High Surf in Hawaii, June 1 to 3, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
835 PM HST SUN MAY 31 2015

.SYNOPSIS...
THE LIGHT TO MODERATE TRADE WIND REGIME CONTINUES DURING THE NEXT
SEVERAL DAYS. LEEWARD AREAS WILL EXPERIENCE LOCALIZED SEA BREEZES...
WHICH WILL BRING PERIODS OF SHOWERS DURING THE AFTERNOON AND EVENING
HOURS. MEANWHILE...THE NORTHEAST TRADES WILL KEEP CLOUDS AND RAIN
FOCUSED OVER WINDWARD AND MOUNTAIN AREAS...ESPECIALLY AT NIGHT
AND DURING THE MORNING HOURS. THE TRADES SHOULD BEGIN GRADUALLY
INCREASING DURING THE SECOND HALF OF THE WEEK.

&&

.DISCUSSION...
THROUGH THE EARLY EVENING HOURS...RADAR DATA SHOWED SHOWERS ANCHORED
OVER THE WINDWARD SLOPES OF HALEAKALA IN MAUI...E MOLOKAI AND
PORTIONS OF THE KOOLAU MOUNTAINS IN OAHU. LOCALIZED HEAVY RAIN IS
ALSO POSSIBLE...MAINLY OVER WINDWARD AREAS WHERE TERRAIN ANCHORING
IS LIKELY TO OCCUR.

A BAND OF CLOUDS ASSOCIATED WITH THE REMNANTS OF A FRONTAL BOUNDARY
SLOWLY SLIDING S INTO MAUI COUNTY AND THE N HALF OF THE BIG
ISLAND...KEEPING ENHANCED MOISTURE ACROSS THE AREA TONIGHT AND INTO
MON.

SOUNDING DATA FROM HILO AND LIHUE DEPICT VERY WEAK INVERSIONS AND
PWAT VALUES BETWEEN 1.25 AND 1.45 INCHES. THIS WILL KEEP FAVORABLE
CONDITIONS FOR SHOWER ACTIVITY TO CONTINUE OVERNIGHT...AND WITH SOME
OF THE LARGER SHOWERS MOVING BEYOND THE MOUNTAINS AND INTO LEEWARD
AREAS AT TIMES.

SATELLITE AND MODEL DATA CONTINUE TO SHOW A WEAK SFC HIGH PRESSURE
SYSTEM FAR N OF THE ISLANDS. MEANWHILE...AN UPPER LEVEL TROUGH FAR
W OF THE ISLAND CHAIN GRADUALLY MIGRATES E TOWARDS THE AREA WHILE
DEVELOPING A CLOSED LOW FEATURE. THIS OVERALL SYNOPTIC SCENARIO WILL
KEEP WEAK PRESSURE GRADIENTS ACROSS THE ISLANDS...THUS ALLOWING FOR
THE LIGHT FLOW OVER LEEWARD AREAS TO CONTINUE ON MON AND TUE.
THEREFORE...EXPECT SEA BREEZE CIRCULATIONS TO BRING PERIODS OF
CLOUDS AND SHOWERS OVER LEEWARD AREAS EACH AFTERNOON AND EARLY
EVENING THROUGH MID WEEK. THIS IN ADDITION TO THE CONTINUING WETTER
SCENARIO OVER THE WINDWARD AND MOUNTAIN AREAS.

THE UPPER TROUGH/LOW COMPLEX IS EXPECTED TO MOVE JUST N OF KAUAI ON
THE TUE-WED TIMEFRAME...WHICH COULD RE-ENERGIZE THE LINGERING BAND
OF CLOUDS AND ENHANCED MOISTURE ACROSS THE ISLANDS. THUS...THE
RATHER ACTIVE SHOWERY PATTERN WILL LIKELY CONTINUE THROUGH THE
MIDDLE OF THE WEEK.

