Small Craft Advisory 368, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
245 PM AKDT SUN JUN 5 2011

.SHORT TERM...WIND INCREASES WILL OCCUR TONIGHT FOR MOST OF OUR
AREA OF RESPONSIBILITY. NW SCA WINDS WILL DEVELOP IN THE COASTAL
WATERS S OF CAPE EDGECUMBE IN CLARENCE STRAIT LATE TONIGHT. THESE
WINDS WILL BE THE RESULT OF THE INTERACTION BETWEEN TWO LARGE
SCALE FEATURES: THE FIRST BEING A STRONG SFC RIDGE EXTENDING N
INTO THE GULF, AND THE SECOND AN INVERTED TROUGH EXTENDING NW
ALONG THE COAST MTN RANGE. CONFIDENCE IS ABOVE AVERAGE. THE MODEL
CONSENSUS IS GOOD. THE CHANGES TO THE FORECAST PACKAGE ARE
MINIMAL.

 500H LOW OVER PAGM IN THE BERING HAS A TROUGH ALOFT EXTENDING  E
TO OVER PAYA. THIS TROUGH ALSO HAS A COLD TONGUE IN THE THICKNESS
FIELD AND IS DEVELOPING A LOW ALOFT OVER PAYA AT THIS TIME. THIS
COLD TROUGH ALOFT HAS ALREADY TURNED OUR ENTIRE FORECAST DOMAIN
TO CONVECTIVE CELLS. A RIDGE ALOFT EXTENDS N INTO THE GLF FM A PT
1200 NM S OF PAMD. THIS RIDGE ALOFT IS BROAD AND STRONG, BUT
LIMITED IN AMPLITUDE IN THE NORTH GULF BY THE TROUGH ALOFT.

 THE RIDGE ALOFT IS SLOWLY INTENSIFYING TO THE NE OVER THE GULF,
BUT THIS CHANGE IS SLOWER THAT HOW THE TROUGH ALOFT GENERATES A
LOW ALOFT THAT WILL TRACK TO OVER PAJN AT 12Z MON AND OVER CZST
00Z TUE.

 MODELS:  NO LARGE VARIATIONS MADE FROM THE NAM/GFS CONSENSUS.

&&

.LONG TERM...MODELS ARE IN GENERAL AGREEMENT THROUGH WEDNESDAY
WITH A WEAK UPPER TROUGH MOVING NORTHEASTWARD ACROSS THE WESTERN
AND CENTRAL GULF...PUSHING THE UPPER RIDGE EASTWARD ACROSS THE
EASTERN GULF AND SOUTHEAST ALASKA. AN UPPER LOW CLUSTER OVER THE
CENTRAL BRITISH COLUMBIA WILL SLIDE SOUTHEAST TO NEAR VANCOUVER
ISLAND EARLY TUESDAY MORNING AND FARTHER SOUTH TO THE PACIFIC
NORTHWEST THROUGH TUESDAY EVENING. THE NAM AND GFS INITIALIZED
WELL AND WERE OPTED TO POPULATE THE GRIDS THROUGH WEDNESDAY.

 A SURFACE RIDGE DOMINATING THE FORECAST DOMAIN ON MONDAY NIGHT
WILL BEGIN ERODING AS A WEAK FRONTAL BOUNDARY MOVES INTO THE
EASTERN GULF BY TUESDAY AFTERNOON. THE FRONT WILL CONTINUE TO
WEAKEN AS IT APPROACHES THE PANHANDLE AND BEGIN SHEARING APART BY
WEDNESDAY MORNING OVER THE PANHANDLE COAST. AN UPPER LEVEL CUT-OFF
LOW ACROSS THE CENTRAL BRITISH COLUMBIA WILL CONTINUE TO SLID
SOUTHEASTWARD TO NEAR VANCOUVER ISLAND THROUGH TUESDAY MORNING. A
SHARP UPPER RIDGE WILL REBUILD BEHIND THE TROUGH ACROSS THE
CENTRAL AND EASTERN GULF.

 INCREASING WESTERLY PRESSURE GRADIENT COMBINED WITH
NORTHWESTERLY FLOW ALONG THE EAST SIDE OF THE RIDGE WILL MAINTAIN
SOLID SMALL CRAFT WINDS ACROSS THE SOUTHERN AREAS THROUGH EARLY
TUESDAY. THESE WINDS MAY REACH NEAR GALE FORCE BRIEFLY MONDAY
NIGHT OVER THE SOUTHERN OUTSIDE WATERS. SOUTHERN COASTAL SECTIONS
FROM SOUTHERN MOST BARANOF ISLAND SOUTHEAST TO KLAWOCK AND CRAIG
AREAS WILL SEE BREEZY CONDITIONS AS WELL AND MAY MEET ADVISORY
LEVEL WIND GUSTS VERY BRIEFLY ON MONDAY NIGHT. AS THE RIDGE BEGINS
ERODING...NEAR SMALL CRAFT SOUTHERLY WINDS ACROSS THE NORTHERN
INNER CHANNELS WILL DECREASE THROUGH THE WEEK. ENHANCED WESTERLY
FLOW WILL LIKELY AFFECT THE MOST INNER CHANNELS WITH SMALL CRAFT
WINDS ON MONDAY NIGHT.

 A SECONDARY UPPER TROUGH WILL TRACK NORTHEASTWARD ACROSS THE
CENTRAL GULF THROUGH THURSDAY MORNING THEN MOVE INTO THE EASTERN
GULF BY THURSDAY NIGHT...CROSSING THE PANHANDLE THROUGH FRIDAY
MORNING. A WEAKER UPPER RIDGE WILL TRY TO REBUILD ACROSS THE GULF
THROUGH THE WEEKEND BUT MODEL SPREAD GROWS RAPIDLY FOR THIS TIME
FRAME FOR THE SCENARIO AND THUS STAYED WITH THE HPC ENSEMBLE
APPROACH.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-036-041>043.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ051-052.

&&

JBT/AHN