High Surf in Hawaii, December 27 to 31, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST THU DEC 27 2012

.SYNOPSIS...
TRADE WINDS WILL HOLD TODAY...WITH SHOWERS FAVORING WINDWARD AND
MAUKA AREAS...BUT WILL BEGIN TURN SOUTHEASTERLY AND WEAKEN OVER THE
SMALLER ISLANDS LATER TONIGHT. THE LIGHTER WINDS WILL ALLOW LAND AND
SEA BREEZES TO DEVELOP DURING THE WEEKEND. A WEAKENING COLD FRONT IS
EXPECTED TO REACH THE NORTHWESTERN PORTIONS OF THE STATE BY EARLY
NEXT WEEK.

&&

.DISCUSSION...
WATER VAPOR IMAGERY SHOWS A WEAK MID-LEVEL TROUGH NORTHEAST OF THE
STATE. A STRONG UPPER LEVEL JET IS LOCATED OVER THE NORTH PACIFIC...
WITH A WEAKER BRANCH OF IT NOSING JUST NORTH OF THE STATE. AT THE
SURFACE...A NEARLY STATIONARY FRONT IS LOCATED NORTH AND NORTHWEST
OF THE STATE...WITH HIGH PRESSURE FAR TO THE NORTHEAST. THE SURFACE
RIDGE IS ABOUT 300-400 MILES NORTH OF THE STATE. 12Z SOUNDINGS FROM
HILO AND LIHUE SHOWED INVERSIONS NEAR 5-6KFT. PRECIPITABLE WATERS
WERE AROUND 1.1 INCHES...SOME OF WAS DUE TO ELEVATED MOISTURE FROM
MID/HIGH LEVEL CLOUDS ASSOCIATED WITH THE TROUGH TO OUR NORTHEAST.

TRADE WINDS WILL CONTINUE THROUGH TODAY...ALBEIT OUT OF A MORE DUE
EASTERLY DIRECTION THAN NORMAL. THE DRY AIRMASS HAS LIMITED RAINFALL
OVERNIGHT. THIS WILL CONTINUE TODAY...WITH SHOWERS FOCUSED ACROSS
WINDWARD AND MAUKA AREAS.

AN UPPER LEVEL IMPULSE WILL HELP TO PROPEL THE FRONT CLOSER TO THE
STATE THIS WEEKEND...STALLING AGAIN OVER THE NORTHWEST OFFSHORE
WATERS. THIS WILL WEAKEN THE RIDGE AND SHIFT IT SOUTHEASTWARD...
TURNING THE LOW-LEVEL GRADIENT OUT OF THE SOUTHEAST...AT LEAST
ACROSS THE SMALLER ISLANDS. THE GFS AND ECMWF ARE RATHER SIMILAR
WITH THE PATTERN NEAR THE STATE. THE LIGHTER GRADIENT WILL ALLOW FOR
LOCALIZED WINDS...WITH ONSHORE SEAS BREEZES DURING THE DAY AND
OFFSHORE LAND BREEZES AT NIGHT. WITH LIMITED MOISTURE AVAILABLE...
RAINFALL AMOUNTS WILL REMAIN LIGHT. CLOUDS AND SHOWERS WILL BE MORE
FOCUSED ACROSS INTERIOR AND LEEWARD SECTIONS OF THE ISLANDS DURING
THE AFTERNOON...WITH SOME CLOUDS LINGERING ACROSS WINDWARD SECTIONS
AT NIGHT. CLEARING SKIES AND LIGHT WINDS ACROSS THE INTERIOR OF THE
ISLANDS WILL LEAD TO GOOD RADIATIONAL COOLING CONDITIONS...AND COOL
STARTS TO THE MORNINGS.

