High Surf in Hawaii, April 13 to 14, 2010

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE HONOLULU HI
429 AM HST TUE APR 13 2010

.SYNOPSIS...
A STRONG HIGH FAR TO THE NORTHWEST WILL MAINTAIN FRESH NORTHEAST
WINDS ACROSS THE STATE TODAY. A WEAK TROUGH PASSING OVER THE AREA
WILL ENHANCE CLOUDS AND SHOWERS THROUGH WEDNESDAY. LOW PRESSURE
DEVELOPING NORTHEAST OF THE ISLANDS LATER THIS WEEK WILL CAUSE THE
WINDS TO SWING TO A MORE NORTHERLY DIRECTION AND PRODUCE COOLER
TEMPERATURES THROUGH SATURDAY. A WEAK COLD FRONT COMING FROM THE
NORTH WILL REACH THE STATE ON FRIDAY. TRADE WINDS ARE EXPECTED TO
BUILD BACK OVER THE AREA THIS WEEKEND.

&&

.DISCUSSION...
SURFACE ANALYSES SHOW A RATHER STRONG HIGH WITH A CENTRAL PRESSURE
AROUND 1035 MB ABOUT 1500 MILES NORTH-NORTHWEST OF OAHU. THIS HIGH
MIGHT NORMALLY BE EXPECTED TO PRODUCE LOCALLY STRONG TRADE WINDS
OVER THE ISLANDS...BUT A SURFACE LOW ABOUT 700 MILES NORTH OF OAHU
AND A WEAK TROUGH OVER THE EASTERN PORTION OF THE STATE ARE
WEAKENING THE PRESSURE GRADIENT AND WILL PREVENT THE WINDS FROM
GETTING THAT STRONG OVER THE NEXT COUPLE OF DAYS.

SATELLITE AND RADAR IMAGERY SHOW A PERSISTENT BAND OF CLOUDS AND
SHOWERS EXTENDING ABOUT 250 MILES EAST FROM OVER MAUI COUNTY AND
OAHU. THIS CLOUD BAND WILL SHIFT SLOWLY SOUTHWEST THROUGH WEDNESDAY
NIGHT. THE BAND WILL MISS KAUAI BUT IT WILL PRODUCE LOTS OF CLOUD
COVER AND SHOWERS OVER OAHU AND MAUI COUNTY TODAY...MOSTLY OVER
WINDWARD AREAS. THE ATMOSPHERE WILL REMAIN STABLE ENOUGH TO PREVENT
HEAVY RAIN. THE BAND WILL GRADUALLY CLEAR OAHU TONIGHT AND SPREAD
DOWN OVER THE BIG ISLAND. THE BAND WILL GRADUALLY WEAKEN...BUT SOME
CLOUDS AND SHOWERS FROM THE BAND MAY LINGER OVER THE BIG ISLAND
THROUGH WEDNESDAY EVENING.

THE GLOBAL MODELS REMAIN IN REASONABLE AGREEMENT SHOWING THE LOW
NORTH OF THE ISLANDS MOVING SOUTHEAST THROUGH TONIGHT BEFORE
CHANGING DIRECTIONS TO THE NORTHEAST. AS THIS HAPPENS...THE
ATMOSPHERE WILL BEGIN TO TEMPORARILY DRY OUT UPWIND OF THE STATE.
PRECIPITABLE WATER VALUES WILL DROP TO AROUND 0.70 INCHES OVER THE
AREA ON THURSDAY. THE LOW HUMIDITY LEVELS COUPLED WITH THE
PERSISTENT FRESH NORTHEAST WINDS COULD MAKE FOR A POSSIBLE FIRE
WEATHER CONCERN FOR LATER THIS WEEK.

MEANWHILE...A NEW LOW IS FORECAST TO DEVELOP IN THE GULF OF ALASKA
WEDNESDAY AND DROP SOUTH ALONG THE WEST SIDE OF THE TROUGH
ASSOCIATED WITH THE OLDER LOW ON THURSDAY EVENTUALLY INGESTING IT
AND FORMING A LARGE LOW COMPLEX NORTHEAST OF THE STATE ON FRIDAY.
THIS WILL CAUSE THE SURFACE WINDS OVER THE ISLANDS TO SHIFT TO A
MORE NORTHERLY DIRECTION AND STRENGTHEN. THIS PATTERN WILL BRING
COOLER TEMPERATURES TO THE ISLANDS THROUGH SATURDAY. MODELS ARE ALSO
HINTING AT A WEAK COLD FRONT COMING OVER THE STATE FROM THE NORTH ON
FRIDAY.

THE LOW COMPLEX MOVES EAST ON SATURDAY AND A SUBTROPICAL HIGH BUILDS
IN FAR NORTHWEST OF THE STATE...BRINGING MODERATE TO FRESH TRADE
WINDS BACK THROUGH THE WEEKEND.

&&

.MARINE...
A NORTHWEST SWELL WILL PRODUCE SURF ABOVE THE ADVISORY THRESHOLD FOR
NORTH AND WEST SHORES OF NIIHAU AND KAUAI AND NORTH FACING SHORES OF
OAHU AND MAUI COUNTY TODAY. EXPANDED THE COVERAGE AREA OF THE SURF
ADVISORY DUE TO HIGHER THAN EXPECTED BUOY READINGS UPSTREAM. BUOY
51100 WAS REPORTING 11 FT SWELL EARLY THIS MORNING.

A NORTH-NORTHEAST SWELL FROM A NEARBY LOW NORTH OF THE STATE WILL
ALSO ARRIVE TODAY AND CONTINUE THROUGH THE REST OF THE
WEEK...PEAKING ON WEDNESDAY. THE SURF COULD REACH ADVISORY LEVELS
FOR EAST FACING SHORES AND THE SIZE AND SIGNIFICANT NORTH COMPONENT
TO THIS SWELL COULD ALSO PRODUCE SURGES IN HILO AND KAHULUI HARBORS
ON WEDNESDAY. NORTHEAST WINDS WILL ALSO STRENGTHEN TO AROUND 25
KNOTS FOR THE TYPICAL WINDIER AREAS BY MID WEEK. SMALL SOUTH SWELLS
WILL CONTINUE ALL WEEK.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY FROM 6 AM THIS MORNING TO 6 PM HST THIS
EVENING FOR OAHU NORTH SHORE-OAHU KOOLAU-MOLOKAI-MAUI WINDWARD
WEST-MAUI CENTRAL VALLEY-WINDWARD HALEAKALA.

HIGH SURF ADVISORY UNTIL 6 PM HST THIS EVENING FOR NIIHAU-KAUAI
WINDWARD-KAUAI LEEWARD.

SMALL CRAFT ADVISORY UNTIL 6 AM HST WEDNESDAY FOR KAUAI
NORTHWEST WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-
KAUAI CHANNEL-OAHU WINDWARD WATERS-OAHU LEEWARD WATERS-KAIWI
CHANNEL-MAUI COUNTY WINDWARD WATERS-PAILOLO CHANNEL-ALENUIHAHA
CHANNEL.

&&

FOSTER