High Surf in Hawaii, April 1 to 2, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
820 PM HST SUN MAR 31 2013

.SYNOPSIS...
A NORTHERLY WIND FLOW WILL MAINTAIN AN UNSEASONABLY COOL AIR MASS
ACROSS THE ALOHA STATE FOR THE NEXT COUPLE OF DAYS...WITH DAY TIME
HIGHS IN THE 70/S AND LOWS IN THE 50/S TO MID 60/S. AN AREA OF LOW
CLOUDS APPROACHING THE ISLANDS FROM THE NORTHWEST WILL BRING SOME
MAINLY LIGHT SHOWERS TO THE SMALLER ISLANDS MONDAY AND MONDAY
NIGHT. THE NORTHERLY WINDS WILL GRADUALLY VEER AND BECOME EAST TO
NORTHEAST TRADES BY THURSDAY...STRENGTHENING FROM LIGHT TO MODERATE
BY THE WEEKEND...AND WITH SLIGHTLY WARMER TEMPERATURES.

&&

.DISCUSSION...
THE COLD FRONT MOVED THROUGH THE BIG ISLAND TODAY. HOWEVER...WITH
THE LOW LEVEL WIND FLOW BEING FROM THE NORTHWEST AND WEST...SOME
MOISTURE IS TRAPPED ON THE SHELTERED EAST SIDE OF MAUNA KEA AND
MAUNA LOA AND MAY TAKE THE OVERNIGHT HOURS TO THIN OUT.

OTHER THAN THAT...THE ISLANDS ENJOYED A RATHER SUNNY BUT COOL EASTER
SUNDAY WITH HIGHS MOSTLY IN THE 70S. WE EXPECT AN AREA OF LOW CLOUDS
WITH A FEW EMBEDDED SHOWERS TO SPREAD ACROSS THE SMALLER ISLANDS
MONDAY AND MONDAY NIGHT. THIS CLOUD COVER IS EXPECTED LINGER AROUND
THE DAY...KEEPING TEMPS IN THE 70S. THE SHOWERS ARE LIKELY TO FAVOR
THE WINDWARD AND MOUNTAIN AREAS ALTHOUGH THE LEEWARD AREAS MAY
EXPERIENCE A DROP OR TWO. WITH A LIGHT NORTHERLY WIND BLOWING...MANY
OF US WILL FEEL COOLER...THANKS TO THE COOLING AFFECT OF THE WIND
AND DRY AIR. WE SHOULD BE WARMING UP THE SECOND HALF OF THE WEEK AS
THE NORTHERLY WINDS GRADUALLY VEER TO THE EAST NORTHEAST TRADES BY
THURSDAY.

THIS UNSEASONABLY COOL WEATHER IS BROUGHT UPON BY A SLOW MOVING AND
DEEP AREA OF LOW ABOUT 900 MILES NORTH NORTHEAST OF OAHU. THE LOW
HAS GALE FORCE WINDS AT THE SURFACE OF 40 TO 50 MPH ACROSS PORTIONS
OF OUR HIGH SEAS AREA OF RESPONSIBILITY. THE STRONG WINDS AROUND THE
LOW HAVE GENERATED A SWELL WHICH IS PRODUCING ADVISORY LEVEL SURF
ACROSS EXPOSED LOCAL SHORES. WINDS ARE STRONGER AT THE HIGHER LEVELS
OF THE ATMOSPHERE...AND ARE AFFECTING ALL THREE SUMMITS. WESTERLY
WINDS HAVE STRENGTHENED OVER THE HALEAKALA SUMMIT THIS EVENING...
WARRANTING A WIND ADVISORY GOOD THROUGH 6 PM HST MONDAY. WE HAVE
ALSO EXTENDED THE HIGH WIND WARNING FOR THE BIG ISLAND SUMMITS TO 6
PM HST MONDAY. THE GFS SOLUTION SHOWS CONTINUING DANGEROUS...WINDY
CONDITIONS FOR THE SUMMITS THROUGH MONDAY NIGHT. THEREAFTER...THE
WINDS SHOULD START CALMING DOWN AS THE THE LOW BEGINS TO MOVE
NORTHEAST...AWAY FROM THE ISLANDS.

