Small Craft Advisory 719, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
543 AM AKST SUN NOV 13 2011

.SHORT TERM...A LOW IN THE NORTHEAST GULF IN THE VICINITY OF
YAKUTAT WEAKENS AND PERSISTS THROUGH SUNDAY NIGHT. A CONTINUED
WEST GALE TO STORM FORCE FLOW OVER THE CENTRAL GULF OF ALASKA AND
THE COASTAL WATERS. SATELLITE IMAGERY AND THE RADAR IMAGERY FROM
BIORKA IS SHOWING NUMEROUS SHOWERS HEADED EAST ACROSS THE GULF
TOWARDS AND ONSHORE THE PANHANDLE. MOST OF THE SHOWER ACTIVITY
TODAY WILL BE SOUTHEAST OF YAKUTAT...THOUGH THERE MAY BE A FEW TO
IMPACT THE YAKUTAT AREA. COLDER AIR IS SPILLING ACROSS THE GULF
SO THE LOWER ATMOSPHERE IS COOLING AND MORE SNOW WILL BE
SPREADING INTO THE PANHANDLE.

LOCALLY GUSTY WINDS ARE RESULTING IN STRONG WIND HEADLINES TO THE
COASTAL ZONES THROUGH TODAY AND INTO THE EVENING. WINDS WILL
SLOWLY BEGIN TO DIMINISH THROUGH THE AFTERNOON AND OVERNIGHT.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...LOW PRESSURE IN THE NORTHERN GULF
WILL CONTINUE THE ONSHORE WESTERLY FLOW MONDAY WITH SCATTERED SNOW
SHOWERS IN THE MORNING MIXING WITH RAIN ACROSS THE SOUTH THROUGH
THE DAY. ANOTHER LOW WILL MOVE INTO THE NORTHERN GULF LATER MONDAY
AND TUESDAY REPLACING THE OTHER ONE. THIS SYSTEM WILL BE THE MAIN
FEATURE FOR THE WEEK. THE LOW WILL SET UP A THERMAL BOUNDARY ALONG
THE FAR NORTHERN ZONES WITH 850MB TEMPS DOWN TO -14C AND COLD
ENOUGH TO KEEP ALL PRECIP AS SNOW FOR THE YAKUTAT/HAINES/SKAGWAY
AREAS. THE ASSOCIATED FRONTAL BOUNDARY MOVING IN FROM THE GULF
WILL BRING IN WARMER AIR ALOFT FROM THE CENTRAL PANHANDLE SOUTH
TUES THROUGH WEDS. THIS WILL CAUSE MOST PRECIP WITH THE FRONT TO
BE RAIN...HOWEVER EARLY MORNING MIN TEMPS WILL BE COLD ENOUGH FOR
RAIN TO MIX WITH SNOW. THE LOW CENTER IS EXPECTED TO GRADUALLY
MOVE SOUTHWARD THROUGH WED AND THURS. THIS WILL TURN MID LEVEL
FLOW OFFSHORE TO THE NORTH OF THE LOW...DECREASING PRECIP
POTENTIAL FOR THE SECOND HALF OF THE WEEK. HIGH PRESSURE WILL
BUILD TO THE NORTH AS THE LOW MOVES SOUTH...CAUSING WINDS TO TURN
OUT OF THE NORTH. THIS WILL SHIFT THE THERMAL GRADIENT MENTIONED
ABOVE SOUTH AS WELL AND ADVECT THE COLD CANADIAN AIR TO THE
REMAINDER OF THE REGION WITH 850MB TEMPS DROPPING TO -20C OVER THE
NORTH. DECREASING CLOUDS WITH THE OFFSHORE DOWNSLOPING WINDS WILL
WORK TO ENHANCE OVERNIGHT COOLING THROUGH FRIDAY. A LOW PRESSURE
SYSTEM WILL MOVE INTO THE GULF SATURDAY...INCREASING CLOUD COVER
AGAIN BUT CURRENT MODEL RUNS HAVE IT SLIDING BY WITH MOST OF THE
PRECIP REMAINING OVER THE OUTSIDE WATERS.

MODELS WERE IN FAIR AGREEMENT FOR THIS FORECAST UPDATE. THERE ARE SOME
TIMING DIFFERENCES WITH THE LOW MOVEMENT...HOWEVER THE OVERALL
RESULT IS SIMILAR KEEPING FORECASTER CONFIDENCE AVERAGE. BLENDED TOWARD
THE ECMWF AS IT INITIALIZED THE PRESSURE FIELD THE BEST. HOWEVER
GFS WAS USED MORE FOR WINDS OFFSHORE...THEN INCREASED VALUES
THROUGH INSIDE PASSES AND GAP WINDS OPEN TO THE NORTH-NORTHEAST
ONCE THE LOW SHIFTS TO THE SOUTH MID-WEEK ON. THIS INCLUDED STORM
FORCE WINDS FOR LYNN CANAL AND YAKUTAT BAY DUE TO WINDS OUT OF
DISENCHANTMENT BAY WED AND THURS.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 9 AM AKST THIS MORNING FOR AKZ027.
         STRONG WIND UNTIL NOON AKST TODAY FOR AKZ022.
         STRONG WIND THROUGH THIS EVENING FOR AKZ023.
MARINE...STORM WARNING FOR PKZ042-043.
         GALE WARNING FOR PKZ022-041-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011>013-021-031>036.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ053.

&&

BEZENEK/HANNON