High Surf in Hawaii, December 22 to 23, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST SAT DEC 22 2012

.SYNOPSIS...
TRADE WINDS WILL SLOWLY DECREASE...AND WILL SHIFT OUT OF THE EAST
SOUTHEAST ON SUNDAY. SHOWERS RIDING THE TRADES WILL FAVOR WINDWARD
AND MAUKA AREAS. SHOWERS WILL PROBABLY INCREASE OVER KAUAI AND OAHU
ON MONDAY AND TUESDAY.

&&

.DISCUSSION...
TRADE WINDS WILL GRADUALLY DECREASE AS A HIGH NORTHEAST OF THE STATE
MOVES OFF TO THE EAST. AS THE PRESSURE GRADIENT WEST OF THE HIGH
FLATTENS...THE TRADES WILL DROP INTO THE MODERATE RANGE ON SATURDAY.

A FRONT APPROACHING THE ISLANDS FROM THE NORTHWEST WILL ROUND OFF
THE WEST END OF THE SUBTROPICAL RIDGE TO OUR NORTH...CAUSING THE
LIGHTER TRADES TO VEER OUT OF THE EAST-SOUTHEAST ON SUNDAY AND
POSSIBLY MONDAY. THE RIDGE WILL STAY IN PLACE...FORCING THE FRONT TO
STALL NORTH OF THE ISLANDS.

THE FORECAST FOR MONDAY AND TUESDAY REMAINS UP IN THE AIR SO TO
SPEAK. IT ALL HAS TO DO WITH HOW THE MODELS HANDLE AN AREA OF DEEP
MOISTURE ABOUT 1000 MILES SOUTHWEST OF KAUAI. THE LAST TWO GFS MODEL
RUNS HAVE BACKED OFF ON HAVING AN UPPER LEVEL TROUGH TO OUR WEST
CARRY THE DEEP MOISTURE UP OVER THE ISLANDS. THE MODEL IS MORE IN
LINE WITH THE ECMWF MODEL WHICH ALSO TAPS INTO THE MOISTURE...BUT
KEEPS THE BULK OF IT WEST AND SOUTHWEST OF HAWAII. THAT SAID...THE
FORECAST CALLS FOR AN INCREASE IN SHOWERS OVER KAUAI AND TO A LESSER
DEGREE OAHU LATE MONDAY AND CHRISTMAS DAY.

A SURFACE HIGH PASSING TO THE NORTH ON MONDAY WILL END UP ABOUT
HALFWAY BETWEEN THE ISLANDS AND CALIFORNIA BY WEDNESDAY. THE RIDGE
TRAILING WEST OF THE HIGH WILL STAY TO OUR NORTH...BRINGING TRADE
WIND WEATHER TO THE STATE FROM TUESDAY THROUGH FRIDAY. BYE BYE.

&&

.MARINE...
NORTH SWELLS PASSING UNDER BUOY 51000 ANCHORED NORTHEAST OF THE
ISLANDS REMAIN LARGE ENOUGH TO WARRANT A HIGH SURF WARNING FOR EAST
FACING SHORES AND A HIGH SURF ADVISORY FOR NORTH FACING SHORES. THE
SWELL AND RESULTING SURF ARE EXPECTED TO LOWER TONIGHT THROUGH
MONDAY. THE NORTH SWELL WILL ALSO PRODUCE SURGES AT HILO AND KAHULUI
HARBORS. A NEAR ADVISORY LEVEL NORTHWEST SWELL IS FORECAST TO ARRIVE
ON TUESDAY.

A SMALL CRAFT ADVISORY /SCA/ WILL CONTINUE FOR BRISK TRADE WINDS
OVER THE TYPICALLY WINDY WATERS AROUND MAUI COUNTY AND THE BIG
ISLAND. THE TRADES WILL LOWER BELOW THE 25 KT THRESHOLD ON SUNDAY OR
MONDAY...BUT MAY RISE AGAIN IN THE MIDDLE OF NEXT WEEK.

A SCA FOR HAZARDOUS SEAS WILL ALSO LAST THROUGH SATURDAY NIGHT. THE
NORTH SWELL DISCUSSED ABOVE ALONG WITH WIND-GENERATED WAVES WILL
KEEP SEAS AT OR ABOVE THE 10 FOOT SCA THRESHOLD INTO SATURDAY NIGHT.

&&

.AVIATION...
SLOWLY DIMINISHING TRADES WILL CARRY SHOWERS OVER WINDWARD SECTIONS.
MVFR CEILING AND VISIBILITIES ARE POSSIBLE WITH THE SHOWERS. TAFS
CALL FOR VFR CONDITIONS THROUGH THE PERIOD.

AIRMET TANGO FOR LLVL TURB WILL LIKELY BE CANCELLED THIS MORNING AS
THE WINDS DIMINISH.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF WARNING UNTIL 6 PM HST SATURDAY FOR EAST FACING SHORES OF
KAUAI OAHU MOLOKAI MAUI AND THE BIG ISLANDS.

HIGH SURF ADVISORY FROM 6 PM HST SATURDAY UNTIL 6 AM HST SUNDAY FOR
THE SAME EAST FACING SHORES.

HIGH SURF ADVISORY UNTIL 6 AM HST SUNDAY FOR NORTH FACING SHORES OF
KAUAI OAHU MOLOKAI MAUI AND THE BIG ISLAND.

SMALL CRAFT ADVISORY UNTIL 6 AM HST SUNDAY FOR WINDWARD WATERS...THE
KAUAI KAIWI PAILOLO AND ALENUIHAHA CHANNELS...MAALAEA BAY...AND
WATERS SOUTH OF THE BIG ISLAND.

&&

CRAIG