High Surf in Hawaii, April 8 to 9, 2007

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE HONOLULU HI
1231 AM HST SUN APR 8 2007

.SYNOPSIS...TRADE WINDS WILL INCREASE A BIT BY MIDWEEK AS THE RIDGE
NORTH OF THE ISLANDS STRENGTHENS AND CONTINUES DRIFTING NORTH.
CLOUDS AND SHOWERS WILL BEGIN TO FAVOR WINDWARD AND MAUKA AREAS BY
LATE SUNDAY. TOTAL RAINFALL WILL BE LIGHT. TRADE WINDS WILL WEAKEN
AGAIN LATE NEXT WEEK AS A TROUGH FAR TO OUR NORTH PUSHES THE RIDGE
SOUTH TOWARDS THE ISLANDS.

&&

.UPDATE...A RAGGED 90 MILE WIDE BAND OF LOW CLOUDS EXTENDS ACROSS
OAHU...KAUAI AND THE KAUAI CHANNEL EARLY THIS MORNING...KEEPING
KAUAI AND OAHU WITH ISOLATED TO SCATTERED SHOWERS. HOWEVER...THE
REMAINING ISLANDS HAVE CLEARED AS FORECAST. THESE CLOUDS ARE RATHER
STABLE...WITH SHOWERS OCCURRING MAINLY OVER WINDWARD PORTIONS AND
ACROSS HONOLULU AND SUBURBS. CLOUDS AND SHOWERS SHOULD DECREASE
AFTER SUNRISE.

&&

.PREVIOUS DISCUSSION...COOLING CONTINUES AND CLOUD COVER GENERATED
THIS AFTERNOON HAS BEGUN TO SLOUGH OFF ACROSS LEEWARD ISLAND AREAS
AND LEEWARD WATERS. TRADE WINDS WERE NOT STRONG ENOUGH TODAY TO
PREVENT AFTERNOON LEE SIDE SEA BREEZE AND MAUKA CLOUD COVER...BUT
TRADES ARE STRONG ENOUGH TO PUSH RESIDUAL CLOUD COVER TO THE WEST
SOUTHWEST THIS EVENING. AFTERNOON SOUNDINGS SHOW OUR AIRMASS
CONTINUES TO MOISTEN...WITH PRECIPITABLE WATER VALUES NOW NEAR AN
INCH. WE ARE ALSO QUITE STABLE...WITH NEGATIVE K INDEX VALUES AND
LESS THAN 100 J/KG OF CONVECTIVE ENERGY.

LATEST GFS SHOWS THE SURFACE RIDGE NORTH OF THE MAIN HAWAIIAN
ISLANDS WILL STRENGTHEN AS IT CONTINUES DRIFTING NORTH. BOTH ACTIONS
WILL TIGHTEN THE PRESSURE GRADIENT...CAUSING TRADE WINDS TO INCREASE
TO NEAR 20 MPH ACROSS THE ISLANDS AND SLIGHTLY HIGHER OVER LOCAL
WATERS AROUND MIDWEEK NEXT WEEK. GFS ALSO SHOWS WE WILL REMAIN
RATHER DRY...WITH NO BIG RAIN MAKING WEATHER SYSTEMS EXPECTED.
HOWEVER...THE AIRMASS WILL BE SUFFICIENTLY MOIST FOR THE USUAL TRADE
WIND WEATHER PATTERN OF WINDWARD AND MAUKA CLOUDS AND SHOWERS. WINDS
ALOFT WILL REMAIN ZONAL THROUGH MOST OF THE FORECAST PERIOD...WITH
NO DESTABILIZING UPPER TROUGHINESS EXPECTED. TOTAL RAINFALL WILL
THEREFORE BE LIGHT.

THE RIDGE NORTH OF US WILL CONSOLIDATE INTO A STRONG HIGH PRESSURE
CENTER BY MIDWEEK. AT ABOUT THE SAME TIME...A LOW MOVING EAST ALONG
40N...WITHIN THE WESTERLY STORM TRACK...WILL PUT A DENT IN THE
NORTHWEST FLANK OF THE HIGH. THE HIGH WILL BE NUDGED TO THE EAST
AND THE RIDGE EXTENDING SOUTHWEST FROM THE HIGH WILL BE PUSHED
SOUTH TOWARDS THE ISLANDS. THIS WILL CAUSE TRADE WINDS ACROSS THE
MAIN HAWAIIAN ISLANDS TO DECREASE AS THE PRESSURE GRADIENT
SLACKENS. HOWEVER...THE RIDGE WILL REMAIN INTACT AND TO OUR
NORTH...PREVENTING A RETURN TO VARIABLE WINDS AND A CONVECTIVE
WEATHER PATTERN SEEN OVER THE PAST WEEK.

&&

.MARINE...A LATE SEASON NORTHWEST SWELL IS EXPECTED TO ENTER
HAWAIIAN WATERS TONIGHT AND SUNDAY...CONTINUING INTO MONDAY. THE
RESULTING WAVES GENERATED ON NORTH AND WEST FACING SHORES WILL BE AT
THE HIGH END OF THE ADVISORY RANGE. BUOY 51001 WILL BE MONITORED
CLOSELY TONIGHT AND WAVE HEIGHTS WILL BE ADJUSTED ACCORDINGLY. IF A
LARGE UPWARD ADJUSTMENT IS NEEDED...THE ADVISORY MAY BE UPGRADED TO
A WARNING. SMALL CRAFT ADVISORIES WILL ALSO BE IN EFFECT FOR LOCAL
WATERS DUE TO THE EXPECTED LARGE SWELL.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY FROM 4 AM SUNDAY TO 4 AM HST MONDAY FOR
NORTH AND WEST FACING SHORES OF NIIHAU...KAUAI...OAHU...MOLOKAI AND
MAUI.

SMALL CRAFT ADVISORY FROM 6 AM SUNDAY TO 6 AM HST MONDAY FOR
KAUAI NORTHWEST WATERS.

SMALL CRAFT ADVISORY FROM 12 PM SUNDAY TO 6 AM HST MONDAY FOR
ALL LOCAL WATERS EXCEPT MAALAEA BAY AND THE PAILOLO CHANNEL.

&&

POWELL