High Surf in Hawaii, May 16 to 18, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST FRI MAY 16 2014

.SYNOPSIS...
WEAK TRADE WINDS WILL VEER OUT OF THE SOUTHEAST THEN SOUTHERLY
DURING THE WEEKEND...LEADING TO AN EXTENDED PERIOD OF DOMINANT LAND
AND SEA BREEZES THROUGH EARLY NEXT WEEK. CLOUDS AND SPOTTY SHOWERS
WILL DEVELOP OVER INTERIOR SECTIONS EACH AFTERNOON FOLLOWED BY
PARTIAL CLEARING AT NIGHT. WEAK TRADE WINDS ARE EXPECTED TO RETURN
WEDNESDAY.

&&

.DISCUSSION...
SHOWER ACTIVITY HAS BEEN FOCUSED NEAR MOLOKAI AND OAHU DURING THE
OVERNIGHT HOURS...THANKS TO A BAND OF MOISTURE MOVING ALONG THE
TRADE WIND FLOW. A WEAK SHORTWAVE ALOFT PASSING OVERHEAD MAY HAVE
PROVIDED SLIGHT ENHANCEMENT OF THE SHOWERS ALONG WITH SOME SCATTERED
HIGH CLOUDS...BUT THIS FEATURE IS FILLING RAPIDLY. A DRIER AIR MASS
IS MOVING OVER THE EASTERN END OF THE STATE IN THE TRADE FLOW...
WHICH IS BEING DRIVEN BY WEAKENING HIGH PRESSURE ABOUT 600 MILES
NORTH OF THE STATE.

ONE LAST DAY OF GENTLE TO MODERATE EAST TO EAST-SOUTHEAST TRADE
WINDS IS DUE TODAY. THE MOISTURE BAND WILL CONTINUE TO FUEL WINDWARD
SHOWERS ON OAHU THIS MORNING...AND SEA BREEZES WILL ONCE AGAIN
OVERPOWER THE BACKGROUND FLOW...LEADING TO AFTERNOON CLOUDS AND
SPOTTY SHOWERS OVER ALL ISLANDS. THE ATMOSPHERE WILL REMAIN CAPPED
BY LOW TO MID LEVEL RIDGING.

BY MAY STANDARDS...AN UNUSUALLY LONG RUN OF DISRUPTED TRADE WINDS IS
STORE. AN UNSEASONABLY LARGE...SLOW-MOVING LONGWAVE TROUGH OCCUPIES
THE CENTRAL NORTH PACIFIC. THIS IS DRIVING A SURFACE LOW CURRENTLY
ABOUT 1300 MILES NORTHWEST OF THE STATE. ITS ASSOCIATED COLD FRONT
WILL ADVANCE TOWARD THE ISLANDS DURING THE WEEKEND...PUSHING THE
SUBTROPICAL RIDGE OVER THE STATE. AS A RESULT...THE LOW LEVEL FLOW
OVER THE ISLANDS TO SHIFT SOUTHEASTERLY THEN SOUTHERLY SUNDAY AND
MONDAY. LIGHT AND VARIABLE WINDS WILL PREVAIL ON LAND...WHERE
DAYTIME SEA BREEZES WILL PRODUCE AFTERNOON CLOUDS AND ISOLATED
SHOWERS FOLLOWED BY CLEARING AT NIGHT. WITH THE LOW LEVEL RIDGE
OVERHEAD...STABLE CONDITIONS WILL PREVAIL WITH LIMITED MOISTURE
OVER MOST ISLANDS. THAT SAID...THE FRONT IS EXPECTED TO STALL JUST
NORTHWEST OF KAUAI...SO RAINFALL CHANCES WILL BE SLIGHTLY HIGHER ON
THE GARDEN ISLE. LIGHT TRADES ARE EXPECTED TO RETURN WEDNESDAY OR
THURSDAY.

&&

.AVIATION...
WEAK SURFACE FLOW ACROSS THE STATE WILL ALLOW FOR THE DEVELOPMENT OF
AFTERNOON AND EARLY EVENING SEA BREEZES ONCE AGAIN TODAY. EXPECT
DAYTIME SHOWER ACTIVITY TO BE CONCENTRATED OVER INLAND AREAS THEN
BECOME LESS FOCUSED AND DIMINISH AFTER SUNSET. MORNING SOUNDINGS
CONFIRM THAT THE AIR MASS REMAINS RELATIVELY DRY. ISOLATED MVFR
CONDS CAN BE ANTICIPATED IN SHOWERS...BUT VFR WILL OTHERWISE PREVAIL
ALL AREAS.

&&

.MARINE...
ADVISORY LEVEL SURF IS EXPECTED ALONG SOUTH FACING SHORES LATER
TODAY. ENERGY FROM THE SSW SWELL HAS BEEN A BIT SLOW TO BUILD
OVERNIGHT...AND WE HAVE PUSHED BACK THE EFFECTIVE TIME FOR THE
ADVISORY UNTIL NOON. THE LONG PERIOD SSW SWELL WILL PEAK AT 3 TO 4
FT LATE TODAY AND SATURDAY THEN SLOWLY SUBSIDE SUNDAY THROUGH
TUESDAY. THE ENDING TIME FOR THE ADVISORY HAS ALSO BEEN TRIMMED BACK
TO EARLY SUNDAY MORNING.

GENTLE TO LOCALLY MODERATE EASTERLY TRADES WILL HANG ON TODAY...
FOLLOWED BY VEERING WINDS DURING THE WEEKEND. A RETURN TO WEAK
TRADES IS FORECAST WEDNESDAY OR THURSDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY FROM NOON TODAY TO 6 AM HST SUNDAY FOR
NIIHAU-KAUAI WINDWARD-KAUAI LEEWARD-OAHU SOUTH SHORE-WAIANAE
COAST-MOLOKAI LEEWARD-LANAI MAKAI-KAHOOLAWE-MAUI LEEWARD WEST-
WINDWARD HALEAKALA-LEEWARD HALEAKALA-KONA-SOUTH BIG ISLAND-BIG
ISLAND NORTH AND EAST.

&&

DISCUSSION/MARINE...WROE
AVIATION...BEDAL