Gale Warning 174, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
1231 PM AKDT SUN MAR 29 2009

.SHORT TERM...THE ONLY SGFNT CHG TO THE CURRENT FCST PKG IS TO
START THE WIND ADVISORY FOR THE SKAGWAY ZONE AS THE WINDS HAVE
ALREADY REACHED THE CATEGORY. OTHERWISE ONLY MINOR CHANGES TO THE
EXISTING FORECASTS THROUGH MON. THE WIND ADVISORIES AND MARINE
CATEGORIES LISTED IN THE TABLE BELOW WILL REMAIN IN THE  NEW
FORECAST PACKAGE.

 THE MODELS ARE STRUGGLING WITH THE CYCLONE EVOLUTION SPCLY  IN
THE GLFALSK. WHAT MATTERS MOST IS THAT THE PEAK WIND EVENT
ASSOCIATED WITH THE LANDFALLING OCFNT WILL BE DELAYED UNTIL  A
FLOG CDFNT CATCHES UP. NCEP/OPC SFC MAP WITH FRONTS AT  12Z FOR
THE NPAC IS ACPTD AND APPLIED WITH ADJUSTMENTS FOR  FASTER
TIMING. NOTE THE NCEP/HPC SFC MAP IMPLIES FOUR DISTINCT
AIRMASSES, AND THE CDFNT FOLLOWING THE OCFNT IS A DISTINCT
FEATURE THAT THE MODELS DO NOT DEPICT AS CLEARLY AS THE GOES  WV
AND IR IMAGERY INDICATE. THE MODELS DO NOT DIRECTLY  SIMULATE
FRONTS DUE TO THE SMALL SCALE OF SUCH BOUNDARIES. HOWEVER, WE CAN
TYPICALLY USE MODEL FIELDS SUCH AS 1000 MB VORTICITY TO INDICATE
ROUGHLY WHERE THE MODELS WOULD PLACE SUCH FEATURES. IN THE
PRESENT CASE, THE GOES LOOP INDICATE A CYCLONE EVOLUTION THAT
SHOULD HAVE THE SECOND CDFNT, I.E.  AFTER THE COLD SIDE OF THE
OCFNT, MORE DISTINCT THAN  ALLUDED TO BY THE MODELS.

 966 MB PARENT LOW ABT 120 SW OF BETHEL IS SLOWLY WKNG  AND WL
MOV NE ACRS PABE ABT 00Z THIS AFTN. ASSOCD MATURE  OCFNT EXTENDS
TO A FORMER TRIPLE POINT LOW NOW ABT 120 NM S OF PAMD. REFER TO
NCEP OPC SFC MAP WITH FRONTS AT 12Z,  WHICH DEPICTS A SLOR TRAC
FOR THIS TRIPLE PT THAN IS BEING  CLAIMED FOR THIS SHORT TERM
FCST.

 CURRENT TRIPLE PT ROUGHLY 200 NM SSW OF PASI AND SHOULD  SHOULD
NOT BE CYCLOGENETIC AS IT TRACKS ENE ACROSS THE SRN  PNHDL S OF
KETCHIKAN FM 06Z TO 12Z. THE OCFNT WILL MAKE  LANDFALL FOR ZONES
23 AND 27 ABT 06Z. THE FLOG CDFNT SHOULD  MAKE LANDFALL ABT 08Z
FOR MOST OF THE PANHANDLE AND THE WINDS  AT THAT TIME SHOULD BE
AT LEAST AS HIGH AS FOR THE OCFNT  LANDFALL.

 &&

 .LONG TERM...LARGE SCALE PATTERN IN THE UPPER LEVELS REMAINS
ZONAL IN NATURE THROUGH THE FIRST HALF OF THE LONG TERM PERIOD.
THE PATTERN STARTS TO SHIFT THURSDAY AS A RIDGE BUILDS OVER THE
PANHANDLE AND A TROUGH DEEPENS OUT OVER THE WESTERN GULF AND
NORTHERN PACIFIC. TROUGH WILL CONTINUE TO DEEPEN AS IT MOVES EAST
UNTIL IT FORMS A CUT OFF LOW OFF THE WEST COAST OF THE LOWER
48 SUNDAY. MODELS ARE IN RATHER GOOD AGREEMENT EVEN THAT FAR OUT.
AS A RESULT VERY FEW CHANGES WERE MADE TO THE PREVIOUS FORECAST.

 MOST SIGNIFICANT CHANGE CAME WITH THE SYSTEM ON WEDNESDAY. TRACK
FORECAST IS A LITTLE FARTHER NORTH THEN PREVIOUS FORECASTS AND
CONSEQUENTLY SO TOO ARE SOME HIGHER POPS. THE CENTRAL PANHANDLE
HAS LIKELY POPS AND THE NORTHERN PANHANDLE STILL RETAINS THE
CHANCE POPS TUESDAY NIGHT INTO WEDNESDAY MORNING. LOW IS STILL
TRACKING FAR ENOUGH SOUTH THAT AT LEAST A MIX OF PRECIP WILL
STILL BE POSSIBLE FOR THE SOUTHERN ZONES WEDNESDAY. NEW SNOW
ACCUMULATION MAY REACH ADVISORY LEVEL IN ZONES 27 AND
28 WEDNESDAY MORNING. THOSE SAME ZONES MAY ALSO SEE SOME BREEZY
CONDITIONS WEDNESDAY MORNING AS WELL AS THE LOW SLIDES BY TO THE
SOUTH.

 NEXT SYSTEM COMES SATURDAY AS A STRONGER LOW MOVES INTO THE
CENTRAL TO SOUTHERN GULF FRIDAY NIGHT. ASSOCIATED FRONT WILL
BRING PRECIP TO THE PANHANDLE FOR THE WEEKEND.

 FORECAST WAS UPDATED WITH A BLEND OF THE NAM AND THE GFS THROUGH
THURSDAY 12Z AND ANY CHANGES AFTER THAT WERE USING A GFS/HPC
BLEND.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY UNTIL 10 PM AKDT THIS EVENING FOR AKZ027.
         WIND ADVISORY UNTIL MIDNIGHT AKDT TONIGHT FOR AKZ025.
         WIND ADVISORY UNTIL 10 PM AKDT THIS EVENING FOR AKZ022-023.
         WIND ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM AKDT MONDAY FOR
     AKZ019.
         WIND ADVISORY UNTIL 4 PM AKDT MONDAY FOR AKZ018.
         WIND ADVISORY UNTIL 6 PM AKDT THIS EVENING FOR AKZ017.
MARINE...GALE WARNING FOR PKZ011>013-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ021-022-031>036.

&&

JBT/EAL