS FROM ALOFT DOWN TO THE SURFACE.
THIS UPCOMING WINDSTORM DOES NOT LOOK QUITE AS STRONG AS THE ONE
WHICH JUST OCCURRED (THURSDAY THROUGH FRIDAY)...BUT IT WILL NOT
BE VERY FAR OFF.

A SURFACE LOW MOVING OVER TOP OF THE NORTH PACIFIC/BERING SEA
RIDGE WILL TRACK RIGHT ACROSS KODIAK ISLAND THIS MORNING. WITH
ABUNDANT TROPICAL MOISTURE EXPECT A DECENT RAIN ON THE WEST SIDE
OF THE ISLAND...WITH LOWER AMOUNTS ON THE EAST SIDE DUE TO
WESTERLY FLOW. DRIER CONDITIONS AND STRONG WINDS WILL THEN RETURN
BEHIND THIS. MEANWHILE...THE SHORT-WAVES TRACKING THROUGH
SOUTHCENTRAL THE NEXT COUPLE DAYS WILL ROTATE IN FROM THE WEST AS
THEY MOVE THROUGH. LIFT OUT AHEAD OF THESE COMBINED WITH
INCREASING INSTABILITY AS THE AIR ALOFT PROGRESSIVELY COOLS WILL
LEAD TO SOME SHOWERS...ESPECIALLY ALONG THE MOUNTAINS. SNOW LEVELS
WILL FLUCTUATE BUT WILL SHOW A GENERAL DOWNWARD TREND...SO CHANCES
ARE THE TOPS OF THE MOUNTAINS WILL BE COVERED WITH A LITTLE SNOW
BY EARLY NEXT WEEK.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 THROUGH 3)...
A FRONTAL SYSTEM AND SURFACE LOW TRACKING ALONG THE SOUTHWEST
ALASKA COAST WILL CONTINUE TO BRING RAIN TO MUCH OF SOUTHWEST
ALASKA THIS MORNING. THE SURFACE LOW WILL CROSS OVER THE ALEUTIAN
RANGE LATE MORNING WITH BREEZY NORTHWESTERLY WINDS PUSHING IN
BEHIND IT AND RAIN CHANGING OVER TO SCATTERED SHOWERS. A COLD
UPPER LEVEL LOW OVER INTERIOR ALASKA WITH A SERIES OF SHORTWAVES
SWINGING THROUGH WILL KEEP SOUTHWEST ALASKA WELL SUPPLIED WITH
COOL AIR THROUGH THE WEEKEND AND SCATTERED TO NUMEROUS SHOWERS
ALONG THE MOUNTAINS. SHOWERS IN SOUTHWEST ALASKA WILL TAPER OFF
MONDAY AS AN UPPER LEVEL RIDGE BUILDS OVER THE ALASKA PENINSULA
WHILE AN ALEUTIAN FRONTAL SYSTEM BEGINS TO GRADUALLY PUSH OVER THE
WESTERN PENINSULA MONDAY AND MONDAY NIGHT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 THROUGH 3)...
THE UPPER LEVEL RIDGE OVER THE CENTRAL ALEUTIANS WILL GRADUALLY
FLATTEN AND SINK SOUTH TONIGHT AND SUNDAY ALLOWING THE FRONTAL
SYSTEM IN THE BERING TO SAG SOUTH OVER THE ALEUTIANS. A VERTICALLY
STACKED SURFACE LOW OFF OF THE KAMCHATKA PENINSULA WILL GRADUALLY
DRIFT TOWARDS SHEMYA THROUGH MONDAY. A LOW FROM THE NORTHERN
PACIFIC AND ASSOCIATED FRONTAL SYSTEM WILL LIFT NORTH OVER THE
CENTRAL AND EASTERN ALEUTIANS SUNDAY NIGHT THROUGH MONDAY NIGHT.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...MON THROUGH FRI)...MODELS
ARE IN FAIRLY GOOD AGREEMENT FOR THE EARLY PART OF NEXT WEEK. SO
FOR THE TIME BEING...FORECAST CONFIDENCE IS RELATIVELY HIGH. THE
HIGHLIGHT OF THIS PERIOD WILL BE THE TRANSITION FROM FAIRLY
STRONG...COOL NORTHWEST FLOW THROUGH MUCH OF SOUTH CENTRAL TO A
CALMER AND SLIGHTLY WARMER PATTERN. THE AREA OF THE LOW PRESSURE
IN THE NORTHEAST GULF WILL WORK IN COMBINATION WITH A DEVELOPING
HIGH OVER THE BRISTOL BAY AREA ON MONDAY TO KEEP THE PRESSURE
GRADIENT TIGHT. BUT AS THIS LOW PULLS FURTHER TO THE SOUTH AND
EAST ON TUESDAY...HIGHER PRESSURE WILL BUILD OVER SOUTHWEST
ALASKA. THIS WILL KEEP THINGS DRY ACROSS JUST ABOUT ALL OF THE
SOUTHERN HALF OF THE MAINLAND THROUGH TUESDAY. TEMPERATURES SHOULD
BE ABLE TO REBOUND TO A FEW DEGREES AS WELL WITH THE FLOW BECOMING
MORE WESTERLY AND 850 MB TEMPERATURES CLIMBING 5 TO 6 DEGREES
CELSIUS.

THE MORE ACTIVE WEATHER WILL BE OVER THE BERING SEA TO START THE
WEEK. THE REMNANTS OF TYPHOON ATSANI WILL CONTINUE TO DRIFT OVER
THE FAR WESTERN BERING. WHILE WINDS SHOULD ALL BE BELOW SMALL
CRAFT LEVEL...IT WILL KEEP A CHANCE FOR RAIN IN THE FORECAST. IT
WILL ALSO LEAVE A DECAYING WARM FRONT ALONG THE CENTRAL AND
EASTERN ALEUTIANS. A WEAK WAVE TRIES TO DEVELOP ALONG THIS
BOUNDARY AS WE GET TO WEDNESDAY. THIS IS WHERE MODELS START TO
DIFFER WITH THE GFS BEING RATHER AGGRESSIVE WITH THIS WAVE AND
SWINGING ANOTHER STORM THROUGH THE BERING STRAIT. MEANWHILE...THE
EC IS MUCH WEAKER AND ONLY BRINGS LIGHT RAIN TO THE SOUTHWEST.
BOTH GLOBAL MODELS SHOW SIGNS OF CYCLOGENESIS IN THE GULF BY THE
LATTER HALF OF THE WEEK WHICH WOULD MEAN A RETURN TO COOLER AND
WETTER WEATHER FOR MUCH OF THE MAINLAND.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 130 131 132 136 137 138 150 155 160 165.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...KH
SOUTHCENTRAL ALASKA...SB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
LONG TERM...MO





000
FXAK68 PAFC 291257
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
457 AM AKDT SAT AUG 29 2015

.ANALYSIS AND UPPER LEVELS...

AN AMPLIFIED UPPER TROUGH OVER THE MAINLAND HAS TWO LOW CENTERS...ONE
AT THE BASE SPINNING OVER THE EASTERN GULF AND THE OTHER IS
SPINNING JUST NORTH OF BARROW. TO THE WEST...A STREAM OF MOISTURE
IS BEING PUMPED NORTH INTO THE BERING BETWEEN THE STRONG RIDGE
CENTERED SOUTH OF THE CENTRAL ALEUTIANS AND A CLOSED LOW SOUTH OF
THE KAMCHATKA PENINSULA. AT THE SURFACE...RAIN CONTINUES TO
DEVELOP ALONG A FRONTAL BOUNDARY THAT IS STRETCHED ALONG THE
NORTHERN WATERS OF THE BERING THROUGH THE SOUTHWEST COAST.
SOUTHCENTRAL AND THE MUCH OF THE GULF STAYED DRY OVERNIGHT WITH
NORTHERLY FLOW BEGINNING TO TAPER OFF THIS MORNING BEHIND THE
FRONT THAT MOVED THROUGH ON FRIDAY.

&&

.MODEL DISCUSSION...

MODELS ARE RELATIVELY IN GOOD AGREEMENT WITH THE SYNOPTIC PATTERN
FOR THE UPCOMING WEEKEND AND THEREFORE ONLY MINOR CHANGES WERE
MADE USING THE HIGHER RESOLUTION MODELS OF THE ECMWF...NAM AND
GEM. THE CHALLENGES FOR THE FORECAST THIS WEEKEND ARE GUSTY WINDS
AND OVERNIGHT LOW TEMPERATURES WHICH ARE DIFFICULT TO RESOLVE
SINCE MODELS HAVE SLIGHT VARIANCES IN THE TIMING OF SHORTWAVES AND
MOISTURE FIELDS. THE OVERALL TREND TODAY IS FOR THE FRONT ACROSS
THE CENTRAL BERING AND SOUTHWEST TO SLIDE SOUTH TO THE SOUTHERN
BERING AND WESTERN GULF AND THEN DISSIPATE THIS AFTERNOON. A COLD
DENSE AIR MASS ACROSS THE BERING STRAIT DIVES SOUTH LATE TODAY
BRINGING GUSTY WINDS BACK ACROSS THE SOUTHERN MAINLAND AND
SURROUNDING WATERS WITH GUSTS CONTINUING THROUGH SUNDAY BEFORE
TAPERING OFF. TO THE WEST...THE RIDGE STARTS TO LOOSE HOLD OVER
THE BERING AS THE ARCTIC LOW AND A LOW NEAR THE WESTERN ALEUTIANS
FORCE A PATTERN CHANGE.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE BIG STORY FOR SOUTHCENTRAL IS THAT THE COOL AND WINDY PATTERN
WILL PERSIST. A SERIES OF UPPER LEVEL SHORT-WAVES DROPPING OUT OF
THE ARCTIC WILL RATCHET WINDS BACK UP AREA-WIDE OVERNIGHT TONIGHT
INTO SUNDAY. WINDS WILL THEN INCREASE FURTHER SUNDAY NIGHT INTO
MONDAY AS AN UPPER LEVEL LOW FORMS AND DROPS THROUGH SOUTHCENTRAL
AND INTO THE GULF. ANOTHER POLAR JET STREAK WILL ENHANCE SUBSIDENCE
HELPING TO MIX DOWN STRONGER WINDS FROM ALOFT DOWN TO THE SURFACE.
THIS UPCOMING WINDSTORM DOES NOT LOOK QUITE AS STRONG AS THE ONE
WHICH JUST OCCURRED (THURSDAY THROUGH FRIDAY)...BUT IT WILL NOT
BE VERY FAR OFF.

A SURFACE LOW MOVING OVER TOP OF THE NORTH PACIFIC/BERING SEA
RIDGE WILL TRACK RIGHT ACROSS KODIAK ISLAND THIS MORNING. WITH
ABUNDANT TROPICAL MOISTURE EXPECT A DECENT RAIN ON THE WEST SIDE
OF THE ISLAND...WITH LOWER AMOUNTS ON THE EAST SIDE DUE TO
WESTERLY FLOW. DRIER CONDITIONS AND STRONG WINDS WILL THEN RETURN
BEHIND THIS. MEANWHILE...THE SHORT-WAVES TRACKING THROUGH
SOUTHCENTRAL THE NEXT COUPLE DAYS WILL ROTATE IN FROM THE WEST AS
THEY MOVE THROUGH. LIFT OUT AHEAD OF THESE COMBINED WITH
INCREASING INSTABILITY AS THE AIR ALOFT PROGRESSIVELY COOLS WILL
LEAD TO SOME SHOWERS...ESPECIALLY ALONG THE MOUNTAINS. SNOW LEVELS
WILL FLUCTUATE BUT WILL SHOW A GENERAL DOWNWARD TREND...SO CHANCES
ARE THE TOPS OF THE MOUNTAINS WILL BE COVERED WITH A LITTLE SNOW
BY EARLY NEXT WEEK.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 THROUGH 3)...
A FRONTAL SYSTEM AND SURFACE LOW TRACKING ALONG THE SOUTHWEST
ALASKA COAST WILL CONTINUE TO BRING RAIN TO MUCH OF SOUTHWEST
ALASKA THIS MORNING. THE SURFACE LOW WILL CROSS OVER THE ALEUTIAN
RANGE LATE MORNING WITH BREEZY NORTHWESTERLY WINDS PUSHING IN
BEHIND IT AND RAIN CHANGING OVER TO SCATTERED SHOWERS. A COLD
UPPER LEVEL LOW OVER INTERIOR ALASKA WITH A SERIES OF SHORTWAVES
SWINGING THROUGH WILL KEEP SOUTHWEST ALASKA WELL SUPPLIED WITH
COOL AIR THROUGH THE WEEKEND AND SCATTERED TO NUMEROUS SHOWERS
ALONG THE MOUNTAINS. SHOWERS IN SOUTHWEST ALASKA WILL TAPER OFF
MONDAY AS AN UPPER LEVEL RIDGE BUILDS OVER THE ALASKA PENINSULA
WHILE AN ALEUTIAN FRONTAL SYSTEM BEGINS TO GRADUALLY PUSH OVER THE
WESTERN PENINSULA MONDAY AND MONDAY NIGHT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 THROUGH 3)...
THE UPPER LEVEL RIDGE OVER THE CENTRAL ALEUTIANS WILL GRADUALLY
FLATTEN AND SINK SOUTH TONIGHT AND SUNDAY ALLOWING THE FRONTAL
SYSTEM IN THE BERING TO SAG SOUTH OVER THE ALEUTIANS. A VERTICALLY
STACKED SURFACE LOW OFF OF THE KAMCHATKA PENINSULA WILL GRADUALLY
DRIFT TOWARDS SHEMYA THROUGH MONDAY. A LOW FROM THE NORTHERN
PACIFIC AND ASSOCIATED FRONTAL SYSTEM WILL LIFT NORTH OVER THE
CENTRAL AND EASTERN ALEUTIANS SUNDAY NIGHT THROUGH MONDAY NIGHT.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...MON THROUGH FRI)...MODELS
ARE IN FAIRLY GOOD AGREEMENT FOR THE EARLY PART OF NEXT WEEK. SO
FOR THE TIME BEING...FORECAST CONFIDENCE IS RELATIVELY HIGH. THE
HIGHLIGHT OF THIS PERIOD WILL BE THE TRANSITION FROM FAIRLY
STRONG...COOL NORTHWEST FLOW THROUGH MUCH OF SOUTH CENTRAL TO A
CALMER AND SLIGHTLY WARMER PATTERN. THE AREA OF THE LOW PRESSURE
IN THE NORTHEAST GULF WILL WORK IN COMBINATION WITH A DEVELOPING
HIGH OVER THE BRISTOL BAY AREA ON MONDAY TO KEEP THE PRESSURE
GRADIENT TIGHT. BUT AS THIS LOW PULLS FURTHER TO THE SOUTH AND
EAST ON TUESDAY...HIGHER PRESSURE WILL BUILD OVER SOUTHWEST
ALASKA. THIS WILL KEEP THINGS DRY ACROSS JUST ABOUT ALL OF THE
SOUTHERN HALF OF THE MAINLAND THROUGH TUESDAY. TEMPERATURES SHOULD
BE ABLE TO REBOUND TO A FEW DEGREES AS WELL WITH THE FLOW BECOMING
MORE WESTERLY AND 850 MB TEMPERATURES CLIMBING 5 TO 6 DEGREES
CELSIUS.

THE MORE ACTIVE WEATHER WILL BE OVER THE BERING SEA TO START THE
WEEK. THE REMNANTS OF TYPHOON ATSANI WILL CONTINUE TO DRIFT OVER
THE FAR WESTERN BERING. WHILE WINDS SHOULD ALL BE BELOW SMALL
CRAFT LEVEL...IT WILL KEEP A CHANCE FOR RAIN IN THE FORECAST. IT
WILL ALSO LEAVE A DECAYING WARM FRONT ALONG THE CENTRAL AND
EASTERN ALEUTIANS. A WEAK WAVE TRIES TO DEVELOP ALONG THIS
BOUNDARY AS WE GET TO WEDNESDAY. THIS IS WHERE MODELS START TO
DIFFER WITH THE GFS BEING RATHER AGGRESSIVE WITH THIS WAVE AND
SWINGING ANOTHER STORM THROUGH THE BERING STRAIT. MEANWHILE...THE
EC IS MUCH WEAKER AND ONLY BRINGS LIGHT RAIN TO THE SOUTHWEST.
BOTH GLOBAL MODELS SHOW SIGNS OF CYCLOGENESIS IN THE GULF BY THE
LATTER HALF OF THE WEEK WHICH WOULD MEAN A RETURN TO COOLER AND
WETTER WEATHER FOR MUCH OF THE MAINLAND.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 130 131 132 136 137 138 150 155 160 165.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...KH
SOUTHCENTRAL ALASKA...SB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
LONG TERM...MO




000
FXAK68 PAFC 290016
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
416 PM AKDT FRI AUG 28 2015

.ANALYSIS AND UPPER LEVELS...

MASSIVE UPPER LEVEL RIDGE PERSISTS OVER THE WESTERN AND CENTRAL
BERING THIS AFTERNOON...WITH CUT-OFF LOWS OVER THE EASTERN GULF OF
AK AND SOUTH OF KAMCHATKA...AS WELL AS CENTERED NORTH OF BARROW.
AT THE SURFACE...THINGS LOOK SIMILAR AS THE ATMOSPHERE IS
VERTICALLY STACKED. HIGH PRESSURE IS CENTERED JUST SOUTH OF THE
CENTRAL ALEUTIANS...WITH A SMALL LOW OVER THE EASTERN GULF...AND
BROADER LOWS SOUTH OF KAMCHATKA AND NORTH OF BARROW. A STRONG
PRESSURE GRADIENT BETWEEN THE HIGH AND THE GULF LOW IS SLOWLY
WEAKENING...BUT IS STILL PRODUCING UNSEASONABLY STRONG WINDS
ACROSS KODIAK ISLAND AND NEAR VALDEZ. A MOISTURE RICH WEATHER
FRONT IS DRAPED AROUND THE BERING HIGH AND BEGINNING TO MAKE ITS
WAY INLAND ALONG THE SOUTHWEST AK COAST.

&&

.MODEL DISCUSSION...

MODELS ARE IN EXCELLENT AGREEMENT. THE BERING RIDGE WILL MOVE
SOUTH...ALLOWING THE SURFACE AND UPPER LOWS NEAR KAMCHATKA TO
REACH THE EXTREME WESTERN BERING DURING THE WEEKEND. THE UPPER
LOWS NORTH OF BARROW AND OVER THE EASTERN GULF WILL BEGIN TO MERGE
INTO A BROAD TROUGH OVER THE EASTERN HALF OF MAINLAND AK...WHILE
THEIR SURFACE REFLECTIONS MERGE INTO A GIANT AREA OF LOW PRESSURE
THAT HAS EMBEDDED LOWS ALONG THE NORTHEAST GULF COAST AND OVER THE
YUKON TERRITORY BY THE END OF THE WEEKEND.

THE PRESSURE GRADIENT CURRENTLY OVER THE AKPEN WILL SLOWLY
DIMINISH THROUGH THIS EVENING AS THE FRONT MOVES INLAND OVER
SOUTHWEST AK...BUT THEN BRIEFLY REDEVELOPS SAT NIGHT INTO EARLY
SUN AS A NEW RIDGE POKES INTO THE BERING FROM EASTERN RUSSIA. THIS
WILL MERGE WITH THE HIGH WHICH BY THEN IS SOUTH OF THE ALEUTIANS
AND WILL PLAY A ROLE EARLY NEXT WEEK.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE NORTHERLY OUTFLOW WINDS WILL CONTINUE THROUGH THE WEEKEND. THE
STRONG GUSTY NORTHERLY GAP WINDS THROUGH WHITTIER...VALDEZ...THOMPSON
PASS AND KODIAK ISLAND WILL BEGIN TO DIMINISH DURING THE EVENING.
THIS WILL COINCIDE WITH THE CONTINUAL WEAKENING OF THE PRESSURE
GRADIENT AS THE SURFACE LOW IN THE EASTERN GULF MOVES FARTHER
EASTWARD. THE NORTHERLY WINDS WILL BRING COOLER TEMPERATURES WITH
LOW TEMPERATURES NEAR FREEZING IN THE VALLEYS WITH THE CLEAR
SKIES TONIGHT. THERE IS A CHANCE THAT THE COLDER AREAS OF THE
MATANUSKA VALLEY AS WELL AS PARTS OF EAST ANCHORAGE MAY SEE
TEMPERATURES DROP TO THE FREEZING MARK TONIGHT. THE BIGGEST FACTOR
WILL BE THE CLOUD COVER AND WHILE IT SHOULD BE MOSTLY CLEAR SOME
HIGH CLOUDS MAY MAKE IT INTO THE REGION TOWARD MORNING WHICH WOULD
BE ENOUGH TO KEEP TEMPERATURES ABOVE FREEZING OVER ALL AREAS.  BY
SATURDAY AN UPPER LEVEL SHORTWAVE WILL DROP DOWN FROM THE NORTH
AND BRING A SLIGHT CHANCE OF SHOWERS THROUGH THE ANCHORAGE BOWL.
THIS SYNOPTIC FEATURE WILL INCREASE THE PRESSURE GRADIENTS
BRINGING THE STRONG GUSTY GAP WINDS BACK INTO PICTURE BY EARLY
SUNDAY MORNING FOR THE SOUTHCENTRAL REGION.


