High Surf Advisory 42, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
930 AM HST MON DEC 24 2012

.SYNOPSIS...
LIGHT AND VARIABLE WINDS WILL GRADUALLY BECOME MORE EASTERLY AND
STRONGER DURING THE NEXT COUPLE DAYS. SHOWER ACTIVITY WILL ALSO
INCREASE...FAVORING WINDWARD AND MAUKA AREAS. RAINFALL IN GENERAL
SHOULD REMAIN LIGHT. EXPECT INCREASING HIGH CLOUDS TODAY FROM WEST
TO EAST. 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 ARE
FLUCTUATING AROUND THE 30 MPH THRESHOLD...FOR WHICH THE WIND
ADVISORY WILL REMAIN IN PLACE AT LEAST THROUGH THE REST OF THE
MORNING HOURS. CONDITIONS WILL CONTINUE TO BE MONITORED AND THE
ADVISORY WILL BE REVISED FOR THE AFTERNOON PACKAGE.

ALSO...LATEST MIMIC/PWAT DATA SUGGEST A GRADUAL INCREASE IN
AVAILABLE LOW LVL MOISTURE STARTING LATER TODAY AS THE GENERALLY
WEAK FLOW ACROSS THE ISLANDS WILL BECOME MORE EASTERLY AND GETTING
STRONGER DURING THE NEXT TWO OR THREE DAYS. THERE IS ALSO A SLIGHT
CHANCE OF SNOW SHOWERS OVER THE BIG ISLAND SUMMITS LATER TONIGHT.
THIS IS MAINLY DUE TO THE RE/ESTABLISHMENT OF THE SFC RIDGE TO THE
NE. MEANWHILE...AN AREA OF CONVECTION W/SW OF THE MAIN HAWAIIAN
ISLANDS WILL CONTINUE TO PRODUCE MID/UPPER LVL OUTFLOW
CLOUDS...WHICH WILL BRING EXTENDED PERIODS OF CLOUD COVER ALOFT
THROUGH TUESDAY. CLOUDS COULD BE THICK ENOUGH TO PRODUCE SOME
STRATIFORM RAIN AT TIMES. THEREFORE...THE OVERALL CHANCES FOR RAIN
ACROSS THE AREA WILL INCREASE...STILL WITH BEST CHANCES OVER
WINDWARD AND MAUKA AREAS THROUGH THE END OF THE WEEK.
HOWEVER...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 WILL REACH HIGH END ADVISORY LEVELS OF AROUND 20
FEET ON CHRISTMAS DAY. A JASON-1 ALTIMETER PASS OVER THE SWELL AREA
YESTERDAY AFTERNOON 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 COULD REACH LOW END WARNING
LEVELS OF AROUND 25 FEET. WE WILL BE MONITORING BUOY 51101 NORTHWEST
OF THE STATE TO DETERMINE IF A WARNING WILL BE ISSUED LATER TODAY OR
WE GO WITH OUR PREVIOUS THOUGHTS ON ISSUING AN ADVISORY.

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...
LIGHT ICING HAS BEEN POSTED FOR MAUI AND AREAS WESTWARD IN
RESPONSE TO THE LAYERED CLOUDS MOVING OVER THE ISLANDS. IF THE
LAYERED CLOUDS MOVE TO THE EAST...THE AIRMET MAY BE EXPANDED TO
COVER THE BIG ISLAND. LOWER LEVELS HAVE LIGHT TRADES/VARIABLE
WINDS...AND THAT IS EXPECTED TO CONTINUE THROUGH MUCH OF THE DAY.
MVFR CONDITIONS EXPECTED OVER AT TIMES OVER MOSTLY WINDWARD/MAUKA
AREAS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 6 PM HST THIS EVENING FOR HALEAKALA SUMMIT.

&&

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