Small Craft Advisory 520, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
351 PM AKDT MON SEP 5 2011

.SHORT TERM...AFTERNOON SATELLITE LOOP REVEALS A LOW...ABOUT
985 MB...SOUTH-SOUTHEAST OF KODIAK WITH AN OCCLUDED FRONT
WRAPPING AROUND THE LOW ACROSS THE CENTRAL GULF. EAST TO
SOUTHEAST PRESSURE GRADIENTS INCREASE ACROSS THE EASTERN GULF AND
SOUTHEAST ALASKA WITH GUSTY WINDS OVER MANY PLACES. STORM FORCE
WINDS PREVAIL ACROSS THE NORTHERN MOST OUTSIDE WATERS AND SOLID
GALES OVER REST OF THE OUTER WATERS AND NEAR OCEAN ENTRANCES.
ROUGH SEAS BUILD UP TO 20 FEET ACROSS THE NORTHERN OUTER WATERS.
AHEAD OF THE INCOMING FRONTAL BOUNDARY...ABUNDANT MOISTURE
CONSOLIDATES OVER THE EASTERN GULF AND ONSHORE OVER THE
PANHANDLE.

 MODELS ARE IN FAIR AGREEMENT WITH THE LOW DEEPENING TO ABOUT
955 MB SOUTHEAST OF KODIAK TONIGHT...THEN TRACK SLOWLY
NORTHWESTWARD ACROSS SHELIKOF STRAIT AND WEAKEN TO ABOUT 985 MB
OVER ALASKA PENINSULA THROUGH LATE TUESDAY. THE OCCLUDED FRONT
WILL CONTINUE TO MOVE NORTHEAST ACROSS SOUTHEAST ALASKA THROUGH
LATE TUESDAY NIGHT WITH CONTINUED MODERATE TO HEAVY RAINFALL.
USED THE GFS TO REFRESH THE EXISTING GRIDS AND MAINTAINED WIND
ADVISORIES AS THEY ARE INHERITED. BEHIND THE FRONTAL
BOUNDARY...INSTABILITY INCREASES RAPIDLY ACROSS THE NORTHEASTERN
OFFSHORE WATERS AND OVER THE NORTHERN OUTSIDE WATERS. INCLUDED
ISOLATED THUNDERSTORMS FOR THE NORTHEASTERN GULF COAST AND
NORTHWESTERN PANHANDLE COAST TONIGHT AND TUESDAY.

 LOCAL STREAMS AND RIVERS HAVE SLOWLY RESPONDED TO THE RECENT
RAINFALL AND MAINTAINED SLIGHTLY ABOVE NORMAL LEVELS AT THIS
TIME. ADDITIONAL MODERATE TO HEAVY RAIN TONIGHT WILL CONTINUE TO
BRING THE WATER LEVELS HIGHER AND A FEW OF THE STREAMS AND RIVERS
MAY REACH TO ACTION STAGES BY TUESDAY MORNING. STREAMS AND RIVERS
LIKELY TO RISE THEIR BANK FULL STAGE WILL BE STANEY CREEK...THE
UPPER EARL WEST...AND TO A SMALL EXTENT MONTANA CREEK AND CHILKAT
RIVERS. REFRESHED THE RIVER STATEMENT THIS AFTERNOON AND
MENTIONED POSSIBILITY OF MUDSLIDES.