&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
ANOTHER ROUND OF RAIN IS IN STORE FOR THE SOUTHWEST MAINLAND THIS
EVENING...AS AN UPPER LEVEL WAVE AND ASSOCIATED FRONTAL SYSTEM AT
THE SURFACE STRETCH AROUND THE NORTHEASTERN PERIPHERY OF THE RIDGE
OVER THE BERING SEA. RAIN ALONG THE SOUTHWEST COAST WILL SPREAD
INLAND OVER MUCH OF THE SOUTHWEST MAINLAND TONIGHT...BEFORE
BECOMING MORE SHOWERY BY SATURDAY AFTERNOON AS THE SURFACE LOW
TRACKS THROUGH THE ALASKA PENINSULA AND INTO THE WESTERN GULF OF
ALASKA. CONDITIONS WILL DRY OUT FAIRLY QUICKLY SATURDAY AFTERNOON
AND EVENING AS GUSTY NORTHWEST FLOW PUSHES ACROSS THE AREA...WITH
THE STRONGEST GUSTS REMAINING MOSTLY CONFINED TO THE ALASKA
PENINSULA. HOWEVER...SCATTERED SHOWERS WILL LIKELY PERSIST
FURTHER INLAND ESPECIALLY ALONG THE MOUNTAINS WITH A SHORTWAVE
DROPPING SOUTH SUNDAY AND SUNDAY NIGHT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
STRONG RIDGING WHICH HAS BROUGHT WIDESPREAD FOG AND STRATUS OVER
THE BERING AND PARTS OF THE ALEUTIAN CHAIN OVER THE PAST FEW DAYS
WILL SLOWLY START TO RETREAT INTO THE NORTHERN PACIFIC...AS AN
UPPER LEVEL DISTURBANCE EXITING NORTHEASTERN RUSSIA TONIGHT TRACKS
INTO THE NORTHERN BERING BY TOMORROW MORNING. THIS FEATURE WILL
CONTINUE TO TRACK SOUTHEAST OVER THE EASTERN BERING/ALEUTIANS...
BRINGING ANOTHER ROUND OF RAIN AND GUSTY WEST TO NORTHWEST FLOW
TO THE EASTERN HALF OF THE BERING AND ALEUTIAN CHAIN. THIS WAVE
WILL QUICKLY WORK ITS WAY THROUGH THE EASTERN BERING/ALEUTIANS BY
SUNDAY MORNING...USHERING IN A SHOT OF COLDER TEMPERATURES FROM
THE NORTH...ALONG WITH DIMINISHING GUSTS AND A TRANSITION TO
SHOWERY CONDITIONS. FURTHER WEST...MOIST SOUTHERLY FLOW WILL
CONTINUE TO DOMINATE WESTERN ALEUTIANS/BERING...AS THEY REMAIN ON
THE WESTERN PERIPHERY OF DEEP RIDGING OVER THE CENTRAL BERING
THROUGH SATURDAY. A FRONTAL SYSTEM ASSOCIATED WITH A VERTICALLY
STACKED LOW WEST OF THE WESTERN ALEUTIANS WILL CLIP THE AREA BY
SUNDAY MORNING...BRINING A WET AND WINDY CONDITIONS TO THE WESTERN
ALEUTIANS THROUGH MONDAY MORNING.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...MON THROUGH FRI)...MODELS
ARE IN FAIRLY GOOD AGREEMENT FOR THE EARLY PART OF NEXT WEEK. SO
FOR THE TIME BEING...FORECAST CONFIDENCE IS RELATIVELY HIGH. THE
HIGHLIGHT OF THIS PERIOD WILL BE THE TRANSITION FROM FAIRLY
STRONG...COOL NORTHWEST FLOW THROUGH MUCH OF SOUTH CENTRAL TO A
CALMER AND SLIGHTLY WARMER PATTERN. THE AREA OF THE LOW PRESSURE
IN THE NORTHEAST GULF WILL WORK IN COMBINATION WITH A DEVELOPING
HIGH OVER THE BRISTOL BAY AREA ON MONDAY TO KEEP THE PRESSURE
GRADIENT TIGHT. BUT AS THIS LOW PULLS FURTHER TO THE SOUTH AND
EAST ON TUESDAY...HIGHER PRESSURE WILL BUILD OVER SOUTHWEST
ALASKA. THIS WILL KEEP THINGS DRY ACROSS JUST ABOUT ALL OF THE
SOUTHERN HALF OF THE MAINLAND THROUGH TUESDAY. TEMPERATURES SHOULD
BE ABLE TO REBOUND TO A FEW DEGREES AS WELL WITH THE FLOW BECOMING
MORE WESTERLY AND 850 MB TEMPERATURES CLIMBING 5 TO 6 DEGREES
CELSIUS.

THE MORE ACTIVE WEATHER WILL BE OVER THE BERING SEA TO START THE
WEEK. THE REMNANTS OF TYPHOON ATSANI WILL CONTINUE TO DRIFT OVER
THE FAR WESTERN BERING. WHILE WINDS SHOULD ALL BE BELOW SMALL
CRAFT LEVEL...IT WILL KEEP A CHANCE FOR RAIN IN THE FORECAST. IT
WILL ALSO LEAVE A DECAYING WARM FRONT ALONG THE CENTRAL AND
EASTERN ALEUTIANS. A WEAK WAVE TRIES TO DEVELOP ALONG THIS
BOUNDARY AS WE GET TO WEDNESDAY. THIS IS WHERE MODELS START TO
DIFFER WITH THE GFS BEING RATHER AGGRESSIVE WITH THIS WAVE AND
SWINGING ANOTHER STORM THROUGH THE BERING STRAIT. MEANWHILE...THE
EC IS MUCH WEAKER AND ONLY BRINGS LIGHT RAIN TO THE SOUTHWEST.
BOTH GLOBAL MODELS SHOW SIGNS OF CYCLOGENESIS IN THE GULF BY THE
LATTER HALF OF THE WEEK WHICH WOULD MEAN A RETURN TO COOLER AND
WETTER WEATHER FOR MUCH OF THE MAINLAND.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 130 131 132 150 155 165.
FIRE WEATHER...NONE.
&&

$$

SYNOPSIS AND MODEL DISCUSSION...DS
SOUTHCENTRAL ALASKA...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP
LONG TERM...MO





000
FXAK68 PAFC 290016
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
416 PM AKDT FRI AUG 28 2015

.ANALYSIS AND UPPER LEVELS...

MASSIVE UPPER LEVEL RIDGE PERSISTS OVER THE WESTERN AND CENTRAL
BERING THIS AFTERNOON...WITH CUT-OFF LOWS OVER THE EASTERN GULF OF
AK AND SOUTH OF KAMCHATKA...AS WELL AS CENTERED NORTH OF BARROW.
AT THE SURFACE...THINGS LOOK SIMILAR AS THE ATMOSPHERE IS
VERTICALLY STACKED. HIGH PRESSURE IS CENTERED JUST SOUTH OF THE
CENTRAL ALEUTIANS...WITH A SMALL LOW OVER THE EASTERN GULF...AND
BROADER LOWS SOUTH OF KAMCHATKA AND NORTH OF BARROW. A STRONG
PRESSURE GRADIENT BETWEEN THE HIGH AND THE GULF LOW IS SLOWLY
WEAKENING...BUT IS STILL PRODUCING UNSEASONABLY STRONG WINDS
ACROSS KODIAK ISLAND AND NEAR VALDEZ. A MOISTURE RICH WEATHER
FRONT IS DRAPED AROUND THE BERING HIGH AND BEGINNING TO MAKE ITS
WAY INLAND ALONG THE SOUTHWEST AK COAST.

&&

.MODEL DISCUSSION...

MODELS ARE IN EXCELLENT AGREEMENT. THE BERING RIDGE WILL MOVE
SOUTH...ALLOWING THE SURFACE AND UPPER LOWS NEAR KAMCHATKA TO
REACH THE EXTREME WESTERN BERING DURING THE WEEKEND. THE UPPER
LOWS NORTH OF BARROW AND OVER THE EASTERN GULF WILL BEGIN TO MERGE
INTO A BROAD TROUGH OVER THE EASTERN HALF OF MAINLAND AK...WHILE
THEIR SURFACE REFLECTIONS MERGE INTO A GIANT AREA OF LOW PRESSURE
THAT HAS EMBEDDED LOWS ALONG THE NORTHEAST GULF COAST AND OVER THE
YUKON TERRITORY BY THE END OF THE WEEKEND.

THE PRESSURE GRADIENT CURRENTLY OVER THE AKPEN WILL SLOWLY
DIMINISH THROUGH THIS EVENING AS THE FRONT MOVES INLAND OVER
SOUTHWEST AK...BUT THEN BRIEFLY REDEVELOPS SAT NIGHT INTO EARLY
SUN AS A NEW RIDGE POKES INTO THE BERING FROM EASTERN RUSSIA. THIS
WILL MERGE WITH THE HIGH WHICH BY THEN IS SOUTH OF THE ALEUTIANS
AND WILL PLAY A ROLE EARLY NEXT WEEK.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE NORTHERLY OUTFLOW WINDS WILL CONTINUE THROUGH THE WEEKEND. THE
STRONG GUSTY NORTHERLY GAP WINDS THROUGH WHITTIER...VALDEZ...THOMPSON
PASS AND KODIAK ISLAND WILL BEGIN TO DIMINISH DURING THE EVENING.
THIS WILL COINCIDE WITH THE CONTINUAL WEAKENING OF THE PRESSURE
GRADIENT AS THE SURFACE LOW IN THE EASTERN GULF MOVES FARTHER
EASTWARD. THE NORTHERLY WINDS WILL BRING COOLER TEMPERATURES WITH
LOW TEMPERATURES NEAR FREEZING IN THE VALLEYS WITH THE CLEAR
SKIES TONIGHT. THERE IS A CHANCE THAT THE COLDER AREAS OF THE
MATANUSKA VALLEY AS WELL AS PARTS OF EAST ANCHORAGE MAY SEE
TEMPERATURES DROP TO THE FREEZING MARK TONIGHT. THE BIGGEST FACTOR
WILL BE THE CLOUD COVER AND WHILE IT SHOULD BE MOSTLY CLEAR SOME
HIGH CLOUDS MAY MAKE IT INTO THE REGION TOWARD MORNING WHICH WOULD
BE ENOUGH TO KEEP TEMPERATURES ABOVE FREEZING OVER ALL AREAS.  BY
SATURDAY AN UPPER LEVEL SHORTWAVE WILL DROP DOWN FROM THE NORTH
AND BRING A SLIGHT CHANCE OF SHOWERS THROUGH THE ANCHORAGE BOWL.
THIS SYNOPTIC FEATURE WILL INCREASE THE PRESSURE GRADIENTS
BRINGING THE STRONG GUSTY GAP WINDS BACK INTO PICTURE BY EARLY
SUNDAY MORNING FOR THE SOUTHCENTRAL REGION.


&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
ANOTHER ROUND OF RAIN IS IN STORE FOR THE SOUTHWEST MAINLAND THIS
EVENING...AS AN UPPER LEVEL WAVE AND ASSOCIATED FRONTAL SYSTEM AT
THE SURFACE STRETCH AROUND THE NORTHEASTERN PERIPHERY OF THE RIDGE
OVER THE BERING SEA. RAIN ALONG THE SOUTHWEST COAST WILL SPREAD
INLAND OVER MUCH OF THE SOUTHWEST MAINLAND TONIGHT...BEFORE
BECOMING MORE SHOWERY BY SATURDAY AFTERNOON AS THE SURFACE LOW
TRACKS THROUGH THE ALASKA PENINSULA AND INTO THE WESTERN GULF OF
ALASKA. CONDITIONS WILL DRY OUT FAIRLY QUICKLY SATURDAY AFTERNOON
AND EVENING AS GUSTY NORTHWEST FLOW PUSHES ACROSS THE AREA...WITH
THE STRONGEST GUSTS REMAINING MOSTLY CONFINED TO THE ALASKA
PENINSULA. HOWEVER...SCATTERED SHOWERS WILL LIKELY PERSIST
FURTHER INLAND ESPECIALLY ALONG THE MOUNTAINS WITH A SHORTWAVE
DROPPING SOUTH SUNDAY AND SUNDAY NIGHT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
STRONG RIDGING WHICH HAS BROUGHT WIDESPREAD FOG AND STRATUS OVER
THE BERING AND PARTS OF THE ALEUTIAN CHAIN OVER THE PAST FEW DAYS
WILL SLOWLY START TO RETREAT INTO THE NORTHERN PACIFIC...AS AN
UPPER LEVEL DISTURBANCE EXITING NORTHEASTERN RUSSIA TONIGHT TRACKS
INTO THE NORTHERN BERING BY TOMORROW MORNING. THIS FEATURE WILL
CONTINUE TO TRACK SOUTHEAST OVER THE EASTERN BERING/ALEUTIANS...
BRINGING ANOTHER ROUND OF RAIN AND GUSTY WEST TO NORTHWEST FLOW
TO THE EASTERN HALF OF THE BERING AND ALEUTIAN CHAIN. THIS WAVE
WILL QUICKLY WORK ITS WAY THROUGH THE EASTERN BERING/ALEUTIANS BY
SUNDAY MORNING...USHERING IN A SHOT OF COLDER TEMPERATURES FROM
THE NORTH...ALONG WITH DIMINISHING GUSTS AND A TRANSITION TO
SHOWERY CONDITIONS. FURTHER WEST...MOIST SOUTHERLY FLOW WILL
CONTINUE TO DOMINATE WESTERN ALEUTIANS/BERING...AS THEY REMAIN ON
THE WESTERN PERIPHERY OF DEEP RIDGING OVER THE CENTRAL BERING
THROUGH SATURDAY. A FRONTAL SYSTEM ASSOCIATED WITH A VERTICALLY
STACKED LOW WEST OF THE WESTERN ALEUTIANS WILL CLIP THE AREA BY
SUNDAY MORNING...BRINING A WET AND WINDY CONDITIONS TO THE WESTERN
ALEUTIANS THROUGH MONDAY MORNING.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...MON THROUGH FRI)...MODELS
ARE IN FAIRLY GOOD AGREEMENT FOR THE EARLY PART OF NEXT WEEK. SO
FOR THE TIME BEING...FORECAST CONFIDENCE IS RELATIVELY HIGH. THE
HIGHLIGHT OF THIS PERIOD WILL BE THE TRANSITION FROM FAIRLY
STRONG...COOL NORTHWEST FLOW THROUGH MUCH OF SOUTH CENTRAL TO A
CALMER AND SLIGHTLY WARMER PATTERN. THE AREA OF THE LOW PRESSURE
IN THE NORTHEAST GULF WILL WORK IN COMBINATION WITH A DEVELOPING
HIGH OVER THE BRISTOL BAY AREA ON MONDAY TO KEEP THE PRESSURE
GRADIENT TIGHT. BUT AS THIS LOW PULLS FURTHER TO THE SOUTH AND
EAST ON TUESDAY...HIGHER PRESSURE WILL BUILD OVER SOUTHWEST
ALASKA. THIS WILL KEEP THINGS DRY ACROSS JUST ABOUT ALL OF THE
SOUTHERN HALF OF THE MAINLAND THROUGH TUESDAY. TEMPERATURES SHOULD
BE ABLE TO REBOUND TO A FEW DEGREES AS WELL WITH THE FLOW BECOMING
MORE WESTERLY AND 850 MB TEMPERATURES CLIMBING 5 TO 6 DEGREES
CELSIUS.

THE MORE ACTIVE WEATHER WILL BE OVER THE BERING SEA TO START THE
WEEK. THE REMNANTS OF TYPHOON ATSANI WILL CONTINUE TO DRIFT OVER
THE FAR WESTERN BERING. WHILE WINDS SHOULD ALL BE BELOW SMALL
CRAFT LEVEL...IT WILL KEEP A CHANCE FOR RAIN IN THE FORECAST. IT
WILL ALSO LEAVE A DECAYING WARM FRONT ALONG THE CENTRAL AND
EASTERN ALEUTIANS. A WEAK WAVE TRIES TO DEVELOP ALONG THIS
BOUNDARY AS WE GET TO WEDNESDAY. THIS IS WHERE MODELS START TO
DIFFER WITH THE GFS BEING RATHER AGGRESSIVE WITH THIS WAVE AND
SWINGING ANOTHER STORM THROUGH THE BERING STRAIT. MEANWHILE...THE
EC IS MUCH WEAKER AND ONLY BRINGS LIGHT RAIN TO THE SOUTHWEST.
BOTH GLOBAL MODELS SHOW SIGNS OF CYCLOGENESIS IN THE GULF BY THE
LATTER HALF OF THE WEEK WHICH WOULD MEAN A RETURN TO COOLER AND
WETTER WEATHER FOR MUCH OF THE MAINLAND.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 130 131 132 150 155 165.
FIRE WEATHER...NONE.
&&

$$

SYNOPSIS AND MODEL DISCUSSION...DS
SOUTHCENTRAL ALASKA...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP
LONG TERM...MO




000
FXAK68 PAFC 290016
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
416 PM AKDT FRI AUG 28 2015

.ANALYSIS AND UPPER LEVELS...

MASSIVE UPPER LEVEL RIDGE PERSISTS OVER THE WESTERN AND CENTRAL
BERING THIS AFTERNOON...WITH CUT-OFF LOWS OVER THE EASTERN GULF OF
AK AND SOUTH OF KAMCHATKA...AS WELL AS CENTERED NORTH OF BARROW.
AT THE SURFACE...THINGS LOOK SIMILAR AS THE ATMOSPHERE IS
VERTICALLY STACKED. HIGH PRESSURE IS CENTERED JUST SOUTH OF THE
CENTRAL ALEUTIANS...WITH A SMALL LOW OVER THE EASTERN GULF...AND
BROADER LOWS SOUTH OF KAMCHATKA AND NORTH OF BARROW. A STRONG
PRESSURE GRADIENT BETWEEN THE HIGH AND THE GULF LOW IS SLOWLY
WEAKENING...BUT IS STILL PRODUCING UNSEASONABLY STRONG WINDS
ACROSS KODIAK ISLAND AND NEAR VALDEZ. A MOISTURE RICH WEATHER
FRONT IS DRAPED AROUND THE BERING HIGH AND BEGINNING TO MAKE ITS
WAY INLAND ALONG THE SOUTHWEST AK COAST.

&&

.MODEL DISCUSSION...

MODELS ARE IN EXCELLENT AGREEMENT. THE BERING RIDGE WILL MOVE
SOUTH...ALLOWING THE SURFACE AND UPPER LOWS NEAR KAMCHATKA TO
REACH THE EXTREME WESTERN BERING DURING THE WEEKEND. THE UPPER
LOWS NORTH OF BARROW AND OVER THE EASTERN GULF WILL BEGIN TO MERGE
INTO A BROAD TROUGH OVER THE EASTERN HALF OF MAINLAND AK...WHILE
THEIR SURFACE REFLECTIONS MERGE INTO A GIANT AREA OF LOW PRESSURE
THAT HAS EMBEDDED LOWS ALONG THE NORTHEAST GULF COAST AND OVER THE
YUKON TERRITORY BY THE END OF THE WEEKEND.

THE PRESSURE GRADIENT CURRENTLY OVER THE AKPEN WILL SLOWLY
DIMINISH THROUGH THIS EVENING AS THE FRONT MOVES INLAND OVER
SOUTHWEST AK...BUT THEN BRIEFLY REDEVELOPS SAT NIGHT INTO EARLY
SUN AS A NEW RIDGE POKES INTO THE BERING FROM EASTERN RUSSIA. THIS
WILL MERGE WITH THE HIGH WHICH BY THEN IS SOUTH OF THE ALEUTIANS
AND WILL PLAY A ROLE EARLY NEXT WEEK.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE NORTHERLY OUTFLOW WINDS WILL CONTINUE THROUGH THE WEEKEND. THE
STRONG GUSTY NORTHERLY GAP WINDS THROUGH WHITTIER...VALDEZ...THOMPSON
PASS AND KODIAK ISLAND WILL BEGIN TO DIMINISH DURING THE EVENING.
THIS WILL COINCIDE WITH THE CONTINUAL WEAKENING OF THE PRESSURE
GRADIENT AS THE SURFACE LOW IN THE EASTERN GULF MOVES FARTHER
EASTWARD. THE NORTHERLY WINDS WILL BRING COOLER TEMPERATURES WITH
LOW TEMPERATURES NEAR FREEZING IN THE VALLEYS WITH THE CLEAR
SKIES TONIGHT. THERE IS A CHANCE THAT THE COLDER AREAS OF THE
MATANUSKA VALLEY AS WELL AS PARTS OF EAST ANCHORAGE MAY SEE
TEMPERATURES DROP TO THE FREEZING MARK TONIGHT. THE BIGGEST FACTOR
WILL BE THE CLOUD COVER AND WHILE IT SHOULD BE MOSTLY CLEAR SOME
HIGH CLOUDS MAY MAKE IT INTO THE REGION TOWARD MORNING WHICH WOULD
BE ENOUGH TO KEEP TEMPERATURES ABOVE FREEZING OVER ALL AREAS.  BY
SATURDAY AN UPPER LEVEL SHORTWAVE WILL DROP DOWN FROM THE NORTH
AND BRING A SLIGHT CHANCE OF SHOWERS THROUGH THE ANCHORAGE BOWL.
THIS SYNOPTIC FEATURE WILL INCREASE THE PRESSURE GRADIENTS
BRINGING THE STRONG GUSTY GAP WINDS BACK INTO PICTURE BY EARLY
SUNDAY MORNING FOR THE SOUTHCENTRAL REGION.


