High Surf in Hawaii, December 31, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST WED DEC 31 2008

.SYNOPSIS...
A WEAK HIGH PRESSURE RIDGE NORTH OF THE STATE WILL MAINTAIN LIGHT
WINDS TODAY. A WEAK UPPER TROUGH NEAR THE ISLANDS CONTINUES TO
PROVIDE INSTABILITY BRINGING WETTER WEATHER WITH A THREAT OF
THUNDERSTORMS. A SURFACE HIGH PRESSURE WILL BUILD TO THE
NORTH THURSDAY. THIS WILL BRING AN INCREASE IN THE TRADE WINDS
ACROSS THE STATE THROUGH THE COMING WEEKEND.

&&

.DISCUSSION...
ACTIVE WEATHER CONTINUES TO AFFECT THE ISLANDS EARLY THIS MORNING.
DEEP MOIST LOW LEVEL FLOW COMBINING WITH LINGERING INSTABILITY FROM
THE UPPER LEVEL TROUGH PROVIDED FAVORABLE CONDITIONS FOR LOCALLY
HEAVY RAIN AS WELL AS ISOLATED THUNDERSTORMS TO DEVELOP THROUGH THE
NIGHT. KAUAI...OAHU AND MAUI SAW THEIR SHARE OF HEAVY RAIN SINCE
LATE LAST NIGHT WHILE A THUNDERSTORM DEVELOPED JUST OFFSHORE OF KONA
ON THE BIG ISLAND WILL BRING SOME HEAVY RAIN TO THAT AREA IN THE
COMING HOURS. THERE ARE STILL SOME SNOW SHOWERS OVER THE SUMMITS OF
MAUNA KEA AND MAUNA LOA...THOUGH THE AMOUNTS HAVE DECREASED SINCE
LAST NIGHT. THUS HAVE CANCELLED THE WINTER STORM WARNING AND ISSUED
A WINTER WEATHER ADVISORY FOR THE BIG ISLAND SUMMITS EFFECTIVE UNTIL
10 AM THIS MORNING. DO EXPECT THE UNSETTLED WEATHER TO PREVAIL
TODAY INTO TONIGHT AS CONDITIONS REMAIN FAVORABLE. HAVE UPDATED
FORECAST PACKAGE WITH MENTION OF LOCALLY HEAVY RAIN AS WELL AS
ISOLATED THUNDERSTORMS TODAY.

THE NEXT UPPER LEVEL TROUGH NOW FAR WEST OF THE ISLANDS CONTINUES TO
ADVANCE EAST SWIFTLY. FORECAST CHARTS STILL INDICATE THIS SYSTEM MAY
BE SLIGHTLY STRONGER THAN PREVIOUSLY EXPECTED...THOUGH IT APPEARS IT
WILL REMAIN FAR WEST OF THE ISLANDS. THUS THE LIGHTER WINDS ARE
EXPECTED TO LAST THROUGH TONIGHT...WITH THE RETURN OF THE STRONGER
TRADE WINDS BY THE NEW YEAR. FORECAST CHARTS CONTINUE TO HINT
LINGERING INSTABILITY OVER THE ISLANDS. THUS THE WET WEATHER REGIME
MAY CONTINUE. TRADES ARE TO INCREASE BY THE WEEKEND AS THE SURFACE
RIDGE STRENGTHENS NORTH OF THE STATE. FORECAST CHARTS INDICATE THE
AIR MASS WILL REMAIN MOIST...AND THUS THE WET TRADE WEATHER WILL
PROBABLY PREVAIL THROUGH THE REST OF WEEK.

ANOTHER LOW PRESSURE TROUGH IS NOW EXPECTED TO PASS NORTH OF THE
STATE EARLY NEXT WEEK. FORECAST CHARTS HAVE BEEN INCONSISTENT IN
HOW MUCH OF THIS SYSTEM WILL AFFECT THE ISLANDS AT TIME. DO EXPECT
THE WINDS TO BECOME LIGHT AGAIN...THOUGH THERE IS HIGH UNCERTAINTY
ON THE EXTEND OF THE SPREAD OF THE VOLCANIC EMISSION FROM THE BIG
ISLAND TO THE SMALLER ISLANDS AT THIS TIME.

&&

.MARINE...
CURRENT WEST NORTHWEST SWELL CONTINUES WITH SURF HEIGHTS REACHING
ADVISORY LEVELS ON NORTH AND WEST FACING SHORES OF KAUAI AND NIIHAU
TODAY...WHILE THE REST OF THE SMALLER ISLANDS WILL BE SOMEWHAT
SHELTERED...AND THUS WILL SEE LOWER HEIGHTS. THIS SWELL WILL REACH
THE BIG ISLAND ALSO...BRINGING ADVISORY LEVEL SURF TO THE WEST
FACING SHORES OF THAT ISLAND.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FOR BIG ISLAND SUMMITS THROUGH 10 AM HST.

HIGH SURF ADVISORY FOR NORTH AND WEST FACING SHORES OF KAUAI AND
NIIHAU AND FOR WEST FACING SHORES OF BIG ISLAND THROUGH THURSDAY.

&&

HUI