Small Craft Advisory 562, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
555 AM AKDT THU SEP 22 2011

.SHORT TERM...EARLY MORNING SATELLITE LOOP REVEALS A WEAK RIDGE
OF HIGH PRESSURE BUILDING ACROSS SOUTHEAST ALASKA AND A
DEVELOPING STORM IN THE NORTHEAST PACIFIC. AS THE RIDGE
BUILDS...SOUTHERLY PRESSURE GRADIENT HAS BEEN MAINTAINING STRONG
WINDS ACROSS THE NORTHERN PANHANDLE WITH GUSTS UP TO 45 MPH AT
SKAGWAY AND HAINES AS WELL AS GALE FORCE WINDS OVER NORTHERN LYNN
CANAL. THE REMNANTS OF OLD LOW STILL BRINGS LIGHT RAINFALL OVER
THE NORTHERN PANHANDLE AND MODERATE RAINFALL ACROSS YAKUTAT AREA.
SPORADIC RAIN SHOWERS PREVAIL FOR THE REST OF SOUTHEAST ALASKA
WITH DECREASING CLOUDS. WINDS ACROSS THE OUTER WATERS REMAIN IN
15 TO 20 KNOT RANGE BUT THE ROUGH SEAS PREVAIL UP TO 13 FEET.

MODELS ARE IN FAIR AGREEMENT WITH THE WEAK RIDGE OF HIGH PRESSURE
ACROSS SOUTHEAST ALASKA DISSIPATES LATE THIS AFTERNOON AS THE
STORM FORCE LOW IN THE NORTHEAST PACIFIC MOVES INTO THE EASTERN
GULF THIS EVENING. THE LOW WILL DEEPEN TO AROUND 962 MB WEST OF
HAIDA GWAII BY THIS EVENING THEN WEAKEN TO AROUND 979 MB AS IT
MOVES ONSHORE OVER THE NORTHERN PANHANDLE BY LATE FRIDAY MORNING.
THE GFS AND NAM MADE A GOOD CONSENSUS AND WERE USED TO REFRESH THE
INHERITED GRIDS FOR TODAY AND TONIGHT.

THE RIDGE OF HIGH PRESSURE WILL CONTINUE TO PUSH THE RAIN BAND
OVER THE NORTHWESTERN PANHANDLE AWAY FROM THE AREA AND RAIN THIS
MORNING WILL EASE TO CHANCE SHOWERS THIS AFTERNOON. CHANCE SHOWERS
ACROSS THE FORECAST DOMAIN WILL BE REPLACED WITH DEVELOPING RAIN
FROM THE SOUTH THIS EVENING INTO TONIGHT ALONG WITH STRONG WINDS
ACROSS THE SOUTHERN AREAS. THE INCOMING LOW HAS POTENTIAL STORM
FORCE WINDS AND HIGH WIND GUSTS ESPECIALLY FOR THE SOUTHERN AREAS.
STORM WARNING WILL BE IN EFFECT FOR THE SOUTHERN OUTER WATERS
TONIGHT. THE HIGH WIND WATCH FOR HYDABURG AND KETCHIKAN AREAS HAS
BEEN REPLACED WITH HIGH WIND WARNING.

.LONG TERM...THE LOW THAT WILL GENERATE HIGH WINDS IN THE SRN PNHDL
BEGINNING TONIGHT IS INTRODUCED IN THE SHORT RANGE SECTION ABOVE.
AT 06Z FRIDAY THIS LOW WILL HAVE ALREADY BEEM RAPIDLY DEEPENING AND
HAVE REACHED 962 MB, LOCATED ABOUT 200 NM SSW OF PASI WITH A
TRACK TO THE NE. LANDFALL SHOULD OCCUR BETWEEN CAPE DECISION AND
PORT ALEXANDER AT 12Z FRI.

OVERALL CONFIDENCE IN THE LONG RANGE PACKAGE IS AVERAGE WITH ONE
IMPORTANT EXCEPTION: THE LANDFALL LOCATION OF SUCH A RAPIDLY
DEEPENING LOW IS DIFFICULT FOR THE MODELS WHEN THE LOW THEN MAKES
A GRAZING PASS, ALMOST A TANGENT, ALONG THE OUTER COAST.

CONFIDENCE IN THIS TRACK IS ONLY FAIR. THE EXISTING POSITION
OF THE WAVE AT THIS TIME IS ABOUT 1000 NM S OF PACV. THE MODELS
ARE ATTEMPTING TO HIT THE DETAILS OF THE WAVE ENTERING RAPID
CYCLOGENESIS, AND SLOWING AND BEGINNING TO FILL JUST BEFORE LANDFALL.
ALTERNATIVE SOLUTIONS SUCH A LANDFALL ONLY ABOUT 60 NM FARTHER N
ARE PLAUSIBLE AND RESULT IN WINDS FIELDS FOR THE COASTAL PANHANDLE
FROM CAPE DECISION TO CAPE EDGECUMBE WOULD AT TIMES BE 180 DEGREES
DIFFERENT FROM THE FORECAST ISSUED.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING FROM 7 PM THIS EVENING TO 7 AM AKDT FRIDAY FOR
     AKZ027.
         HIGH WIND WARNING FROM 1 AM TO 10 AM AKDT FRIDAY FOR AKZ028.
MARINE...STORM WARNING FOR PKZ036-041-042.
         GALE WARNING FOR PKZ012-033-035-043.
         SMALL CRAFT ADVISORY FOR PKZ011-013-021-022-031-032-034-051.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ052.

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AHN/JBT