&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
ANOTHER ROUND OF RAIN IS IN STORE FOR THE SOUTHWEST MAINLAND THIS
EVENING...AS AN UPPER LEVEL WAVE AND ASSOCIATED FRONTAL SYSTEM AT
THE SURFACE STRETCH AROUND THE NORTHEASTERN PERIPHERY OF THE RIDGE
OVER THE BERING SEA. RAIN ALONG THE SOUTHWEST COAST WILL SPREAD
INLAND OVER MUCH OF THE SOUTHWEST MAINLAND TONIGHT...BEFORE
BECOMING MORE SHOWERY BY SATURDAY AFTERNOON AS THE SURFACE LOW
TRACKS THROUGH THE ALASKA PENINSULA AND INTO THE WESTERN GULF OF
ALASKA. CONDITIONS WILL DRY OUT FAIRLY QUICKLY SATURDAY AFTERNOON
AND EVENING AS GUSTY NORTHWEST FLOW PUSHES ACROSS THE AREA...WITH
THE STRONGEST GUSTS REMAINING MOSTLY CONFINED TO THE ALASKA
PENINSULA. HOWEVER...SCATTERED SHOWERS WILL LIKELY PERSIST
FURTHER INLAND ESPECIALLY ALONG THE MOUNTAINS WITH A SHORTWAVE
DROPPING SOUTH SUNDAY AND SUNDAY NIGHT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
STRONG RIDGING WHICH HAS BROUGHT WIDESPREAD FOG AND STRATUS OVER
THE BERING AND PARTS OF THE ALEUTIAN CHAIN OVER THE PAST FEW DAYS
WILL SLOWLY START TO RETREAT INTO THE NORTHERN PACIFIC...AS AN
UPPER LEVEL DISTURBANCE EXITING NORTHEASTERN RUSSIA TONIGHT TRACKS
INTO THE NORTHERN BERING BY TOMORROW MORNING. THIS FEATURE WILL
CONTINUE TO TRACK SOUTHEAST OVER THE EASTERN BERING/ALEUTIANS...
BRINGING ANOTHER ROUND OF RAIN AND GUSTY WEST TO NORTHWEST FLOW
TO THE EASTERN HALF OF THE BERING AND ALEUTIAN CHAIN. THIS WAVE
WILL QUICKLY WORK ITS WAY THROUGH THE EASTERN BERING/ALEUTIANS BY
SUNDAY MORNING...USHERING IN A SHOT OF COLDER TEMPERATURES FROM
THE NORTH...ALONG WITH DIMINISHING GUSTS AND A TRANSITION TO
SHOWERY CONDITIONS. FURTHER WEST...MOIST SOUTHERLY FLOW WILL
CONTINUE TO DOMINATE WESTERN ALEUTIANS/BERING...AS THEY REMAIN ON
THE WESTERN PERIPHERY OF DEEP RIDGING OVER THE CENTRAL BERING
THROUGH SATURDAY. A FRONTAL SYSTEM ASSOCIATED WITH A VERTICALLY
STACKED LOW WEST OF THE WESTERN ALEUTIANS WILL CLIP THE AREA BY
SUNDAY MORNING...BRINING A WET AND WINDY CONDITIONS TO THE WESTERN
ALEUTIANS THROUGH MONDAY MORNING.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...MON THROUGH FRI)...MODELS
ARE IN FAIRLY GOOD AGREEMENT FOR THE EARLY PART OF NEXT WEEK. SO
FOR THE TIME BEING...FORECAST CONFIDENCE IS RELATIVELY HIGH. THE
HIGHLIGHT OF THIS PERIOD WILL BE THE TRANSITION FROM FAIRLY
STRONG...COOL NORTHWEST FLOW THROUGH MUCH OF SOUTH CENTRAL TO A
CALMER AND SLIGHTLY WARMER PATTERN. THE AREA OF THE LOW PRESSURE
IN THE NORTHEAST GULF WILL WORK IN COMBINATION WITH A DEVELOPING
HIGH OVER THE BRISTOL BAY AREA ON MONDAY TO KEEP THE PRESSURE
GRADIENT TIGHT. BUT AS THIS LOW PULLS FURTHER TO THE SOUTH AND
EAST ON TUESDAY...HIGHER PRESSURE WILL BUILD OVER SOUTHWEST
ALASKA. THIS WILL KEEP THINGS DRY ACROSS JUST ABOUT ALL OF THE
SOUTHERN HALF OF THE MAINLAND THROUGH TUESDAY. TEMPERATURES SHOULD
BE ABLE TO REBOUND TO A FEW DEGREES AS WELL WITH THE FLOW BECOMING
MORE WESTERLY AND 850 MB TEMPERATURES CLIMBING 5 TO 6 DEGREES
CELSIUS.

THE MORE ACTIVE WEATHER WILL BE OVER THE BERING SEA TO START THE
WEEK. THE REMNANTS OF TYPHOON ATSANI WILL CONTINUE TO DRIFT OVER
THE FAR WESTERN BERING. WHILE WINDS SHOULD ALL BE BELOW SMALL
CRAFT LEVEL...IT WILL KEEP A CHANCE FOR RAIN IN THE FORECAST. IT
WILL ALSO LEAVE A DECAYING WARM FRONT ALONG THE CENTRAL AND
EASTERN ALEUTIANS. A WEAK WAVE TRIES TO DEVELOP ALONG THIS
BOUNDARY AS WE GET TO WEDNESDAY. THIS IS WHERE MODELS START TO
DIFFER WITH THE GFS BEING RATHER AGGRESSIVE WITH THIS WAVE AND
SWINGING ANOTHER STORM THROUGH THE BERING STRAIT. MEANWHILE...THE
EC IS MUCH WEAKER AND ONLY BRINGS LIGHT RAIN TO THE SOUTHWEST.
BOTH GLOBAL MODELS SHOW SIGNS OF CYCLOGENESIS IN THE GULF BY THE
LATTER HALF OF THE WEEK WHICH WOULD MEAN A RETURN TO COOLER AND
WETTER WEATHER FOR MUCH OF THE MAINLAND.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 130 131 132 150 155 165.
FIRE WEATHER...NONE.
&&

$$

SYNOPSIS AND MODEL DISCUSSION...DS
SOUTHCENTRAL ALASKA...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP
LONG TERM...MO




000
FXAK68 PAFC 281307
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
507 AM AKDT FRI AUG 28 2015

.ANALYSIS AND UPPER LEVELS...
AN AMPLIFIED UPPER TROUGH SPANS FROM THE ALASKA ARCTIC COAST
THROUGH THE GULF. THE SPIN OF THE GULF LOW IS SEEN CLEARLY ON
IR/WV SATELLITE IMAGERY EARLY THIS MORNING...PULLING A DRIER AND
COOLER AIR MASS INTO THE GULF. TO THE WEST...THE PERSISTENT RIDGE
PATTERN REMAINS OVER THE CENTRAL ALEUTIANS WITH ABUNDANT MOISTURE
RIDING OVER THE RIDGE ACROSS THE NORTHERN BERING. AT THE
SURFACE...NORTH TO WEST FLOW SET UP ACROSS THE SOUTHERN MAINLAND
BEHIND A COLD FRONT THAT MOVED THROUGH LAST NIGHT. GUSTY
CONDITIONS WERE STRONGEST ACROSS ANTICIPATED AREAS ALONG PRINCE
WILLIAM SOUND...KENAI...AND WESTERN GULF WITH MAXIMUM GUSTS
RECORDED BETWEEN 60 TO 70 MPH. ACROSS THE BERING...A FRONT IS
STRETCHED ALONG THE NORTHERN WATERS BRINGING RAIN INTO THE
PRIBILOFS. AREAS OF FOG AND LOW CLOUDS CONTINUE ACROSS MUCH OF THE
SOUTHERN BERING AND ALEUTIANS.

&&

.MODEL DISCUSSION...
THERE IS A GREAT AMOUNT OF COMPLEXITY WITH THE EVOLVING PATTERN
THROUGH THE WEEKEND. MODELS HAVE TO HANDLE TWO CLOSED LOWS WITHIN THE
TROUGH OVER ALASKA AND STRONG SHORTWAVES THAT PASS FROM THE ARCTIC
TO GULF. MODELS ARE COMPARABLE WITH THE OVERALL SYNOPTIC
PATTERN...HOWEVER THERE IS UNCERTAINTY IN ALL OF THE SOLUTIONS
THROUGH THE WEEKEND. THE MODELS ARE ALL SHOWING SIGNIFICANT HEIGHT
FALLS FOR THE LOW OVER THE MAINLAND GOING FROM 543 DAM TO 528 DAM
BY EARLY SUNDAY MORNING. MODEL MOISTURE AND TEMPERATURE FIELDS DO
NOT LOOK REPRESENTATIVE OF THIS PATTERN AS THE SURFACE PATTERN
REMAINS RELATIVELY THE SAME...WHEREAS MODELS SHOULD BE SHOWING A
COOLER TREND WITH HIGHER SURFACE MOISTURE. THE CURRENT FORECAST
PACKAGE WAS UPDATED WITH THE NAM...GEM...AND ECMWF TO CAPTURE THE
THE TRENDS INTO THE WEEKEND WITH ONLY MINOR CHANGES MADE.

&&

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
NORTHWESTERLY FLOW ALOFT WILL CONTINUE OVER THE AREA INTO
SATURDAY. THIS WILL KEEP SOUTH CENTRAL ALASKA DRY WITH SOME
OFFSHORE FLOW AT THE LOWER LEVELS. THE PRESSURE GRADIENT WILL
WEAKEN TODAY HOWEVER AS THE LOW OVER THE SOUTHEAST GULF OF ALASKA
CONTINUES TO EXIT TO THE SOUTHEAST. WITH A DRY AND COLD AIR MASS
OVER THE AREA TEMPERATURES ARE EXPECTED TO BY QUITE COOL OVER THE
NEXT COUPLE OF DAYS...WITH SOME BELOW FREEZING TEMPERATURES
POSSIBLE TONIGHT AND FRIDAY NIGHT OVER MUCH OF THE AREA. THIS
INCLUDES EAST ANCHORAGE AND THE MATANUSKA VALLEY. A STRONG
ARCTIC LOW WILL SLOWLY PUSH SOUTH THROUGH SATURDAY NIGHT AND COVER
MUCH OF ALASKA BY EARLY SUNDAY MORNING. THIS WILL TURN THE UPPER
LEVEL MORE WESTERLY RATHER THAN NORTHWESTERLY AND BRING IN SOME
CYCLONIC FLOW. THIS WILL RE-INTRODUCE A CHANCE OF SHOWERS TO SOUTH
CENTRAL...BEGINNING IN THE SUSITNA VALLEY SATURDAY AFTERNOON AND
PUSHING SOUTH THROUGH ANCHORAGE AND THE KENAI PENINSULA SATURDAY
NIGHT. BUT THE CHANCES OF SHOWERS WILL BE FAIRLY LOW DUE TO THE
DOWN-SLOPING OFF THE ALASKA RANGE AND THE LINGERING DRY AIR MASS
OVER THE AREA.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 THROUGH 3)... A
FRONTAL SYSTEM STRETCHED OVER TOP THE LARGE RIDGE IN THE BERING
WILL START BRINGING RAIN TO THE WESTERN CAPES AND WESTERN
PENINSULA THIS MORNING THEN THE BRISTOL BAY AREA AND REMAINDER OF
THE ALASKA PENINSULA THIS AFTERNOON AND EVENING. RAIN ALONG AND
NEAR THE COAST WILL CONTINUE THROUGH THE OVERNIGHT HOURS AND INTO
SATURDAY MORNING AS A SURFACE LOW TRACK FROM NORTHWEST TO
SOUTHEAST ALONG THE COAST OF MAINLAND SOUTHWEST ALASKA. CONDITIONS
WILL DRY OUT FAIRLY QUICKLY SATURDAY AFTERNOON AND EVENING AS
NORTHWEST FLOW PUSHES ACROSS THE AREA...THOUGH SCATTERED SHOWERS
WILL LIKELY PERSIST FURTHER INLAND ESPECIALLY ALONG THE MOUNTAINS
WITH A SHORTWAVE DROPPING SOUTH SUNDAY AND SUNDAY NIGHT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 THROUGH 3)...
STRONG RIDGING WILL CONTINUE TO PERSIST OVER THE CENTRAL ALEUTIANS
AND EXTEND INTO THE BERING. A TROUGH WILL SWING TOWARDS THE
WESTERN ALEUTIANS LATE FRIDAY NIGHT AND EARLY SATURDAY MORNING
WITH A VERTICALLY STACKED LOW FOLLOWING SATURDAY NIGHT AND
REMAINING FAIRLY STATIONARY TO THE WEST OF SHEMYA THROUGH SUNDAY
NIGHT. A SMALL LOW TRACKING ACROSS THE NORTHEASTERN SIDE OF
BRISTOL BAY WILL BRING SOME WESTERLY GALES BEHIND IT LATE FRIDAY
NIGHT THROUGH SATURDAY MORNING.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

BEGINNING THE EXTENDED PERIOD ON SATURDAY EVENING...THE STATE OF
ALASKA WILL BE UNDER THE INFLUENCE OF A LARGE ARCTIC TROUGH
CENTERED OVER WESTERN ALASKA...WITH A WEAKLY PHASED SHORTWAVE
TROUGH IN NORTHWEST FLOW TRACKING INTO THE GULF OF ALASKA. AN
ASSOCIATED 140 KT UPPER LEVEL JET STREAK WILL BE TRACKING OVER
THE GULF AS THE ARCTIC TROUGH MAKES SOUTHWARD PROGRESS THROUGH
MONDAY. THIS WILL REINVIGORATE THE OFFSHORE FLOW PATTERN AS A
SURFACE LOW FORMS IN THE GULF OF ALASKA AND TRACKS TOWARD THE
PANHANDLE. RAIN AND SNOW SHOWERS WILL REMAIN LARGELY OVER THE
MOUNTAINS THROUGH MONDAY...ALTHOUGH LOWER ELEVATION SHOWERS WILL
BE MORE PREVALENT ACROSS THE LOWER KUSKOKWIM VALLEY AND BRISTOL
BAY REGIONS. OTHERWISE...RAPID DRYING WILL COMMENCE ON MONDAY AS
THE TROUGH CONTINUES TO DIG THROUGH THE SOUTHEAST GULF...AND
OFFSHORE AND DOWNSLOPE FLOW DRIES THE ATMOSPHERIC COLUMN. WEAK
RIDGING ALOFT WILL MOVE OVER THE STATE FROM WEST TO EAST TUESDAY
AND WEDNESDAY...WITH A SLOW WARMUP BUT CONTINUED DRY CONDITIONS.
PRECIPITATION CHANCES REDEVELOP TOWARD LATE WEEK AS A SERIES OF
WEAK LOWS TRACK FROM THE BERING INTO SOUTHWEST ALASKA. WITH THAT
SAID...THE UPPER LEVEL FLOW WILL REMAIN RATHER WEAK...WITH NO
SIGNIFICANT STORMS OR WET PERIODS ANTICIPATED WITH THE CHANGE IN
PATTERN. DUE TO SLIGHT UNCERTAINTY IN THE EXTENDED PERIOD TOWARD
THE END OF NEXT WEEK...A BLENDED WPC ENSEMBLE APPROACH WAS FAVORED
WITH SOME BLEND OF ECMWF AND GFS SATURDAY EVENING THROUGH MONDAY
TO CAPTURE OUTFLOW WINDS ALONG THE COAST.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING 125 131.
MARINE...GALE WARNING 119 121 127 128 130 131 132 150 155 165.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...KH
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
LONG TERM...JA





000
FXAK68 PAFC 281307
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
507 AM AKDT FRI AUG 28 2015

.ANALYSIS AND UPPER LEVELS...
AN AMPLIFIED UPPER TROUGH SPANS FROM THE ALASKA ARCTIC COAST
THROUGH THE GULF. THE SPIN OF THE GULF LOW IS SEEN CLEARLY ON
IR/WV SATELLITE IMAGERY EARLY THIS MORNING...PULLING A DRIER AND
COOLER AIR MASS INTO THE GULF. TO THE WEST...THE PERSISTENT RIDGE
PATTERN REMAINS OVER THE CENTRAL ALEUTIANS WITH ABUNDANT MOISTURE
RIDING OVER THE RIDGE ACROSS THE NORTHERN BERING. AT THE
SURFACE...NORTH TO WEST FLOW SET UP ACROSS THE SOUTHERN MAINLAND
BEHIND A COLD FRONT THAT MOVED THROUGH LAST NIGHT. GUSTY
CONDITIONS WERE STRONGEST ACROSS ANTICIPATED AREAS ALONG PRINCE
WILLIAM SOUND...KENAI...AND WESTERN GULF WITH MAXIMUM GUSTS
RECORDED BETWEEN 60 TO 70 MPH. ACROSS THE BERING...A FRONT IS
STRETCHED ALONG THE NORTHERN WATERS BRINGING RAIN INTO THE
PRIBILOFS. AREAS OF FOG AND LOW CLOUDS CONTINUE ACROSS MUCH OF THE
SOUTHERN BERING AND ALEUTIANS.

&&

.MODEL DISCUSSION...
THERE IS A GREAT AMOUNT OF COMPLEXITY WITH THE EVOLVING PATTERN
THROUGH THE WEEKEND. MODELS HAVE TO HANDLE TWO CLOSED LOWS WITHIN THE
TROUGH OVER ALASKA AND STRONG SHORTWAVES THAT PASS FROM THE ARCTIC
TO GULF. MODELS ARE COMPARABLE WITH THE OVERALL SYNOPTIC
PATTERN...HOWEVER THERE IS UNCERTAINTY IN ALL OF THE SOLUTIONS
THROUGH THE WEEKEND. THE MODELS ARE ALL SHOWING SIGNIFICANT HEIGHT
FALLS FOR THE LOW OVER THE MAINLAND GOING FROM 543 DAM TO 528 DAM
BY EARLY SUNDAY MORNING. MODEL MOISTURE AND TEMPERATURE FIELDS DO
NOT LOOK REPRESENTATIVE OF THIS PATTERN AS THE SURFACE PATTERN
REMAINS RELATIVELY THE SAME...WHEREAS MODELS SHOULD BE SHOWING A
COOLER TREND WITH HIGHER SURFACE MOISTURE. THE CURRENT FORECAST
PACKAGE WAS UPDATED WITH THE NAM...GEM...AND ECMWF TO CAPTURE THE
THE TRENDS INTO THE WEEKEND WITH ONLY MINOR CHANGES MADE.

