High Surf in Hawaii, December 25 to 26, 2010

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST SAT DEC 25 2010

CORRECTED WATCH/WARNING/ADVISORY SECTION FOR THE SMALL CRAFT
ADVISORY AREAS

.SYNOPSIS...
CLOUDS AND SHOWERS WILL RETURN AGAIN OVER MOST ISLANDS THIS
AFTERNOON. LIGHT AND VARIABLE WINDS WILL GRADUALLY SHIFT TO A
SOUTHERLY DIRECTION LATER TODAY AND SUNDAY IN ADVANCE OF A COLD
FRONT APPROACHING KAUAI FROM THE WEST. AS THE FRONT NEARS...THE
CHANCE OF LOCALLY HEAVY RAINFALL WILL INCREASE...MAINLY OVER KAUAI
COUNTY AND OAHU FROM SUNDAY NIGHT THROUGH TUESDAY.

&&

.DISCUSSION...
THE ATMOSPHERE OVER HAWAII REMAINS MOIST AND SLIGHTLY UNSTABLE.
SATELLITE DERIVED PRECIPITABLE WATER /PW/ VALUES AND DATA COLLECTED
BY THE EARLY MORNING WEATHER BALLOONS INDICATE VALUES ARE 1.5 TO 1.6
INCHES. THESE PW VALUES ARE MUCH HIGHER THAN THE NORMAL VALUE FOR
THE ISLANDS...WHICH IS APPROXIMATELY 1.1 INCHES.

AS A RESULT OF THESE WET CONDITIONS...SHOWERS...AND EVEN A
THUNDERSTORM OR TWO...OCCURRED ACROSS THE STATE LATE YESTERDAY AS
DAYTIME HEATING OVER LAND CAUSED LOCAL SEA BREEZE CIRCULATIONS TO
DEVELOP. A FEW BRIEF THUNDERSTORMS WERE OBSERVED OVER PARTS OF THE
BIG ISLAND YESTERDAY AFTERNOON AND EVENING...WHILE ANOTHER
THUNDERSTORM WAS OBSERVED OVER THE KOOLAU MOUNTAINS ABOVE KANEOHE
AFTER SUNSET FRIDAY EVENING. A FLOOD ADVISORY FOR WINDWARD OAHU WAS
UPGRADED TO A FLASH FLOOD WARNING AS A RESULT OF THE LOCALLY HEAVY
RAINFALL THAT OCCURRED WITH THIS THUNDERSTORM.

EXAMPLES OF THE LARGEST RAINFALL TOTALS BY ISLAND FOR THE 12 HOUR
PERIOD ENDING AT 200 AM HST INCLUDE...1.21 INCHES AT MOUNT WAIALEALE
ON KAUAI...3.20 INCHES AT THE AHUIMANU LOOP GAGE ON OAHU...0.07
INCHES AT THE MOLOKAI AIRPORT...0.56 INCHES AT ULUPALAKUA ON MAUI...
AND 1.68 INCHES AT PAHALA ON THE BIG ISLAND.

CURRENTLY...SCATTERED SHOWERS WERE OCCURRING IN THE VICINITY OF
KAUAI AND NIIHAU...AND OVER THE COASTAL WATERS ADJACENT TO THE
SOUTHEASTERN BIG ISLAND COASTLINE. IT APPEARS THAT LAND BREEZES ARE
KEEPING MOST OF THESE SHOWERS OFFSHORE EARLY THIS MORNING.
ADDITIONAL SHOWERS...SOME WITH LOCALLY HEAVY RAINFALL ARE IN THE BIG
ISLAND PLUME WEST OF THE KONA COAST OF THE BIG ISLAND.

A 1020 MB SURFACE HIGH IS CENTERED ABOUT 770 MILES NORTHEAST OF
HONOLULU. THIS HIGH WILL MOVE RAPIDLY TOWARD THE EAST SOUTHEAST TO A
POSITION FAR EAST NORTHEAST OF THE STATE LATE TONIGHT...CAUSING OUR
SURFACE WINDS TO SHIFT TO A MORE SOUTHEASTERLY TO SOUTHERLY
DIRECTION LATER TODAY AND TONIGHT. THE WINDS WILL REMAIN LIGHT
TODAY...SO SEA BREEZES WILL LIKELY DEVELOP ONCE AGAIN OVER MOST
ISLANDS. THE DAYTIME HEATING AND SEA BREEZES WILL LIKELY LEAD TO
CLOUD BUILDUPS AND SHOWERS OVER INTERIOR SECTIONS OF THE ISLANDS
STARTING THIS AFTERNOON. ALSO...THERE IS A SLIGHT CHANCE OF
THUNDERSTORMS OVER THE BIG ISLAND THIS AFTERNOON. AS THE FLOW SHIFTS
TO A MORE SOUTHEASTERLY DIRECTION...THERE IS A CHANCE SOME OF THE
SHOWERS EMBEDDED WITHIN THE BIG ISLAND PLUME MAY AFFECT SOME OF THE
SMALLER ISLANDS...ESPECIALLY LANAI AND MOLOKAI. THIS FEATURE MAY
ALSO HAVE AN IMPACT ON OAHU LATE TODAY OR TONIGHT.

