Gale Warning 263, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
230 PM AKDT THU SEP 24 2009

.SHORT TERM...SATELLITE REVEALS 984MB LOW SOUTH OF THE AK
PENISULA WITH ASSOCIATED STRONG OCCLUDED FRONT EXTENDING EAST
FROM THE LOW AND MOVING NORTHEAST THROUGH THE NORTHERN AND
EASTERN GULF ATTM. AREAS OF RAIN...HEAVY AT TIMES...AHEAD OF
FRONT CONTINUES TO MOVE NORTHEAST THROUGH THE PANHANDLE. JUNEAU
WFO PICKED NEARLY ONE QUARTER OF AN INCH WITH FIRST AREA OF RAIN.
RAIN WILL CONTINUE TO EXPAND IN COVERAGE AND INTENSITY THIS
AFTERNOON. 6HR QPF RATES OF ONE HALF TO THREE QUARTERS OF AN INCH
ON TAP STARTING THIS EVENING AND TONIGHT FOR MOST LOCATIONS. RAIN
WILL BE HEAVY AT TIMES. LOW PRESSURE SYSTEM IS VERY MOIST STEM
GIVEN THE REMNANTS OF TYPHOON CHOI WAN ARE EMBEDDED IN THE
SYSTEM.

WINDS WILL INCREASE AS THE FRONT APPROACHES ESPECIALLY ALONG THE
OUTER COAST WHERE WIND ADVISORIES ARE POSTED FOR ZONES 22 AND 23
THIS AFTERNOON AND ZONE 27 THIS EVENING. BARRIER JET INDICATED
ALONG NORTHERN COAST WILL BRING GUSTY CONDITIONS WEST OF PAYA BUT
SHOULD BE SHORT LIVED. WIND ADVISORY ALSO POSTED FOR ZONE 28 THIS
EVENING WITH FAVORABLE SOUTHERLY FETCH. GALES FOR OFFSHORE AND ALL
OUTSIDE WATERS THIS EVENING.

PARENT LOW CONTINUES TO SLOWLY FILL JUST EAST OF KODIAK OVERNIGHT
AS FRONT CONTINUES TO MOVE NORTHEAST THROUGH THE PANHANDLE.
GRADIENT RELAXES IN SOUTHERN ZONES LATE TONIGHT BUT INCREASES
AGAIN TOMORROW EVENING AS SHORTWAVE ROTATING AROUND PARENT LOW
MOVES INTO THE CENTRAL GULF. WINDS INCREASE TO GALES IN MZ 310 IN
RESPONSE. ONSHORE FLOW TOMORROW BEHIND FRONT LEADING TO
CATEGORICAL TO LIKELY OPS FOR PANHANDLE.

MODELS WHERE IN GOOD AGREEMENT AGAIN TODAY WITH GFS ECMWF AND
UKMET VERY SIMILAR ON POSITION...TRACK AND STRENGTH OF LOW IN
WESTERN GULF AND CONSISTENT WITH THE TIMING OF THE FROPA THROUGH
THE PANHANDLE. NAM12 DID BRING STRONGER WINDS ALOFT OVER PANHANDLE
WITH 60KTS OVER PAJN VS 45 KTS WITH REST OF THE MODELS. OPTED TO
BLEND 06Z WSWRF TO CAPTURE SMALL SCALE FEATURES AND GRADIENTS INTO
A BLEND OF 12 GFS AND INHERITED GRIDS FOR THE PRESSURE AND WIND
FIELDS THROUGH THE TONIGHT PERIOD. FOR THE TOMORROW PERIOD A BLEND
OF INHERITED GRIDS AND GFS WAS USED. FORECAST CONFIDENCE IF ABOVE
AVERAGE BASED ON RUN TO RUN CONSISTENCY WITH THE GFS AND MINIMAL
SPREAD BETWEEN MODEL FAMILIES.

&&

.LONG TERM...THROUGH THE WEEKEND THE 12Z MODEL RUNS WERE IN
FAIRLY GOOD AGREEMENT. THERE WERE SOME BRIEF PERIODS LARGER
DISCREPANCY HEADING AROUND SUNDAY NIGHT OVER THE EASTERN GULF.
HOWEVER MODELS RE-CONVERGE AND THERE SEEMS TO BE GOOD AGREEMENT
EVEN INTO MID WEEK YET. BASED THE GRID ADJUSTMENTS THROUGH SUNDAY
ON THE GFS SOLUTION AND THEN WAS USING HPC GUIDANCE FOR THE LAST
FEW DAYS.

AS THE MAIN LOW WEAKENING THROUGH FRIDAY NIGHT MOVES INLAND NEAR
PRINCE WILLIAM SOUND A FAIRLY STRONG WESTERLY GALE WILL DEVELOP
OVER THE GULF AND WILL BUILD A STRONG SWELL TO MOVE THE COASTAL
AREAS FOR THE WEEKEND EXPECT SEAS 20+ FT FOR MARINES 41>43. NEXT
LOW WILL MOVE INTO THE GULF BY SUNDAY AFTERNOON.

AHEAD OF THE NEXT MAJOR SYSTEM MOVING TO THE BERING SUNDAY A
RIDGE IS BUILT UP IN ADVANCE OF THIS LOW. THE RIDGE WILL MOVE EAST
THROUGH MID-WEEK. AT THE PRESENT THE FRONTAL BAND OF THIS LAST LOW
SHOULD MOVE INTO THE GULF TUESDAY AND SHOULD IMPACT SOUTHEAST
ALASKA BY WEDNESDAY.

CONFIDENCE IS GENERALLY ABOVE AVERAGE FOR THIS FORECAST PACKAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY FROM 9 PM THIS EVENING TO 6 AM AKDT FRIDAY FOR
     AKZ027-028.
         WIND ADVISORY UNTIL MIDNIGHT AKDT TONIGHT FOR AKZ022-023.
MARINE...GALE WARNING FOR PKZ022-033-036-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011>013-021-031-032-034-035.

&&

CCC/BEZENEK