&&

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
NORTHWESTERLY FLOW ALOFT WILL CONTINUE OVER THE AREA INTO
SATURDAY. THIS WILL KEEP SOUTH CENTRAL ALASKA DRY WITH SOME
OFFSHORE FLOW AT THE LOWER LEVELS. THE PRESSURE GRADIENT WILL
WEAKEN TODAY HOWEVER AS THE LOW OVER THE SOUTHEAST GULF OF ALASKA
CONTINUES TO EXIT TO THE SOUTHEAST. WITH A DRY AND COLD AIR MASS
OVER THE AREA TEMPERATURES ARE EXPECTED TO BY QUITE COOL OVER THE
NEXT COUPLE OF DAYS...WITH SOME BELOW FREEZING TEMPERATURES
POSSIBLE TONIGHT AND FRIDAY NIGHT OVER MUCH OF THE AREA. THIS
INCLUDES EAST ANCHORAGE AND THE MATANUSKA VALLEY. A STRONG
ARCTIC LOW WILL SLOWLY PUSH SOUTH THROUGH SATURDAY NIGHT AND COVER
MUCH OF ALASKA BY EARLY SUNDAY MORNING. THIS WILL TURN THE UPPER
LEVEL MORE WESTERLY RATHER THAN NORTHWESTERLY AND BRING IN SOME
CYCLONIC FLOW. THIS WILL RE-INTRODUCE A CHANCE OF SHOWERS TO SOUTH
CENTRAL...BEGINNING IN THE SUSITNA VALLEY SATURDAY AFTERNOON AND
PUSHING SOUTH THROUGH ANCHORAGE AND THE KENAI PENINSULA SATURDAY
NIGHT. BUT THE CHANCES OF SHOWERS WILL BE FAIRLY LOW DUE TO THE
DOWN-SLOPING OFF THE ALASKA RANGE AND THE LINGERING DRY AIR MASS
OVER THE AREA.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 THROUGH 3)... A
FRONTAL SYSTEM STRETCHED OVER TOP THE LARGE RIDGE IN THE BERING
WILL START BRINGING RAIN TO THE WESTERN CAPES AND WESTERN
PENINSULA THIS MORNING THEN THE BRISTOL BAY AREA AND REMAINDER OF
THE ALASKA PENINSULA THIS AFTERNOON AND EVENING. RAIN ALONG AND
NEAR THE COAST WILL CONTINUE THROUGH THE OVERNIGHT HOURS AND INTO
SATURDAY MORNING AS A SURFACE LOW TRACK FROM NORTHWEST TO
SOUTHEAST ALONG THE COAST OF MAINLAND SOUTHWEST ALASKA. CONDITIONS
WILL DRY OUT FAIRLY QUICKLY SATURDAY AFTERNOON AND EVENING AS
NORTHWEST FLOW PUSHES ACROSS THE AREA...THOUGH SCATTERED SHOWERS
WILL LIKELY PERSIST FURTHER INLAND ESPECIALLY ALONG THE MOUNTAINS
WITH A SHORTWAVE DROPPING SOUTH SUNDAY AND SUNDAY NIGHT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 THROUGH 3)...
STRONG RIDGING WILL CONTINUE TO PERSIST OVER THE CENTRAL ALEUTIANS
AND EXTEND INTO THE BERING. A TROUGH WILL SWING TOWARDS THE
WESTERN ALEUTIANS LATE FRIDAY NIGHT AND EARLY SATURDAY MORNING
WITH A VERTICALLY STACKED LOW FOLLOWING SATURDAY NIGHT AND
REMAINING FAIRLY STATIONARY TO THE WEST OF SHEMYA THROUGH SUNDAY
NIGHT. A SMALL LOW TRACKING ACROSS THE NORTHEASTERN SIDE OF
BRISTOL BAY WILL BRING SOME WESTERLY GALES BEHIND IT LATE FRIDAY
NIGHT THROUGH SATURDAY MORNING.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

BEGINNING THE EXTENDED PERIOD ON SATURDAY EVENING...THE STATE OF
ALASKA WILL BE UNDER THE INFLUENCE OF A LARGE ARCTIC TROUGH
CENTERED OVER WESTERN ALASKA...WITH A WEAKLY PHASED SHORTWAVE
TROUGH IN NORTHWEST FLOW TRACKING INTO THE GULF OF ALASKA. AN
ASSOCIATED 140 KT UPPER LEVEL JET STREAK WILL BE TRACKING OVER
THE GULF AS THE ARCTIC TROUGH MAKES SOUTHWARD PROGRESS THROUGH
MONDAY. THIS WILL REINVIGORATE THE OFFSHORE FLOW PATTERN AS A
SURFACE LOW FORMS IN THE GULF OF ALASKA AND TRACKS TOWARD THE
PANHANDLE. RAIN AND SNOW SHOWERS WILL REMAIN LARGELY OVER THE
MOUNTAINS THROUGH MONDAY...ALTHOUGH LOWER ELEVATION SHOWERS WILL
BE MORE PREVALENT ACROSS THE LOWER KUSKOKWIM VALLEY AND BRISTOL
BAY REGIONS. OTHERWISE...RAPID DRYING WILL COMMENCE ON MONDAY AS
THE TROUGH CONTINUES TO DIG THROUGH THE SOUTHEAST GULF...AND
OFFSHORE AND DOWNSLOPE FLOW DRIES THE ATMOSPHERIC COLUMN. WEAK
RIDGING ALOFT WILL MOVE OVER THE STATE FROM WEST TO EAST TUESDAY
AND WEDNESDAY...WITH A SLOW WARMUP BUT CONTINUED DRY CONDITIONS.
PRECIPITATION CHANCES REDEVELOP TOWARD LATE WEEK AS A SERIES OF
WEAK LOWS TRACK FROM THE BERING INTO SOUTHWEST ALASKA. WITH THAT
SAID...THE UPPER LEVEL FLOW WILL REMAIN RATHER WEAK...WITH NO
SIGNIFICANT STORMS OR WET PERIODS ANTICIPATED WITH THE CHANGE IN
PATTERN. DUE TO SLIGHT UNCERTAINTY IN THE EXTENDED PERIOD TOWARD
THE END OF NEXT WEEK...A BLENDED WPC ENSEMBLE APPROACH WAS FAVORED
WITH SOME BLEND OF ECMWF AND GFS SATURDAY EVENING THROUGH MONDAY
TO CAPTURE OUTFLOW WINDS ALONG THE COAST.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING 125 131.
MARINE...GALE WARNING 119 121 127 128 130 131 132 150 155 165.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...KH
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
LONG TERM...JA




000
FXAK68 PAFC 281307
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
507 AM AKDT FRI AUG 28 2015

.ANALYSIS AND UPPER LEVELS...
AN AMPLIFIED UPPER TROUGH SPANS FROM THE ALASKA ARCTIC COAST
THROUGH THE GULF. THE SPIN OF THE GULF LOW IS SEEN CLEARLY ON
IR/WV SATELLITE IMAGERY EARLY THIS MORNING...PULLING A DRIER AND
COOLER AIR MASS INTO THE GULF. TO THE WEST...THE PERSISTENT RIDGE
PATTERN REMAINS OVER THE CENTRAL ALEUTIANS WITH ABUNDANT MOISTURE
RIDING OVER THE RIDGE ACROSS THE NORTHERN BERING. AT THE
SURFACE...NORTH TO WEST FLOW SET UP ACROSS THE SOUTHERN MAINLAND
BEHIND A COLD FRONT THAT MOVED THROUGH LAST NIGHT. GUSTY
CONDITIONS WERE STRONGEST ACROSS ANTICIPATED AREAS ALONG PRINCE
WILLIAM SOUND...KENAI...AND WESTERN GULF WITH MAXIMUM GUSTS
RECORDED BETWEEN 60 TO 70 MPH. ACROSS THE BERING...A FRONT IS
STRETCHED ALONG THE NORTHERN WATERS BRINGING RAIN INTO THE
PRIBILOFS. AREAS OF FOG AND LOW CLOUDS CONTINUE ACROSS MUCH OF THE
SOUTHERN BERING AND ALEUTIANS.

&&

.MODEL DISCUSSION...
THERE IS A GREAT AMOUNT OF COMPLEXITY WITH THE EVOLVING PATTERN
THROUGH THE WEEKEND. MODELS HAVE TO HANDLE TWO CLOSED LOWS WITHIN THE
TROUGH OVER ALASKA AND STRONG SHORTWAVES THAT PASS FROM THE ARCTIC
TO GULF. MODELS ARE COMPARABLE WITH THE OVERALL SYNOPTIC
PATTERN...HOWEVER THERE IS UNCERTAINTY IN ALL OF THE SOLUTIONS
THROUGH THE WEEKEND. THE MODELS ARE ALL SHOWING SIGNIFICANT HEIGHT
FALLS FOR THE LOW OVER THE MAINLAND GOING FROM 543 DAM TO 528 DAM
BY EARLY SUNDAY MORNING. MODEL MOISTURE AND TEMPERATURE FIELDS DO
NOT LOOK REPRESENTATIVE OF THIS PATTERN AS THE SURFACE PATTERN
REMAINS RELATIVELY THE SAME...WHEREAS MODELS SHOULD BE SHOWING A
COOLER TREND WITH HIGHER SURFACE MOISTURE. THE CURRENT FORECAST
PACKAGE WAS UPDATED WITH THE NAM...GEM...AND ECMWF TO CAPTURE THE
THE TRENDS INTO THE WEEKEND WITH ONLY MINOR CHANGES MADE.

&&

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
NORTHWESTERLY FLOW ALOFT WILL CONTINUE OVER THE AREA INTO
SATURDAY. THIS WILL KEEP SOUTH CENTRAL ALASKA DRY WITH SOME
OFFSHORE FLOW AT THE LOWER LEVELS. THE PRESSURE GRADIENT WILL
WEAKEN TODAY HOWEVER AS THE LOW OVER THE SOUTHEAST GULF OF ALASKA
CONTINUES TO EXIT TO THE SOUTHEAST. WITH A DRY AND COLD AIR MASS
OVER THE AREA TEMPERATURES ARE EXPECTED TO BY QUITE COOL OVER THE
NEXT COUPLE OF DAYS...WITH SOME BELOW FREEZING TEMPERATURES
POSSIBLE TONIGHT AND FRIDAY NIGHT OVER MUCH OF THE AREA. THIS
INCLUDES EAST ANCHORAGE AND THE MATANUSKA VALLEY. A STRONG
ARCTIC LOW WILL SLOWLY PUSH SOUTH THROUGH SATURDAY NIGHT AND COVER
MUCH OF ALASKA BY EARLY SUNDAY MORNING. THIS WILL TURN THE UPPER
LEVEL MORE WESTERLY RATHER THAN NORTHWESTERLY AND BRING IN SOME
CYCLONIC FLOW. THIS WILL RE-INTRODUCE A CHANCE OF SHOWERS TO SOUTH
CENTRAL...BEGINNING IN THE SUSITNA VALLEY SATURDAY AFTERNOON AND
PUSHING SOUTH THROUGH ANCHORAGE AND THE KENAI PENINSULA SATURDAY
NIGHT. BUT THE CHANCES OF SHOWERS WILL BE FAIRLY LOW DUE TO THE
DOWN-SLOPING OFF THE ALASKA RANGE AND THE LINGERING DRY AIR MASS
OVER THE AREA.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 THROUGH 3)... A
FRONTAL SYSTEM STRETCHED OVER TOP THE LARGE RIDGE IN THE BERING
WILL START BRINGING RAIN TO THE WESTERN CAPES AND WESTERN
PENINSULA THIS MORNING THEN THE BRISTOL BAY AREA AND REMAINDER OF
THE ALASKA PENINSULA THIS AFTERNOON AND EVENING. RAIN ALONG AND
NEAR THE COAST WILL CONTINUE THROUGH THE OVERNIGHT HOURS AND INTO
SATURDAY MORNING AS A SURFACE LOW TRACK FROM NORTHWEST TO
SOUTHEAST ALONG THE COAST OF MAINLAND SOUTHWEST ALASKA. CONDITIONS
WILL DRY OUT FAIRLY QUICKLY SATURDAY AFTERNOON AND EVENING AS
NORTHWEST FLOW PUSHES ACROSS THE AREA...THOUGH SCATTERED SHOWERS
WILL LIKELY PERSIST FURTHER INLAND ESPECIALLY ALONG THE MOUNTAINS
WITH A SHORTWAVE DROPPING SOUTH SUNDAY AND SUNDAY NIGHT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 THROUGH 3)...
STRONG RIDGING WILL CONTINUE TO PERSIST OVER THE CENTRAL ALEUTIANS
AND EXTEND INTO THE BERING. A TROUGH WILL SWING TOWARDS THE
WESTERN ALEUTIANS LATE FRIDAY NIGHT AND EARLY SATURDAY MORNING
WITH A VERTICALLY STACKED LOW FOLLOWING SATURDAY NIGHT AND
REMAINING FAIRLY STATIONARY TO THE WEST OF SHEMYA THROUGH SUNDAY
NIGHT. A SMALL LOW TRACKING ACROSS THE NORTHEASTERN SIDE OF
BRISTOL BAY WILL BRING SOME WESTERLY GALES BEHIND IT LATE FRIDAY
NIGHT THROUGH SATURDAY MORNING.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

BEGINNING THE EXTENDED PERIOD ON SATURDAY EVENING...THE STATE OF
ALASKA WILL BE UNDER THE INFLUENCE OF A LARGE ARCTIC TROUGH
CENTERED OVER WESTERN ALASKA...WITH A WEAKLY PHASED SHORTWAVE
TROUGH IN NORTHWEST FLOW TRACKING INTO THE GULF OF ALASKA. AN
ASSOCIATED 140 KT UPPER LEVEL JET STREAK WILL BE TRACKING OVER
THE GULF AS THE ARCTIC TROUGH MAKES SOUTHWARD PROGRESS THROUGH
MONDAY. THIS WILL REINVIGORATE THE OFFSHORE FLOW PATTERN AS A
SURFACE LOW FORMS IN THE GULF OF ALASKA AND TRACKS TOWARD THE
PANHANDLE. RAIN AND SNOW SHOWERS WILL REMAIN LARGELY OVER THE
MOUNTAINS THROUGH MONDAY...ALTHOUGH LOWER ELEVATION SHOWERS WILL
BE MORE PREVALENT ACROSS THE LOWER KUSKOKWIM VALLEY AND BRISTOL
BAY REGIONS. OTHERWISE...RAPID DRYING WILL COMMENCE ON MONDAY AS
THE TROUGH CONTINUES TO DIG THROUGH THE SOUTHEAST GULF...AND
OFFSHORE AND DOWNSLOPE FLOW DRIES THE ATMOSPHERIC COLUMN. WEAK
RIDGING ALOFT WILL MOVE OVER THE STATE FROM WEST TO EAST TUESDAY
AND WEDNESDAY...WITH A SLOW WARMUP BUT CONTINUED DRY CONDITIONS.
PRECIPITATION CHANCES REDEVELOP TOWARD LATE WEEK AS A SERIES OF
WEAK LOWS TRACK FROM THE BERING INTO SOUTHWEST ALASKA. WITH THAT
SAID...THE UPPER LEVEL FLOW WILL REMAIN RATHER WEAK...WITH NO
SIGNIFICANT STORMS OR WET PERIODS ANTICIPATED WITH THE CHANGE IN
PATTERN. DUE TO SLIGHT UNCERTAINTY IN THE EXTENDED PERIOD TOWARD
THE END OF NEXT WEEK...A BLENDED WPC ENSEMBLE APPROACH WAS FAVORED
WITH SOME BLEND OF ECMWF AND GFS SATURDAY EVENING THROUGH MONDAY
TO CAPTURE OUTFLOW WINDS ALONG THE COAST.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING 125 131.
MARINE...GALE WARNING 119 121 127 128 130 131 132 150 155 165.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...KH
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
LONG TERM...JA





000
FXAK68 PAFC 280055
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
455 PM AKDT THU AUG 27 2015

.ANALYSIS AND UPPER LEVELS...

THE WEATHER PATTERN ACROSS THE ALASKAN DOMAIN IS IN A STATE OF
TRANSITION TODAY. WEST/SOUTHWEST FLOW ACROSS THE ENTIRE AREA IS
BECOMING MORE NORTH/NORTHWESTERLY AS THE UPPER LEVEL RIDGE IN THE
BERING AND AN UPPER TROUGH ARE BOTH BEGINNING A RAPID
AMPLIFICATION. A PAIR OF SHORTWAVE TROUGHS ARE MOVING
SOUTHEASTWARD ACROSS SOUTHERN ALASKA REPRESENTING THE BEGINNING
OF THIS PATTERN SHIFT. THE FIRST SHORTWAVE CAME THROUGH COOK INLET
THIS MORNING MOSTLY DRY...WITH RAIN FALLING LARGELY OVER THE
COPPER RIVER BASIN AND EASTERN PRINCE WILLIAM SOUND. THE SECOND
SHORTWAVE IS CROSSING THE ALASKA RANGE AS OF MIDDAY...BUT IS EVEN
MORE MOISTURE-STARVED THAN THE EARLIER SHORTWAVE...SO MINIMAL
ADDITIONAL SHOWER ACTIVITY IS EXPECTED. SOUTHERLY AND EASTERLY
WINDS ACROSS SOUTHCENTRAL ALASKA HAVE LARGELY CEASED AND THE
WIDELY ANTICIPATED NORTHWESTERLY "COLD AND DRY" WINDS ARE
BEGINNING IN EARNEST...WITH THE PREDICTABLE AREA IN TERRAIN GAPS
SUCH AS SEWARD AND WHITTIER ALREADY SHOWING ABRUPT INCREASES IN
WIND SPEED.

OUT WEST...SPRAWLING HIGH PRESSURE REMAINS IN PLACE ACROSS THE
CENTRAL ALEUTIANS...WITH FREEZING LEVELS AT COLD BAY ON THE 12Z
MORNING UPPER AIR SOUNDING AN IMPRESSIVE 17000 FT. FOG AND STRATUS
REMAIN WIDESPREAD OVER MUCH OF THE AREA...INCLUDING LOW CLOUDS
THAT HAVE BEEN PUSHED ONSHORE THE KUSKOKWIM DELTA AND PARTS OF
BRISTOL BAY.

&&

.MODEL DISCUSSION...

THE MODELS HAVE "LOCKED INTO" THE EVOLUTION OF MAJOR FEATURES OVER
THE NEXT DAY OR SO. THERE HAS BEEN A SMALL INCREASE IN FORWARD
SPEED OF SOME OF THE WEAKER SHORTWAVES MOVING THROUGH THE
AMPLIFIED NORTHWEST FLOW ON FRIDAY AND SATURDAY...BUT THIS IS NOT
SURPRISING GIVEN THE IMPRESSIVE STRONG JET STREAM ALREADY IN PLACE
OVER THE AREA (160+ KT AT MCGRATH THIS MORNING ON THE 12Z RAOB).
THE HIGHER RESOLUTION MODELS (NAM/WRF) WILL PROVIDE THE BASIS FOR
FORECAST UPDATES...DUE TO OBVIOUS ADVANTAGES AS STRONG WINDS
ACCELERATE THROUGH THE COMPLEX TERRAIN GAPS AROUND SOUTHERN
ALASKA.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...

THE BIG FORECAST CHALLENGE FOR THE DAY IS PINPOINTING THE
INTENSITY OF THE WINDS EXPECTED OVERNIGHT TONIGHT AND THROUGH
TOMORROW MORNING ACROSS THE AREA. THE COASTAL COMMUNITIES WILL
STILL BEAR THE BRUNT OF THE STRONG WINDS. ATMOSPHERICALLY
SPEAKING...ALL THE MAJOR PIECES ARE IN PLACE FOR AN IMPRESSIVE
"OUTFLOW" WIND EVENT FROM THE NORTH AND WEST. THIS INCLUDES
IMPRESSIVE JET SUPPORT (FROM THE NORTHWEST)...A LOW IN THE GULF TO
SETUP AN OFFSHORE PRESSURE GRADIENT...AND RELATIVELY COLD AND
DENSE AIR MOVING INTO THE AREA FROM INTERIOR ALASKA. WHAT IS MORE
UNUSUAL IN THIS CASE IS THE TIME OF YEAR. THIS IS A FAIRLY TYPICAL
LATE FALL/WINTER PATTERN...BUT NOT A COMMON LATE SUMMER/EARLY
FALL PATTERN. AS SUCH...HIGH WIND WARNINGS HAVE BEEN ISSUED FOR
THE VALDEZ AREA (INCLUDING IN TOWN) AS WELL AS WHITTIER AND
SEWARD. THE WORST CONDITIONS WILL BE OVERNIGHT TONIGHT...BUT WINDS
WILL REMAIN GENERALLY GUSTY THROUGH FRIDAY NIGHT IN MOST AREAS.

