Area Forecast Discussion
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FXAK67 PAJK 292321
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
321 PM AKDT FRI MAY 29 2015

.SHORT TERM...UPPER LOW SE OF THE PANHANDLE WILL DRIFT EWD INTO
CENTRAL BC BY EARLY SAT. SEVERAL SHORTWAVE TROFS WILL ROTATE AROUND
THE UPPER LOW AND ACROSS THE FAR SERN PANHANDLE THRU SAT. A WEAK
SHORTWAVE TROF WILL MOVE SE TO NEAR THE FAR NRN PANHANDLE SAT
AFTERNOON. SFC HIGH OVER THE GULF WILL SLOWLY WEAKEN THRU SAT.
WEAK SFC TROF WILL REMAIN ACROSS THE SERN PANHANDLE THRU SAT.
MODELS IN GOOD AGREEMENT ON THESE FEATURES...AND NO CHANGE WAS
NEEDED TO THE PRESSURE GRIDS.

MAIN FORECAST CONCERNS ARE MARINE LAYER CLOUDS/FOG...CLOUDS AND
PRECIP THREAT FROM UPPER LOW AND SHORTWAVES TO THE SRN
PANHANDLE...AND POTENTIAL FOR ANY TSTMS FROM TROF REACHING THE FAR
N SAT. WITH THE SFC HIGH OVER THE GULF WEAKENING SOME...AND
BOUNDARY LAYER FLOW GETTING A MORE ONSHORE COMPONENT SAT...THINK
MARINE LAYER MAY NOT COMPLETELY BURN OFF ESPECIALLY ALONG THE
CAPE SPENCER TO CAPE DECISION COASTAL AREA. DO EXPECT MARINE LAYER
TO COVER ENTIRE OUTER COAST BY LATE THIS EVENING WITH LOWERING
CLOUDS...AND FOG WILL LIKELY MOVE IN TO THE COAST LATE TONIGHT.
THE FOG SHOULD LIFT ALONG THE OUTER COAST BY LATE SAT MORNING
ALTHOUGH IT COULD HANG TOUGH NEAR PAEL. SOME LOW CLOUDS WILL
LIKELY GET INTO THE PAGS AREA OVERNIGHT TONIGHT...BUT THEY SHOULD
DISSIPATE BY LATE SAT MORNING.

FOR THE SRN PANHANDLE AREA...EXPECT BANDS OF MAINLY MID-LEVEL
CLOUDS TO MOVE ACROSS MAINLY THE INNER CHANNELS TO THE SOUTH OF
SUMNER STRAIT TONIGHT AND SAT. THE WRN EDGE OF THE CLOUD BANDS
WILL GRADUALLY SHIFT EWD LATE TONIGHT AND SAT. THERE MAY BE SOME
SHOWERS MAINLY IN THE MISTY FJORDS AREA THIS EVENING...THEN
ISOLATED TSTMS WILL BE POSSIBLE MAINLY NEAR HYDER SAT AS MORE
SHORTWAVE ENERGY BRUSHES BY THEM...AND THEY SHOULD BE WARMER SAT
AS WELL HELPING WITH THE DEEPER CONVECTION POTENTIAL.

OVER THE FAR NRN AREA SAT AFTERNOON...SHORTWAVE TROF DROPPING
SOUTH TOWARD THE AREA WILL TRIGGER TSTMS OVER THE SRN YUKON...AND
SOME OF THESE MAY GET INTO THE PAGY AREA LATE IN THE DAY. WILL AT
LEAST SEE MORE MID-LEVEL CLOUDS MOVE IN DURING THE AFTERNOON THERE.

OTHERWISE...WINDS WILL DO THEIR USUAL DIURNAL CYCLE TONIGHT AND
SAT OVER MOST OF THE INNER CHANNELS. LARGER SCALE PRESSURE GRADIENT
IS FAVORING MORE NWLY FLOW...SO CHANNELS THAT FAVOR THAT FLOW WILL
SEE STRONGER WINDS. SCA LEVEL WINDS ARE OCCURRING NEAR CAPE
SPENCER ATTM...AND THESE SHOULD DROP OFF TONIGHT...BUT MORE SCA
LEVEL WINDS ARE LIKELY THERE SAT AFTERNOON. WINDS OVER THE GULF
WILL GENERALLY STAY IN THE 15-20 KT RANGE...WITH LIGHTER FLOW OVER
THE FAR NRN GULF NEAR THE COAST.

MAX TEMPS SAT SHOULD BE NEAR WHERE THEY GOT TO TODAY OVER MOST
INNER CHANNELS...BUT SOME PLACES NEAR THE OUTER COAST WILL LIKELY BE A
BIT COOLER DUE TO A SLIGHTLY MORE ONSHORE WIND.

.LONG TERM...MODELS REMAIN IN FAIR AGREEMENT THROUGH EARLY NEXT
WEEK FOR THE WEAKENING UPPER LEVEL LOW OVER BRITISH COLUMBIA
SATURDAY NIGHT GRADUALLY MOVE EAST ON SUNDAY AND DISSIPATE BY
SUNDAY EVENING. UPPER RIDGE WILL REBUILD BEHIND AND MOVE EAST
THROUGH MONDAY WHILE ANOTHER UPPER LEVEL SHORTWAVE TROUGH ACROSS
THE YUKON DRIFTS SOUTH TO TOUCH NORTHERNMOST PANHANDLE. THIS UPPER
TROUGH MAY BRING A SLIGHT CHANCE OF SHOWERS OVER THE
SKAGWAY...HAINES AND YAKUTAT AREAS. REFRESHED THE INHERITED
FORECAST WITH THE 12Z RUN ECMWF THROUGH LATE MONDAY.

SURFACE HIGH PRESSURE WILL CONTINUE TO DOMINATE ACROSS THE GULF
WITH AN INVERTED TROUGH OF LOW PRESSURE PERSISTING OVER THE
PANHANDLE. MODERATE TO STRONG SUBSIDENCE WILL LIKELY TO MAINTAIN
MARINE STRATUS OVER THE OPEN OCEAN AND INVADE THE PANHANDLE
COASTAL SECTIONS...ESPECIALLY FARTHER INLAND ACROSS THE SOUTHERN
PANHANDLE. THE HIGH PRESSURE WILL SLOWLY WEAKEN AND DRIFT SOUTH AS
THE INVERTED TROUGH EXPANDS A LITTLE FARTHER NORTHWEST.

MODELS DIVERT BY MID WEEK AND USED THE NEW WPC ENSEMBLE GUIDANCE
AND MAINTAINED A PATTERN CHANGE FROM DRY TO WET WEATHER BY MID
WEEK THROUGH THE SECOND HALF OF THE WEEK. ANOTHER UPPER LEVEL
SHORTWAVE TROUGH MOVING INTO THE WESTERN GULF ON MONDAY WILL
CONTINUE TO PUSH UPPER RIDGE EASTWARD AND GRADUALLY MOVE INTO THE
CENTRAL GULF BY WEDNESDAY. A COUPLE OF UPPER LEVEL LOWS ASSOCIATED
WITH THE TROUGH WILL MOVE NORTH TO NORTHEAST ACROSS THE NORTHERN
GULF THROUGH THE SECOND HALF OF THE WEEK. CLOUDS WILL BEGIN
INCREASING ON TUESDAY AND WEDNESDAY ACROSS THE PANHANDLE WITH
INCREASING RAIN CHANCES THROUGH THE SECOND HALF OF THE WEEK.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ022.

&&

$$

RWT/AHN

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