Gale Warning 171, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE JUNEAU AK
1108 PM AKDT FRI APR 22 2016

.SYNOPSIS...A BROAD TROUGH OF LOW PRESSURE EXTENDS FROM THE
WESTERN ALEUTIANS TO BRITISH COLUMBIA. AN ORGANIZED 986 MB LOW
SITS ROUGHLY 400 NM SOUTH-SOUTHEAST OF KODIAK ISLAND. A HIGH
PRESSURE FROM THE ARCTIC OCEAN TO NORTHERN CANADA PERSISTS.

&&

.SHORT TERM...THE LOW IN THE SOUTHERN GULF WILL DRIFT NORTH
TONIGHT AND STALL ABOUT 200 NM SOUTHEAST OF KODIAK ISLAND AND
BECOME VERTICALLY STACKED BY SATURDAY. A NARROW WEAK RIDGE ALONG
THE PANHANDLE COAST WILL DEVELOP SATURDAY AFTER THE ASSOCIATED
WEATHER MOVES INLAND OVER SOUTHEAST ALASKA. A WEAK TROUGH ALONG
THE BRITISH COLUMBIA COAST MOVES NORTH FRIDAY EVENING USHERING
MOISTURE AND CLOUDS NORTH INTO THE PANHANDLE DURING THE EVENING
AND OVERNIGHT. RAIN IS EXPECTED TO START IN THE SOUTHERN HALF OF
THE PANHANDLE BY MIDNIGHT. THE FRONTAL BAND APPROACHING FROM THE
SOUTHWEST WILL THEN ENHANCE THE LIFT INCREASING RAIN CHANCES TO
CATEGORICAL FOR LATE FRIDAY NIGHT AND SATURDAY FOR THE ENTIRE
PANHANDLE.

AS THE FRONT APPROACHES SOUTHEAST ALASKA LOOK FOR SMALL CRAFT
WINDS TO SPREAD INTO THE WESTERN PARTS OF THE OUTER COASTAL MARINE
ZONES SOUTH OF SITKA. CLOSER TO THE LOW IN THE CENTRAL GULF OF
ALASKA WINDS WILL GENERALLY BLOW 25 TO 30 KT. UPON FRONTAL
LANDFALL OR NEAR LANDFALL THE INNER CHANNEL WINDS WILL PICK UP AS
WELL...THINK THAT THEY WILL LIKELY STAY BELOW SMALL CRAFT AT THE
MOMENT. HOWEVER A FEW GUSTS TO GET UP TO 30+ KT FOR CLARENCE
STRAIT AND CROSS SOUND.

.LONG TERM...AN UPPER LOW WILL BE LOCATED OVER THE CENTRAL GULF AT
THE START OF THE EXTENDED RANGE FORECAST SATURDAY EVENING. AN
UPPER TROUGH WILL EXTEND SOUTHEAST PARALLEL TO THE COAST BUT WELL
OFFSHORE. THIS FEATURE WILL PIVOT NORTH, TO BE OVER SOUTHEAST
ALASKA BY MONDAY MORNING. AT THE SURFACE, A SECOND WRAP OFF THE
LOW ASSOCIATED WITH TOMORROW'S FRONT WILL KEEP MUCH OF SOUTHEAST
ALASKA WET ON MONDAY. THE SECOND FRONT ASSOCIATED WITH THE UPPER
TROUGH WILL BRING CATEGORICAL PRECIP TO AREAS NORTH OF CAPE
FAIRWEATHER BY MONDAY EVENING, BUT A WAVE THAT WILL FORM ON THE
FRONT MAY PULL IT AWAY FROM THE OUTER COAST AND DELAY THE ONSET OF
RAIN OVER THE SOUTHERN HALF UNTIL LATE TUESDAY NIGHT OR WEDNESDAY
MORNING. LATER IN THE WEEK, MODELS INDICATING AT LEAST ONE MORE
FRONT THURSDAY INTO FRIDAY, ALTHOUGH THEY ARE DIFFERING ON DETAILS
AND TIMING. QPF VALUES SIMILAR TO PREVIOUS FORECAST THROUGH
TUESDAY NIGHT.

AM ANTICIPATING LOW END GALE FORCE WINDS ASSOCIATED WITH THE
MONDAY EVENING FRONT OUT OVER THE GULF AND HAVE ADJUSTED WIND
SPEEDS UPWARD ACCORDINGLY. WITH THE WAVE LIMITING EASTWARD
PROGRESS OF THE FRONT, AM NOT EXPECTING MUCH OF A RESPONSE OVER
THE INNER CHANNELS SO HAVE KEPT WITH THE 15 TO 20 KTS THAT WAS IN
THE PREVIOUS FORECAST AND HAVE SOUTHEASTERLIES TO 25 KTS FOR THE
CENTRAL AND SOUTHERN OUTER WATERS.

UPDATES TODAY FOCUSED ON THE MONDAY AND MONDAY NIGHT TIME FRAME.
USED A BLEND OF THE GFS22 AND ECMWF FOR PRESSURE AND WIND. USED
GFS40 AND GFS22 FOR POP AND QPF. MODEL CHOICE BASED HEAVILY ON HOW
GFS DEVELOPED THE FRONTAL WAVE DURING THIS PERIOD. OVERALL
FORECAST CONFIDENCE IS AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ052.
     SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041>043-051.
&&

BEZENEK/FRITSCH

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