THE OTHER SIDE OF THE COIN IS THE UNSEASONABLY COLD NATURE OF THIS
AIRMASS. ONCE WINDS START TO DIMINISH LATE FRIDAY...THE TYPICAL
COLD SPOTS OF EAST ANCHORAGE...THE BUTTE...AND MEADOW LAKES AREA
IN THE MATANUSKA VALLEY WILL MAKE A STRONG RUN AT FREEZING
TEMPERATURES EARLY SATURDAY MORNING. THE MAIN UNCERTAINTY AT THIS
POINT IS IF ANY MID-LEVEL CLOUDS WILL LOITER AROUND THE AREA TO
HELP KEEP OVERNIGHT TEMPERATURES A FEW DEGREES WARMER. THIS WILL
BE MONITORED CLOSELY OVER THE NEXT 24 HOURS...BUT EVEN IF FREEZING
TEMPERATURES ARE NOT REACHED IN THESE AREAS IT WILL STILL BE
CLOSE...WITH TEMPERATURES THE COLDEST OF THE SEASON SO FAR ACROSS
THE REGION.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
PRECIPITATION OVER MUCH OF THE SOUTHWEST MAINLAND WILL CONTINUE
TO DIMINISH THIS EVENING...AS THE SECOND OF THESE WAVES DEPARTS
INTO THE GULF OF ALASKA AND USHERS IN BRISK NORTHWEST FLOW ON THE
BACKSIDE OF THE DIGGING TROUGH. THIS WILL PRODUCE GUSTY NORTHWEST
WINDS AND ALSO CONTRIBUTE TO COLDER TEMPERATURES TONIGHT...AS
OVERNIGHT LOWS DIP INTO THE 30S ACROSS MUCH OF THE AREA BENEATH
DECREASING CLOUD COVER. THE PERIOD OF DRY WEATHER WILL BE SHORT
LIVED AS ANOTHER WAVE PUSHES INTO THE SOUTHWEST MAINLAND FRIDAY
AFTERNOON. THIS WILL BRING ANOTHER ROUND OF RAINFALL TO THE AREA
FRIDAY NIGHT INTO SATURDAY MORNING...BEFORE SWITCHING OVER TO
SHOWERS LATE SATURDAY MORNING AS THE WAVE TRACKS INTO THE WESTERN
GULF. WITH WINDS SHIFTING TO A STRONGER ONSHORE FLOW OVERNIGHT
TONIGHT...PATCHY FOG OFF THE BERING SEA IS EXPECTED TO PUSH INTO
THE KUSKOKWIM DELTA AND PERSIST THROUGH FRIDAY EVENING.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
ASIDE FROM A FEW SHOWERS IN NORTHWEST FLOW ACROSS THE ALASKA
PENINSULA AND EASTERN ALEUTIANS...THE BULK OF THE RAINFALL WILL
REMAIN CONFINED TO THE FAR WESTERN PARTS OF THE ALEUTIAN CHAIN
THROUGH TONIGHT AS THE NORTH PACIFIC RIDGE IS RE-ESTABLISHED OVER
THE CENTRAL BERING SEA. RAIN WILL THEN SPREAD TO THE NORTHERN AND
EASTERN BERING FRIDAY AS AN UPPER WAVE ROUNDS THE TOP OF THE
RIDGE...WITH RAIN RETURNING TO THE REST OF THE ALEUTIAN CHAIN BY
THE WEEKEND AS THE RIDGE BREAKS DOWN. WIDESPREAD STRATUS AND FOG
IS EXPECTED TO ACCOMPANY THE RIDGE AS IS PERSISTS OVER THE BERING
THROUGH SATURDAY.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

BEGINNING THE EXTENDED PERIOD ON SATURDAY EVENING...THE STATE OF
ALASKA WILL BE UNDER THE INFLUENCE OF A LARGE ARCTIC TROUGH
CENTERED OVER WESTERN ALASKA...WITH A WEAKLY PHASED SHORTWAVE
TROUGH IN NORTHWEST FLOW TRACKING INTO THE GULF OF ALASKA. AN
ASSOCIATED 140 KT UPPER LEVEL JET STREAK WILL BE TRACKING OVER
THE GULF AS THE ARCTIC TROUGH MAKES SOUTHWARD PROGRESS THROUGH
MONDAY. THIS WILL REINVIGORATE THE OFFSHORE FLOW PATTERN AS A
SURFACE LOW FORMS IN THE GULF OF ALASKA AND TRACKS TOWARD THE
PANHANDLE. RAIN AND SNOW SHOWERS WILL REMAIN LARGELY OVER THE
MOUNTAINS THROUGH MONDAY...ALTHOUGH LOWER ELEVATION SHOWERS WILL
BE MORE PREVALENT ACROSS THE LOWER KUSKOKWIM VALLEY AND BRISTOL
BAY REGIONS. OTHERWISE...RAPID DRYING WILL COMMENCE ON MONDAY AS
THE TROUGH CONTINUES TO DIG THROUGH THE SOUTHEAST GULF...AND
OFFSHORE AND DOWNSLOPE FLOW DRIES THE ATMOSPHERIC COLUMN. WEAK
RIDGING ALOFT WILL MOVE OVER THE STATE FROM WEST TO EAST TUESDAY
AND WEDNESDAY...WITH A SLOW WARMUP BUT CONTINUED DRY CONDITIONS.
PRECIPITATION CHANCES REDEVELOP TOWARD LATE WEEK AS A SERIES OF
WEAK LOWS TRACK FROM THE BERING INTO SOUTHWEST ALASKA. WITH THAT
SAID...THE UPPER LEVEL FLOW WILL REMAIN RATHER WEAK...WITH NO
SIGNIFICANT STORMS OR WET PERIODS ANTICIPATED WITH THE CHANGE IN
PATTERN. DUE TO SLIGHT UNCERTAINTY IN THE EXTENDED PERIOD TOWARD
THE END OF NEXT WEEK...A BLENDED WPC ENSEMBLE APPROACH WAS FAVORED
WITH SOME BLEND OF ECMWF AND GFS SATURDAY EVENING THROUGH MONDAY
TO CAPTURE OUTFLOW WINDS ALONG THE COAST.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING 125 131.
MARINE...GALE 119-125 127-138 150 165.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...AMD
SOUTHCENTRAL ALASKA...AMD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP
LONG TERM...JA





000
FXAK68 PAFC 280055
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
455 PM AKDT THU AUG 27 2015

.ANALYSIS AND UPPER LEVELS...

THE WEATHER PATTERN ACROSS THE ALASKAN DOMAIN IS IN A STATE OF
TRANSITION TODAY. WEST/SOUTHWEST FLOW ACROSS THE ENTIRE AREA IS
BECOMING MORE NORTH/NORTHWESTERLY AS THE UPPER LEVEL RIDGE IN THE
BERING AND AN UPPER TROUGH ARE BOTH BEGINNING A RAPID
AMPLIFICATION. A PAIR OF SHORTWAVE TROUGHS ARE MOVING
SOUTHEASTWARD ACROSS SOUTHERN ALASKA REPRESENTING THE BEGINNING
OF THIS PATTERN SHIFT. THE FIRST SHORTWAVE CAME THROUGH COOK INLET
THIS MORNING MOSTLY DRY...WITH RAIN FALLING LARGELY OVER THE
COPPER RIVER BASIN AND EASTERN PRINCE WILLIAM SOUND. THE SECOND
SHORTWAVE IS CROSSING THE ALASKA RANGE AS OF MIDDAY...BUT IS EVEN
MORE MOISTURE-STARVED THAN THE EARLIER SHORTWAVE...SO MINIMAL
ADDITIONAL SHOWER ACTIVITY IS EXPECTED. SOUTHERLY AND EASTERLY
WINDS ACROSS SOUTHCENTRAL ALASKA HAVE LARGELY CEASED AND THE
WIDELY ANTICIPATED NORTHWESTERLY "COLD AND DRY" WINDS ARE
BEGINNING IN EARNEST...WITH THE PREDICTABLE AREA IN TERRAIN GAPS
SUCH AS SEWARD AND WHITTIER ALREADY SHOWING ABRUPT INCREASES IN
WIND SPEED.

OUT WEST...SPRAWLING HIGH PRESSURE REMAINS IN PLACE ACROSS THE
CENTRAL ALEUTIANS...WITH FREEZING LEVELS AT COLD BAY ON THE 12Z
MORNING UPPER AIR SOUNDING AN IMPRESSIVE 17000 FT. FOG AND STRATUS
REMAIN WIDESPREAD OVER MUCH OF THE AREA...INCLUDING LOW CLOUDS
THAT HAVE BEEN PUSHED ONSHORE THE KUSKOKWIM DELTA AND PARTS OF
BRISTOL BAY.

&&

.MODEL DISCUSSION...

THE MODELS HAVE "LOCKED INTO" THE EVOLUTION OF MAJOR FEATURES OVER
THE NEXT DAY OR SO. THERE HAS BEEN A SMALL INCREASE IN FORWARD
SPEED OF SOME OF THE WEAKER SHORTWAVES MOVING THROUGH THE
AMPLIFIED NORTHWEST FLOW ON FRIDAY AND SATURDAY...BUT THIS IS NOT
SURPRISING GIVEN THE IMPRESSIVE STRONG JET STREAM ALREADY IN PLACE
OVER THE AREA (160+ KT AT MCGRATH THIS MORNING ON THE 12Z RAOB).
THE HIGHER RESOLUTION MODELS (NAM/WRF) WILL PROVIDE THE BASIS FOR
FORECAST UPDATES...DUE TO OBVIOUS ADVANTAGES AS STRONG WINDS
ACCELERATE THROUGH THE COMPLEX TERRAIN GAPS AROUND SOUTHERN
ALASKA.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...

THE BIG FORECAST CHALLENGE FOR THE DAY IS PINPOINTING THE
INTENSITY OF THE WINDS EXPECTED OVERNIGHT TONIGHT AND THROUGH
TOMORROW MORNING ACROSS THE AREA. THE COASTAL COMMUNITIES WILL
STILL BEAR THE BRUNT OF THE STRONG WINDS. ATMOSPHERICALLY
SPEAKING...ALL THE MAJOR PIECES ARE IN PLACE FOR AN IMPRESSIVE
"OUTFLOW" WIND EVENT FROM THE NORTH AND WEST. THIS INCLUDES
IMPRESSIVE JET SUPPORT (FROM THE NORTHWEST)...A LOW IN THE GULF TO
SETUP AN OFFSHORE PRESSURE GRADIENT...AND RELATIVELY COLD AND
DENSE AIR MOVING INTO THE AREA FROM INTERIOR ALASKA. WHAT IS MORE
UNUSUAL IN THIS CASE IS THE TIME OF YEAR. THIS IS A FAIRLY TYPICAL
LATE FALL/WINTER PATTERN...BUT NOT A COMMON LATE SUMMER/EARLY
FALL PATTERN. AS SUCH...HIGH WIND WARNINGS HAVE BEEN ISSUED FOR
THE VALDEZ AREA (INCLUDING IN TOWN) AS WELL AS WHITTIER AND
SEWARD. THE WORST CONDITIONS WILL BE OVERNIGHT TONIGHT...BUT WINDS
WILL REMAIN GENERALLY GUSTY THROUGH FRIDAY NIGHT IN MOST AREAS.

THE OTHER SIDE OF THE COIN IS THE UNSEASONABLY COLD NATURE OF THIS
AIRMASS. ONCE WINDS START TO DIMINISH LATE FRIDAY...THE TYPICAL
COLD SPOTS OF EAST ANCHORAGE...THE BUTTE...AND MEADOW LAKES AREA
IN THE MATANUSKA VALLEY WILL MAKE A STRONG RUN AT FREEZING
TEMPERATURES EARLY SATURDAY MORNING. THE MAIN UNCERTAINTY AT THIS
POINT IS IF ANY MID-LEVEL CLOUDS WILL LOITER AROUND THE AREA TO
HELP KEEP OVERNIGHT TEMPERATURES A FEW DEGREES WARMER. THIS WILL
BE MONITORED CLOSELY OVER THE NEXT 24 HOURS...BUT EVEN IF FREEZING
TEMPERATURES ARE NOT REACHED IN THESE AREAS IT WILL STILL BE
CLOSE...WITH TEMPERATURES THE COLDEST OF THE SEASON SO FAR ACROSS
THE REGION.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
PRECIPITATION OVER MUCH OF THE SOUTHWEST MAINLAND WILL CONTINUE
TO DIMINISH THIS EVENING...AS THE SECOND OF THESE WAVES DEPARTS
INTO THE GULF OF ALASKA AND USHERS IN BRISK NORTHWEST FLOW ON THE
BACKSIDE OF THE DIGGING TROUGH. THIS WILL PRODUCE GUSTY NORTHWEST
WINDS AND ALSO CONTRIBUTE TO COLDER TEMPERATURES TONIGHT...AS
OVERNIGHT LOWS DIP INTO THE 30S ACROSS MUCH OF THE AREA BENEATH
DECREASING CLOUD COVER. THE PERIOD OF DRY WEATHER WILL BE SHORT
LIVED AS ANOTHER WAVE PUSHES INTO THE SOUTHWEST MAINLAND FRIDAY
AFTERNOON. THIS WILL BRING ANOTHER ROUND OF RAINFALL TO THE AREA
FRIDAY NIGHT INTO SATURDAY MORNING...BEFORE SWITCHING OVER TO
SHOWERS LATE SATURDAY MORNING AS THE WAVE TRACKS INTO THE WESTERN
GULF. WITH WINDS SHIFTING TO A STRONGER ONSHORE FLOW OVERNIGHT
TONIGHT...PATCHY FOG OFF THE BERING SEA IS EXPECTED TO PUSH INTO
THE KUSKOKWIM DELTA AND PERSIST THROUGH FRIDAY EVENING.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
ASIDE FROM A FEW SHOWERS IN NORTHWEST FLOW ACROSS THE ALASKA
PENINSULA AND EASTERN ALEUTIANS...THE BULK OF THE RAINFALL WILL
REMAIN CONFINED TO THE FAR WESTERN PARTS OF THE ALEUTIAN CHAIN
THROUGH TONIGHT AS THE NORTH PACIFIC RIDGE IS RE-ESTABLISHED OVER
THE CENTRAL BERING SEA. RAIN WILL THEN SPREAD TO THE NORTHERN AND
EASTERN BERING FRIDAY AS AN UPPER WAVE ROUNDS THE TOP OF THE
RIDGE...WITH RAIN RETURNING TO THE REST OF THE ALEUTIAN CHAIN BY
THE WEEKEND AS THE RIDGE BREAKS DOWN. WIDESPREAD STRATUS AND FOG
IS EXPECTED TO ACCOMPANY THE RIDGE AS IS PERSISTS OVER THE BERING
THROUGH SATURDAY.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

BEGINNING THE EXTENDED PERIOD ON SATURDAY EVENING...THE STATE OF
ALASKA WILL BE UNDER THE INFLUENCE OF A LARGE ARCTIC TROUGH
CENTERED OVER WESTERN ALASKA...WITH A WEAKLY PHASED SHORTWAVE
TROUGH IN NORTHWEST FLOW TRACKING INTO THE GULF OF ALASKA. AN
ASSOCIATED 140 KT UPPER LEVEL JET STREAK WILL BE TRACKING OVER
THE GULF AS THE ARCTIC TROUGH MAKES SOUTHWARD PROGRESS THROUGH
MONDAY. THIS WILL REINVIGORATE THE OFFSHORE FLOW PATTERN AS A
SURFACE LOW FORMS IN THE GULF OF ALASKA AND TRACKS TOWARD THE
PANHANDLE. RAIN AND SNOW SHOWERS WILL REMAIN LARGELY OVER THE
MOUNTAINS THROUGH MONDAY...ALTHOUGH LOWER ELEVATION SHOWERS WILL
BE MORE PREVALENT ACROSS THE LOWER KUSKOKWIM VALLEY AND BRISTOL
BAY REGIONS. OTHERWISE...RAPID DRYING WILL COMMENCE ON MONDAY AS
THE TROUGH CONTINUES TO DIG THROUGH THE SOUTHEAST GULF...AND
OFFSHORE AND DOWNSLOPE FLOW DRIES THE ATMOSPHERIC COLUMN. WEAK
RIDGING ALOFT WILL MOVE OVER THE STATE FROM WEST TO EAST TUESDAY
AND WEDNESDAY...WITH A SLOW WARMUP BUT CONTINUED DRY CONDITIONS.
PRECIPITATION CHANCES REDEVELOP TOWARD LATE WEEK AS A SERIES OF
WEAK LOWS TRACK FROM THE BERING INTO SOUTHWEST ALASKA. WITH THAT
SAID...THE UPPER LEVEL FLOW WILL REMAIN RATHER WEAK...WITH NO
SIGNIFICANT STORMS OR WET PERIODS ANTICIPATED WITH THE CHANGE IN
PATTERN. DUE TO SLIGHT UNCERTAINTY IN THE EXTENDED PERIOD TOWARD
THE END OF NEXT WEEK...A BLENDED WPC ENSEMBLE APPROACH WAS FAVORED
WITH SOME BLEND OF ECMWF AND GFS SATURDAY EVENING THROUGH MONDAY
TO CAPTURE OUTFLOW WINDS ALONG THE COAST.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING 125 131.
MARINE...GALE 119-125 127-138 150 165.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...AMD
SOUTHCENTRAL ALASKA...AMD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP
LONG TERM...JA




000
FXAK68 PAFC 280055
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
455 PM AKDT THU AUG 27 2015

.ANALYSIS AND UPPER LEVELS...

THE WEATHER PATTERN ACROSS THE ALASKAN DOMAIN IS IN A STATE OF
TRANSITION TODAY. WEST/SOUTHWEST FLOW ACROSS THE ENTIRE AREA IS
BECOMING MORE NORTH/NORTHWESTERLY AS THE UPPER LEVEL RIDGE IN THE
BERING AND AN UPPER TROUGH ARE BOTH BEGINNING A RAPID
AMPLIFICATION. A PAIR OF SHORTWAVE TROUGHS ARE MOVING
SOUTHEASTWARD ACROSS SOUTHERN ALASKA REPRESENTING THE BEGINNING
OF THIS PATTERN SHIFT. THE FIRST SHORTWAVE CAME THROUGH COOK INLET
THIS MORNING MOSTLY DRY...WITH RAIN FALLING LARGELY OVER THE
COPPER RIVER BASIN AND EASTERN PRINCE WILLIAM SOUND. THE SECOND
SHORTWAVE IS CROSSING THE ALASKA RANGE AS OF MIDDAY...BUT IS EVEN
MORE MOISTURE-STARVED THAN THE EARLIER SHORTWAVE...SO MINIMAL
ADDITIONAL SHOWER ACTIVITY IS EXPECTED. SOUTHERLY AND EASTERLY
WINDS ACROSS SOUTHCENTRAL ALASKA HAVE LARGELY CEASED AND THE
WIDELY ANTICIPATED NORTHWESTERLY "COLD AND DRY" WINDS ARE
BEGINNING IN EARNEST...WITH THE PREDICTABLE AREA IN TERRAIN GAPS
SUCH AS SEWARD AND WHITTIER ALREADY SHOWING ABRUPT INCREASES IN
WIND SPEED.

OUT WEST...SPRAWLING HIGH PRESSURE REMAINS IN PLACE ACROSS THE
CENTRAL ALEUTIANS...WITH FREEZING LEVELS AT COLD BAY ON THE 12Z
MORNING UPPER AIR SOUNDING AN IMPRESSIVE 17000 FT. FOG AND STRATUS
REMAIN WIDESPREAD OVER MUCH OF THE AREA...INCLUDING LOW CLOUDS
THAT HAVE BEEN PUSHED ONSHORE THE KUSKOKWIM DELTA AND PARTS OF
BRISTOL BAY.

&&

.MODEL DISCUSSION...

THE MODELS HAVE "LOCKED INTO" THE EVOLUTION OF MAJOR FEATURES OVER
THE NEXT DAY OR SO. THERE HAS BEEN A SMALL INCREASE IN FORWARD
SPEED OF SOME OF THE WEAKER SHORTWAVES MOVING THROUGH THE
AMPLIFIED NORTHWEST FLOW ON FRIDAY AND SATURDAY...BUT THIS IS NOT
SURPRISING GIVEN THE IMPRESSIVE STRONG JET STREAM ALREADY IN PLACE
OVER THE AREA (160+ KT AT MCGRATH THIS MORNING ON THE 12Z RAOB).
THE HIGHER RESOLUTION MODELS (NAM/WRF) WILL PROVIDE THE BASIS FOR
FORECAST UPDATES...DUE TO OBVIOUS ADVANTAGES AS STRONG WINDS
ACCELERATE THROUGH THE COMPLEX TERRAIN GAPS AROUND SOUTHERN
ALASKA.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...

THE BIG FORECAST CHALLENGE FOR THE DAY IS PINPOINTING THE
INTENSITY OF THE WINDS EXPECTED OVERNIGHT TONIGHT AND THROUGH
TOMORROW MORNING ACROSS THE AREA. THE COASTAL COMMUNITIES WILL
STILL BEAR THE BRUNT OF THE STRONG WINDS. ATMOSPHERICALLY
SPEAKING...ALL THE MAJOR PIECES ARE IN PLACE FOR AN IMPRESSIVE
"OUTFLOW" WIND EVENT FROM THE NORTH AND WEST. THIS INCLUDES
IMPRESSIVE JET SUPPORT (FROM THE NORTHWEST)...A LOW IN THE GULF TO
SETUP AN OFFSHORE PRESSURE GRADIENT...AND RELATIVELY COLD AND
DENSE AIR MOVING INTO THE AREA FROM INTERIOR ALASKA. WHAT IS MORE
UNUSUAL IN THIS CASE IS THE TIME OF YEAR. THIS IS A FAIRLY TYPICAL
LATE FALL/WINTER PATTERN...BUT NOT A COMMON LATE SUMMER/EARLY
FALL PATTERN. AS SUCH...HIGH WIND WARNINGS HAVE BEEN ISSUED FOR
THE VALDEZ AREA (INCLUDING IN TOWN) AS WELL AS WHITTIER AND
SEWARD. THE WORST CONDITIONS WILL BE OVERNIGHT TONIGHT...BUT WINDS
WILL REMAIN GENERALLY GUSTY THROUGH FRIDAY NIGHT IN MOST AREAS.

