High Surf in Hawaii, December 28 to 29, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST WED DEC 28 2011

.SYNOPSIS...
BREEZY TRADE WINDS WILL CONTINUE BEFORE WEAKENING THURSDAY NIGHT
THROUGH THE NEW YEARS WEEKEND. TRADES WILL USHER IN BRIEF PASSING
SHOWERS TO WINDWARD AND MAUKA AREAS...MOST LIKELY DURING NIGHTS AND
MORNINGS...WHILE LEEWARD AREAS WILL REMAIN MOSTLY DRY AND PLEASANT.

&&

.DISCUSSION...
LATEST SURFACE ANALYSIS SHOWS THE SUBTROPICAL RIDGE ABOUT 500 MILES
NORTH OF HONOLULU. THE RIDGE IS GRADUALLY WEAKENING...AND SHOULD
KEEP TRADE WINDS AT MODERATE TO LOCALLY FRESH SPEEDS TODAY. THE
AIRMASS OVER THE ISLANDS IS RELATIVELY DRY AND STABLE THANKS TO A
PERSISTENT MID-AND-UPPER LEVEL RIDGE NEAR AND TO THE NW OF THE
ISLANDS. THE UPSTREAM CLOUD COVER IS MOSTLY STABLE...WITH ONLY A FEW
SHOWERY CUMULUS MIXED IN. THE MOIST LAYER IS A LITTLE DEEPER NEAR
THE BIG ISLAND WHERE THERE ARE A FEW MORE SHOWERS OVER AND UPSTREAM
FROM THE WINDWARD SIDE.

THE WEATHER PATTERN LOOKS QUIET FOR THE NEXT SEVERAL DAYS WITH
BELOW NORMAL RAINFALL ACROSS THE STATE. THE RIDGE TO THE NORTH WILL
CONTINUE TO WEAKEN TODAY AND THURSDAY. TRADES WILL VERY GRADUALLY
LOWER INITIALLY. THEN BY FRIDAY...THE RIDGE WILL BEGIN TO SHIFT
SOUTH TOWARD THE ISLANDS AS A SERIES OF LARGE NORTH PACIFIC LOWS
BEGIN TO TRAVERSE THE HIGHER LATITUDES. OUR CURRENT FORECAST
MAINTAINS LIGHT TO MODERATE TRADES THROUGH THE NEW YEARS HOLIDAY
WEEKEND. A WEAK HIGH IS EXPECTED TO PASS N OF THE ISLANDS NEW YEARS
EVE...WHICH SHOULD HELP TO MAINTAIN TRADE WINDS.

THE SUBTROPICAL RIDGE WILL EVENTUALLY BE SHUNTED SOUTH OVER THE
ISLANDS FOR THE FIRST COUPLE DAYS OF 2012...IN RESPONSE TO A HUGE
AREA OF LOW PRESSURE OVER THE HIGHER LATITUDES. NIGHTTIME LAND
BREEZES AND DAYTIME SEA BREEZES WILL TAKE OVER. STRONG RIDGING AT
THE MID AND UPPER LEVELS SHOULD KEEP THE AIRMASS DRY AND STABLE...
SO FEW IF ANY AFTERNOON CONVECTIVE SHOWERS ARE EXPECTED.

WINDS ARE STILL GUSTING OVER 50 MPH AT THE SUMMIT OF HALEAKALA...IN
RESPONSE TO A STRONG MID LEVEL RIDGE TO THE NW OF THE ISLANDS AND A
PERSISTENT TROUGH TO THE SE. MAUNA KEA WINDS ARE NOT AS STRONG...BUT
STILL FLIRTING WITH ADVISORY LEVELS. THE MID-LEVEL HEIGHT GRADIENT
IS EXPECTED TO RELAX OVER THE NEXT COUPLE OF DAYS...LEADING TO A
SLOW DIMINISHING OF THE WINDS. IT IS POSSIBLE WE MAY NEED TO EXTEND
THE ADVISORY A LITTLE LONGER INTO THURSDAY.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL AT THE TERMINALS...WITH BRIEF AND
ISOLATED MVFR CIG/VIS ASSOCIATED WITH PASSING TRADE WIND SHRA.
ALTHOUGH TRADE WINDS ARE GRADUALLY DIMINISHING...AIRMET TANGO
REMAINS POSTED FOR LLVL TURB TO THE LEE OF THE MOUNTAINS...AND WILL
LIKELY REMAIN IN PLACE THROUGH TODAY...AS A STRONG LOW LEVEL
INVERSION WILL AID IN THE FORMATION OF MT WAVES.

SIGMET QUEBEC IS IN EFFECT FOR OCNL SEVERE HIGH LEVEL TURB S OF THE
ISLANDS...DUE TO A W-E ORIENTED JET AXIS AND STRONG WIND SHEAR FROM
FL260-FL390. THE JET AXIS IS SHIFTING SE AWAY FROM THE ISLANDS AND
GRADUALLY WEAKENING...AND THE SIGMET MAY BE CANCELLED LATER TODAY.

&&

.MARINE...
BUOY 51101 CONTINUING TO SHOW LONG PERIOD SWELL ENERGY ON THE
WAY...FROM A LOW THAT PASSED FAR TO THE N OF THE ISLANDS MONDAY
NIGHT. THIS SWELL IS EXPECTED TO BRING HIGH SURF TO KAUAI THIS
AFTERNOON...BUILDING TO THE OTHER ISLANDS TONIGHT. SURF SHOULD PEAK
ON THURSDAY BEFORE SLOWLY DECLINING.

ALTHOUGH TRADES ARE GRADUALLY DECLINING...THE NORMALLY WINDY SPOTS
NEAR MAUI COUNTY AND THE BIG ISLAND WILL CONTINUE TO SEE SMALL
CRAFT ADVISORY LEVEL WINDS. THE  INCOMING NORTH TO NORTH-NORTHWEST
SWELL MAY TRIGGER SMALL CRAFT ADVISORIES FOR COMBINED SEAS ABOVE 10
FEET.

&&

.FIRE WEATHER...
AFTERNOON RELATIVE HUMIDITY SHOULD REMAIN HIGH ENOUGH TO KEEP US
AWAY FROM RED FLAG CRITERIA...THOUGH THE KBDI IS UP TO 605 AND WINDS
WILL REMAIN ELEVATED. THE AFTERNOON HUMIDITY WILL BE A LITTLE LOWER
TOMORROW...BUT WINDS WILL ALSO BE LOWER AS WELL.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 6 AM HST THURSDAY FOR HALEAKALA SUMMIT-BIG
ISLAND SUMMITS.

SMALL CRAFT ADVISORY UNTIL 6 PM HST THURSDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.

HIGH SURF ADVISORY FROM NOON TODAY TO 6 PM HST THURSDAY FOR NORTH
AND WEST FACING SHORES OF KAUAI AND NIIHAU...AND FOR NORTH FACING
SHORES OF OAHU MOLOKAI AND MAUI.

&&

R BALLARD