High Surf in Hawaii, January 9 to 12, 2016

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1003 AM HST SAT JAN 9 2016

.SYNOPSIS...
A WEAK FRONT WILL MOVE ACROSS KAUAI AND OAHU TODAY...MOVE SOUTHWARD
INTO THE CENTRAL ISLANDS TONIGHT...THEN DISSIPATE NEAR THE BIG
ISLAND SUNDAY. WEAK HIGH PRESSURE ESTABLISHED OVER THE ISLANDS
FROM SUNDAY THROUGH THE MIDDLE OF NEXT WEEK. SEVERAL FRONTS WILL
PASS JUST NORTH OF THE ISLANDS NEXT WEEK...BUT HAWAII WILL REMAIN
MOSTLY DRY AND UNDER A LIGHT WIND FLOW PATTERN.

&&

.DISCUSSION...
RADAR AND VISIBLE SATELLITE SHOW LOW CLOUDS AND SCATTERED SHOWERS
ASSOCIATED WITH A PRE-FRONTAL BAND ARE CONCENTRATED ACROSS THE
WESTERN HALF OF THE ISLAND CHAIN THIS MORNING. RAIN AMOUNTS HAVE
BEEN LIGHT WITH MOST OF THE ACCUMULATIONS OCCURRING ON KAUAI
EARLIER. THESE SHOWERS ARE SPREADING WEST TO EAST AT AROUND 20
MPH. THE RATHER DIFFUSE COLD FRONT IS LOCATED JUST NORTHWEST OF
KAUAI AND RESULTING LIGHT TO MODERATE WEST TO SOUTHWEST WINDS
PREVAIL OVER THE STATE. THE WESTERLY FLOW IS ALLOWING MOST OF THE
CLOUDS AND SHOWERS TO FOCUS OVER THE TYPICAL LEEWARD AREAS AND
WESTERN FACING SLOPES FROM MAUI TO KAUAI. MEANWHILE...THE BIG
ISLAND IS SUNNY THIS MORNING.

THE 12Z LIHUE SOUNDING SHOWS THAT THE MOIST LAYER HAS DEEPENED TO
NEAR 10 KFT WITH PRECIPITABLE WATER /PW/ VALUES UP TO 1.48
INCHES...WHILE THE 12Z HILO SOUNDING STILL SHOWS RATHER DRY AND
STABLE CONDITIONS WITH PW JUST OVER ONE INCH AND THE INVERSION
BASED NEAR 7 KFT. ALOFT...A VERY STRONG JET STREAM PERSISTS OVER
THE NORTH PACIFIC OCEAN...WITH THE SUBTROPICAL RIDGE CENTERED WEST
OF THE INTERNATIONAL DATELINE. HAWAII REMAINS ON THE SOUTHERN EDGE
OF THE STRONG WESTERLIES.

WESTERLY WINDS HAVE RECENTLY INCREASED TO WARNING LEVELS ON THE
BIG ISLAND SUMMITS. THESE STRONG WINDS ARE EXPECTED TO CONTINUE
INTO THIS EVENING DUE TO A PASSING UPPER LEVEL TROUGH. A HIGH WIND
WARNING IS POSTED FOR THE BIG ISLAND SUMMITS UNTIL 10 PM HST
TONIGHT.

THE FRONT IS FORECAST TO MOVE ACROSS KAUAI AND OAHU LATER TODAY...WEAKEN
OVER MAUI COUNTY TONIGHT...AND DISSIPATE NEAR THE NORTHERN END OF
THE BIG ISLAND ON SUNDAY. A FEW ROUNDS OF SCATTERED SHOWERS WILL
BE POSSIBLE FOR THE REST OF TODAY INTO TONIGHT AHEAD OF AND ALONG
THE FRONT FROM KAUAI THROUGH MAUI COUNTY...BUT WITH LIMITED
MOISTURE AVAILABLE MOST OF THESE SHOWERS WILL REMAIN LIGHT TO
MODERATE. NO WIDESPREAD HEAVY RAINS OR THUNDERSTORMS ARE EXPECTED.
ONLY ISOLATED SHOWERS ARE EXPECTED THIS AFTERNOON ACROSS THE BIG
ISLAND DUE TO DAYTIME HEATING.

A MORE DIURNAL SHOWER PATTERN WILL RETURN BY SUNDAY AFTERNOON AS
THE FRONT DISSIPATES AND A WEAK HIGH PRESSURE RIDGE BECOMES RE-
ESTABLISHED OVER THE STATE. SEABREEZES WILL BE DOMINANT ONCE
AGAIN...WITH CLOUDS AND ISOLATED SHOWERS FOCUSED ACROSS THE
INTERIORS OF THE ISLANDS DURING THE AFTERNOON AND EARLY EVENING
HOURS.