THE OTHER SIDE OF THE COIN IS THE UNSEASONABLY COLD NATURE OF THIS
AIRMASS. ONCE WINDS START TO DIMINISH LATE FRIDAY...THE TYPICAL
COLD SPOTS OF EAST ANCHORAGE...THE BUTTE...AND MEADOW LAKES AREA
IN THE MATANUSKA VALLEY WILL MAKE A STRONG RUN AT FREEZING
TEMPERATURES EARLY SATURDAY MORNING. THE MAIN UNCERTAINTY AT THIS
POINT IS IF ANY MID-LEVEL CLOUDS WILL LOITER AROUND THE AREA TO
HELP KEEP OVERNIGHT TEMPERATURES A FEW DEGREES WARMER. THIS WILL
BE MONITORED CLOSELY OVER THE NEXT 24 HOURS...BUT EVEN IF FREEZING
TEMPERATURES ARE NOT REACHED IN THESE AREAS IT WILL STILL BE
CLOSE...WITH TEMPERATURES THE COLDEST OF THE SEASON SO FAR ACROSS
THE REGION.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
PRECIPITATION OVER MUCH OF THE SOUTHWEST MAINLAND WILL CONTINUE
TO DIMINISH THIS EVENING...AS THE SECOND OF THESE WAVES DEPARTS
INTO THE GULF OF ALASKA AND USHERS IN BRISK NORTHWEST FLOW ON THE
BACKSIDE OF THE DIGGING TROUGH. THIS WILL PRODUCE GUSTY NORTHWEST
WINDS AND ALSO CONTRIBUTE TO COLDER TEMPERATURES TONIGHT...AS
OVERNIGHT LOWS DIP INTO THE 30S ACROSS MUCH OF THE AREA BENEATH
DECREASING CLOUD COVER. THE PERIOD OF DRY WEATHER WILL BE SHORT
LIVED AS ANOTHER WAVE PUSHES INTO THE SOUTHWEST MAINLAND FRIDAY
AFTERNOON. THIS WILL BRING ANOTHER ROUND OF RAINFALL TO THE AREA
FRIDAY NIGHT INTO SATURDAY MORNING...BEFORE SWITCHING OVER TO
SHOWERS LATE SATURDAY MORNING AS THE WAVE TRACKS INTO THE WESTERN
GULF. WITH WINDS SHIFTING TO A STRONGER ONSHORE FLOW OVERNIGHT
TONIGHT...PATCHY FOG OFF THE BERING SEA IS EXPECTED TO PUSH INTO
THE KUSKOKWIM DELTA AND PERSIST THROUGH FRIDAY EVENING.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
ASIDE FROM A FEW SHOWERS IN NORTHWEST FLOW ACROSS THE ALASKA
PENINSULA AND EASTERN ALEUTIANS...THE BULK OF THE RAINFALL WILL
REMAIN CONFINED TO THE FAR WESTERN PARTS OF THE ALEUTIAN CHAIN
THROUGH TONIGHT AS THE NORTH PACIFIC RIDGE IS RE-ESTABLISHED OVER
THE CENTRAL BERING SEA. RAIN WILL THEN SPREAD TO THE NORTHERN AND
EASTERN BERING FRIDAY AS AN UPPER WAVE ROUNDS THE TOP OF THE
RIDGE...WITH RAIN RETURNING TO THE REST OF THE ALEUTIAN CHAIN BY
THE WEEKEND AS THE RIDGE BREAKS DOWN. WIDESPREAD STRATUS AND FOG
IS EXPECTED TO ACCOMPANY THE RIDGE AS IS PERSISTS OVER THE BERING
THROUGH SATURDAY.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

BEGINNING THE EXTENDED PERIOD ON SATURDAY EVENING...THE STATE OF
ALASKA WILL BE UNDER THE INFLUENCE OF A LARGE ARCTIC TROUGH
CENTERED OVER WESTERN ALASKA...WITH A WEAKLY PHASED SHORTWAVE
TROUGH IN NORTHWEST FLOW TRACKING INTO THE GULF OF ALASKA. AN
ASSOCIATED 140 KT UPPER LEVEL JET STREAK WILL BE TRACKING OVER
THE GULF AS THE ARCTIC TROUGH MAKES SOUTHWARD PROGRESS THROUGH
MONDAY. THIS WILL REINVIGORATE THE OFFSHORE FLOW PATTERN AS A
SURFACE LOW FORMS IN THE GULF OF ALASKA AND TRACKS TOWARD THE
PANHANDLE. RAIN AND SNOW SHOWERS WILL REMAIN LARGELY OVER THE
MOUNTAINS THROUGH MONDAY...ALTHOUGH LOWER ELEVATION SHOWERS WILL
BE MORE PREVALENT ACROSS THE LOWER KUSKOKWIM VALLEY AND BRISTOL
BAY REGIONS. OTHERWISE...RAPID DRYING WILL COMMENCE ON MONDAY AS
THE TROUGH CONTINUES TO DIG THROUGH THE SOUTHEAST GULF...AND
OFFSHORE AND DOWNSLOPE FLOW DRIES THE ATMOSPHERIC COLUMN. WEAK
RIDGING ALOFT WILL MOVE OVER THE STATE FROM WEST TO EAST TUESDAY
AND WEDNESDAY...WITH A SLOW WARMUP BUT CONTINUED DRY CONDITIONS.
PRECIPITATION CHANCES REDEVELOP TOWARD LATE WEEK AS A SERIES OF
WEAK LOWS TRACK FROM THE BERING INTO SOUTHWEST ALASKA. WITH THAT
SAID...THE UPPER LEVEL FLOW WILL REMAIN RATHER WEAK...WITH NO
SIGNIFICANT STORMS OR WET PERIODS ANTICIPATED WITH THE CHANGE IN
PATTERN. DUE TO SLIGHT UNCERTAINTY IN THE EXTENDED PERIOD TOWARD
THE END OF NEXT WEEK...A BLENDED WPC ENSEMBLE APPROACH WAS FAVORED
WITH SOME BLEND OF ECMWF AND GFS SATURDAY EVENING THROUGH MONDAY
TO CAPTURE OUTFLOW WINDS ALONG THE COAST.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING 125 131.
MARINE...GALE 119-125 127-138 150 165.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...AMD
SOUTHCENTRAL ALASKA...AMD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP
LONG TERM...JA





000
FXAK68 PAFC 280055
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
455 PM AKDT THU AUG 27 2015

.ANALYSIS AND UPPER LEVELS...

THE WEATHER PATTERN ACROSS THE ALASKAN DOMAIN IS IN A STATE OF
TRANSITION TODAY. WEST/SOUTHWEST FLOW ACROSS THE ENTIRE AREA IS
BECOMING MORE NORTH/NORTHWESTERLY AS THE UPPER LEVEL RIDGE IN THE
BERING AND AN UPPER TROUGH ARE BOTH BEGINNING A RAPID
AMPLIFICATION. A PAIR OF SHORTWAVE TROUGHS ARE MOVING
SOUTHEASTWARD ACROSS SOUTHERN ALASKA REPRESENTING THE BEGINNING
OF THIS PATTERN SHIFT. THE FIRST SHORTWAVE CAME THROUGH COOK INLET
THIS MORNING MOSTLY DRY...WITH RAIN FALLING LARGELY OVER THE
COPPER RIVER BASIN AND EASTERN PRINCE WILLIAM SOUND. THE SECOND
SHORTWAVE IS CROSSING THE ALASKA RANGE AS OF MIDDAY...BUT IS EVEN
MORE MOISTURE-STARVED THAN THE EARLIER SHORTWAVE...SO MINIMAL
ADDITIONAL SHOWER ACTIVITY IS EXPECTED. SOUTHERLY AND EASTERLY
WINDS ACROSS SOUTHCENTRAL ALASKA HAVE LARGELY CEASED AND THE
WIDELY ANTICIPATED NORTHWESTERLY "COLD AND DRY" WINDS ARE
BEGINNING IN EARNEST...WITH THE PREDICTABLE AREA IN TERRAIN GAPS
SUCH AS SEWARD AND WHITTIER ALREADY SHOWING ABRUPT INCREASES IN
WIND SPEED.

OUT WEST...SPRAWLING HIGH PRESSURE REMAINS IN PLACE ACROSS THE
CENTRAL ALEUTIANS...WITH FREEZING LEVELS AT COLD BAY ON THE 12Z
MORNING UPPER AIR SOUNDING AN IMPRESSIVE 17000 FT. FOG AND STRATUS
REMAIN WIDESPREAD OVER MUCH OF THE AREA...INCLUDING LOW CLOUDS
THAT HAVE BEEN PUSHED ONSHORE THE KUSKOKWIM DELTA AND PARTS OF
BRISTOL BAY.

&&

.MODEL DISCUSSION...

THE MODELS HAVE "LOCKED INTO" THE EVOLUTION OF MAJOR FEATURES OVER
THE NEXT DAY OR SO. THERE HAS BEEN A SMALL INCREASE IN FORWARD
SPEED OF SOME OF THE WEAKER SHORTWAVES MOVING THROUGH THE
AMPLIFIED NORTHWEST FLOW ON FRIDAY AND SATURDAY...BUT THIS IS NOT
SURPRISING GIVEN THE IMPRESSIVE STRONG JET STREAM ALREADY IN PLACE
OVER THE AREA (160+ KT AT MCGRATH THIS MORNING ON THE 12Z RAOB).
THE HIGHER RESOLUTION MODELS (NAM/WRF) WILL PROVIDE THE BASIS FOR
FORECAST UPDATES...DUE TO OBVIOUS ADVANTAGES AS STRONG WINDS
ACCELERATE THROUGH THE COMPLEX TERRAIN GAPS AROUND SOUTHERN
ALASKA.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...

THE BIG FORECAST CHALLENGE FOR THE DAY IS PINPOINTING THE
INTENSITY OF THE WINDS EXPECTED OVERNIGHT TONIGHT AND THROUGH
TOMORROW MORNING ACROSS THE AREA. THE COASTAL COMMUNITIES WILL
STILL BEAR THE BRUNT OF THE STRONG WINDS. ATMOSPHERICALLY
SPEAKING...ALL THE MAJOR PIECES ARE IN PLACE FOR AN IMPRESSIVE
"OUTFLOW" WIND EVENT FROM THE NORTH AND WEST. THIS INCLUDES
IMPRESSIVE JET SUPPORT (FROM THE NORTHWEST)...A LOW IN THE GULF TO
SETUP AN OFFSHORE PRESSURE GRADIENT...AND RELATIVELY COLD AND
DENSE AIR MOVING INTO THE AREA FROM INTERIOR ALASKA. WHAT IS MORE
UNUSUAL IN THIS CASE IS THE TIME OF YEAR. THIS IS A FAIRLY TYPICAL
LATE FALL/WINTER PATTERN...BUT NOT A COMMON LATE SUMMER/EARLY
FALL PATTERN. AS SUCH...HIGH WIND WARNINGS HAVE BEEN ISSUED FOR
THE VALDEZ AREA (INCLUDING IN TOWN) AS WELL AS WHITTIER AND
SEWARD. THE WORST CONDITIONS WILL BE OVERNIGHT TONIGHT...BUT WINDS
WILL REMAIN GENERALLY GUSTY THROUGH FRIDAY NIGHT IN MOST AREAS.

THE OTHER SIDE OF THE COIN IS THE UNSEASONABLY COLD NATURE OF THIS
AIRMASS. ONCE WINDS START TO DIMINISH LATE FRIDAY...THE TYPICAL
COLD SPOTS OF EAST ANCHORAGE...THE BUTTE...AND MEADOW LAKES AREA
IN THE MATANUSKA VALLEY WILL MAKE A STRONG RUN AT FREEZING
TEMPERATURES EARLY SATURDAY MORNING. THE MAIN UNCERTAINTY AT THIS
POINT IS IF ANY MID-LEVEL CLOUDS WILL LOITER AROUND THE AREA TO
HELP KEEP OVERNIGHT TEMPERATURES A FEW DEGREES WARMER. THIS WILL
BE MONITORED CLOSELY OVER THE NEXT 24 HOURS...BUT EVEN IF FREEZING
TEMPERATURES ARE NOT REACHED IN THESE AREAS IT WILL STILL BE
CLOSE...WITH TEMPERATURES THE COLDEST OF THE SEASON SO FAR ACROSS
THE REGION.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
PRECIPITATION OVER MUCH OF THE SOUTHWEST MAINLAND WILL CONTINUE
TO DIMINISH THIS EVENING...AS THE SECOND OF THESE WAVES DEPARTS
INTO THE GULF OF ALASKA AND USHERS IN BRISK NORTHWEST FLOW ON THE
BACKSIDE OF THE DIGGING TROUGH. THIS WILL PRODUCE GUSTY NORTHWEST
WINDS AND ALSO CONTRIBUTE TO COLDER TEMPERATURES TONIGHT...AS
OVERNIGHT LOWS DIP INTO THE 30S ACROSS MUCH OF THE AREA BENEATH
DECREASING CLOUD COVER. THE PERIOD OF DRY WEATHER WILL BE SHORT
LIVED AS ANOTHER WAVE PUSHES INTO THE SOUTHWEST MAINLAND FRIDAY
AFTERNOON. THIS WILL BRING ANOTHER ROUND OF RAINFALL TO THE AREA
FRIDAY NIGHT INTO SATURDAY MORNING...BEFORE SWITCHING OVER TO
SHOWERS LATE SATURDAY MORNING AS THE WAVE TRACKS INTO THE WESTERN
GULF. WITH WINDS SHIFTING TO A STRONGER ONSHORE FLOW OVERNIGHT
TONIGHT...PATCHY FOG OFF THE BERING SEA IS EXPECTED TO PUSH INTO
THE KUSKOKWIM DELTA AND PERSIST THROUGH FRIDAY EVENING.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
ASIDE FROM A FEW SHOWERS IN NORTHWEST FLOW ACROSS THE ALASKA
PENINSULA AND EASTERN ALEUTIANS...THE BULK OF THE RAINFALL WILL
REMAIN CONFINED TO THE FAR WESTERN PARTS OF THE ALEUTIAN CHAIN
THROUGH TONIGHT AS THE NORTH PACIFIC RIDGE IS RE-ESTABLISHED OVER
THE CENTRAL BERING SEA. RAIN WILL THEN SPREAD TO THE NORTHERN AND
EASTERN BERING FRIDAY AS AN UPPER WAVE ROUNDS THE TOP OF THE
RIDGE...WITH RAIN RETURNING TO THE REST OF THE ALEUTIAN CHAIN BY
THE WEEKEND AS THE RIDGE BREAKS DOWN. WIDESPREAD STRATUS AND FOG
IS EXPECTED TO ACCOMPANY THE RIDGE AS IS PERSISTS OVER THE BERING
THROUGH SATURDAY.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

BEGINNING THE EXTENDED PERIOD ON SATURDAY EVENING...THE STATE OF
ALASKA WILL BE UNDER THE INFLUENCE OF A LARGE ARCTIC TROUGH
CENTERED OVER WESTERN ALASKA...WITH A WEAKLY PHASED SHORTWAVE
TROUGH IN NORTHWEST FLOW TRACKING INTO THE GULF OF ALASKA. AN
ASSOCIATED 140 KT UPPER LEVEL JET STREAK WILL BE TRACKING OVER
THE GULF AS THE ARCTIC TROUGH MAKES SOUTHWARD PROGRESS THROUGH
MONDAY. THIS WILL REINVIGORATE THE OFFSHORE FLOW PATTERN AS A
SURFACE LOW FORMS IN THE GULF OF ALASKA AND TRACKS TOWARD THE
PANHANDLE. RAIN AND SNOW SHOWERS WILL REMAIN LARGELY OVER THE
MOUNTAINS THROUGH MONDAY...ALTHOUGH LOWER ELEVATION SHOWERS WILL
BE MORE PREVALENT ACROSS THE LOWER KUSKOKWIM VALLEY AND BRISTOL
BAY REGIONS. OTHERWISE...RAPID DRYING WILL COMMENCE ON MONDAY AS
THE TROUGH CONTINUES TO DIG THROUGH THE SOUTHEAST GULF...AND
OFFSHORE AND DOWNSLOPE FLOW DRIES THE ATMOSPHERIC COLUMN. WEAK
RIDGING ALOFT WILL MOVE OVER THE STATE FROM WEST TO EAST TUESDAY
AND WEDNESDAY...WITH A SLOW WARMUP BUT CONTINUED DRY CONDITIONS.
PRECIPITATION CHANCES REDEVELOP TOWARD LATE WEEK AS A SERIES OF
WEAK LOWS TRACK FROM THE BERING INTO SOUTHWEST ALASKA. WITH THAT
SAID...THE UPPER LEVEL FLOW WILL REMAIN RATHER WEAK...WITH NO
SIGNIFICANT STORMS OR WET PERIODS ANTICIPATED WITH THE CHANGE IN
PATTERN. DUE TO SLIGHT UNCERTAINTY IN THE EXTENDED PERIOD TOWARD
THE END OF NEXT WEEK...A BLENDED WPC ENSEMBLE APPROACH WAS FAVORED
WITH SOME BLEND OF ECMWF AND GFS SATURDAY EVENING THROUGH MONDAY
TO CAPTURE OUTFLOW WINDS ALONG THE COAST.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING 125 131.
MARINE...GALE 119-125 127-138 150 165.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...AMD
SOUTHCENTRAL ALASKA...AMD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP
LONG TERM...JA




000
FXAK68 PAFC 271313
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
513 AM AKDT THU AUG 27 2015

.ANALYSIS AND UPPER LEVELS...

A 150 KT JET STREAK IN THE SUBTROPICAL JET IS NEARLY ZONAL ACROSS
THE NORTHERN BERING AND NOSING INTO SOUTHERN ALASKA THIS MORNING
WITH THE POLAR JET MIGRATING INTO THE BERING STRAIT. ABUNDANT
SUBTROPICAL MOISTURE ADVECTED OVER SOUTHCENTRAL AND THE GULF
DURING THE LAST 24 HOURS WITH THE LARGE PLUME OF MOISTURE EVIDENT
ON IR SATELLITE IMAGERY. A SHORTWAVE MOVING OUT AHEAD OF THE JET
STREAK IS BRINGING SHOWER ACTIVITY TO THE COPPER RIVER BASIN AND
ACROSS THE GULF OF ALASKA.

OVER THE BERING...THE STRONG VERTICALLY STACKED SUBTROPICAL HIGH
REMAINS STATIONARY OVER THE CENTRAL AND EASTERN ALEUTIANS. WATER
VAPOR IMAGERY SHOWS VERY DRY AIR ASSOCIATED WITH THE HIGH OVER THE
BERING MOVING EAST INTO SOUTHWEST ALASKA. COLD BAYS SOUNDING FROM
YESTERDAY EVENING AND THIS MORNING SAMPLED THE WARM AND DRY AIR
FROM ABOUT 800 TO 400 MB. TO PUT THE BREADTH OF THE WARM AIR INTO
PERSPECTIVE... THE FREEZING LEVEL ON THE COLD BAY SOUNDING THIS
MORNING WAS OVER 16700 FEET. THAT IS HIGHER THAN MIAMI
FLORIDA...PHOENIX ARIZONA...AND EVEN HILO HAWAIIS SOUNDINGS FROM
THIS MORNING. ALONG THE WESTERN ALEUTIANS...A STRONG FRONT MOVED
INTO SHEMYA WITH A TROPICAL MOISTURE FEED STREAMING IN FROM THE
REMNANTS OF TYPHOON ATSANI. THE STRONG SOUTHERLY WINDS MOVING OVER
THE RELATIVELY COOLER WATERS IS CAUSING WARM ADVECTION FOG OVER
THE WESTERN ALEUTIANS REDUCING VISIBILITIES TO ONE QUARTER MILE AT
TIMES.

ONE LAST NOTE THIS MORNING ON THE POLAR JET AS IT WILL BE A
SIGNIFICANT PATTERN TO WATCH THROUGH THE REMAINDER OF THE
WEEK...THIS JET BEING DRAWN SOUTHWARD IS MOVING A POLAR AIR MASS
FROM THE ARCTIC OCEAN. WATER VAPOR IMAGERY SHOWS A STRONG SHORTWAVE
NOW MOVING INTO THE SEWARD PENINSULA AND REPRESENTS THE LEADING
EDGE OF A JET STREAK. WHEN THIS ENERGY REACHES SOUTHCENTRAL THIS
AFTERNOON...AN ACTIVE WEATHER CHANGE BEGINS AS THE COLD AIR MERGES
WITH THE WARM AND MOIST SUBTROPICAL AIR MASS CURRENTLY OVER
SOUTHCENTRAL.

&&

.MODEL DISCUSSION...