THE LOW LEVEL FLOW WILL STRENGTHEN AND TURN OUT OF THE SOUTH IN
ADVANCE OF A SURFACE COLD FRONT AND A LARGE UPPER TROPOSPHERIC
TROUGH APPROACHING KAUAI FROM THE WEST LATE TONIGHT AND SUNDAY. THE
SOUTHERLY WINDS WILL BRING EVEN MORE TROPICAL MOISTURE UP OVER THE
STATE. MODELS INDICATE THE BEST CHANCE OF HEAVY SHOWERS WILL BE OVER
THE WEST END OF THE STATE STARTING SUNDAY NIGHT. HAVE ALSO
INTRODUCED ISOLATED THUNDERSTORMS FOR KAUAI DURING THE DAY ON MONDAY
BASED ON THE LATEST MODEL GUIDANCE. THEREFORE...A HYDROLOGIC OUTLOOK
REMAINS POSTED FOR KAUAI COUNTY AND OAHU FROM SUNDAY NIGHT THROUGH
TUESDAY. THE WET WEATHER IS ALSO FORECAST TO EVENTUALLY SPREAD OVER
ALL ISLANDS THROUGH THE REST OF THE UPCOMING WORK WEEK.

&&

.MARINE...
THE LATEST FORECAST KEEPS WINDS BELOW THE SMALL CRAFT ADVISORY /SCA/
THRESHOLD THROUGH EARLY NEXT WEEK. HOWEVER...WITH THE ARRIVAL OF A
NEW NORTH SWELL...SEAS WILL INCREASE TO THE SCA THRESHOLD OF 10 FEET
FOR MOST OF THE WINDWARD HAWAIIAN WATERS...AND THE KAUAI...KAIWI AND
ALENUIHAHA CHANNELS LATER TODAY. THESE SEAS WILL GRADUALLY DIMINISH
DURING THE DAY ON SUNDAY.

THE BUILDING NORTH SWELL WILL LIKELY CAUSE SURF HEIGHTS TO REACH THE
HIGH SURF ADVISORY THRESHOLD ALONG NORTH AND EAST FACING SHORES OF
NIIHAU...KAUAI...OAHU...MOLOKAI...MAUI AND THE BIG ISLAND FROM LATE
TODAY THROUGH SUNDAY AFTERNOON. BUOY 51100 LOCATED NORTHEAST OF THE
BIG ISLAND IS CURRENTLY INDICATING THE SWELL HEIGHT HAS INCREASED TO
9 FEET WITH A WAVE PERIOD OF AROUND 13 SECONDS. THIS SWELL WILL
GRADUALLY DIMINISH LATE SUNDAY AND MONDAY. NO OTHER SIGNIFICANT
SWELLS ARE EXPECTED.

FINALLY...A MARINE WEATHER STATEMENT HAS BEEN ISSUED FOR NORTH
FACING HARBORS...INCLUDING HILO AND KAHULUI HARBORS...WHERE MODERATE
TO HEAVY SURGES MAY OCCUR STARTING THIS MORNING. THESE SURGES MAY
OCCUR WITHIN THESE HARBORS AS LONG AS THE NORTH SWELL IS AFFECTING
THE ISLANDS.

&&

.AVIATION...
BRIEF MVFR CONDS WITH THE SHRA. OTHERWISE...ALL TERMINALS EXPECTED
TO BE VFR TODAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY THROUGH 600 PM HST SUNDAY AFTERNOON FOR NORTH AND
EAST FACING SHORES OF NIIHAU...KAUAI...OAHU...MOLOKAI... MAUI AND
THE BIG ISLAND.

SMALL CRAFT ADVISORY THROUGH 600 PM HST SUNDAY AFTERNOON FOR KAUAI
NORTHWEST WATERS...KAUAI WINDWARD WATERS...KAUAI LEEWARD WATERS...
KAUAI CHANNEL...OAHU WINDWARD WATERS...OAHU LEEWARD WATERS...KAIWI
CHANNEL...MAUI COUNTY WINDWARD WATERS...ALENUIHAHA CHANNEL...AND THE
BIG ISLAND WINDWARD WATERS.

&&

DISCUSSION/MARINE...HOUSTON
AVIATION...H LAU