High Surf in Hawaii, December 30 to 31, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
906 PM HST WED DEC 30 2015

.SYNOPSIS...
A WEAK FRONT ACROSS MAUI WILL DISSIPATE TONIGHT. HIGH PRESSURE
NORTH OF THE STATE WILL SLOWLY SETTLE SOUTHWARD OVER THE ISLANDS
THURSDAY AND THURSDAY NIGHT AS A COLD FRONT APPROACHES FROM THE
NORTHWEST. THIS COLD FRONT WILL PUSH SOUTHWARD THROUGH THE
STATE NEW YEARS DAY...CLEARING THE BIG ISLAND BY DAYBREAK
SATURDAY. HIGH PRESSURE WILL THEN BUILD NORTH OF THE ISLANDS OVER
THE WEEKEND...WITH ANOTHER COLD FRONT PUSHING SLOWLY SOUTHWARD
THROUGH THE  STATE DURING THE EARLY TO MIDDLE PART OF NEXT WEEK.

&&

.DISCUSSION...
CURRENTLY AT THE SURFACE...A HIGH PRESSURE RIDGE AXIS STRETCHES
FROM WEST-SOUTHWEST TO EAST NORTHEAST...FROM 24N170W
TO30N150W...WHICH POSITIONS THE RIDGE AXIS ROUGHLY 250 MILES TO
THE NORTH-NORTHWEST OF KAUAI. A WEAKENING FRONT IN THE
DISSIPATING STAGE IS LOCATED OVER MAUI...AND IS SLOWLY PUSHING
SOUTHWARD AS THE HIGH TO THE NORTH OF THE STATE BEGINS TO BECOME
MORE DOMINANT. INFRARED SATELLITE IMAGERY SHOWS THE GREATEST
COVERAGE OF CLOUD COVER INCLOSE PROXIMITY TO THE WEAKENING FRONT
OVER MAUI COUNTY...WITH RADAR IMAGERY SHOWING THE GREATEST SHOWER
COVERAGE IN THE SAME AREA AS WELL. MAIN SHORT TERM CONCERNS FOR
THE OVERNIGHT REVOLVE AROUND RAIN CHANCES AND BUILDING SURF
HEIGHTS.

TONIGHT...
THE RIDGE AXIS TO THE NORTH OF THE STATE WILL SETTLE SLOWLY
SOUTHWARD OVERNIGHT...REACHING A LOCATION AROUND 175 MILES NORTH-
NORTHWEST OF KAUAI BY DAYBREAK THURSDAY. AT THE SAME TIME...THE
WEAKENING FRONT IS EXPECTED TO HAVE DISSIPATED BETWEEN MAUI AND
THE BIG ISLAND BY DAYBREAK AS WELL. THE INCREASED
MOISTURE ASSOCIATED WITH THIS BOUNDARY WILL KEEP THE HIGHEST RAIN
CHANCES ACROSS WINDWARD AND MAUKA SECTIONS OF THE THE BIG ISLAND
AND MAUI COUNTY OVERNIGHT...WITH SHOWER ACTIVITY DECREASING
ACROSS OAHU AND LITTLE OR NO RAINFALL EXPECTED OVER KAUAI IN
CLOSER PROXIMITY TO THE RIDGE AXIS. OVERNIGHT LOWS ARE EXPECTED
TO BOTTOM OUT IN THE MID 60STO AROUND 70 NEAR THE COAST.

THURSDAY AND THURSDAY NIGHT... THE RIDGE AXIS WILL SLIP SOUTHWARD
TO NEAR KAUAI BY THURSDAY EVENING...THEN WILL CONTINUE TO
PUSH SOUTHWARD OVER THE CENTRAL ISLANDS THURSDAY NIGHT AS A COLD
FRONT APPROACHES KAUAI FROM THE NORTHWEST BY DAYBREAK FRIDAY.
WITH THE RIDGE AXIS MOVING SOUTHWARD TOWARD THE ISLANDS...THE
WINDS WILL LIGHTEN UP ENOUGH FOR SEA BREEZE DEVELOPMENT IN SOME
AREAS ON THURSDAY...WITH LAND BREEZES EXPECTED IN MANY AREAS
THURSDAY NIGHT.WE EXPECT THE SHOWER ACTIVITY WILL BE QUITE LIMITED
ON THURSDAY DUE TO A STRENGTHENING LOW LEVEL INVERSION. ANY
LINGERING SHOWERS ARE EXPECTED TO FAVOR WINDWARD/MAUKA SECTIONS
OF THE BIG ISLAND AND MAUI THURSDAY MORNING...WITH ISOLATED TO
WIDELY SCATTERED SHOWERS POSSIBLE ACROSS THE INTERIOR AND LEEWARD
SECTIONS OF THE ISLANDS THURSDAY AFTERNOON DUE TO DIURNAL
HEATING. LOOKS LIKE A DRY NEW YEARS EVE ACROSS THE ISLANDS AS ANY
SHOWERS THAT DEVELOP DURING THE DAY SHOULD DIMINISH QUICKLY
DURING THE EARLY EVENING HOURS. CAN/T RULE OUT SOME ISOLATED
SHOWERS LATE AT THURSDAY NIGHT AFFECTING KAUAI AND WINDWARD
SECTIONS OF OAHU AS THE COLD FRONT APPROACHES FROM THE NORTH.