THE MODELS ARE IN CLOSE AGREEMENT ON THE LATEST EVOLUTION
REGARDING THE ANTICIPATED WIND EVENT ACROSS SOUTHCENTRAL TODAY
THROUGH FRIDAY. THE NAMS HIGH RESOLUTION MADE IT THE MODEL OF
CHOICE IN DETERMINING THE MAGNITUDE AND LOCATION OF THE STRONGEST
WINDS. THE NEXT CHALLENGE IN THE FORECAST IS ON SATURDAY AS THE
NEXT SHORTWAVE ROUNDS THE FLOW OF A PARENT LOW DIVING FROM THE
NORTHWEST COAST. MODELS ARE STRUGGLING WITH THE STRENGTH AND TRACK
OF THIS NEXT SYSTEM AS THE FIRST CLOSED LOW SLOWLY DRIFTS SOUTH
ACROSS THE EASTERN GULF. THE GFS IS THE CURRENT OUTLIER SHOWING
STRONGER PRECIPITATION INTENSITY...BUT TIMING IT ABOUT 6 HOURS
SLOWER THAN THE NAM AND EC.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
A COUPLE OF UPPER LEVEL SYSTEMS WILL CROSS THE AREA TODAY. THE
FIRST IS A STRONG VORTICITY MAXIMUM THAT WILL PUSH QUICKLY
THROUGH SOUTH CENTRAL ALASKA THIS MORNING. DOWN-SLOPING OFF OF
THE ALASKA RANGE WILL KEEP PRECIPITATION AT A MINIMUM AROUND COOK
INLET AND THE SUSITNA VALLEY...WITH POPS RANGING FROM ZERO UP TO
JUST SCATTERED SHOWERS. FURTHER EAST WILL HAVE MUCH BETTER CHANCES
OF PRECIPITATION...WITH LIKELY TO CATEGORICAL POPS OVER THE COPPER
RIVER BASIN THROUGH THE EASTERN PRINCE WILLIAM SOUND AREA. AS THE
VORT MAX SLIDES TOWARD THE CANADIAN BORDER THIS AFTERNOON A
SURFACE LOW WILL DEVELOP OVER THE NORTHEAST GULF OF ALASKA. THE
NEXT VORT MAX WILL PUSH INTO SOUTH CENTRAL THIS AFTERNOON AS THE
FLOW ALOFT TURNS MORE NORTHERLY. THIS SYSTEM WILL PRODUCE LITTLE
OR NO PRECIPITATION BUT BRINGS WITH IT A DECENT COLD FRONT. 850 MB
TEMPERATURES WILL DROP BELOW ZERO OVER MOST OF SOUTH CENTRAL
TONIGHT AS THE COLD FRONT PUSHES THROUGH. THE SURFACE GRADIENT
WILL ALSO INCREASE DRAMATICALLY THURSDAY NIGHT AS THE GULF LOW
DEEPENS AND HIGH PRESSURE BUILDS INTO CENTRAL ALASKA BEHIND THE
FRONT. THE SURFACE GRADIENT WILL SLACKEN FRIDAY AND FRIDAY NIGHT
AS THE GULF LOW SLIDES SOUTHEAST AND THE CENTRAL ALASKA SURFACE
HIGH WEAKENS AHEAD OF A SYSTEM MOVING INTO WESTERN ALASKA.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
WIDESPREAD SHOWER ACTIVITY WILL CONTINUE INTO THIS AFTERNOON
ACROSS THE SOUTHWEST MAINLAND...WITH STEADIER RAIN ACROSS THE
KUSKOKWIM VALLEY AND THE WESTERN SLOPES OF THE ALASKA RANGE AS A
PAIR OF VIGOROUS SHORTWAVES MOVES OVERHEAD IN RAPID SUCCESSION.
PRECIPITATION WILL THEN QUICKLY DIMINISH THIS EVENING AS THE
SECOND OF THESE WAVES DEPARTS INTO THE GULF OF ALASKA AND USHERS
IN BRISK NORTHWEST FLOW ON THE BACKSIDE OF THE DIGGING TROUGH.
THIS WILL PRODUCE GUSTY NORTHWEST WINDS AND ALSO CONTRIBUTE TO
COLDER TEMPERATURES TONIGHT AS OVERNIGHT LOWS DIP INTO THE 30S
ACROSS MUCH OF THE AREA BENEATH DECREASING CLOUD COVER. THE PERIOD
OF DRY WEATHER WILL BE SHORT LIVED AS ANOTHER WAVE MOVES OVER THE
TOP OF THE BERING RIDGE AND BRINGS ANOTHER ROUND OF RAINFALL TO
THE SOUTHWEST MAINLAND BY FRIDAY AFTERNOON.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
ASIDE FROM A FEW SHOWERS IN NORTHWEST FLOW ACROSS THE ALASKA
PENINSULA...THE BULK OF THE RAINFALL WILL REMAIN CONFINED TO THE
FAR WESTERN PARTS OF THE ALEUTIAN CHAIN THROUGH TONIGHT AS THE
NORTH PACIFIC RIDGE IS RE-ESTABLISHED OVER THE CENTRAL BERING SEA
YIELDING WIDESPREAD STRATUS AND FOG. RAIN WILL THEN GRADUALLY
SPREAD TO THE NORTHERN AND EASTERN BERING FRIDAY AND FRIDAY NIGHT
AS AN UPPER WAVE ROUNDS THE TOP OF THE RIDGE...WITH RAIN RETURNING
TO THE REST OF THE ALEUTIAN CHAIN BY THE WEEKEND AS THE RIDGE
BREAKS DOWN.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

BEGINNING THE EXTENDED PERIOD FRIDAY NIGHT...THE REGION WILL BE
UNDER THE INFLUENCE OF AN ELONGATED TROUGH EXTENDING FROM THE
NORTH SLOPE OF ALASKA TO THE COAST OF BRITISH COLUMBIA. THE
OUTFLOW WIND EVENT WILL BE WINDING DOWN FRIDAY NIGHT AS THE GULF
LOW CONTINUES TO WEAKEN AND DRIFT SOUTHEAST. EVENTUALLY WITH
TIME...A SHORTWAVE TROUGH IN NORTHWEST FLOW ORIGINATING FROM
EASTERN SIBERIA WILL MERGE WITH THE AFOREMENTIONED ARCTIC TROUGH
OVER THE NORTH SLOPE SATURDAY AND SUNDAY. THERE UNFORTUNATELY
REMAINS MUCH UNCERTAINTY WITH THE DEVELOPMENT OF THIS LOW AS IT
MOVES FROM THE NORTHERN BERING SEA TO THE GULF OF ALASKA. THE
UNCERTAINTY SEEMS TO LIE IN HOW MUCH SUBTROPICAL ENERGY OVER THE
WESTERN BERING MERGES WITH THE DIGGING TROUGH. THE GFS FAVORS A
STRONGER SOLUTION AND MORE INTACT MERGER...WHICH BRINGS MORE
PRECIPITATION INTO SOUTHWEST ALASKA FRIDAY NIGHT INTO
SATURDAY...AND EVENTUALLY INTO SOUTHCENTRAL SATURDAY AFTERNOON AND
EVENING. THE WEAKER SOLUTIONS SUCH AS THE ECMWF AND CANADIAN GDPS
FAVOR A FARTHER SOUTH TRACK OF THE LOW...AND WEAKER DEVELOPMENT IN
THE GULF OF ALASKA. FOR THIS FORECAST...A CONTINUED CONSERVATIVE
FORECAST WAS TAKEN FAVORING A WPC ENSEMBLE BLEND ALONG WITH SOME
ECMWF. THIS WILL KEEP LOWER END CHANCES FOR PRECIPITATION OVER
MAINLAND LOCATIONS...WITH HIGHER CHANCES REMAINING LARGELY OVER
THE BERING AND GULF OF ALASKA AS THE LOW SKIRTS THE REGION.
THEREAFTER...THERE IS HIGHER CONFIDENCE LEADING INTO MIDWEEK AS
SOUTHCENTRAL REMAINS UNDER THE INFLUENCE OF DRY AND COOLER
OFFSHORE FLOW...WITH A SLOWLY DEVELOPING FLAT RIDGE OVER THE
BERING. PRECIPITATION CHANCES INCREASE AGAIN TOWARDS THE MIDDLE TO
END OF NEXT WEEK...WITH A SLOW REBOUND IN TEMPERATURES AFTER THE
COOL PERIOD THIS WEEKEND AND EARLY NEXT WEEK.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WATCH 131.
MARINE...GALE WARNING 119 120 121 127 128 129 130 131 132 136 137
 150.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...JW/KH
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CB
LONG TERM...JA




000
FXAK68 PAFC 271313
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
513 AM AKDT THU AUG 27 2015

.ANALYSIS AND UPPER LEVELS...

A 150 KT JET STREAK IN THE SUBTROPICAL JET IS NEARLY ZONAL ACROSS
THE NORTHERN BERING AND NOSING INTO SOUTHERN ALASKA THIS MORNING
WITH THE POLAR JET MIGRATING INTO THE BERING STRAIT. ABUNDANT
SUBTROPICAL MOISTURE ADVECTED OVER SOUTHCENTRAL AND THE GULF
DURING THE LAST 24 HOURS WITH THE LARGE PLUME OF MOISTURE EVIDENT
ON IR SATELLITE IMAGERY. A SHORTWAVE MOVING OUT AHEAD OF THE JET
STREAK IS BRINGING SHOWER ACTIVITY TO THE COPPER RIVER BASIN AND
ACROSS THE GULF OF ALASKA.

OVER THE BERING...THE STRONG VERTICALLY STACKED SUBTROPICAL HIGH
REMAINS STATIONARY OVER THE CENTRAL AND EASTERN ALEUTIANS. WATER
VAPOR IMAGERY SHOWS VERY DRY AIR ASSOCIATED WITH THE HIGH OVER THE
BERING MOVING EAST INTO SOUTHWEST ALASKA. COLD BAYS SOUNDING FROM
YESTERDAY EVENING AND THIS MORNING SAMPLED THE WARM AND DRY AIR
FROM ABOUT 800 TO 400 MB. TO PUT THE BREADTH OF THE WARM AIR INTO
PERSPECTIVE... THE FREEZING LEVEL ON THE COLD BAY SOUNDING THIS
MORNING WAS OVER 16700 FEET. THAT IS HIGHER THAN MIAMI
FLORIDA...PHOENIX ARIZONA...AND EVEN HILO HAWAIIS SOUNDINGS FROM
THIS MORNING. ALONG THE WESTERN ALEUTIANS...A STRONG FRONT MOVED
INTO SHEMYA WITH A TROPICAL MOISTURE FEED STREAMING IN FROM THE
REMNANTS OF TYPHOON ATSANI. THE STRONG SOUTHERLY WINDS MOVING OVER
THE RELATIVELY COOLER WATERS IS CAUSING WARM ADVECTION FOG OVER
THE WESTERN ALEUTIANS REDUCING VISIBILITIES TO ONE QUARTER MILE AT
TIMES.

ONE LAST NOTE THIS MORNING ON THE POLAR JET AS IT WILL BE A
SIGNIFICANT PATTERN TO WATCH THROUGH THE REMAINDER OF THE
WEEK...THIS JET BEING DRAWN SOUTHWARD IS MOVING A POLAR AIR MASS
FROM THE ARCTIC OCEAN. WATER VAPOR IMAGERY SHOWS A STRONG SHORTWAVE
NOW MOVING INTO THE SEWARD PENINSULA AND REPRESENTS THE LEADING
EDGE OF A JET STREAK. WHEN THIS ENERGY REACHES SOUTHCENTRAL THIS
AFTERNOON...AN ACTIVE WEATHER CHANGE BEGINS AS THE COLD AIR MERGES
WITH THE WARM AND MOIST SUBTROPICAL AIR MASS CURRENTLY OVER
SOUTHCENTRAL.

&&

.MODEL DISCUSSION...

THE MODELS ARE IN CLOSE AGREEMENT ON THE LATEST EVOLUTION
REGARDING THE ANTICIPATED WIND EVENT ACROSS SOUTHCENTRAL TODAY
THROUGH FRIDAY. THE NAMS HIGH RESOLUTION MADE IT THE MODEL OF
CHOICE IN DETERMINING THE MAGNITUDE AND LOCATION OF THE STRONGEST
WINDS. THE NEXT CHALLENGE IN THE FORECAST IS ON SATURDAY AS THE
NEXT SHORTWAVE ROUNDS THE FLOW OF A PARENT LOW DIVING FROM THE
NORTHWEST COAST. MODELS ARE STRUGGLING WITH THE STRENGTH AND TRACK
OF THIS NEXT SYSTEM AS THE FIRST CLOSED LOW SLOWLY DRIFTS SOUTH
ACROSS THE EASTERN GULF. THE GFS IS THE CURRENT OUTLIER SHOWING
STRONGER PRECIPITATION INTENSITY...BUT TIMING IT ABOUT 6 HOURS
SLOWER THAN THE NAM AND EC.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
A COUPLE OF UPPER LEVEL SYSTEMS WILL CROSS THE AREA TODAY. THE
FIRST IS A STRONG VORTICITY MAXIMUM THAT WILL PUSH QUICKLY
THROUGH SOUTH CENTRAL ALASKA THIS MORNING. DOWN-SLOPING OFF OF
THE ALASKA RANGE WILL KEEP PRECIPITATION AT A MINIMUM AROUND COOK
INLET AND THE SUSITNA VALLEY...WITH POPS RANGING FROM ZERO UP TO
JUST SCATTERED SHOWERS. FURTHER EAST WILL HAVE MUCH BETTER CHANCES
OF PRECIPITATION...WITH LIKELY TO CATEGORICAL POPS OVER THE COPPER
RIVER BASIN THROUGH THE EASTERN PRINCE WILLIAM SOUND AREA. AS THE
VORT MAX SLIDES TOWARD THE CANADIAN BORDER THIS AFTERNOON A
SURFACE LOW WILL DEVELOP OVER THE NORTHEAST GULF OF ALASKA. THE
NEXT VORT MAX WILL PUSH INTO SOUTH CENTRAL THIS AFTERNOON AS THE
FLOW ALOFT TURNS MORE NORTHERLY. THIS SYSTEM WILL PRODUCE LITTLE
OR NO PRECIPITATION BUT BRINGS WITH IT A DECENT COLD FRONT. 850 MB
TEMPERATURES WILL DROP BELOW ZERO OVER MOST OF SOUTH CENTRAL
TONIGHT AS THE COLD FRONT PUSHES THROUGH. THE SURFACE GRADIENT
WILL ALSO INCREASE DRAMATICALLY THURSDAY NIGHT AS THE GULF LOW
DEEPENS AND HIGH PRESSURE BUILDS INTO CENTRAL ALASKA BEHIND THE
FRONT. THE SURFACE GRADIENT WILL SLACKEN FRIDAY AND FRIDAY NIGHT
AS THE GULF LOW SLIDES SOUTHEAST AND THE CENTRAL ALASKA SURFACE
HIGH WEAKENS AHEAD OF A SYSTEM MOVING INTO WESTERN ALASKA.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
WIDESPREAD SHOWER ACTIVITY WILL CONTINUE INTO THIS AFTERNOON
ACROSS THE SOUTHWEST MAINLAND...WITH STEADIER RAIN ACROSS THE
KUSKOKWIM VALLEY AND THE WESTERN SLOPES OF THE ALASKA RANGE AS A
PAIR OF VIGOROUS SHORTWAVES MOVES OVERHEAD IN RAPID SUCCESSION.
PRECIPITATION WILL THEN QUICKLY DIMINISH THIS EVENING AS THE
SECOND OF THESE WAVES DEPARTS INTO THE GULF OF ALASKA AND USHERS
IN BRISK NORTHWEST FLOW ON THE BACKSIDE OF THE DIGGING TROUGH.
THIS WILL PRODUCE GUSTY NORTHWEST WINDS AND ALSO CONTRIBUTE TO
COLDER TEMPERATURES TONIGHT AS OVERNIGHT LOWS DIP INTO THE 30S
ACROSS MUCH OF THE AREA BENEATH DECREASING CLOUD COVER. THE PERIOD
OF DRY WEATHER WILL BE SHORT LIVED AS ANOTHER WAVE MOVES OVER THE
TOP OF THE BERING RIDGE AND BRINGS ANOTHER ROUND OF RAINFALL TO
THE SOUTHWEST MAINLAND BY FRIDAY AFTERNOON.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
ASIDE FROM A FEW SHOWERS IN NORTHWEST FLOW ACROSS THE ALASKA
PENINSULA...THE BULK OF THE RAINFALL WILL REMAIN CONFINED TO THE
FAR WESTERN PARTS OF THE ALEUTIAN CHAIN THROUGH TONIGHT AS THE
NORTH PACIFIC RIDGE IS RE-ESTABLISHED OVER THE CENTRAL BERING SEA
YIELDING WIDESPREAD STRATUS AND FOG. RAIN WILL THEN GRADUALLY
SPREAD TO THE NORTHERN AND EASTERN BERING FRIDAY AND FRIDAY NIGHT
AS AN UPPER WAVE ROUNDS THE TOP OF THE RIDGE...WITH RAIN RETURNING
TO THE REST OF THE ALEUTIAN CHAIN BY THE WEEKEND AS THE RIDGE
BREAKS DOWN.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

BEGINNING THE EXTENDED PERIOD FRIDAY NIGHT...THE REGION WILL BE
UNDER THE INFLUENCE OF AN ELONGATED TROUGH EXTENDING FROM THE
NORTH SLOPE OF ALASKA TO THE COAST OF BRITISH COLUMBIA. THE
OUTFLOW WIND EVENT WILL BE WINDING DOWN FRIDAY NIGHT AS THE GULF
LOW CONTINUES TO WEAKEN AND DRIFT SOUTHEAST. EVENTUALLY WITH
TIME...A SHORTWAVE TROUGH IN NORTHWEST FLOW ORIGINATING FROM
EASTERN SIBERIA WILL MERGE WITH THE AFOREMENTIONED ARCTIC TROUGH
OVER THE NORTH SLOPE SATURDAY AND SUNDAY. THERE UNFORTUNATELY
REMAINS MUCH UNCERTAINTY WITH THE DEVELOPMENT OF THIS LOW AS IT
MOVES FROM THE NORTHERN BERING SEA TO THE GULF OF ALASKA. THE
UNCERTAINTY SEEMS TO LIE IN HOW MUCH SUBTROPICAL ENERGY OVER THE
WESTERN BERING MERGES WITH THE DIGGING TROUGH. THE GFS FAVORS A
STRONGER SOLUTION AND MORE INTACT MERGER...WHICH BRINGS MORE
PRECIPITATION INTO SOUTHWEST ALASKA FRIDAY NIGHT INTO
SATURDAY...AND EVENTUALLY INTO SOUTHCENTRAL SATURDAY AFTERNOON AND
EVENING. THE WEAKER SOLUTIONS SUCH AS THE ECMWF AND CANADIAN GDPS
FAVOR A FARTHER SOUTH TRACK OF THE LOW...AND WEAKER DEVELOPMENT IN
THE GULF OF ALASKA. FOR THIS FORECAST...A CONTINUED CONSERVATIVE
FORECAST WAS TAKEN FAVORING A WPC ENSEMBLE BLEND ALONG WITH SOME
ECMWF. THIS WILL KEEP LOWER END CHANCES FOR PRECIPITATION OVER
MAINLAND LOCATIONS...WITH HIGHER CHANCES REMAINING LARGELY OVER
THE BERING AND GULF OF ALASKA AS THE LOW SKIRTS THE REGION.
THEREAFTER...THERE IS HIGHER CONFIDENCE LEADING INTO MIDWEEK AS
SOUTHCENTRAL REMAINS UNDER THE INFLUENCE OF DRY AND COOLER
OFFSHORE FLOW...WITH A SLOWLY DEVELOPING FLAT RIDGE OVER THE
BERING. PRECIPITATION CHANCES INCREASE AGAIN TOWARDS THE MIDDLE TO
END OF NEXT WEEK...WITH A SLOW REBOUND IN TEMPERATURES AFTER THE
COOL PERIOD THIS WEEKEND AND EARLY NEXT WEEK.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WATCH 131.
MARINE...GALE WARNING 119 120 121 127 128 129 130 131 132 136 137
 150.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...JW/KH
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CB
LONG TERM...JA




000
FXAK68 PAFC 271313
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
513 AM AKDT THU AUG 27 2015

.ANALYSIS AND UPPER LEVELS...

A 150 KT JET STREAK IN THE SUBTROPICAL JET IS NEARLY ZONAL ACROSS
THE NORTHERN BERING AND NOSING INTO SOUTHERN ALASKA THIS MORNING
WITH THE POLAR JET MIGRATING INTO THE BERING STRAIT. ABUNDANT
SUBTROPICAL MOISTURE ADVECTED OVER SOUTHCENTRAL AND THE GULF
DURING THE LAST 24 HOURS WITH THE LARGE PLUME OF MOISTURE EVIDENT
ON IR SATELLITE IMAGERY. A SHORTWAVE MOVING OUT AHEAD OF THE JET
STREAK IS BRINGING SHOWER ACTIVITY TO THE COPPER RIVER BASIN AND
ACROSS THE GULF OF ALASKA.

OVER THE BERING...THE STRONG VERTICALLY STACKED SUBTROPICAL HIGH
REMAINS STATIONARY OVER THE CENTRAL AND EASTERN ALEUTIANS. WATER
VAPOR IMAGERY SHOWS VERY DRY AIR ASSOCIATED WITH THE HIGH OVER THE
BERING MOVING EAST INTO SOUTHWEST ALASKA. COLD BAYS SOUNDING FROM
YESTERDAY EVENING AND THIS MORNING SAMPLED THE WARM AND DRY AIR
FROM ABOUT 800 TO 400 MB. TO PUT THE BREADTH OF THE WARM AIR INTO
PERSPECTIVE... THE FREEZING LEVEL ON THE COLD BAY SOUNDING THIS
MORNING WAS OVER 16700 FEET. THAT IS HIGHER THAN MIAMI
FLORIDA...PHOENIX ARIZONA...AND EVEN HILO HAWAIIS SOUNDINGS FROM
THIS MORNING. ALONG THE WESTERN ALEUTIANS...A STRONG FRONT MOVED
INTO SHEMYA WITH A TROPICAL MOISTURE FEED STREAMING IN FROM THE
REMNANTS OF TYPHOON ATSANI. THE STRONG SOUTHERLY WINDS MOVING OVER
THE RELATIVELY COOLER WATERS IS CAUSING WARM ADVECTION FOG OVER
THE WESTERN ALEUTIANS REDUCING VISIBILITIES TO ONE QUARTER MILE AT
TIMES.