A STRONGER UPPER LEVEL TROUGH IS EXPECTED EARLY NEXT WEEK...WHICH
WILL LEAD TO CYCLOGENESIS FAR NORTH OF THE STATE ALONG THE EXISTING
BAROCLINIC ZONE. THIS LOW WILL TRACK NORTHEAST AWAY FROM THE
STATE...BUT WILL PULL THE FRONT CLOSER TO THE ISLANDS. THE GFS AND
ECMWF ARE STILL RATHER SIMILAR WITH THIS PATTERN...SHOWING THE FRONT
REACHING KAUAI ON MONDAY. THE GFS WEAKENS THE FRONT OVER KAUAI WHILE
THE ECMWF BRINGS IT TO MAUI COUNTY BEFORE DISSIPATING...BUT BOTH
SOLUTIONS SHOW AN INCREASE IN MOISTURE AND SHOWERS FOR
MONDAY/TUESDAY. AS THE FRONT DISSIPATES...STRONGER
NORTH-NORTHEASTERLY WINDS WILL FILL IN BEHIND IT...EVENTUALLY
VEERING TO A MORE TYPICAL TRADE WIND DIRECTION BY MID WEEK.
CURRENTLY IT APPEARS THAT WINDS WILL REMAIN LIGHT ON MONDAY...THEN
INCREASE MONDAY NIGHT.

FOR THE LONG RANGE...HIGH PRESSURE WILL QUICKLY BUILD BACK IN BEHIND
THE FRONT...WITH MODERATE TO FRESH TRADE WINDS ESTABLISHING BY THE
MIDDLE OF NEXT WEEK.

&&

.MARINE...
A NEW NORTHWEST SWELL IS CURRENTLY BUILDING...AND IS EXPECTED TO
BRING WARNING LEVEL SURF TO NORTH AND WEST FACING SHORES OF THE
SMALLER ISLANDS. /WITH THE SWELL FROM THIS DIRECTION...THE BIG
ISLAND SHOULD BE BLOCKED BY THE SMALLER ISLANDS./ THE WAVE HEIGHT AT
BUOY 51101 WAS SLOWER TO RESPOND THAN WAVEWATCH III GUIDANCE BY
ABOUT 6 HOURS...BUT HAS RAPIDLY BUILT TO 10 FEET BY 19Z. EVEN WITH
THE SLOWER ONSET...IT APPEARS AS THOUGH HEIGHTS ARE STILL ON TRACK.
THE CURRENT FORECAST HAS SURF OF 20 TO 25 FEET BY TONIGHT...
LINGERING INTO FRIDAY BEFORE DIMINISHING.

A SMALL CRAFT ADVISORY IS CURRENTLY IN EFFECT FOR THE TYPICALLY
WINDIER CHANNELS NEAR MAUI AND THE BIG ISLAND. WINDS WILL DIMINISH
TONIGHT...BUT SEAS WILL INCREASE AS THE LARGE NORTHWEST SWELL
ARRIVES. WE HAVE EXPANDED THE SMALL CRAFT TO INCLUDE ALL COASTAL
WATERS EXCEPT MAALAEA BAY THROUGH THE DAY ON FRIDAY DUE TO HAZARDOUS
SEAS OVER 10 FEET.

&&

.AVIATION...
A SURFACE HIGH FAR NORTH OF THE ISLANDS WILL MOVE TO THE EAST...
CAUSING THE EASTERLY TRADE WINDS TO DECREASE AND TURN OUT OF THE
SOUTHEAST LATE TONIGHT AND FRIDAY. MVFR CEILINGS AND VISIBILITIES
MAY BRIEFLY OCCUR WITH ISOLATED SHOWERS OVER WINDWARD AND MAUKA
AREAS. OTHERWISE...VFR CONDITIONS WILL PREVAIL ACROSS THE STATE.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF WARNING FOR NORTH FACING SHORES OF NIIHAU KAUAI OAHU
MOLOKAI AND MAUI UNTIL 6 AM HST FRIDAY.

HIGH SURF WARNING FOR WEST FACING SHORES OF NIIHAU AND KAUAI
UNTIL 6 AM HST FRIDAY.

HIGH SURF ADVISORY FOR WEST FACING SHORES OF OAHU AND MOLOKAI
UNTIL 6 AM HST FRIDAY.

SMALL CRAFT ADVISORY UNTIL 6 PM HST THIS EVENING FOR MAALAEA BAY.

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

SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 PM HST FRIDAY
FOR KAUAI NORTHWEST WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD
WATERS-KAUAI CHANNEL-OAHU WINDWARD WATERS-OAHU LEEWARD WATERS-
KAIWI CHANNEL-MAUI COUNTY WINDWARD WATERS-MAUI COUNTY LEEWARD
WATERS-BIG ISLAND WINDWARD WATERS.

&&

DISCUSSION/MARINE...BRAVENDER
AVIATION...CRAIG