THE BAND OF CLOUDS AND MOISTURE FINALLY BEGINS DISSIPATING TOWARDS
THE END OF THE WORK WEEK AS THE UPPER LOW MOVES FURTHER AWAY FROM
THE AREA. THE SFC HIGH REGAINS SOME STRENGTH IN THE WAKE OF THE
TROUGH AND BRINGS INCREASING TRADES ACROSS THE ISLANDS ON THU-FRI.
ANOTHER FRONT MAY APPROACH THE STATE FROM THE NW NEXT WEEKEND...BUT
STALLING OUT WELL SHORT OF THE ISLANDS. SOME AREAS OF THE STATE
COULD BE IMPACTED BY AN ASSOCIATED BAND OF PRE-FRONTAL SHOWERS...BUT
CONFIDENCE IN THIS SCENARIO REMAINS LOW ATTM.

&&

.AVIATION...
A DIFFUSE BAND OF MOISTURE WILL CONTINUE TO AFFECT MOST OF THE
MAIN HAWAIIAN ISLANDS INTO MONDAY. THUS...AIRMET SIERRA FOR MOUNTAIN
OBSCURATION WILL CONT THROUGH AT LEAST 011800Z. THE WATERS JUST OFF
THE KONA CST MAY HAVE AN ISOL SHOWER OR TWO OVERNIGHT. OTHERWISE...
VFR CONDS WILL PREVAIL FOR THE LEEWARD AREAS. NO OTHER AIRMETS
EXPECTED.

&&

.MARINE...
A LONG-PERIOD SSW SWELL CONTINUES TO BUILD AT BUOYS NEAR AND S OF
THE ISLANDS...AND A HIGH SURF ADVISORY REMAINS IN EFFECT FOR S
FACING SHORES OF ALL ISLANDS THROUGH MONDAY. BASED ON CURRENT TRENDS
HOWEVER...THERE IS A STRONG LIKELIHOOD THE ADVISORY WILL NEED AN
EXTENSION IN TIME. OBSERVATIONS OF 6-7 FOOT OPEN OCEAN SWELL HEIGHTS
AT BUOYS 51002 AND 51003 INDICATE THAT THE SWELL IS LARGER THAN WAVE
WATCH GUIDANCE...AND AN EARLIER UPDATE INCREASED FORECAST SURF
HEIGHTS FOR TONIGHT AND MONDAY. CURRENT MARINE FORECAST ANTICIPATES
A 5 FOOT S SWELL...AND THIS MAY NEED TO BE NUDGED UPWARD IF CURRENT
BUOY TRENDS CONTINUE. THE SWELL IS EXPECTED TO PEAK ON MONDAY...
THEN GRADUALLY DIMINISH TUESDAY AND WEDNESDAY. A MARINE WEATHER
STATEMENT HAS ALSO BEEN ISSUED DUE TO POTENTIAL IMPACTS IN S FACING
HARBORS AND HARBOR ENTRANCES...AS THIS IS THE LARGEST S SWELL OF THE
SEASON THE FAR.

A SLIGHTLY SMALLER SSW SWELL IS EXPECTED FROM WEDNESDAY INTO
SATURDAY...WITH PEAK HEIGHTS ON THURSDAY/FRIDAY RESULTING IN SURF
NEAR ADVISORY LEVELS. SMALL AND RELATIVELY SHORT-PERIOD NW SWELLS
WILL CONTINUE THROUGHOUT THE WEEK...WITH A SLIGHTLY LARGER NW SWELL
EXPECTED NEXT WEEKEND. HURRICANE ANDRES IN THE FAR E PACIFIC HAS
GENERATED A LONG PERIOD E SWELL THAT IS FORECAST TO ARRIVE AROUND
TUESDAY...AND THEN PERSIST INTO NEXT WEEKEND. INITIAL SWELLS ARE
EXPECTED TO BE SMALL...BUT THE SWELL IS FORECAST TO GROW TO THE
POINT THAT AN ADVISORY MAY BE NEEDED FOR E FACING SHORES BEFORE
NEXT WEEKEND.

WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW THE SMALL CRAFT ADVISORY
/SCA/ CRITERIA THROUGH MONDAY NIGHT...HOWEVER WINDS MAY BRIEFLY
REACH SCA THRESHOLD IN THE WINDIER AREAS AROUND MAUI AND THE BIG
ISLAND ON TUESDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST MONDAY FOR SOUTH
FACING SHORES OF ALL ISLANDS.

&&

SYNOPSIS/DISCUSSION...REYNES
MARINE...BIRCHARD
AVIATION...LAU