High Surf in Hawaii, December 24 to 26, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
330 PM HST MON DEC 24 2012

.SYNOPSIS...
WINDS ACROSS THE ISLANDS WILL GRADUALLY BECOME MORE EASTERLY AND
STRONGER DURING THE NEXT COUPLE DAYS AS HIGH PRESSURE TO THE
NORTHEAST INTENSIFIES. SHOWER ACTIVITY WILL INCREASE...BUT STILL
FAVORING WINDWARD AND MAUKA AREAS. RAINFALL IN GENERAL SHOULD REMAIN
LIGHT. EXPECT HIGH CLOUDS TO ALSO REMAIN IN PLACE TONIGHT AND
THROUGH CHRISTMAS DAY. CONDITIONS WILL BECOME INCREASINGLY STABLE BY
LATE IN THE WEEK...WITH WINDS POSSIBLY TURNING TO THE SOUTHEAST
AGAIN DURING THE WEEKEND.

&&

.DISCUSSION...
LATEST OBSERVATIONS FROM HALEAKALA SHOW THAT WIND SPEEDS HAVE
DECREASED TO WELL BELOW ADVISORY LEVELS. THEREFORE...THE WIND
ADVISORY FOR THE HALEAKALA SUMMIT HAS BEEN CANCELLED. MODEL DATA
SUGGEST THAT WIND SPEEDS WILL CONTINUE TO FLUCTUATE DURING THE NEXT
COUPLE OF DAYS OVER THE HALEAKALA SUMMIT...BUT EXPECTED TO REMAIN
BELOW THRESHOLD LEVELS.

LATEST MODEL RH/MIMIC/PWAT DATA STILL SUGGEST A GRADUAL INCREASE IN
AVAILABLE LOW LVL MOISTURE ACROSS THE AREA AS THE GENERALLY
PREVAILING WEAK FLOW BECOMES MORE EASTERLY AND STRONGER DURING THE
NEXT TWO OR THREE DAYS. THIS IS DUE TO A SFC RIDGE NE OF THE ISLANDS
INTENSIFYING AND RE/ESTABLISHING ITS DOMINANCE ACROSS THE AREA.
ALSO...THERE IS A SLIGHT CHANCE OF SNOW SHOWERS OVER THE BIG ISLAND
SUMMITS LATER TONIGHT.

MEANWHILE...THE AREA OF CONVECTION W/SW OF THE MAIN HAWAIIAN ISLANDS
CONTINUES TO PRODUCE ABUNDANT MID/UPPER LVL CLOUDS...WITH EXTENDED
PERIODS OF MOSTLY CLOUDY TO CLOUDY SKIES OVER THE AREA THROUGH
TUESDAY. CLOUDS COULD BE THICK ENOUGH TO PRODUCE SOME STRATIFORM
RAIN AT TIMES. EXPECT OVERALL CHANCES FOR RAIN ACROSS THE ISLANDS TO
INCREASE...STILL WITH BEST CHANCES OVER WINDWARD AND MAUKA AREAS
THROUGH THE END OF THE WEEK. RAINFALL ACCUMULATIONS SHOULD REMAIN
LIGHT FOR THE MOST PART WITH AN OCCASIONAL DOWNPOUR POSSIBLE...
MAINLY OVER MOUNTAIN AREAS.

FOR THE WEEKEND...MODEL SOLUTIONS SHOW POTENTIAL FOR A DEEP
MID/UPPER LVL TROUGH TO DEVELOP TO THE WEST OF THE ISLANDS WITH A
SERIES OF FRONTS BEING PUSHED TOWARDS THE ALOHA STATE. THIS
COULD VEER WINDS TO A MORE SE OR EVEN S FLOW AT TIMES...ALONG WITH
INCREASING SHOWER COVERAGE AROUND THE ISLANDS FOR THE BEGINNING OF
NEXT WEEK. MODELS CONSENSUS REMAINS LOW IN TERMS OF HAVING ONE OR
MORE OF THESE FRONTS ACTUALLY REACHING AND MOVING ACROSS THE
ISLANDS EARLY NEXT WEEK.