NEW YEARS DAY AND NIGHT...
THE COLD FRONT WILL PUSH THROUGH KAUAI AND OAHU DURING THE
DAYLIGHT HOURS AND THROUGH MAUI COUNTY AND THE BIG ISLAND
OVERNIGHT. PRECIPITABLE WATER VALUES REMAIN LOW...GENERALLY AN
INCH OR LESS...EVEN WITH THE FRONTAL PASSAGE. AT THE SAME
TIME...THE LOW LEVEL INVERSION WILL REMAIN STRONG WITH INVERSION
HEIGHTS AT OR BELOW 7 KFT. AS A RESULT...WE ARE NOT EXPECTING MUCH
SHOWER ACTIVITY THROUGH THE PERIOD...WITH ONLY ISOLATED TO WIDELY
SCATTERED SHOWERS MAINLY IN WINDWARD AND MAUKA LOCALES.

SATURDAY THROUGH NEXT WEDNESDAY...
HIGH PRESSURE WILL BUILD NORTH OF THE ISLANDS KEEPING A
RELATIVELY DRY WEATHER PATTERN IN PLACE. A COLD FRONT WILL
APPROACH FROM THE NORTHWEST SUNDAY NIGHT...THEN SLOWLY PUSH
SOUTHWARD THROUGH THE ISLAND CHAIN MONDAY AND TUESDAY BEFORE
DISSIPATING NEAR THE BIG ISLAND ON WEDNESDAY. PRECIPITABLE WATER
VALUES DO INCREASE ABOVE AN INCH IN ASSOCIATION WITH THIS FRONTAL
PASSAGE...SO WE SHOULD SEE AN UPTICK IN SHOWER COVERAGE DURING THE
EARLY TO MIDDLE PART OF NEXT WEEK.

&&

.AVIATION...
VFR WILL PREVAIL OVER MOST OF THE STATE THIS EVENING AND IN THE
OVERNIGHT HOURS. HOWEVER...TEMPO MVFR CONDITIONS ARE LIKELY IN
WINDWARD AREAS...ESPECIALLY FROM OAHU TO THE BIG ISLAND...AS
REMNANT CLOUDINESS FROM AN OLD FRONT AFFECTS THE ISLES. LIGHT TO
MODERATE TRADE WINDS WILL PERSIST THROUGH THE NIGHT.

NO AIRMETS ARE CURRENTLY IN EFFECT.

&&

.MARINE...
A LARGE NORTHWEST SWELL IS EXPECTED TO BUILD LATER TONIGHT INTO
THURSDAY...THEN REMAIN ELEVATED INTO THE WEEKEND WITH A LARGER
REINFORCING NORTHWEST SWELL ARRIVING FRIDAY NIGHT/SATURDAY.
SWELL HEIGHTS HAVE INCREASED SINCE NOON UPSTREAM AT BUOY
51101...BUT HAVE YET TO REACH THE HANALEI BUOY SO FAR THIS
EVENING. THE SWELL IS EXPECTED TO ARRIVE AT KAUAI LATE TONIGHT
AND SPREAD SOUTHEAST DOWN THE ISLAND CHAIN ON THURSDAY. A HIGH
SURF ADVISORY GOES INTO EFFECT AT 10 PM HST THIS EVENING FOR
NORTH AND WEST FACING SHORES...SEE CFWHFO PRODUCT ON OUR WEBSITE
FOR INFORMATION OR ADVISORY LIST BELOW FOR AFFECTED AREAS.

THE LATEST WAVEWATCH MODEL III GUIDANCE SHOWS AN EVEN LARGER
NORTHWEST SWELL ARRIVING SUNDAY NIGHT INTO MONDAY...WHICH COULD
PRODUCE WARNING LEVEL SURF EARLY NEXT WEEK. WITH ASTRONOMICAL NEAP
TIDES OCCURRING THIS WEEKEND...THERE MAY BE SOME REDUCTION OF THE
IMPACTS OF THE HIGHEST TIDES ALONG MOST COASTAL AREAS DURING THIS
HIGH SURF EVENT. THE SWELL MAY BE LARGE ENOUGH TO PRODUCE SURF
APPROACHING ADVISORY THRESHOLDS ALONG NORTH AND/OR WEST
FACING SHORES OF THE BIG ISLAND STARTING LATE FRIDAY NIGHT OR
SATURDAY.

A SMALL CRAFT ADVISORY /SCA/ ALSO GOES INTO EFFECT AT 10 PM HST
TONIGHT. THERE MAY BE BRIEF SURGE IN THE TRADE WINDS REACHING 25
KNOTS IN THE IN THE ALENUIHAHA CHANNEL TONIGHT...BUT WILL BE SHORT
LIVED. THE MAIN THREAT FOR SCA CONDITIONS WILL BE INCREASING SEAS
DUE TO THE UPCOMING LARGE NORTHWEST SWELLS BEGINNING TONIGHT AND
CONTINUING INTO EARLY NEXT WEEK. THESE SWELLS WILL LEAD TO COMBINED
SEAS OF 10 FEET OR GREATER FOR AREAS EXPOSED TO THE SWELL.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 AM HST FRIDAY FOR NIIHAU-KAUAI
WINDWARD-KAUAI LEEWARD-WAIANAE COAST-OAHU NORTH SHORE-OAHU
KOOLAU-MOLOKAI-MAUI WINDWARD WEST-WINDWARD HALEAKALA.

SMALL CRAFT ADVISORY UNTIL 8 PM HST FRIDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-
OAHU WINDWARD WATERS-KAIWI CHANNEL-MAUI COUNTY WINDWARD WATERS-
ALENUIHAHA CHANNEL-BIG ISLAND WINDWARD WATERS.

&&

DISCUSSION/MARINE...JELSEMA
AVIATION...KINEL