High Surf in Hawaii, November 15 to 17, 2004

HAWAIIAN ISLANDS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST MON NOV 15 2004

.SYNOPSIS...
STRONG AND GUSTY TRADE WINDS WILL WEAKEN SLIGHTLY ON TUESDAY...BUT
WILL LIKELY REMAIN FRESH UNTIL FRIDAY. SHOWERS ASSOCIATED WITH A
SHEARLINE WILL WET WINDWARD AND MAUKA SECTIONS OF THE BIG ISLAND FOR
THE NEXT COUPLE OF DAYS. THE SMALLER ISLANDS WILL CONTINUE TO SEE
CLOUDY CONDITIONS WINDWARD...WHILE SHOWERS WILL BE LESS FREQUENT.
LEEWARD SECTIONS OF ALL ISLANDS WILL HAVE SUNNY PERIODS...EXCEPT
WHEN A FEW LIGHT SHOWERS DRIFT LEEWARD WITH THE STRONG TRADES.

&&

.DISCUSSION...
A CLOUD AND SHOWER BAND ASSOCIATED WITH A SHEAR LINE IS BECOMING
MORE EAST TO WEST ORIENTED...AS A SURFACE HIGH NORTH-NORTHWEST OF
THE ISLANDS MOVES EASTWARD. THE SHOWERY PORTION OF THE BAND LOOKS TO
BE CLEARING THE SMALLER ISLANDS...AND WILL LIKELY ONLY AFFECT
WINDWARD BIG ISLAND TODAY AND TONIGHT...BEFORE SPREADING WESTWARD
BACK TO WINDWARD MAUI ON TUESDAY. ACTUALLY...MOISTURE ASSOCIATED
WITH THE SHEAR LINE IS EXPECTED TO BRING MUCH NEEDED RAINFALL TO
WINDWARD BIG ISLAND THROUGH THURSDAY NIGHT...BEFORE DISSIPATING AND
MOVING WEST. CLOUD ELEMENTS APPROACHING THE SMALLER ISLANDS WITHIN
THE BRISK LOW LEVEL FLOW APPEAR TO BE RATHER STABLE IN
NATURE...WHICH MEANS THAT WINDWARD LOCATIONS WILL CONTINUE TO BE
CLOUDY...BUT THAT RAINFALL AMOUNTS SHOULD BE MEAGER OVERALL.

STRONG NORTHEAST TRADE WINDS NORTH OF THE SHEAR LINE ARE IN THE
PROCESS OF VEERING AND BECOMING A STANDARD EAST-NORTHEAST DIRECTION
WHILE REMAINING STRONG. WIND SPEEDS ARE EXPECTED TO MAINTAIN THEIR
CURRENT VELOCITIES...NEAR 25 KT OPEN WATER SPEED...THROUGH
TONIGHT...BEFORE DROPPING A NOTCH ON TUESDAY. A WIND ADVISORY WAS
ISSUED AT 217 AM TO ACCOUNT FOR THE STRONG WINDS. WINDS WILL REMAIN
RATHER FRESH HOWEVER...UNTIL FRIDAY...WHEN A FAST MOVING FRONT
PASSING NORTH OF THE ISLANDS IS EXPECTED TO WEAKEN THE RIDGE.

THE SURFACE HIGH...AND RIDGE ALONG 35N...THAT ARE PROVIDING THE
GUSTY TRADES...WILL BE WEAKENED SLIGHTLY DUE TO CYCLOGENESIS THAT IS
FORECAST TO OCCUR ALONG 40N BETWEEN 170W AND 150W BY TUESDAY. THIS
WILL PUSH THE HIGH CENTER WESTWARD WHILE WEAKENING THE RIDGE AND
ALLOWING WINDS TO DIMINISH...ALBEIT ONLY MINIMALLY. A HIGH FOLLOWING
THIS DEVELOPING LOW WILL REINFORCE THE HIGH THAT CURRENTLY EXISTS
ALONG 35N...AND WILL HELP MAINTAIN FRESH TRADE WINDS THROUGH
THURSDAY NIGHT. THIS HIGH CENTER WILL MOVE SMARTLY EASTWARD THROUGH
THE WEEK...AND A FRONT IS EXPECTED TO WEAKEN THE RIDGE THURSDAY
NIGHT AND FRIDAY...ALLOWING WINDS TO ADOPT A MORE SOUTHEASTERLY
COMPONENT AND WEAKEN. THE FRONT THAT WEAKENS THE RIDGE IS
FORECAST TO REMAIN NORTH OF THE ISLANDS...WITH THE SURFACE RIDGE
REMAINING INTACT ALONG 25N. THE HIGH FOLLOWING THIS FRONT WILL
REINFORCE THE RIDGE...THUS SUPPORTING AT LEAST MODERATE TRADES. IN
SUMMARY...STRONG AND GUSTY TRADES WILL EASE A LITTLE ON
TUESDAY...REMAIN FRESH THROUGH LATE THURSDAY...AND THEN WEAKEN LATE
IN THE WEEK BEFORE INCREASING AGAIN LATE SATURDAY AND SUNDAY.

A MID LEVEL RIDGE CURRENTLY OVER THE ISLANDS IS FORECAST TO WEAKEN
AND MOVE WEST AWAY FROM THE ISLANDS BY TUESDAY. IN ITS PLACE...AN
EAST TO WEST ORIENTED MID LEVEL TROUGH IS PROGGED TO BE NEAR THE
ISLANDS ON TUESDAY...AND BECOME BETTER DEFINED ON WEDNESDAY AND
THURSDAY AS THE TROUGH AXIS MOVES SOUTHWARD TOWARDS THE BIG ISLAND.
THE TROUGH IS FORECAST TO WEAKEN BY NEXT WEEKEND. AS OF THIS
TIME...IT APPEARS THAT THE TROUGH WILL ENHANCE THE LOW LEVEL
MOISTURE ASSOCIATED WITH THE SHEAR LINE...WITH THE BULK OF THIS
MOISTURE NEAR THE BIG ISLAND. SIGNIFICANT CHANGES TO THE GRIDS WERE
NOT MADE DUE TO UNCERTAINTY IN THE FORECAST IN THIS TIME FRAME.

&&

.MARINE...
THE STRONG TRADE WINDS WILL BRING HIGH SURF TO EAST FACING SHORES...
WITH SEAS AND SWELLS REMAINING ELEVATED THROUGH TUESDAY. WIND
WAVES...WITH 8 TO 9 SECOND PERIODS...ARE NEAR 12 FEET AT THE KAILUA
BUOY OFF OAHU/S EAST SIDE...THUS SURF ALONG EAST FACING SHORES TODAY
SHOULD BE BETWEEN 8 AND 12 FEET. SURF ALONG NORTH FACING SHORES IS
EXPECTED TO BE JUST BELOW THE ADVISORY LEVEL OF 15 FEET...WITH A
COMBINATION OF SWELL DIRECTIONS AND PERIODS. SWELL HEIGHTS AT THE
WAIMEA BUOY HAVE DECREASED FROM A PEAK YESTERDAY EVENING...THUS A
HIGH SURF ADVISORY HAS NOT BEEN ISSUED FOR NORTH FACING SHORES.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY WATERS NORTH AND WEST OF THE BIG ISLAND.
HIGH SURF ADVISORY FOR EAST FACING SHORES.
WIND ADVISORY ALL ISLAND AREAS EXCEPT BIG ISLAND SUMMITS.
&&

BIRCHARD