Gale Warning 280, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
556 AM AKDT MON OCT 12 2009

.SHORT TERM...UPPER LEVEL HIGH CLOSED OFF OVER THE ALASKAN
INTERIOR WITH AN UPPER LEVEL LOW MOVING SOUTHWEST FROM NORTHERN
ALBERTA ACROSS BRITISH COLUMBIA TO THE SOUTHEAST GULF OF ALASKA
BY LATE MONDAY NIGHT. AT THE SURFACE HIGH PRESSURE OVER NORTHWEST
CANADA A LOBE OF THE HIGHER PRESSURE EXTENDS INTO NORTHERN
BRITISH COLUMBIA WHICH IS TIGHTENING UP THE GRADIENT ALONG THE
COAST MOUNTAINS WITH A GOOD GAP FLOW SETTING UP. AT LOWER TO MID
LEVELS THERE IS INCREASED OFF SHORE FLOW FROM CANADA INTO THE
GULF ACROSS THE PANHANDLE. A GOOD PUSH OF COLD POOL OF COLD AIR
FROM MONDAY NIGHT FOR THE SOUTHERN HALF OF THE PANHANDLE. 850 MB
TEMPERATURES FALL TO -10 C OVER MISTY FJORDS BY LATE MONDAY
NIGHT.

MAINLY CLEAR SKIES AREA EXPECTED TO CONTINUE OVER SOUTHEAST
ALASKA MONDAY AND MONDAY NIGHT. THE DRIER AIRMASS MOVING INTO THE
AREA WILL LIKELY HELP RESTRICT THE FOG DEVELOPMENT TONIGHT. WIND
SHELTERED AREAS WILL SEE TEMPERATURES FALL ACROSS MOST OF THE
INNER CHANNEL AREAS TONIGHT AS WELL.

THE STRONG OFF SHORE FLOW PATTERN IS RESULTING IN SOME LOW TO MID
LEVEL TURBULENCE AND SOME LLWS ESPECIALLY NEAR THE COAST RANGE
WITH WINDS OVER THE RIDGE TOPS.

.LONG TERM...LITTLE CHG TO THE LONG RANGE PKG. THIS INCLUDES
THE RETAINING OF THE FORECAST OF N 45 KT IN NRN LYNN CANAL FOR
TUE NIGHT, AND AT LEAST MIN GALES OCCURRING IN MOST OF THE INNER
CHANNELS FOR AT LEAST A 12 HOUR PERIOD TUE NIGHT THROUGH THU.

THE UPPER LEVEL HIGH MENTIONED IN THE SHORT RANGE SXN ABV IS
ASSOCD WITH A LONG WV 500H RIDGE THAT THE GFS 5-WV DEPICTS AS
XTDG NE OVR A PADQ TO BANKS IS. THE STRONG N TO NE OUTFLOW
ALONG THE PNHDL IS ASSOCD WITH THESE FEATURES SUPPORTING
THE HIGH BOUNDARY LAYER PRESSURES TO THE NE OF OUR FCST DOMAIN.

THE PERSISTENCE OF DRYING MECHANISMS ON ALL LEVELS IS DUE BOTH
TO THE HIGH PRESSURE SYSTEMS, AND THE DEVELOPMENT OF AN ASSOCD
REX BLOCK. THE LARGE-SCALE TROUGH ALOFT DOWNSTREAM IS DEPICTED
ON THE 5-WV AS XTDG, ON A LARGE SCALE, SW OVR CYVR. THIS UPPER
LEVEL SUPPORT WILL AID IN THE REX DVLPMNT THAT ABT 18Z WED
SHOULD HAVE THE 500H LOW ABT 400 NM S OF PAKT AND THE 500H HIGH
OVR CYDB.

REX BLOCKS DO NOT LOCK IN PLACE AS WELL AS OMEGA BLOCKS,
AND THIS TRAIT HAS BEEN PLAYING A ROLE IN HOW THE MODEL SOLUTIONS
SPREAD OUT THEREAFTER. MODEL CONSENSUS HAS SIGNIFICANTLY
IMPROVED ESPECIALLY FOR WED AND THU. THE GFS HAS BEEN USED AS
PRIMARY GUIDANCE, ALBEIT FOR FRI ONWARD SOME CLIMATE AND HPC
FIELDS WERE FIGURED IN.

MOUNTAIN WV CONDITIONS SIGNIFICANT TO FORECASTS IN THE CNTRL
PNHDL INC INVOF PAJN COULD BEGIN TUE NIGHT.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...FROST ADVISORY UNTIL 7 AM AKDT THIS MORNING FOR AKZ019-024-026-
     027.
         DENSE FOG ADVISORY UNTIL 7 AM AKDT THIS MORNING FOR AKZ024-026.
         FREEZE WARNING UNTIL 7 AM AKDT THIS MORNING FOR AKZ028-029.
MARINE...GALE WARNING FOR PKZ041.
         SMALL CRAFT ADVISORY FOR PKZ011>013-021-031>036-042.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ043-051-052.

&&

BEZENEK/JBT