Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 261300
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKDT THU MAR 26 2015

.ANALYSIS AND UPPER LEVELS...
THE MAIN FEATURE OF INTEREST IMPACTING THE REGION THIS MORNING IS
A LOW PRESSURE SYSTEM LOCATED JUST SOUTH OF KODIAK ISLAND. THIS
LOW IS EMBEDDED WITHIN A LONGWAVE TROUGH OVER THE NORTH PACIFIC
WHICH HAS DISPLACED THE MAINLAND RIDGE EASTWARD INTO THE YUKON
TERRITORY. A FRONT ASSOCIATED WITH THE LOW IS SPREADING RAIN OVER
KODIAK ISLAND AND THE GULF COAST...WITH AN AREA OF GALE FORCE
WINDS OVER THE NORTHERN GULF. A SECONDARY LOW DEVELOPING SOUTH OF
THE SHUMAGIN ISLANDS IS SPREADING RAIN SHOWERS OVER THE ALASKA
PENINSULA...WITH A WEAK FRONTAL BOUNDARY STALLED OVER THE CENTRAL
BERING BRINGING RAIN TO THE EASTERN ALEUTIANS AND AREAS OF
BLOWING SNOW TO THE PRIBILOF ISLANDS.

&&

.MODEL DISCUSSION...
MODELS REMAIN IN GOOD SHORT TERM AGREEMENT AND HAVE CONVERGED
SOMEWHAT ON A SOLUTION FOR THE PRIMARY LOW AS IT TRACKS OVER THE
WESTERN GULF TODAY...BRINGING THE LOW CENTER OVER KODIAK ISLAND
LATER THIS AFTERNOON BEFORE IT IS ABSORBED INTO THE NEW LOW
FORMING SOUTH OF THE AKPEN. GREATER DIFFERENCES BEGIN TO ARISE BY
FRIDAY AS ANOTHER NORTH PACIFIC LOW ROUNDING THE BASE OF THE
LONGWAVE TROUGH BEGINS TO MOVE INTO THE GULF ALONG A TRACK SIMILAR
TO THE CURRENT LOW. THE NAM APPEARS TO BE THE BIGGEST OUTLIER
WITH THIS FEATURE...AND THUS PREFERRED A GFS/EC SOLUTION FOR THE
FORECAST. ALSO UTILIZED THE CANADIAN REGIONAL MODEL IN THE FIRST
36 HOURS FOR FINER DETAIL WITH WINDS OVER THE BERING SEA AND
SOUTHWEST MAINLAND.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (TODAY AND FRIDAY)...
THE LOW IN THE NORTHEAST GULF OF ALASKA WILL CONTINUE TO MOVE
NORTH AND NORTHWEST THROUGH THE DAY. RAINFALL WILL CONTINUE ALONG
THE GULF COAST WITH ONLY SOME SHOWERS MAKING IN INLAND AS THE AIR
ONE THE LEEWARD SIDE OF THE MOUNTAINS IS MUCH DRYER WITH DEWPOINTS
20 TO 25 DEGREES LOWER THAN COASTAL STATIONS THIS MORNING. THESE
DEWPOINTS SHOULD INCREASE DURING THE DAY AS MORE MOISTURE FROM
THIS LOW PUSHES INTO SOUTHCENTRAL. WINDS WILL REMAIN FROM THE EAST
TO NORTHEAST THROUGHOUT MOST OF THE DAY BUT THEN START TO SWITCH
TO THE SOUTHEAST DURING THE LATE AFTERNOON TO EARLY EVENING AS THE
FRONT PUSHES NORTHWEST OF THE AREA. THIS WILL ALLOW SOME STRONG
WINDS IN TURNAGAIN ARM THIS AFTERNOON BUT WINDS WILL NOT COME INTO
THE ANCHORAGE BOWL UNTIL LATE AFTERNOON OR EARLY EVENING. THE
MATANUSKA AREA MAY ACTUALLY SEE WINDS TURN TO THE SOUTHEAST BEFORE
THE ANCHORAGE BOWL DOES WHICH IS COMMON IN THIS PATTERN.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (TODAY AND FRIDAY)...
THE MAINLAND CONTINUES TO BE UNDER THE INFLUENCE OF CYCLONIC FLOW
ASSOCIATED WITH THE COMPLEX LOW PRESSURE SYSTEM IN THE GULF. A
COUPLE EMBEDDED WAVES IN THE FLOW ARE TRYING TO FORCE SOME
PRECIPITATION OVER THE AREA BUT MOST OF IT APPEARS TO BE VIRGA AS
LOW LEVEL EASTERLY FLOW KEEPS RESUPPLYING DRY AIR FROM DOWNSLOPE
FLOW. CHANCES FOR RAIN SHOWERS SHOULD INCREASE TONIGHT WITH A BIT
BETTER FORCING ALOFT AND A MOISTER SOUTHEAST FLOW...HOWEVER...DEEP
LAYER CROSS BARRIER FLOW STILL EXISTS OVER THE ALEUTIAN RANGE SO A
LARGE SWATH OF THE INTERIOR BRISTOL BAY ZONE WILL REMAIN DRY. THE
BEST CHANCE FOR PRECIPITATION IN THIS PATTERN WILL BE WEST OF
DILLINGHAM WHERE UPSLOPE FLOW ALONG THE AHKLUN/KILBUCK RANGES WILL
PROMOTE RAIN...WITH SNOW AT HIGHER ELEVATIONS ON FRIDAY. BEHIND
THE FRONT ON FRIDAY STRONG GUSTY EASTERLY WINDS WILL DEVELOP FOR
MOST OF THE INTERIOR BRISTOL BAY ZONE.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (TODAY AND FRIDAY)...
THE WARM FRONT HAS STALLED OVER THE SOUTHCENTRAL BERING SEA
KEEPING RAIN IN THE FORECAST FOR THE EASTERN ALEUTAINS
TRANSITIONING TO SNOW TO THE WEST. THE REMAINDER OF THE EASTERN
BERING SEA WILL RESIDE UNDER CYCLONIC FLOW AND A MORE SHOWERY
REGIME THROUGH FRIDAY.

