High Surf Advisory 4, NWS Honolulu, HI

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HONOLULU HI
426 AM HST MON JAN 21 2013

.UPDATE...
CANCELLED THE HIGH SURF ADVISORY FOR BIG ISLAND WEST SHORES.

&&

.SYNOPSIS...
A WEAK HIGH PRESSURE SYSTEM NORTH OF THE AREA WILL SLIDE TO THE
NORTHEAST...AND TRADE WINDS WILL RETURN BY TONIGHT. UPPER RIDGING
WILL MAINTAIN STABLE AND DRY CONDITIONS THROUGH WEDNESDAY. THE TRADE
WINDS WILL GRADUALLY BRING IN MORE MOISTURE THE SECOND HALF OF THE
WEEK.

&&

.PREV DISCUSSION.../ISSUED 345 AM HST MON JAN 21 2013/

A 1019 MB HIGH IS CURRENTLY ABOUT 600 MILES NORTH OF KAUAI AND
MOVING SLOWLY TO THE NORTHEAST. THE RESULTING NORTH-NORTHEASTERLY
WINDS HAVE BEEN PUSHING STRATOCUMULUS CLOUDS SOUTH TOWARDS HAWAII
THIS MORNING. THESE STABLE CLOUDS SHOULD BLOCK OUT A LITTLE MORE SUN
TODAY THAN THE PAST FEW DAYS FOR WINDWARD AND MAUKA AREAS. WATER
VAPOR LOOP SHOWS VERY STRONG SUBSIDENCE OVER THE STATE THANKS TO
HIGH PRESSURE ALOFT. THE LOW INVERSION AND STRONG STABILITY WILL
KEEP SHOWERS VERY SCARCE THROUGH WEDNESDAY WHEN MODELS SHOW THE
RIDGE BREAKING DOWN TO A ZONAL FLOW ALOFT. BALLOON SOUNDINGS FROM
EARLY THIS MORNING AT LIHUE SHOWED AN INVERSION HEIGHT OF 4500 FEET
WITH PRECIPITABLE WATER VALUES AT 0.67 INCHES...ALL OF IT
CONCENTRATED AT THE LOW LEVELS OF THE ATMOSPHERE.

WINDS ALOFT HAVE FINALLY DROPPED BELOW ADVISORY LEVELS AT THE
SUMMITS ON MAUI AND BIG ISLAND AND EXPECTING IT TO CONTINUE TO
WEAKEN TODAY. THEREFORE...THE WIND ADVISORY IS CANCELLED.

THE NORTH-NORTHEAST WINDS SHOULD VEER TO A TYPICAL EASTERLY TRADE
WIND DIRECTION BY THE END OF TODAY...WHICH WILL THEN CONTINUE
THROUGH MOST OF THIS WEEK AND WINDS WILL BE IN THE MODERATE TO FRESH
RANGE. THE MORE EASTERLY COMPONENT TO THE WIND SHOULD ALLOW FOR
SLIGHTLY WARMER TEMPERATURES AND MORE MOISTURE IN THE AIR.

THE WEATHER PATTERN WILL REMAIN STABLE WITH LITTLE RAIN THROUGH
WEDNESDAY. A BIT MORE LOW LEVEL MOISTURE ALSO BEGINS TO CARRY IN
WITH THE TRADE WINDS WEDNESDAY NIGHT AND CAN EXPECT A FEW MORE
WINDWARD AND MAUKA SHOWERS THROUGH THE SECOND HALF OF THE WORK WEEK.
WHILE MORE SHOWERS WILL BE PRESENT...THEY/RE NOT EXPECTED TO BE
MAJOR RAIN PRODUCERS.

ON FRIDAY...AN UPPER TROUGH IS EXPECTED TO NOSE IN FROM THE NORTHWEST
WHILE A SURFACE COLD FRONT APPROACHES THE ISLANDS. LONG-RANGE GFS
AND ECMWF VARY ON THEIR SOLUTIONS THROUGH THE WEEKEND...SO CONFIDENCE
REMAINS LOW ON IMPACT TO THE ISLANDS AND TIMING.

&&

.AVIATION...
STABLE LOW CLOUDS ACROSS THE ISLAND CHAIN IS INCREASING AND MAY
BRING BRIEF MVFR CONDITIONS DUE TO CEILINGS. OTHERWISE...VFR
CONDITIONS PREVAIL THROUGHOUT TODAY.

VAD WIND PROFILE HAS SHOWN A SLIGHT INCREASE IN NORTH-NORTHEAST WIND
SPEEDS. WILL CONTINUE TO MONITOR WHETHER IT MAY WARRANT THE ISSUANCE
OF AN AIRMET FOR LOW LEVEL TURBULENCE.

&&

.MARINE...
WHILE DIMINISHING...THE CURRENT NORTHWEST SWELL CONTINUES TO HAVE
ENOUGH ENERGY TO GENERATE ADVISORY LEVEL SURF ALONG EXPOSED
SHORELINES. A HIGH SURF ADVISORY IS IN EFFECT FOR NORTH AND WEST
SHORES OF NIIHAU...KAUAI...OAHU...MOLOKAI AND MAUI. WEST SHORES OF
THE BIG ISLAND HAVE FALLEN BELOW CRITERIA AND HAVE CANCELLED THAT
PORTION OF THE ADVISORY. ANOTHER LARGE NORTHWEST SWELL IS EXPECTED
TO ARRIVE LATE THIS AFTERNOON AND EVENING...LIKELY PUSHING SURF
HEIGHTS INTO WARNING LEVELS TONIGHT INTO TUESDAY MORNING. THE
HIGHEST SURF WILL OCCUR DURING THE DARKNESS AND IT WILL DROP OFF
FAIRLY QUICKLY TUESDAY. SINCE AN ADVISORY IS ALREADY IN
EFFECT...WILL WAIT UNTIL THE NEW SWELL REACHES BUOY 51101 TO
DETERMINE IF AND WHEN WE WOULD REQUIRE A SURF WARNING.

CURRENT SEAS MEET SMALL CRAFT ADVISORY /SCA/ CRITERIA FOR WINDS
AND SEAS IN ALL HAWAIIAN COASTAL WATER ZONES. THE INCOMING
NORTHWEST SWELL WILL KEEP SEAS UP AT LEAST FOR ANOTHER DAY...SO
HAVE EXTENDED THE SCA UNTIL 600 PM HST TUESDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 PM HST MONDAY FOR NORTH AND WEST FACING
SHORES OF NIIHAU KAUAI OAHU MOLOKAI MAUI.

SMALL CRAFT ADVISORY UNTIL 6 PM HST TUESDAY FOR ALL HAWAIIAN
WATERS-

&&

UPDATE/DISCUSSION/MARINE...FOSTER
AVIATION...LUTU-MCMOORE