High Surf in Hawaii, September 4 to 9, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
345 AM HST THU SEP 4 2008

.SYNOPSIS...
THE TRADE WINDS PREVAIL BUT WILL REMAIN WEAK THROUGH EARLY
SATURDAY. A DRY AND STABLE AIR MASS WILL REMAIN IN PLACE OVER THE
ISLANDS. THE LIGHTER TRADE WINDS WILL ALLOW AFTERNOON CLOUDS AND
POSSIBLY AN ISOLATED SHOWER TO DEVELOP OVER LEEWARD AREAS THE NEXT
COUPLE OF DAYS. THE TRADE WINDS WILL REBUILD OVER THE WEEKEND AND
INTO THE EARLY PART OF NEXT WEEK.

&&

.DISCUSSION...
BENIGN CONDITIONS REIGNED ACROSS THE HAWAIIAN ISLANDS OVERNIGHT.
WINDS WERE LIGHT AND SKIES WERE MOSTLY CLEAR. SHOWER ACTIVITY WAS
LIGHT STATEWIDE AS RADAR IMAGERY WAS PEPPERED WITH WEAK RETURNS
MAINLY OVER THE WINDWARD COASTAL WATERS. A FEW LIGHT SHOWERS OVER
THE WINDWARD MOUNTAINS WERE SEEN...BUT THAT/S ABOUT IT. STABLE
CONDITIONS ARE CREATED BY RIDGING IN THE MID LEVELS. IT IS ALSO
INDICATED BY THE SIGNIFICANT WARMING TAKING PLACE IN THE MIDDLE
ATMOSPHERE...AS OBSERVED ON THE MORNING SOUNDINGS. THE QUIET
WEATHER CAN BE ATTRIBUTED TO THESE DRY AND STABLE CONDITIONS...AND
LIGHT TRADE WINDS WHICH MINIMIZES OROGRAPHIC INDUCED RAINFALL.

THE TRADE WINDS...HAVE BEEN ON A DOWNWARD TREND AND WILL CONTINUE TO
BE GENTLE THROUGH SATURDAY. HIGH PRESSURE FAR TO THE NORTHEAST OF
THE STATE IS BEING PUSHED FURTHER AWAY BY A LOW DEEPENING IN THE
CENTRAL NORTH PACIFIC. THE ASSOCIATED FRONT IS NOT EXPECTED TO
AFFECT THE ISLANDS...BUT IT WILL PUSH THE SURFACE RIDGE CLOSER TO
THE ISLANDS...RESULTING IN THE WEAKER TRADE WINDS. THE WEAK TRADE
FLOW WILL ALLOW LOCAL LAND AND SEA BREEZE CIRCULATIONS TO DEVELOP
THE NEXT COUPLE OF DAYS AND NIGHTS. AFTERNOON CLOUDS WILL DEVELOP
OVER LEEWARD AREAS WHILE MOSTLY CLEAR SKIES PREVAIL OVERNIGHT.
MOISTURE IS A LIMITING FACTOR FOR ANY SIGNIFICANT RAINFALL TO OCCUR.
THE DRY AND STABLE AIRMASS OVER THE ISLANDS WILL INHIBIT ANY DEEP
CONVECTION. HIGH PRESSURE WILL REBUILD NORTH OF THE STATE SATURDAY
NIGHT THROUGH THE EARLY PART OF NEXT WEEK...WITH TRADES REBOUNDING
BACK TO MODERATE LEVELS.

LIGHT WINDS MAKE THE DISPERSION OF VOLCANIC EMISSIONS LESS
PREDICTABLE. EMISSIONS FROM PUU OO AND THE HALEMAUMAU CRATER WILL
SUCCUMB TO THE ISLAND SCALE CIRCULATIONS THAT DEVELOP ON THE BIG
ISLAND. ACCUMULATION OF EMISSIONS NEAR THE SOURCES IS POSSIBLE IN
THE LATE NIGHT AND EARLY MORNINGS. AFTERNOON SEA BREEZES COULD
TRANSPORT THE GASES TO MORE POPULATED AREAS. AS THE TRADE WINDS
REBOUND TO MODERATE LEVELS BY SATURDAY EVENING...THE GASES WILL BE
TRANSPORTED OUT TO SEA MORE EFFECTIVELY.

&&

.MARINE...
A LARGE SOUTH SWELL IS EXPECTED TO BUILD THROUGH FRIDAY. A HIGH
SURF ADVISORY REMAINS IN EFFECT FOR SOUTH FACING SHORES. THE LARGER
THAN NORMAL SURF IS EXPECTED TO CONTINUE THROUGH THE WEEKEND.

THIS SWELL IS EXPECTED TO CAUSE SURGES IN HARBORS THAT FACE SOUTH...
AND BOATERS AND BEACHGOERS SHOULD BE ALERT FOR INCREASED WAVE ACTION
IN CHANNEL ENTRANCES AND ANCHORAGES WITH SOUTHERN EXPOSURES FOR THE
NEXT COUPLE OF DAYS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY FROM 12 PM THURSDAY TO 6 PM HST SUNDAY FOR
NIIHAU-KAUAI WINDWARD-KAUAI LEEWARD-OAHU SOUTH SHORE-WAIANAE
COAST-MOLOKAI LEEWARD-LANAI MAKAI-KAHOOLAWE-MAUI LEEWARD WEST-
MAUI CENTRAL VALLEY-WINDWARD HALEAKALA-LEEWARD HALEAKALA-KONA-
SOUTH BIG ISLAND-BIG ISLAND NORTH AND EAST-KOHALA.

&&

ELAU