ONE LAST NOTE THIS MORNING ON THE POLAR JET AS IT WILL BE A
SIGNIFICANT PATTERN TO WATCH THROUGH THE REMAINDER OF THE
WEEK...THIS JET BEING DRAWN SOUTHWARD IS MOVING A POLAR AIR MASS
FROM THE ARCTIC OCEAN. WATER VAPOR IMAGERY SHOWS A STRONG SHORTWAVE
NOW MOVING INTO THE SEWARD PENINSULA AND REPRESENTS THE LEADING
EDGE OF A JET STREAK. WHEN THIS ENERGY REACHES SOUTHCENTRAL THIS
AFTERNOON...AN ACTIVE WEATHER CHANGE BEGINS AS THE COLD AIR MERGES
WITH THE WARM AND MOIST SUBTROPICAL AIR MASS CURRENTLY OVER
SOUTHCENTRAL.

&&

.MODEL DISCUSSION...

THE MODELS ARE IN CLOSE AGREEMENT ON THE LATEST EVOLUTION
REGARDING THE ANTICIPATED WIND EVENT ACROSS SOUTHCENTRAL TODAY
THROUGH FRIDAY. THE NAMS HIGH RESOLUTION MADE IT THE MODEL OF
CHOICE IN DETERMINING THE MAGNITUDE AND LOCATION OF THE STRONGEST
WINDS. THE NEXT CHALLENGE IN THE FORECAST IS ON SATURDAY AS THE
NEXT SHORTWAVE ROUNDS THE FLOW OF A PARENT LOW DIVING FROM THE
NORTHWEST COAST. MODELS ARE STRUGGLING WITH THE STRENGTH AND TRACK
OF THIS NEXT SYSTEM AS THE FIRST CLOSED LOW SLOWLY DRIFTS SOUTH
ACROSS THE EASTERN GULF. THE GFS IS THE CURRENT OUTLIER SHOWING
STRONGER PRECIPITATION INTENSITY...BUT TIMING IT ABOUT 6 HOURS
SLOWER THAN THE NAM AND EC.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
A COUPLE OF UPPER LEVEL SYSTEMS WILL CROSS THE AREA TODAY. THE
FIRST IS A STRONG VORTICITY MAXIMUM THAT WILL PUSH QUICKLY
THROUGH SOUTH CENTRAL ALASKA THIS MORNING. DOWN-SLOPING OFF OF
THE ALASKA RANGE WILL KEEP PRECIPITATION AT A MINIMUM AROUND COOK
INLET AND THE SUSITNA VALLEY...WITH POPS RANGING FROM ZERO UP TO
JUST SCATTERED SHOWERS. FURTHER EAST WILL HAVE MUCH BETTER CHANCES
OF PRECIPITATION...WITH LIKELY TO CATEGORICAL POPS OVER THE COPPER
RIVER BASIN THROUGH THE EASTERN PRINCE WILLIAM SOUND AREA. AS THE
VORT MAX SLIDES TOWARD THE CANADIAN BORDER THIS AFTERNOON A
SURFACE LOW WILL DEVELOP OVER THE NORTHEAST GULF OF ALASKA. THE
NEXT VORT MAX WILL PUSH INTO SOUTH CENTRAL THIS AFTERNOON AS THE
FLOW ALOFT TURNS MORE NORTHERLY. THIS SYSTEM WILL PRODUCE LITTLE
OR NO PRECIPITATION BUT BRINGS WITH IT A DECENT COLD FRONT. 850 MB
TEMPERATURES WILL DROP BELOW ZERO OVER MOST OF SOUTH CENTRAL
TONIGHT AS THE COLD FRONT PUSHES THROUGH. THE SURFACE GRADIENT
WILL ALSO INCREASE DRAMATICALLY THURSDAY NIGHT AS THE GULF LOW
DEEPENS AND HIGH PRESSURE BUILDS INTO CENTRAL ALASKA BEHIND THE
FRONT. THE SURFACE GRADIENT WILL SLACKEN FRIDAY AND FRIDAY NIGHT
AS THE GULF LOW SLIDES SOUTHEAST AND THE CENTRAL ALASKA SURFACE
HIGH WEAKENS AHEAD OF A SYSTEM MOVING INTO WESTERN ALASKA.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
WIDESPREAD SHOWER ACTIVITY WILL CONTINUE INTO THIS AFTERNOON
ACROSS THE SOUTHWEST MAINLAND...WITH STEADIER RAIN ACROSS THE
KUSKOKWIM VALLEY AND THE WESTERN SLOPES OF THE ALASKA RANGE AS A
PAIR OF VIGOROUS SHORTWAVES MOVES OVERHEAD IN RAPID SUCCESSION.
PRECIPITATION WILL THEN QUICKLY DIMINISH THIS EVENING AS THE
SECOND OF THESE WAVES DEPARTS INTO THE GULF OF ALASKA AND USHERS
IN BRISK NORTHWEST FLOW ON THE BACKSIDE OF THE DIGGING TROUGH.
THIS WILL PRODUCE GUSTY NORTHWEST WINDS AND ALSO CONTRIBUTE TO
COLDER TEMPERATURES TONIGHT AS OVERNIGHT LOWS DIP INTO THE 30S
ACROSS MUCH OF THE AREA BENEATH DECREASING CLOUD COVER. THE PERIOD
OF DRY WEATHER WILL BE SHORT LIVED AS ANOTHER WAVE MOVES OVER THE
TOP OF THE BERING RIDGE AND BRINGS ANOTHER ROUND OF RAINFALL TO
THE SOUTHWEST MAINLAND BY FRIDAY AFTERNOON.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
ASIDE FROM A FEW SHOWERS IN NORTHWEST FLOW ACROSS THE ALASKA
PENINSULA...THE BULK OF THE RAINFALL WILL REMAIN CONFINED TO THE
FAR WESTERN PARTS OF THE ALEUTIAN CHAIN THROUGH TONIGHT AS THE
NORTH PACIFIC RIDGE IS RE-ESTABLISHED OVER THE CENTRAL BERING SEA
YIELDING WIDESPREAD STRATUS AND FOG. RAIN WILL THEN GRADUALLY
SPREAD TO THE NORTHERN AND EASTERN BERING FRIDAY AND FRIDAY NIGHT
AS AN UPPER WAVE ROUNDS THE TOP OF THE RIDGE...WITH RAIN RETURNING
TO THE REST OF THE ALEUTIAN CHAIN BY THE WEEKEND AS THE RIDGE
BREAKS DOWN.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

BEGINNING THE EXTENDED PERIOD FRIDAY NIGHT...THE REGION WILL BE
UNDER THE INFLUENCE OF AN ELONGATED TROUGH EXTENDING FROM THE
NORTH SLOPE OF ALASKA TO THE COAST OF BRITISH COLUMBIA. THE
OUTFLOW WIND EVENT WILL BE WINDING DOWN FRIDAY NIGHT AS THE GULF
LOW CONTINUES TO WEAKEN AND DRIFT SOUTHEAST. EVENTUALLY WITH
TIME...A SHORTWAVE TROUGH IN NORTHWEST FLOW ORIGINATING FROM
EASTERN SIBERIA WILL MERGE WITH THE AFOREMENTIONED ARCTIC TROUGH
OVER THE NORTH SLOPE SATURDAY AND SUNDAY. THERE UNFORTUNATELY
REMAINS MUCH UNCERTAINTY WITH THE DEVELOPMENT OF THIS LOW AS IT
MOVES FROM THE NORTHERN BERING SEA TO THE GULF OF ALASKA. THE
UNCERTAINTY SEEMS TO LIE IN HOW MUCH SUBTROPICAL ENERGY OVER THE
WESTERN BERING MERGES WITH THE DIGGING TROUGH. THE GFS FAVORS A
STRONGER SOLUTION AND MORE INTACT MERGER...WHICH BRINGS MORE
PRECIPITATION INTO SOUTHWEST ALASKA FRIDAY NIGHT INTO
SATURDAY...AND EVENTUALLY INTO SOUTHCENTRAL SATURDAY AFTERNOON AND
EVENING. THE WEAKER SOLUTIONS SUCH AS THE ECMWF AND CANADIAN GDPS
FAVOR A FARTHER SOUTH TRACK OF THE LOW...AND WEAKER DEVELOPMENT IN
THE GULF OF ALASKA. FOR THIS FORECAST...A CONTINUED CONSERVATIVE
FORECAST WAS TAKEN FAVORING A WPC ENSEMBLE BLEND ALONG WITH SOME
ECMWF. THIS WILL KEEP LOWER END CHANCES FOR PRECIPITATION OVER
MAINLAND LOCATIONS...WITH HIGHER CHANCES REMAINING LARGELY OVER
THE BERING AND GULF OF ALASKA AS THE LOW SKIRTS THE REGION.
THEREAFTER...THERE IS HIGHER CONFIDENCE LEADING INTO MIDWEEK AS
SOUTHCENTRAL REMAINS UNDER THE INFLUENCE OF DRY AND COOLER
OFFSHORE FLOW...WITH A SLOWLY DEVELOPING FLAT RIDGE OVER THE
BERING. PRECIPITATION CHANCES INCREASE AGAIN TOWARDS THE MIDDLE TO
END OF NEXT WEEK...WITH A SLOW REBOUND IN TEMPERATURES AFTER THE
COOL PERIOD THIS WEEKEND AND EARLY NEXT WEEK.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WATCH 131.
MARINE...GALE WARNING 119 120 121 127 128 129 130 131 132 136 137
 150.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...JW/KH
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CB
LONG TERM...JA





000
FXAK68 PAFC 271313
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
513 AM AKDT THU AUG 27 2015

.ANALYSIS AND UPPER LEVELS...

A 150 KT JET STREAK IN THE SUBTROPICAL JET IS NEARLY ZONAL ACROSS
THE NORTHERN BERING AND NOSING INTO SOUTHERN ALASKA THIS MORNING
WITH THE POLAR JET MIGRATING INTO THE BERING STRAIT. ABUNDANT
SUBTROPICAL MOISTURE ADVECTED OVER SOUTHCENTRAL AND THE GULF
DURING THE LAST 24 HOURS WITH THE LARGE PLUME OF MOISTURE EVIDENT
ON IR SATELLITE IMAGERY. A SHORTWAVE MOVING OUT AHEAD OF THE JET
STREAK IS BRINGING SHOWER ACTIVITY TO THE COPPER RIVER BASIN AND
ACROSS THE GULF OF ALASKA.

OVER THE BERING...THE STRONG VERTICALLY STACKED SUBTROPICAL HIGH
REMAINS STATIONARY OVER THE CENTRAL AND EASTERN ALEUTIANS. WATER
VAPOR IMAGERY SHOWS VERY DRY AIR ASSOCIATED WITH THE HIGH OVER THE
BERING MOVING EAST INTO SOUTHWEST ALASKA. COLD BAYS SOUNDING FROM
YESTERDAY EVENING AND THIS MORNING SAMPLED THE WARM AND DRY AIR
FROM ABOUT 800 TO 400 MB. TO PUT THE BREADTH OF THE WARM AIR INTO
PERSPECTIVE... THE FREEZING LEVEL ON THE COLD BAY SOUNDING THIS
MORNING WAS OVER 16700 FEET. THAT IS HIGHER THAN MIAMI
FLORIDA...PHOENIX ARIZONA...AND EVEN HILO HAWAIIS SOUNDINGS FROM
THIS MORNING. ALONG THE WESTERN ALEUTIANS...A STRONG FRONT MOVED
INTO SHEMYA WITH A TROPICAL MOISTURE FEED STREAMING IN FROM THE
REMNANTS OF TYPHOON ATSANI. THE STRONG SOUTHERLY WINDS MOVING OVER
THE RELATIVELY COOLER WATERS IS CAUSING WARM ADVECTION FOG OVER
THE WESTERN ALEUTIANS REDUCING VISIBILITIES TO ONE QUARTER MILE AT
TIMES.

ONE LAST NOTE THIS MORNING ON THE POLAR JET AS IT WILL BE A
SIGNIFICANT PATTERN TO WATCH THROUGH THE REMAINDER OF THE
WEEK...THIS JET BEING DRAWN SOUTHWARD IS MOVING A POLAR AIR MASS
FROM THE ARCTIC OCEAN. WATER VAPOR IMAGERY SHOWS A STRONG SHORTWAVE
NOW MOVING INTO THE SEWARD PENINSULA AND REPRESENTS THE LEADING
EDGE OF A JET STREAK. WHEN THIS ENERGY REACHES SOUTHCENTRAL THIS
AFTERNOON...AN ACTIVE WEATHER CHANGE BEGINS AS THE COLD AIR MERGES
WITH THE WARM AND MOIST SUBTROPICAL AIR MASS CURRENTLY OVER
SOUTHCENTRAL.

&&

.MODEL DISCUSSION...

THE MODELS ARE IN CLOSE AGREEMENT ON THE LATEST EVOLUTION
REGARDING THE ANTICIPATED WIND EVENT ACROSS SOUTHCENTRAL TODAY
THROUGH FRIDAY. THE NAMS HIGH RESOLUTION MADE IT THE MODEL OF
CHOICE IN DETERMINING THE MAGNITUDE AND LOCATION OF THE STRONGEST
WINDS. THE NEXT CHALLENGE IN THE FORECAST IS ON SATURDAY AS THE
NEXT SHORTWAVE ROUNDS THE FLOW OF A PARENT LOW DIVING FROM THE
NORTHWEST COAST. MODELS ARE STRUGGLING WITH THE STRENGTH AND TRACK
OF THIS NEXT SYSTEM AS THE FIRST CLOSED LOW SLOWLY DRIFTS SOUTH
ACROSS THE EASTERN GULF. THE GFS IS THE CURRENT OUTLIER SHOWING
STRONGER PRECIPITATION INTENSITY...BUT TIMING IT ABOUT 6 HOURS
SLOWER THAN THE NAM AND EC.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
A COUPLE OF UPPER LEVEL SYSTEMS WILL CROSS THE AREA TODAY. THE
FIRST IS A STRONG VORTICITY MAXIMUM THAT WILL PUSH QUICKLY
THROUGH SOUTH CENTRAL ALASKA THIS MORNING. DOWN-SLOPING OFF OF
THE ALASKA RANGE WILL KEEP PRECIPITATION AT A MINIMUM AROUND COOK
INLET AND THE SUSITNA VALLEY...WITH POPS RANGING FROM ZERO UP TO
JUST SCATTERED SHOWERS. FURTHER EAST WILL HAVE MUCH BETTER CHANCES
OF PRECIPITATION...WITH LIKELY TO CATEGORICAL POPS OVER THE COPPER
RIVER BASIN THROUGH THE EASTERN PRINCE WILLIAM SOUND AREA. AS THE
VORT MAX SLIDES TOWARD THE CANADIAN BORDER THIS AFTERNOON A
SURFACE LOW WILL DEVELOP OVER THE NORTHEAST GULF OF ALASKA. THE
NEXT VORT MAX WILL PUSH INTO SOUTH CENTRAL THIS AFTERNOON AS THE
FLOW ALOFT TURNS MORE NORTHERLY. THIS SYSTEM WILL PRODUCE LITTLE
OR NO PRECIPITATION BUT BRINGS WITH IT A DECENT COLD FRONT. 850 MB
TEMPERATURES WILL DROP BELOW ZERO OVER MOST OF SOUTH CENTRAL
TONIGHT AS THE COLD FRONT PUSHES THROUGH. THE SURFACE GRADIENT
WILL ALSO INCREASE DRAMATICALLY THURSDAY NIGHT AS THE GULF LOW
DEEPENS AND HIGH PRESSURE BUILDS INTO CENTRAL ALASKA BEHIND THE
FRONT. THE SURFACE GRADIENT WILL SLACKEN FRIDAY AND FRIDAY NIGHT
AS THE GULF LOW SLIDES SOUTHEAST AND THE CENTRAL ALASKA SURFACE
HIGH WEAKENS AHEAD OF A SYSTEM MOVING INTO WESTERN ALASKA.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
WIDESPREAD SHOWER ACTIVITY WILL CONTINUE INTO THIS AFTERNOON
ACROSS THE SOUTHWEST MAINLAND...WITH STEADIER RAIN ACROSS THE
KUSKOKWIM VALLEY AND THE WESTERN SLOPES OF THE ALASKA RANGE AS A
PAIR OF VIGOROUS SHORTWAVES MOVES OVERHEAD IN RAPID SUCCESSION.
PRECIPITATION WILL THEN QUICKLY DIMINISH THIS EVENING AS THE
SECOND OF THESE WAVES DEPARTS INTO THE GULF OF ALASKA AND USHERS
IN BRISK NORTHWEST FLOW ON THE BACKSIDE OF THE DIGGING TROUGH.
THIS WILL PRODUCE GUSTY NORTHWEST WINDS AND ALSO CONTRIBUTE TO
COLDER TEMPERATURES TONIGHT AS OVERNIGHT LOWS DIP INTO THE 30S
ACROSS MUCH OF THE AREA BENEATH DECREASING CLOUD COVER. THE PERIOD
OF DRY WEATHER WILL BE SHORT LIVED AS ANOTHER WAVE MOVES OVER THE
TOP OF THE BERING RIDGE AND BRINGS ANOTHER ROUND OF RAINFALL TO
THE SOUTHWEST MAINLAND BY FRIDAY AFTERNOON.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
ASIDE FROM A FEW SHOWERS IN NORTHWEST FLOW ACROSS THE ALASKA
PENINSULA...THE BULK OF THE RAINFALL WILL REMAIN CONFINED TO THE
FAR WESTERN PARTS OF THE ALEUTIAN CHAIN THROUGH TONIGHT AS THE
NORTH PACIFIC RIDGE IS RE-ESTABLISHED OVER THE CENTRAL BERING SEA
YIELDING WIDESPREAD STRATUS AND FOG. RAIN WILL THEN GRADUALLY
SPREAD TO THE NORTHERN AND EASTERN BERING FRIDAY AND FRIDAY NIGHT
AS AN UPPER WAVE ROUNDS THE TOP OF THE RIDGE...WITH RAIN RETURNING
TO THE REST OF THE ALEUTIAN CHAIN BY THE WEEKEND AS THE RIDGE
BREAKS DOWN.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

BEGINNING THE EXTENDED PERIOD FRIDAY NIGHT...THE REGION WILL BE
UNDER THE INFLUENCE OF AN ELONGATED TROUGH EXTENDING FROM THE
NORTH SLOPE OF ALASKA TO THE COAST OF BRITISH COLUMBIA. THE
OUTFLOW WIND EVENT WILL BE WINDING DOWN FRIDAY NIGHT AS THE GULF
LOW CONTINUES TO WEAKEN AND DRIFT SOUTHEAST. EVENTUALLY WITH
TIME...A SHORTWAVE TROUGH IN NORTHWEST FLOW ORIGINATING FROM
EASTERN SIBERIA WILL MERGE WITH THE AFOREMENTIONED ARCTIC TROUGH
OVER THE NORTH SLOPE SATURDAY AND SUNDAY. THERE UNFORTUNATELY
REMAINS MUCH UNCERTAINTY WITH THE DEVELOPMENT OF THIS LOW AS IT
MOVES FROM THE NORTHERN BERING SEA TO THE GULF OF ALASKA. THE
UNCERTAINTY SEEMS TO LIE IN HOW MUCH SUBTROPICAL ENERGY OVER THE
WESTERN BERING MERGES WITH THE DIGGING TROUGH. THE GFS FAVORS A
STRONGER SOLUTION AND MORE INTACT MERGER...WHICH BRINGS MORE
PRECIPITATION INTO SOUTHWEST ALASKA FRIDAY NIGHT INTO
SATURDAY...AND EVENTUALLY INTO SOUTHCENTRAL SATURDAY AFTERNOON AND
EVENING. THE WEAKER SOLUTIONS SUCH AS THE ECMWF AND CANADIAN GDPS
FAVOR A FARTHER SOUTH TRACK OF THE LOW...AND WEAKER DEVELOPMENT IN
THE GULF OF ALASKA. FOR THIS FORECAST...A CONTINUED CONSERVATIVE
FORECAST WAS TAKEN FAVORING A WPC ENSEMBLE BLEND ALONG WITH SOME
ECMWF. THIS WILL KEEP LOWER END CHANCES FOR PRECIPITATION OVER
MAINLAND LOCATIONS...WITH HIGHER CHANCES REMAINING LARGELY OVER
THE BERING AND GULF OF ALASKA AS THE LOW SKIRTS THE REGION.
THEREAFTER...THERE IS HIGHER CONFIDENCE LEADING INTO MIDWEEK AS
SOUTHCENTRAL REMAINS UNDER THE INFLUENCE OF DRY AND COOLER
OFFSHORE FLOW...WITH A SLOWLY DEVELOPING FLAT RIDGE OVER THE
BERING. PRECIPITATION CHANCES INCREASE AGAIN TOWARDS THE MIDDLE TO
END OF NEXT WEEK...WITH A SLOW REBOUND IN TEMPERATURES AFTER THE
COOL PERIOD THIS WEEKEND AND EARLY NEXT WEEK.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WATCH 131.
MARINE...GALE WARNING 119 120 121 127 128 129 130 131 132 136 137
 150.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...JW/KH
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CB
LONG TERM...JA





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