&&

.LONG TERM FORECAST (SATURDAY THROUGH WEDNESDAY)...
THE SECOND GALE FORCE NORTH PACIFIC LOW WILL TRACK SOUTH OF KODIAK
ISLAND BY SATURDAY MORNING. THE ASSOCIATED WEATHER FRONT WITH THIS
SYSTEM WILL BE LOCATED FROM KODIAK ISLAND NORTHWARD ALONG THE
NORTHERN GULF COASTLINE. THIS WILL BRING WIDESPREAD RAIN MAINLY
ALONG THE COAST BUT SOME RAIN SHOWERS WILL MAKE IT OVER THE
CHUGACH MOUNTAINS INTO THE ANCHORAGE BOWL. OTHERWISE...THE MATSU
VALLEY AND THE ANCHORAGE BOWL WILL DOWNSLOPE RESULTING IN DRIER
CONDITIONS THROUGH THE WEEKEND. THIS LOW PRESSURE SYSTEM WILL
SLOWLY MOVE TO THE NORTHERN GULF BY MONDAY AND BECOME STATIONARY
BEFORE DISSIPATING BY LATE TUESDAY. THIS SYSTEM WILL CONTINUE TO
BRING WARM TEMPERATURES AND PRECIPITATION ALL IN THE FORM OF RAIN
ALONG THE COASTAL REGION THROUGH WEDNESDAY. THE CHUGACH AND KENAI
MOUNTAINS WILL AGAIN KEEP MAJORITY OF INLAND AREAS DRY EXCEPT FOR
SOME SLOP-OVER RAIN SHOWERS MAKING IT OVER THE MOUNTAINS BEFORE
THE LOW DISSIPATES BY LATE TUESDAY.

THE BERING SEA AND THE ALEUTIANS...REMAIN IN PERSISTENT NORTHERLY
FLOW THROUGH THE WEEKEND. THE EASTERN BERING SEA/ALEUTIANS AND THE
BRISTOL BAY AREA WILL RECEIVE THE EFFECTS FROM THE NORTH PACIFIC
LOW AS IT MOVES NEAR KODIAK ISLAND. THE PRECIPITATION WILL SPREAD
OVER INTO THE EASTERN BERING SEA/ALEUTIANS THROUGH THE WEEK. BY
SATURDAY THE NEXT NORTH PACIFIC LOW TRACKS TOWARDS KODIAK ISLAND.
THIS WILL CONTINUE TO BRING WARMER TEMPERATURES AND RAIN ALONG
THE EASTERN ALEUTAINS AND THE BRISTOL BAY AREA. BY MONDAY A SERIES
OF WEAK WAVES WILL ENTER THE WESTERN ALEUTIANS AND MOVE ALONG THE
CHAIN TO THE EASTERN ALEUTIANS BY WEDNESDAY. THIS WILL BRING
WARMER TEMPERATURES WITH RAIN...WHICH WILL SPILL OVER INTO THE
LOWER BERING SEA AS THE LOW TRACKS EASTWARD THROUGH THE MIDDLE OF
NEXT WEEK. FARTHER NORTH IN THE BERING THEY WILL SEE A WINTRY MIX
DUE TO THE COOLER TEMPERATURES.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 119 130 132 139
         HEAVY FREEZING SPRAY 179.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...CB
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML
LONG TERM...PD


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