&&

.MARINE...
A NEW AND RATHER LARGE NORTHWEST WILL FILL IN OVERNIGHT...PEAK ON
TUESDAY...THEN LOWER SLOWLY ON WEDNESDAY. WAVEWATCH III MODEL OUTPUT
INDICATES THAT SURF WOULD REACH HIGH END ADVISORY LEVELS OF AROUND
20 FEET ON CHRISTMAS DAY. A JASON-1 ALTIMETER PASS OVER THE SWELL
AREA YESTERDAY AFTERNOON AS WELL AS ONE EARLIER TODAY INDICATES THAT
THE WAVEWATCH III MODEL OUTPUT MAY HAVE UNDERDONE THE SIZE OF THE
SWELL. THE ALTIMETER DATA SHOWS THAT THE SWELL MY BE ABOUT 2 FEET
HIGHER THAN THE MODEL OUTPUT. IF THIS DATA IS CORRECT THAN SURF
HEIGHTS WOULD REACH LOW END WARNING LEVELS OF AROUND 25 FEET. LONG
PERIOD FORERUNNERS HAVE BEGIN TO ARRIVE AT BUOY 51101 NORTHWEST OF
THE STATE. BASED ON THE ALTIMETER DATA WE HAVE DECIDED TO GO WITH A
HIGH SURF WARNING FOR THIS EVENT FOR NORTH AND WEST FACING SHORES OF
NIIHAU AND KAUAI...NORTH FACING SHORES OF OAHU...MOLOKAI AND
MAUI...WITH A HIGH SURF ADVISORY FOR WEST FACING SHORES OF OAHU AND
MOLOKAI...AND FOR NORTH FACING SHORES OF THE BIG ISLAND.

THIS NEW NORTHWEST SWELL WILL ALSO CAUSE SEAS TO REACH 10 FEET OR
HIGHER OVER WATERS EXPOSED TO THIS SWELL. THUS A SMALL CRAFT
ADVISORY WILL BE ISSUED LATER TODAY FOR THESE CONDITIONS. TRADE
WINDS WILL ALSO INCREASE TO SMALL CRAFT ADVISORY LEVELS ON TUESDAY
FOR THE USUAL WINDY WATERS AROUND MAUI COUNTY AND THE BIG ISLAND.

&&

.AVIATION...
DUE TO LAYERED HIGH CLOUDS OVER THE ISLANDS...LIGHT ICING IS
POSSIBLE OVER ALL THE ISLANDS. THE UPPER LEVEL TROUGH FAR WEST OF
THE ISLANDS BRINGING THE HIGH CLOUDS SHOULD MOVE TO THE WEST WITH
HIGH CLOUDS SLOWLY CLEARING THE ISLANDS FROM EAST TO WEST OVER THE
NEXT 24 HOURS. LIGHT WINDS ARE EXPECTED TO CONTINUE INTO
TUESDAY...RESULTING IN SOME LOCAL LAND AND SEA BREEZES. SOME MVFR
CONDITIONS ARE EXPECTED OVER MOSTLY WINDWARD/MOUNTAIN AREAS OF THE
BIG ISLAND...AND OVER THE MOUNTAINS AND INTERIOR OF THE SMALLER
ISLANDS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF WARNING UNTIL 6 AM HST WEDNESDAY FOR NIIHAU-KAUAI
WINDWARD-KAUAI LEEWARD-OAHU NORTH SHORE-OAHU KOOLAU-MOLOKAI-MAUI
WINDWARD WEST-MAUI CENTRAL VALLEY-WINDWARD HALEAKALA.

HIGH SURF ADVISORY UNTIL 6 AM HST WEDNESDAY FOR WAIANAE COAST-
BIG ISLAND NORTH AND EAST.

SMALL CRAFT ADVISORY UNTIL 6 AM HST WEDNESDAY FOR ALL HAWAIIAN
WATERS-

&&

SYNOPSIS/DISCUSSION...REYNES
MARINE...BURKE
AVIATION...M. BALLARD