Small Craft Advisory 558, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
350 PM AKDT WED SEP 21 2011

.SHORT TERM...STORM FORCE LOW OFF THE COAST OF SITKA HAS
CONTINUED TO TRACK NORTH THROUGH THE DAY MOVING SOUTH OF YAKUTAT.
THIS LOW HAS PRODUCED HEAVY RAIN FROM A LONG FETCH OF TROPICAL
MOISTURE AND STRONG WINDS OVER THE PANHANDLE. STORM FORCE WINDS
ALONG THE COASTAL WATERS HAVE DIMINISHED TO UPPER LEVEL GALES AND
SEAS HEIGHTS, WHILE STILL HIGH, WILL BEGIN TO DROP IN THE EVENING.
STRONG WINDS FROM THE FIRST LOW BAND OVER THE SOUTHERN PANHANDLE
CONTINUE TO DIMINISH THROUGH THE AFTERNOON. THE SECOND WRAP FROM
THE LOW NOW MOVING OVER THE CENTRAL AND NORTHERN REGIONS HAS
PRODUCED MUCH STRONGER WINDS WITH NUMEROUS GUSTS OF 60 MPH BEING
REPORTED. A HIGH WIND WARNING HAS BEEN ISSUED FOR THE CENTRAL
PANHANDLE UNTIL 8 PM WED EVENING. GALE FORCE WINDS IN THE SOUTHERN
INSIDE WATERS WILL DIMINISH THROUGH THE EARLY EVENING WHILE
CENTRAL AND NORTHERN INNER CHANNEL WINDS WILL CONTINUE TO
INCREASE. RIVER LEVELS ARE STILL BELOW ACTION STAGE BUT WITH THE
ADDITIONAL RAINFALL LEVELS WILL JUST REACH ACTION STAGE LATE
TONIGHT. DO NOT EXPECT AND SIGNIFICANT FLOODING AT THIS TIME. RAIN
WILL BEGIN TO DIMINISHED THIS EVENING AND OVERNIGHT AND
TRANSITION TO SHOWERS. SHOWERS WILL BECOME SCATTERED THROUGH THE DAY
THURSDAY. THE LOW WILL WEAKEN AS IT TRACKS NORTH, BECOMING AN OPEN
WAVE TROUGH THIS EVENING. WIND AND RAIN WILL DIMINISH AS THE LOW
WEAKENS. A WEAK HIGH PRESSURE RIDGE WILL BUILD OVER THE PANHANDLE
THURSDAY. SOUTHERLY PRESSURE GRADIENT WILL KEEP SOUTHERLY SMALL
CRAFT WINDS IN THE NORTH INNER CHANNELS THU MORNING. ONSHORE FLOW
WILL KEEP MOISTURE FLOW TO SUPPORT SHOWER ACTIVITY THROUGH THE
DAY. NEXT LOW PRESSURE SYSTEM WILL ENTER THE SOUTHEASTERN GULF
LATE THU.

 MODELS WERE IN GOOD AGREEMENT TODAY, USED A BLEND OF NAM AND GFS
TO UPDATE INHERITED GRIDS. MAIN CHANGES WERE IN INCREASE WINDS
FOR TONIGHT. FORECAST CONFIDENCE IS ABOVE AVERAGE.

&&

.LONG TERM...EXTENDED RANGE FORECAST BEGINS WITH ANOTHER HIGH WIND
EVENT OVER MUCH OF THE SOUTHERN PANHANDLE AND BARANOF ISLAND. A
HIGH WIND WATCH REMAINS IN EFFECT FOR THIS EVENT AND PERSONS
LOCATED IN THE WATCH AREA SHOULD EXPECT TO SEE THIS WATCH
CONVERTED TO A WARNING BY TOMORROW MORNING. THE LOW IN QUESTION IS
BEING DEPICTED VERY WELL BY ALL GUIDANCE WITH A TIGHT GROUPING AND
CENTRAL PRESSURES RANGING FROM 964 MB TO 973 MB AT LANDFALL EARLY
FRIDAY MORNING VICINITY CAPE DECISION. THIS WIND EVENT WILL WIND
DOWN THROUGH THE DAY FRIDAY AS THE LOW TRACKS TO THE NORTHEAST AND
WEAKENS ON ITS WAY TOWARD BRITISH COLUMBIA. RAIN WILL DIMINISH
FROM WEST TO EAST ON SATURDAY AND SUNDAY IS LOOKING LIKE A DRY DAY
WITH A WEAK OFFSHORE PRESSURE GRADIENT OVER SOUTHEAST ALASKA. THE
BRIEF BREAK WILL BE OVER BY MONDAY MORNING AS THE NEXT LOW TRACKS
INTO THE EASTERN GULF FROM THE SOUTH. THIS ONE IS FORECAST TO
REMAIN FARTHER TO THE WEST BEFORE WEAKENING AND FILLING VICINITY
CAPE FAIRWEATHER TUESDAY AFTERNOON. ASSOCIATED RAINS WILL
PRIMARILY BE OVER THE SOUTHERN HALF OF THE PANHANDLE.

USED A NAM/ECMWF BLEND THROUGH FRIDAY NIGHT AND A GFS/ECMWF BLEND
THEREAFTER. FORECAST CONFIDENCE IS ABOVE AVERAGE THROUGH SATURDAY
MORNING AND AVERAGE THEREAFTER.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WATCH FROM THURSDAY EVENING THROUGH FRIDAY MORNING FOR
     AKZ027-028.
         HIGH WIND WARNING UNTIL 8 PM AKDT THIS EVENING FOR AKZ020>023-
     025.
MARINE...GALE WARNING FOR PKZ011>013-021-022-031>036-041>043.
         SMALL CRAFT ADVISORY FOR PKZ051.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ052.

&&

PRB/FRITSCH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
945 PM AKDT WED SEP 21 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1134 AM     NON-TSTM WND GST PORT ALEXANDER          56.25N 134.64W
09/21/2011  M72.00 MPH                          AK   CO-OP OBSERVER

            A-PAID OBSERVER AT PORT ALEXANDER MEASURED GUSTS TO 72
            MPH.

1134 AM     NON-TSTM WND GST 26 SE PORT ALEXANDER    55.98N 134.16W
09/21/2011  M79.00 MPH       PKZ041             AK   OFFICIAL NWS OBS

            79 MPH GUSTS RECORDED AT CAPE DECISION WITH SUSTAINED
            WINDS OF AROUND 51 MPH.

1134 AM     NON-TSTM WND GST 10 W ELFIN COVE         58.19N 136.61W
09/21/2011  M80.00 MPH       PKZ022             AK   OFFICIAL NWS OBS

            80 MPH GUSTS MEASURED AT CAPE SPENCER WITH SUSTAINED
            WINDS MEASURED TO 63 MPH

1134 AM     NON-TSTM WND GST EDNA BAY                55.95N 133.66W
09/21/2011  E60.00 MPH                          AK   TRAINED SPOTTER

            MID DAY ON THE 21ST SAW SW WINDS 50 MPH WITH GUSTS TO 60
            MPH.

1234 PM     NON-TSTM WND GST SITKA                   57.05N 135.34W
09/21/2011  M63.00 MPH                          AK   ASOS

            PEAK WIND GUST OF 63 MPH AT SITKA AIRPORT.

0234 PM     NON-TSTM WND GST JUNEAU                  58.30N 134.41W
09/21/2011  M71.00 MPH                          AK   ASOS

            PEAK GUST OF 71 MPH AT JUNEAU AIRPORT.

&&

EAL