Area Forecast Discussion
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000
FXAK67 PAJK 020030
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
430 PM AKDT SUN MAY 1 2016

.SHORT TERM...A FRONT ACROSS THE CENTRAL PANHANDLE SSW INTO THE SE
GULF WILL MOVE NWWD AND BACK INTO THE ERN GULF AS A SLOWLY
DEEPENING LOW PRESSURE WAVE MOVES N THRU THE ERN GULF TONIGHT. THE
FRONT WILL THEN PUSH BACK ONSHORE MON MORNING BUT STALL AGAIN OVER
THE FAR ERN INNER CHANNELS BY LATE AFTERNOON. USED BLEND OF THE
12Z GEM AND GFS THROUGH MON...MAINLY FOR WAY THEY HANDLED THE LOW
PRESSURE WAVE. ECMWF WAS ALSO USABLE. NAM APPEARED TOO FAST WITH
THE WAVE.

MAIN FORECAST CONCERNS WILL BE PRECIP POTENTIAL/AMOUNTS AND WINDS.
STEADIER RAIN IS CURRENTLY SPREADING INTO THE NRN AREA LATE THIS
AFTERNOON. RAIN WILL INCREASE IN INTENSITY THIS EVENING AS STRONG
LIFT ASSOCIATED WITH THE LOW PRESSURE WAVE OVERSPREADS THE AREA.
HOWEVER...THE FAR SERN AREA WILL LIKELY SEE THE PRECIP LIFT N OF
THEM BY LATE EVENING AS DRIER MID-LEVEL AIR WITH THE WARM SECTOR
MOVES IN. THE PAYA AREA SHOULD SEE THEIR SHOWERS BECOME A STEADIER
RAIN DURING THIS EVENING. AFTER THE FRONT PUSHED BACK
ONSHORE...PRECIP WILL TRANSITION TO SHOWERS WITH MAINLY SCATTERED
COVERAGE EXPECTED BEHIND THE FRONT. THE FAR ERN INNER CHANNELS
WILL STAY IN THE STEADIER RAIN ESPECIALLY ACROSS THE CENTRAL AREA
AS FRONT HANGS UP THERE AGAIN. THE RAINFALL INTENSITY SHOULD
DECREASE MON THOUGH AS STRONGER LIFT WITH THE LOW PRESSURE WAVE
WILL MOVE NE OF THE AREA BY LATE MORNING.

RAINFALL WILL BE LOCALLY HEAVY ESPECIALLY ACROSS THE CENTRAL AND
NRN AREAS TONIGHT. UP TO 2.5 INCHES OF RAIN IS POSSIBLE WITH
LOCALLY HIGHER AMOUNTS IN THE MTNS THROUGH 15Z MON. THERE MAY BE
AN ADDITIONAL 0.5 TO 1.5 INCHES MON WITH HIGHEST AMOUNTS OVER THE
ERN AREAS. SEE HYDROLOGY SECTION FOR IMPACTS ON AREA RIVERS.

STRONGEST WINDS WILL BE ON E SIDE OF THE LOW PRESSURE WAVE. GALE
FORCE S-SE WINDS WILL OCCUR OVER THE FAR ERN GULF TONIGHT WITH SCA
TO GALE FORCE WINDS OVER THE CENTRAL AND SRN INNER CHANNELS. WILL
ALSO HAVE STRONG WIND HEADLINE FOR THE EVENING HOURS IN PUBLIC
ZONE 27. ZONES 23 AND 28 COULD BE A CLOSE CALL AS WELL. THESE
WINDS WILL DECREASE AS LOW PRESSURE WAVE MOVES ONSHORE MON MORNING
AND FRONT MOVES INLAND. BY MON AFTERNOON...STRONGEST WINDS ARE
EXPECTED OVER NRN LYNN CANAL WHERE SCA LEVEL S WINDS WILL DEVELOP.
WHILE WINDS OVER THE GULF WILL DROP BELOW SCA MON...SEAS WILL
REMAIN RATHER HIGH SO SCA FOR SEAS WILL CONTINUE AFTER WINDS DROP
OFF. SOME OF THESE HIGHER SEAS WILL REACH OCEAN ENTRANCES OF THE
INNER CHANNELS AND MOST OF YAKUTAT BAY.

.LONG TERM...RAIN WILL LINGER OVER THE EASTERN HALF OF THE
PANHANDLE MONDAY NIGHT...NAMELY EAST OF CHATHAM STRAIT THEN
DIMINISH TO SCATTERED SHOWERS ALONG THE COASTAL MOUNTAINS TUESDAY.
WEST OF CHATHAM STRAIT/ADMIRALTY ISOLATED TUESDAY LOOKS TO BE THE
DRIEST DAY OF THE WEEK DUE TO A BROAD RIDGE OF HIGH PRESSURE OVER
THE EASTERN GULF. THIS WILL RESULT IN LIGHT WESTERLY WINDS OVER
THE AREA ANS SOME SUNNY BREAKS OVER THE NORTHERN INNER CHANNELS.
WEDNESDAY THERE MAY BE ISOLATED SHOWERS AROUND STILL BUT THESE
WILL DIMINISH OVERNIGHT AS ENERGY IS PULLED INTO THE NEXT SYSTEM
MOVING INTO THE GULF. THE RIDGE WILL SHIFT EAST OVER THE PANHANDLE
AND WINDS WILL TURN BACK TO A MORE SE DIRECTION BY THURS MORNING.

EXPECT RAIN ASSOC WITH THE NEXT SYSTEM TO ARRIVE THURS NIGHT
(EARLIER FOR YAKUTAT) AND MAKE FOR A WET DAY FRIDAY. MODELS DIFFER
SOME ON HOW THIS SYSTEM AND THE NEXT FOR SATURDAY MOVE THROUGH...BUT
THEY AGREE THAT IT WILL BE WET. THESE TWO SYSTEMS WILL LIKELY HAVE
SOME HEAVY RAIN AND WIND TO GALE FORCE OVER THE OUTSIDE WATERS AS
WELL.

USED AN ENSEMBLE APPROACH FOR FORECAST UPDATES TODAY WITH AN
EMPHASIS ON THE GFS22. FORECAST CONFIDENCE IS AVERAGE.

&&

.HYDROLOGY...THE LARGEST RISES ON RIVERS WILL LIKELY BE AROUND THE
JUNEAU AREA. LATEST FORECAST HAS BOTH JORDAN CREEK AND MONTANA
CREEKS RISING SIGNIFICANTLY BUT STAYING BELOW BANKFULL LEVELS.
THE TAKU RIVER SHOULD ALSO RISE QUITE A BIT...6 TO 7 FEET...BY
TUE MORNING...BUT IT SHOULD REMAIN WELL BELOW BANKFULL AS WELL.
STILL...PEOPLE SHOULD BE AWARE OF THE RISING WATERS AROUND THE
JUNEAU AREA TONIGHT AND MON. REST OF THE AREA WILL SEE LESSER
RISES...OR EVEN FALL SOME TONIGHT AND MON OVER THE S DUE TO PRECIP
DIMINISHING.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 10 PM AKDT THIS EVENING FOR AKZ027.
MARINE...GALE WARNING FOR PKZ036-041>043.
     SMALL CRAFT ADVISORY FOR PKZ012-021-022-031>035-052.
     SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ051-053.
&&

$$

RWT/FERRIN

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