AS NOTED ABOVE...THE TRADE WINDS ARE SLATED TO RULE THE AREA THE
SECOND HALF OF THE WEEK...AND INTO THE WEEKEND. SHOWER-WISE...THE
FREQUENCY OF THE TRADE SHOWERS WILL GRADUALLY INCREASE AS THE TRADE
WINDS STRENGTHEN. THESE SHOWERS WILL FAVOR THE WINDWARD AND MOUNTAIN
AREAS.

&&

.AVIATION...
SUFFICIENT VERTICAL SPEED SHEAR WILL WARRANT THE CONTINUATION OF
AIRMET TANGO FOR TURB ABV FL300 THROUGH AT LEAST 1600Z.

AIRMET TANGO IS ALSO IN EFFECT FOR MOD MECHANICAL TURB BLW 070 S
THROUGH W OF MTNS OF KAUAI AND OAHU. VFR COND SHOULD PREVAIL FOR
MOST AREAS AROUND THE STATE...WITH ISOL MVFR CIGS AND MTN OBSC NEAR
SHRA ACROSS THE HAMAKUA AND SOUTHEAST LOWER SLOPES OF  WINDWARD
BIG ISLAND.

&&

.MARINE...
A SMALL CRAFT ADVISORY /SCA/ REMAINS IN EFFECT FOR MOST OF THE
HAWAIIAN COASTAL WATERS AND CHANNELS EXPOSED TO LARGE NORTH AND
NORTHWEST SWELLS AND LOCALLY GENERATED WIND WAVES...WHICH ARE
COMBINING TO PRODUCE ELEVATED AND ROUGH SEAS. THIS SCA IS IN EFFECT
THROUGH MONDAY NIGHT...AND INCLUDES ALL HAWAIIAN WATERS...EXCEPT FOR
MAALAEA BAY...AND THE SOUTHEAST AND LEEWARD BIG ISLAND COASTAL
WATERS.

THE LARGE NORTHWEST AND NORTH SWELLS COMBINED WITH LOCALLY GENERATED
WIND WAVES WILL CONTINUE TO PRODUCE ELEVATED AND ROUGH SURF ALONG
NORTH AND WEST FACING SHORES OF KAUAI AND NIIHAU...AND ALONG NORTH
FACING SHORES OF OAHU MOLOKAI AND MAUI THROUGH MONDAY NIGHT.
THEREFORE...A HIGH SURF ADVISORY REMAINS IN EFFECT FOR THOSE AREAS.
THE SIGNIFICANT WAVE HEIGHTS AT THE BUOY NORTHEAST OF THE BIG ISLAND
HAVE INCREASED TO ABOUT 13 FEET WITH A PERIOD OF 11 SECONDS. THIS
BUILDING NORTH SWELL WILL CONTINUE TO INCREASE WAVE HEIGHTS ALONG
NORTH FACING SHORES OF THE BIG ISLAND OVERNIGHT. AS A RESULT...A
HIGH SURF ADVISORY HAS BEEN ISSUED FOR THE NORTH FACING SHORES OF
THE BIG ISLAND STARTING EARLY MONDAY MORNING...AND CONTINUING
THROUGH MONDAY NIGHT.

FINALLY...THE BUILDING NORTH SWELL HAS A POTENTIAL OF IMPACTING
NORTH FACING HARBORS...SUCH AS AT KAHULUI ON MAUI AND HILO ON THE
BIG ISLAND. AS A RESULT...A MARINE WEATHER STATEMENT HAS JUST BEEN
ISSUED TO ALERT MARINERS OF THE POTENTIAL THREATS DUE TO THIS
BUILDING SWELL.

&&

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

HIGH SURF ADVISORY FOR THE NORTH FACING SHORES OF THE BIG ISLAND IS
EFFECTIVE AT 4 AM HST MONDAY...THROUGH 6 AM HST TUESDAY.

SMALL CRAFT ADVISORY UNTIL 6 AM HST TUESDAY FOR MOST HAWAIIAN WATERS.

HIGH WIND WARNING FOR BIG ISLAND SUMMITS UNTIL 6 PM HST MONDAY.

WIND ADVISORY FOR HALEAKALA SUMMIT OF MAUI UNTIL 6 PM HST MONDAY.

&&

PUBLIC/AVIATION...LAU
MARINE...HOUSTON