High Surf in Hawaii, April 12 to 14, 2016

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE HONOLULU HI
657 AM HST TUE APR 12 2016

.SYNOPSIS...
TRADE WINDS WILL CONTINUE THROUGH THE REST OF THE WORK WEEK AND
INTO THE UPCOMING WEEKEND. THE MODERATE TO STRONG TRADES WILL EASE
OFF TO MODERATE SPEEDS BY FRIDAY. CLOUDS AND SHOWERS WILL FAVOR
THE WINDWARD AND MOUNTAINS ESPECIALLY NIGHTS AND MORNINGS...
ALTHOUGH THE TRADES WILL BE CARRYING SOME OF THESE SHOWERS WELL
INTO THE LEEWARD AREAS OF THE SMALLER ISLANDS FROM TIME TO TIME.
THE REMNANTS OF A FRONT IS FORECAST TO BRING SOME WET TRADEWIND
WEATHER TO THE ISLANDS OVER THE WEEKEND. MODERATE TO STRONG TRADES
MAY RETURN ON SUNDAY.

&&

.DISCUSSION...
A 1030 MILLIBAR SURFACE HIGH CONTINUES TO PULL AWAY FROM THE
ISLANDS. THE CENTER IS NOW 1100 MILES 1200 MILES NORTHEAST OF
OAHU. ANOTHER HIGH OF EQUAL STRENGTH IS FORECAST TO FORM 730 MILES
NORTH OF OAHU THIS AFTERNOON AND DRIFT TOWARD THE NORTHEAST
THROUGH THURSDAY. THIS NEW HIGH WILL MAINTAIN FRESH TO STRONG
TRADE WINDS OVER THE ISLANDS TO THURSDAY NIGHT. THE AIR MASS OVER
THE ISLANDS IS SUPPORTIVE OF A SEMI-WET TRADE PATTERN WITH HIGH
POPS FOR THE WINDWARD AND MOUNTAIN AREAS. ALSO...THE SHOWERS THAT
DO CROSS OVER THE MOUNTAINS...WILL GO DEEP INTO LEEWARD TERRITORY
OF THE SMALLER ISLANDS...ESPECIALLY DURING THE NIGHTS AND
MORNINGS. THE SHOWERS WILL TAPER OFF TEMPORARILY BY THE AFTERNOON
BUT START INCREASING AGAIN AROUND NIGHTFALL. IN ESSENCE WE ARE
LOOKING AT A PASSING SHOWER TYPE PATTERN. THE KONA SIDE OF THE BIG
ISLAND MAY HAVE AN ISOLATED SHOWER OR TWO IN THE
AFTERNOON...LASTING WELL INTO THE EVENING HOURS.

THE TRADE WIND EASES OFF TO MODERATE SPEEDS ON FRIDAY DUE TO THE
PRESENCE OF AN APPROACHING DISSIPATING FRONT NORTH OF THE ISLANDS.
THE REMNANTS OF THIS FRONT IS FORECAST TO BRING SOME WET TRADE
WIND WEATHER TO THE ISLANDS OVER THE WEEKEND. IT WILL HAVE SOME
UPPER LEVEL SUPPORT AS WELL EARLY ON...A SHORT WAVE TROUGH WITH A
POOL OF COLD AIR OF MINUS 11 TO MINUS 12 C AT 500 MB. THE COLD
TEMPS ALOFT WILL BE COLD ENOUGH TO SUPPORT AN ISOLATED THUNDERSTORM
ESPECIALLY OVER HIGHER TERRAIN SUCH AS INTERIOR BIG ISLAND AND
SUMMITS...BUT WILL NOT RULE OUT OTHER PARTS OF THE ISLAND CHAIN.
THIS IS A BIT DOWN THE ROAD SO THE THUNDERSTORMS WON/T BE PART OF
THE OFFICIAL FORECAST JUST YET.

THE SHOWERY WEATHER IS SLATED TO CONTINUE INTO SUNDAY WITH THE
REMNANTS REMAINING STALLED EAST TO WEST ACROSS THE ISLAND CHAIN
ALTHOUGH THE UPPER TROUGH WILL BE SOUTH AND EAST OF THE BIG ISLAND.
THE TRADES WILL ALSO BE STRENGTHENING SATURDAY NIGHT AS WELL
REACHING MODERATE TO STRONG SPEEDS.

