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FXAK67 PAJK 152335
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
335 PM AKDT MON SEP 15 2014

.SHORT TERM...SATELLITE IMAGERY THIS AFTERNOON SHOWING A WEAKENING
WEATHER FRONT AND SHORT WAVE OVER THE FAR EASTERN AK GULF PUSHING
OVER THE AK PANHANDLE. THIS FRONT HAS BEEN PRODUCING PRECIP OVER
THE YAKUTAT AREA AND ALONG THE CENTRAL COAST BUT CURRENTLY NO
OTHER LOCATIONS REPORTING ANY RAIN. THE FRONT MOVES OVERLAND
SHEARING APART AND BEGINS TO DISSIPATE TONIGHT. MODELS ARE KEEPING
A BAND OF CATEGORICAL POP FROM A CORRIDOR FROM SITKA NORTHWEST
INTO JUNEAU ALONG THE TRACK THE SHORT WAVE WILL MOVE. THINK MODELS
MAY BE OVER DOING POP DUE TO THE WEAKENING NATURE OF THE SYSTEM
HOWEVER HAVE KEPT IN CHANCE PRECIP FOR THIS AREA. FOR YAKUTAT RAIN
WILL DIMINISH THIS EVENING THEN PICK UP AGAIN LATE TONIGHT AS
SHORT WAVE REMNANTS OF THE ORIGINAL LOW MOVE INTO THE AK INTERIOR
AND JUST TAG THE ZONE. HIGH PRESSURE WILL REBUILD OVER THE AK GULF
BEHIND THESE WEAK SHORT WAVES. SOUTHWEST FLOW WILL SHIFT THE THE
NORTHWEST THROUGH TUESDAY RESULTING IN SOME PARTLY CLOUD SKIES
OVER PORTIONS OF THE PANHANDLE AND A DRY DAY OVERALL.

WITH THE EXCEPTION OF CROSS SOUND WHICH HAS EASTERLY WINDS IN THE
15 KT RANGE DUE TO THE ADVANCING FRONT WINDS ARE SOUTHEASTERLY AND
GENERALLY LESS THAN 10 KTS DUE TO THE WEAK GRADIENT. THESE LIGHT
WINDS WILL LAST INTO TUESDAY WITH SOME 10 KTS BREEZES IN THE
AFTERNOON AS DAY TIME TEMPS INCREASE. THE SOUTHERN HALF OF THE
PANHANDLE WILL HAVE FOG REDEVELOP LATE TONIGHT INTO TUESDAY
MORNING AS STABLE ATMOSPHERE LIMITS ANY MIXING ALONG WITH
LINGERING MOISTURE AND COOLING OVER NIGHT TEMPS. WITH SOME HIGHER
CLOUD COVER FROM THE ADVANCING FRONT FOR NOW NOT EXPECTING FOG TO
BE AS DENSE OR WIDE SPREAD.

MODEL DIFFERENCES WERE VERY MINOR AND MATCHED WELL WITH INHERITED
FORECAST FOR PRESSURE AND WINDS. MAIN ISSUE IS THE EXTEND OF
PRECIP FROM THESE SHORTWAVES AND IF THE MODELS ARE OVER DOING
CATEGORICAL POPS DUE TO THE WEAKENING SYSTEM. KEPT WITH A BLEND OF
NAM/GEM WITH SOME ECMWF/GFS, ANY CHANGES WERE MINIMAL. FORECAST
CONFIDENCE IS AVERAGE WITH HIGHER CONFIDENCE IN WIND FORECAST BUT
LOWER CONFIDENCE WITH PRECIP.

.LONG TERM...ACTIVE PATTERN FOR THE LATTER HALF OF THE WEEK AND
WEEKEND AS LONG WAVE TROF SETS UP OVER MUCH OF AK AND THE ERN PAC.
A FAIRLY STRONG LOW AND FRONT WILL MOVE NE INTO THE GULF FOR WED
NIGHT INTO THU EVENING...WITH THE LOW TRACK INTO THE WRN HALF OF
THE GULF. THE LOW SHOULD REMAIN OVER THE NW GULF INTO THE
WEEKEND...WHILE ONE OR MORE LOW PRESSURE AREAS DEVELOP AND MOVE
INTO THE CENTRAL OR ERN GULF FRI-SUN. AFTER COORD WITH WFO
PAFC...USED A BLEND OF THE 12Z GFS/ECMWF/NAM FOR TUE NIGHT THRU
FRI EVENING...THEN WENT WITH MOSTLY WPC FOR FRI NIGHT ON OUT. THE
TRANSITION BETWEEN THE MODEL BLEND WAS FAIRLY SMOOTH SO DID NOT
NEED TO BLEND ANY OTHER MODELS WITH WPC.

FOR TUE NIGHT AND WED...UPPER TROF WILL BEGIN TO SLIDE EWD INTO
THE GULF. OCCLUDED FRONT MOVING TO THE FAR SW GULF BY LATE TUE
NIGHT..THEN REACH THE CENTRAL GULF WED. MEANWHILE...REMNANT OF
FRONT OVER SE AK MAY SLOWLY REDEVELOP OVER THE AREA AS LEADING
PART OF UPPER TROF MOVES IN. THERE MAY BE SPOTTY PRECIP WED OVER
THE AREA.

FOR WED NIGHT INTO THU NIGHT...LOW DEVELOPS AND MOVES INTO THE SW
GULF BY WED EVENING...AND A STRONGER OCCLUDED FRONT WILL MOVE INTO
THE CENTRAL GULF WED EVENING. THIS FRONT WILL SPREAD NE INTO THE
ERN GULF AND SE AK THU. LOOKS FAIRLY WINDY AND WET WITH THIS
SYSTEM...AND THERE MAY BE FURTHER DEVELOPMENT AND ENHANCEMENT OF
PRECIP WITH THE OLD FRONT OVER THE PANHANDLE WED NIGHT AND THU
MORNING BEFORE PRECIP WITH THE OCCLUDED FRONT MOVES ONSHORE.
BOOSTED WINDS SOME ESPECIALLY OVER THE GULF WED NIGHT AND THU AS
SYSTEM HAS TRENDED A BIT STRONGER. MAIN OCCLUDED FRONT SHOULD PUSH
THRU SE AK THU NIGHT.

FOR FRI INTO THE WEEKEND...MAIN LOW WILL STAY OVER THE NW
GULF...BUT WILL NEED TO WATCH OUT FOR MORE LOWS MOVING INTO THE ERN
HALF OF THE GULF. GIVEN THE MODEL DIFFERENCES ON THESE...LATER
SHIFTS WILL NEED TO KEEP AN EYE ON THIS. FOR NOW WPC WAS GENERALLY
USED TO HANDLE THIS PERIOD...ALTHOUGH LATER ON DID LIMIT POPS TO
LIKELY ON HIGH END.

&&

.AVIATION...LOW CEILINGS OVER THE PANHANDLE WILL LIFT THIS EVENING
FOR MAJORITY OF THE PANHANDLE. FOG AND LOW CLOUDS WILL REFORM LATE
TONIGHT INTO TUESDAY MORNING WITH IFR CONDITIONS FOR THE SOUTHERN
THIRD OF THE PANHANDLE. CONDITIONS WILL IMPROVE THROUGH THE
MORNING AS THE SUN RISES AND BURNS OFF THE FOG.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041>043-051-052.

&&

$$

PRB/RWT

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