High Surf Advisory 18, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST TUE MAR 15 2011

.SYNOPSIS...
A HIGH FAR NORTHWEST OF THE AREA WILL MOVE EAST AND STRENGTHEN...
PRODUCING BREEZY TRADE WINDS THROUGH THE WEEK. RIDGING ALOFT WILL
KEEP THE ATMOSPHERE DRY AND STABLE...SO RAINFALL WILL BE LIGHT
THROUGH THURSDAY AFTERNOON. A CLOUD BAND SAGGING SOUTH OVER THE
ISLANDS MAY BRING AN INCREASE IN SHOWERS THURSDAY NIGHT THROUGH
FRIDAY NIGHT. DRIER WEATHER SHOULD RETURN NEXT WEEKEND.

&&

.DISCUSSION...
THE GLOBAL MODELS AND THE PRELIMINARY 18Z SURFACE ANALYSIS SHOW A
1028 MB SURFACE HIGH ABOUT 1000 MILES NORTHWEST OF KAUAI WITH
TRADE-WIND FLOW OVER THE MAIN HAWAIIAN ISLANDS. SATELLITE LOOPS SHOW
SCATTERED TO BROKEN LOW CLOUDS...MOSTLY STABLE STRATOCUMULUS...
MOVING OVER THE ISLANDS IN THE TRADE-WIND FLOW. RADARS SHOW ONLY
ISOLATED LIGHT SHOWERS FALLING FROM THESE CLOUDS.

WATER VAPOR IMAGERY SHOWS A RIDGE ALOFT OVER THE ISLANDS WITH UPPER
AIR ANALYSES SHOWING AN ANTICYCLONE NEAR THE BIG ISLAND AT 400 MB.
THE RIDGING ALOFT IS PRODUCING STRONG SUBSIDENCE NEAR THE ISLANDS...
WITH STRONG INVERSIONS AT BOTH HILO AND LIHUE ON THE 200 AM BALLOON
SOUNDINGS.

THE GLOBAL MODELS REMAIN IN GOOD AGREEMENT. THEY SHOW THE SURFACE
HIGH MOVING EAST ALONG 35N AND BUILDING. THE GFS SHOWS THE HIGH
REACHING 1036 MB WHEN THE HIGH IS NORTH NORTHEAST OF THE ISLANDS
WEDNESDAY EVENING...WHILE THE ECMWF SHOWS THE HIGH REACHING 1035 MB.
AS THE HIGH MOVES INTO POSITION NORTH OF THE ISLANDS...THE TRADE
WINDS WILL STRENGTHEN...BUT THE LATEST RUNS OF THE GLOBAL SHOW THE
WINDS NOT GETTING AS STRONG AS SOME OF THE EARLIER RUNS. THERE WILL
BE WIDESPREAD BREEZY CONDITIONS OVER LAND...AND WITH STRONG AND LOW
INVERSIONS...WINDS WILL ACCELERATE DOWNSLOPE. WIND ADVISORIES MAY BE
NEEDED FOR THESE STRONG AND GUSTY WINDS.

LATER IN THE WEEK AS THE HIGH MOVES FARTHER EAST THE WINDS OVER THE
ISLANDS WILL SUBSIDE BUT SHOWERS ARE LIKELY TO INCREASE. THE
TRAILING END OF A FRONTAL BAND WILL SAG SOUTH AND SHOULD REACH THE
ISLANDS BY FRIDAY MORNING. THE WEATHER WILL BE MORE SHOWERY FRIDAY
AND SATURDAY AS THIS BAND SHIFTS SOUTH OVER THE ISLANDS. THE
ATMOSPHERE WILL REMAIN STABLE SO EXCESSIVE RAINFALL IS UNLIKELY.
DRIER WEATHER SHOULD RETURN EARLY NEXT WEEK.

&&

.MARINE...
BUOYS NEAR THE ISLANDS SHOWED THE NORTH NORTHWEST SWELL PEAKING
EARLY THIS MORNING. SO FAR THERE HAVE BEEN NO REPORTS OF PROBLEMS
WITH SURGES IN THE HARBORS. THE SWELL SHOULD GRADUALLY DECREASE OVER
THE NEXT FEW DAYS.

AS THE TRADE WINDS STRENGTHEN...SURF WILL RISE OVER EAST FACING
SHORES AND ARE LIKELY TO REQUIRE HIGH SURF ADVISORIES BY TOMORROW.
WIDESPREAD SMALL CRAFT ADVISORIES WILL CONTINUE FOR STRONG TRADE
WINDS BUT IT NOW SEEMS LESS LIKELY WE WILL NEED TO ISSUE GALE
WARNINGS. OUR FORECAST NOW SHOW WINDS REACHING GALE FORCE...BUT IF
THE MODELS REMAIN CONSISTENT TODAY WE WILL PROBABLY TAKE THE GALES
OUT OF THE FORECAST THIS AFTERNOON.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF WARNING UNTIL 600 AM  WEDNESDAY FOR NORTH AND WEST FACING
SHORES OF NIIHAU KAUAI AND OAHU...AND NORTH FACING SHORES OF MOLOKAI
MAUI AND THE BIG ISLAND.

HIGH SURF ADVISORY THROUGH 600 AM WEDNESDAY FOR NORTH FACING SHORES
OF WINDWARD OAHU.

SMALL CRAFT ADVISORY UNTIL 6 AM HST WEDNESDAY FOR ALL AREAS EXCEPT
MAALAEA BAY AND WATERS SOUTH OF THE BIG ISLAND.

&&

DONALDSON