&&

.AVIATION...
HIGH PRESSURE NORTH OF THE ISLANDS WILL KEEP BREEZY EAST-NORTHEAST
TRADE WINDS IN PLACE THROUGH TONIGHT...WITH CLOUDS AND SHOWERS
FOCUSED PRIMARILY ACROSS WINDWARD AND MAUKA AREAS. COULD SEE TEMPO
MVFR CIGS AND VSBYS IMPACT THE PHTO AND PHLI TERMINALS...MAINLY
THROUGH MID MORNING AND AGAIN LATER ON TONIGHT.
ELSEWHERE...PREDOMINANTLY VFR CONDITIONS ARE EXPECTED.

AIRMET SIERRA IS IN EFFECT FOR MOUNTAIN OBSCURATION ACROSS MOLOKAI
MAUI AND THE BIG ISLAND. CONDITIONS SHOULD IMPROVE HERE BY MID TO
LATE MORNING.

AIRMET TANGO REMAINS IN EFFECT FOR LOW LEVEL TURBULENCE IN AREAS
SOUTH THRU WEST OF THE MOUNTAINS ON ALL ISLANDS. AIRMET TANGO MAY BE
NEEDED FOR UPPER LEVEL TURBULENCE LATER TODAY AND TONIGHT DUE TO A
STRENGTHENING UPPER LEVEL JET.

&&

.MARINE...
HAZARDOUS BOATING CONDITIONS WILL CONTINUE THROUGH THE WEEK DUE TO A
COMBINATION OF FRESH TO STRONG TRADE WINDS AND SMALL CRAFT ADVISORY-
LEVEL SEAS. IN ADDITION TO THE WINDS AND SEAS...TWO MODERATE SIZED
NORTHWEST SWELLS WILL GENERATE ADVISORY-LEVEL SURF ALONG NORTH AND
WEST FACING SHORES OF THE SMALLER ISLANDS THIS WEEK. LATER IN THE
WEEK AND INTO THE UPCOMING WEEKEND...AN UPPER TROUGH WILL APPROACH
AND MOVE OVER THE ISLANDS...WHICH COULD TRANSLATE TO INCREASING
RAIN CHANCES.

DESPITE THE RECENT TIMING AND SWELL MAGNITUDE DIFFERENCES WITH PAST
SWELLS...THE EARLY MORNING BUOY OBSERVATIONS NORTHWEST OF KAUAI ARE
LINING UP WELL WITH THE ENSEMBLE AND DETERMINISTIC WAVE GUIDANCE AND
APPEAR TO HAVE PEAKED SLIGHTLY OVER 10 FT BY OR AROUND MIDNIGHT.
THIS WILL TRANSLATE TO A BUILDING SWELL/SURF THROUGH THE MORNING
HOURS TODAY AND A PEAK AROUND NOON FOR KAUAI AND OAHU...THEN LATER
THIS AFTERNOON FOR THE EXPOSED SHORES OF MAUI. THE SURF SHOULD DIP
BELOW ADVISORY LEVELS BY WEDNESDAY MORNING ALONG NORTH AND WEST
FACING SHORES OF THE SMALLER ISLANDS AND CONTINUE TO EASE THROUGH
THURSDAY. THE SECOND NORTHWEST SWELL IS FORECAST TO ARRIVE LATE
THURSDAY NIGHT...PEAK LATE FRIDAY AND THROUGH THE OVERNIGHT HOURS
FRIDAY NIGHT...THEN GRADUALLY EASE THROUGH THE WEEKEND. ADVISORY-
LEVEL SURF WILL BE LIKELY BY FRIDAY ALONG THE EXPOSED NORTH AND WEST
FACING SHORES.

WE MAY START SCALING DOWN THE AREAS UNDER THE SMALL CRAFT ADVISORY
/SCA/ AS EARLY AS WEDNESDAY. BUT THE NEXT NW SWELL ON FRIDAY MAY
COMPLICATE THINGS. CERTAINLY...THE SCA WILL LIKELY BE NEEDED FOR
MOST MARINE ZONES OVER THE WEEKEND DUE TO THE STRENGTHENING NE TRADES.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 AM HST WEDNESDAY FOR NORTH AND WEST
SHORES OF NIIHAU KAUAI OAHU MOLOKAI...AND NORTH FACING SHORES OF
MAUI.

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

&&

SYNOPSIS/DISCUSSION...LAU
AVIATION...JELSEMA
MARINE...A GIBBS