.LONG TERM...THE MODELS ARE IN FAIR AGREEMENT THROUGH MID WEEK
THEN THERE IS SOME RUN TO RUN DIFFERENCES WITH A LOW PRESSURE
SYSTEMS MOVING OUT OF THE NORTH PACIFIC LATE IN THE WEEK INTO THE
WEEKEND. THE LATEST 12Z EC HAS MOVED TOWARDS THE GFS SOLUTION WITH
THE LOW LIFTING INTO THE WESTERN GULF OVER THE WEEKEND WITH A
SURFACE HIGH PRESSURE OVER THE PANHANDLE. THERE IS LARGE SPREADS
BETWEEN INDIVIDUAL ENSEMBLE MEMBERS BUT THE MEAN HAVE A TROF
EXTENDING INTO THE WESTERN GULF. SO WITH THAT SAID THERE IS THERE
IS ABOVE AVERAGE FORECASTER CONFIDENCE THROUGH WED NIGHT THEN
BELOW AVERAGE THROUGH THE REST OF THE FORECAST PERIOD...BUT
CONFIDENCE IS INCREASING. USED A BLEND OF THE EC/GFS THROUGH WED
NIGHT THEN UPDATED THE FORECAST WITH HPC GUIDANCE.

AT THE BEGINNING OF THE LONG TERM PERIOD A DEEP UPPER TOF OVER THE
STATE AND EXTENDING DEEP INTO THE NORTH PACIFIC WILL CONTINUE TO
LIFT ENERGY ALONG WITH SUB-TROPICAL MOISTURE NORTH INTO THE SE
GULF THROUGH MID WEEK. AT THE SURFACE THE STRONG LOW NEAR KODIAK
WILL CONTINUE TO WEAKEN AND SLOWLY DRIFT W FROM TUE NIGHT THROUGH
WED. OVER THE PANHANDLE A RIDGE OF HIGH PRESSURE WILL REMAIN OVER
THE FORECAST AREA BUT WEAKEN BY WED EVENING. SHOWERS WILL REMAIN
CAT TO LIKELY OVER THE NORTHERN HALF OF THE INNER CHANNELS WITH
DEEP ONSHORE FLOW THROUGH EARLY WED MORNING THEN THEY WILL BECOME
SCATTERED SHOWERS WILL THE LAKE OF MID-LEVEL DYNAMICS. OVER THE
SOUTHERN THIRD THE BAROCLINIC ZONE WILL REMAIN SOUTH OF FREDRICK
SOUND AND WITH THE ATMOSPHERIC RIVER POINTED AND MULTIPLE
DEVELOPING WAVES RAIN WILL REMAIN HEAVY AT TIMES THROUGH THURSDAY
MORNING. THIS WILL KEEP RIVER AND STREAMS ELEVATED WITH A
POTENTIAL FOR MINOR FLOODING. THIS BAROCLINIC ZONE/WARM FRONT WILL
DRIFT NORTH THROUGH THURSDAY TO INCREASE THE THREAT OF RAIN OVER
THE REST OF THE PANHANDLE.

WINDS OVER THE GULF WILL BE LESS THAN 20 KT FROM THE SOUTH TO
SOUTHWEST THROUGH MID WEEK. THE OVER THE INNER CHANNELS WILL ALSO
RANGE FROM 10 TO 15 KT WITH THE EXCEPTION TO NORTHERN LYNN WHERE
SMALL CRAFT WINDS WILL PERSIST INTO WED MORNING BEFORE DIMINISHING
BY WED AFTERNOON.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY UNTIL 5 AM AKDT TUESDAY FOR AKZ024-026-027.
         WIND ADVISORY FROM 10 PM THIS EVENING TO 7 AM AKDT TUESDAY FOR
     AKZ020-021-025.
         WIND ADVISORY UNTIL 10 PM AKDT THIS EVENING FOR AKZ022.
         WIND ADVISORY UNTIL 10 PM AKDT THIS EVENING FOR AKZ023.
         WIND ADVISORY FROM 7 PM THIS EVENING TO 10 AM AKDT TUESDAY FOR
     AKZ028.
         WIND ADVISORY UNTIL 10 AM AKDT TUESDAY FOR AKZ017.
MARINE...STORM WARNING FOR PKZ043-051-052.
         GALE WARNING FOR PKZ021-022-031>036-041-042.
         SMALL CRAFT ADVISORY FOR PKZ011>013-053.

&&

AHN/ABJ