THE HIGH PRESSURE RIDGE AXIS WILL REMAIN CENTERED NEAR OR OVER
THE ISLAND CHAIN THROUGH MUCH OF NEXT WEEK...WITH SEVERAL FAST
MOVING COLD FRONTS BRUSHING PAST JUST TO THE NORTH OF THE STATE.
THIS IS A TYPICAL PATTERN FOR HAWAII DURING EL NINO WINTERS...
WITH DRY AND STABLE CONDITIONS ALONG THE RIDGE AXIS AND AN ABSENCE
OF TRADE WINDS PROVIDING LITTLE RAINFALL FOR MOST AREAS. A
CONTINUED LIGHT WIND FLOW REGIME WILL ALLOW FOR DAYTIME SEABREEZES
AND NIGHTTIME LAND BREEZES TO PREVAIL. ISOLATED SHOWERS WILL
REMAIN POSSIBLE EACH DAY...MAINLY DURING THE AFTERNOON AND EARLY
EVENING HOURS ACROSS THE INTERIOR OF THE ISLANDS...WHILE NIGHTS
WILL BE MOSTLY CLEAR AND RELATIVELY COOL.

&&

.AVIATION...
A PRE-FRONTAL CLOUD BAND PASSING ACROSS THE CENTRAL ISLANDS MAY
BRING TEMPORARY MVFR CEILINGS TO OAHU AND THE ISLANDS OF MAUI COUNTY
TODAY. AIRMET SIERRA IS IN EFFECT FOR MOUNTAIN OBSCURATION ABOVE
2500 FEET ON OAHU...BUT THIS MAY BE DROPPED LATER TODAY IF
CONDITIONS IMPROVE. SOUTHWEST FLOW MAY BRING IFR CEILINGS TO LANAI
FROM TIME TO TIME...BUT VFR IS EXPECTED AT MOST TERMINAL SITES TODAY.

&&

.MARINE...
A LARGE NORTHWEST SWELL IS EXPECTED TO ARRIVE LATE IN THE TODAY...THEN
PEAK TONIGHT AND SUNDAY. A HIGH SURF WARNING IS IN EFFECT WITH THE
ANTICIPATED UPTICK IN WAVE HEIGHTS FOR NORTH AND WEST FACING
SHORES OF NIIHAU KAUAI OAHU MOLOKAI...AND NORTH FACING SHORES OF
MAUI. SWELL HEIGHTS UPSTREAM AT BUOY 51101 HAVE BOOSTED UP THIS
MORNING BUT HAVE NOT PEAKED YET ACCORDING TO WAVEWATCH III GUIDANCE.
THE HANALEI BUOY IS SHOWING SOME FORERUNNER ENERGY IN THE HIGHER
PERIODS...BUT SEAS REMAIN LOW ACROSS ALL EXPOSED BUOYS THIS MORNING.
THE ARRIVAL TIME OF THE SWELL TO THE ISLANDS COULD VARY FROM LATE
THIS AFTERNOON INTO TONIGHT OVER THE NORTHWEST WATERS...THEN
SPREAD EASTWARD THROUGH THE ISLAND CHAIN.

A SMALL CRAFT ADVISORY /SCA/ HAS BEEN EXPANDED ACROSS MOST OF THE
MARINE ZONES THROUGH THE REMAINDER OF THE WEEKEND. A COMBINATION
OF THE LARGE NORTHWEST SWELL AND HIGHER THAN NORMAL HIGH TIDES
THAT ARE EXPECTED TO SLIGHTLY EXCEED THE MHHW DATUM THROUGH THE
WEEKEND COULD TRANSLATE TO MINOR COASTAL IMPACTS FROM OVERWASH IN
THE TYPICALLY VULNERABLE LOCATIONS AROUND THE HIGH TIDE CYCLE
AFTER MIDNIGHT TONIGHT THROUGH EARLY SUNDAY MORNING. OTHER
IMPACTS COULD INCLUDE LARGE BREAKING WAVES NEAR EXPOSED HARBOR
ENTRANCES. THIS SWELL WILL GRADUALLY BEGIN TO EASE SUNDAY...THROUGH
SCA AND HIGH SURF ADVISORY CONDITIONS WILL PERSIST MONDAY AND TUESDAY
AS THIS SWELL MAINTAINS HEIGHT DUE TO REINFORCEMENT ENERGY BEHIND
THIS SWELL/S INITIAL PEAK.

A SMALL SOUTHWEST SWELL WILL REMAIN POSSIBLE FROM DISTANT TROPICAL
STORM PALI FROM TONIGHT THROUGH MONDAY. SCATTEROMETER PASSES
REFLECTED A DECENT BATCH OF SOUTHWEST WINDS SOUTHEAST OF PALI OVER
THE PAST 24 HRS...WHICH RESULTED IN SEAS REACHING 18 TO 24 FT FROM
AN ALTIMETER PASS YESTERDAY. THE LATEST HIRES NEARSHORE WAVE
GUIDANCE THAT IS INITIALIZED WITH THE WAVEWATCH III REFLECTS THIS
POTENTIAL AND INDICATES A 2 TO 3 FT SWELL AT 13 SECONDS IMPACTING
THE SOUTH FACING SHORES THROUGH THIS TIME...WHICH SHOULD REMAIN
BELOW ADVISORY LEVEL.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF WARNING UNTIL 6 PM HST SUNDAY FOR NORTH AND WEST FACING
SHORES OF NIIHAU KAUAI OAHU MOLOKAI AND NORTH FACING SHORES OF MAUI.

HIGH WIND WARNING UNTIL 10 PM HST THIS EVENING FOR BIG ISLAND
SUMMITS.

SMALL CRAFT ADVISORY UNTIL 6 PM HST SUNDAY 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-BIG ISLAND WINDWARD
WATERS.

&&

DISCUSSION/MARINE...FOSTER
AVIATION...POWELL