High Surf in Hawaii, March 4 to 5, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
930 AM HST MON MAR 4 2013

.SYNOPSIS...
A TRADE WIND WEATHER REGIME CONTINUES THROUGH THE MIDDLE OF THE WEEK
AS STRONG SURFACE HIGH PRESSURE REMAINS FAR NORTHWEST OF THE ISLAND
CHAIN. A SLIGHT INCREASE IN TRADE WIND SHOWERS IS EXPECTED FROM
TUESDAY THROUGH WEDNESDAY AS AN UPPER LEVEL TROUGH MOVES ACROSS THE
AREA. THEN THE TRADES WILL WEAKEN AND A MORE ACTIVE WEATHER PATTERN
WILL DEVELOP BY THE END OF THE WORK WEEK AS A COLD FRONT APPROACHES
THE ISLANDS FROM THE NORTHWEST.

&&

.DISCUSSION...
STRONG SURFACE HIGH PRESSURE NW OF THE MAIN HAWAIIAN ISLANDS WILL
KEEP MIGRATING EAST AND MAINTAINING A TIGHT PRESSURE GRADIENT ACROSS
THE AREA TODAY. THIS WILL KEEP THE BREEZE TRADES IN PLACE.
MEANWHILE...AN UPPER LVL RIDGE IS ALLOWING FOR RELATIVELY STABLE
CONDITIONS TO PREVAIL THROUGH AT LEAST EARLY TUE. BROKEN TO OVERCAST
LOW LVL STRATOCU CLOUDS CONTINUE TO FOCUS WINDWARD AND MAUKA AREAS
AND THE ADJACENT COASTAL WATERS.

A WEAK UPPER LVL TROUGH IS BEING IDENTIFIED IN WV/IR SAT IMAGERY
ABOUT 250-300 MILES NW OF KAUAI...WHICH WILL GRADUALLY SLIDE DOWN
TOWARDS THE ISLANDS LATER TODAY. THIS FEATURE SHOULD DESTABILIZE THE
AIR MASS ACROSS THE AREA AND ALLOW FOR A SLIGHT INCREASE IN TRADE
WIND SHOWERS STARTING EARLY TUE. MOST OF THESE SHOWERS WILL CONTINUE
TO FAVOR WINDWARD AND MAUKA AREAS...BUT A FEW BRIEF SHOWERS MAY
REACH LEEWARD LOCATIONS OF THE SMALLER ISLANDS AT TIMES.

THE UPPER LVL TROUGH WILL MOVE OUT OF THE AREA...AND RELOCATE JUST
TO THE SE OF THE BIG ISLAND BY LATE WED. RIDGING ALOFT WILL FOLLOW
WITH MORE STABLE CONDITIONS AND LESS SHOWER ACTIVITY EXPECTED WED
AND THU.

AT THE SFC...AS THE HIGH EVENTUALLY MOVES FURTHER AWAY FROM THE
STATE...PRESSURE GRADIENTS WILL RELAX AND WEAKENING THE TRADES
TOWARDS THE END OF THE WORK WEEK. MODEL GUIDANCE SUGGESTS A BROAD
UPPER LVL TROUGH AND AN ASSOCIATED SFC COLD FRONT BOUNDARY
APPROACHING KAUAI FROM THE NW FOR THE THU-FRI TIME FRAME. THIS WILL
PUSH THE SFC RIDGE DOWN CLOSER TO THE ISLANDS. CONSENSUS AMONG MODEL
SOLUTIONS REMAINS FAIRLY LOW REGARDING HOW FAR EAST INTO THE ISLAND
CHAIN THE COLD FRONT WILL ACTUALLY REACH. HOWEVER...CONFIDENCE ALSO
REMAINS HIGH IN HAVING THE FRONT CLOSE TO KAUAI AROUND FRIDAY. THIS
WILL BRING A WEAKENING AND VEERING TREND IN WINDS...TURNING TO THE
SE AND POSSIBLY  BECOMING LIGHT FOR THE UPCOMING WEEKEND. THIS
SYNOPTIC SETUP WILL THEN ALLOW FOR LOCAL AFTERNOON SEA BREEZE AND
NIGHTTIME LAND BREEZE CIRCULATIONS TO DEVELOP OVER MOST OF THE
ISLANDS LATE THU AND BEYOND. THIS WOULD FAVOR AN INCREASE IN CLOUDS
AND SHOWERS OVER THE LEEWARD AND INTERIOR SECTIONS OF THE ISLANDS
DURING THE AFTERNOON AND EARLY EVENING HOURS...WITH SKIES CLEARING
LATER AT NIGHT.

THE WEAKER AND SE WIND REGIME NORMALLY TRANSLATES INTO A RETURN TO
HAZY CONDITIONS ACROSS THE ISLAND CHAIN AS VOLCANIC HAZE BEGINS
MOVING UP OVER MOST OF THE SMALLER ISLANDS...POSSIBLY STARTING LATE
THU OR EARLY FRI.

&&

.MARINE...
A SMALL CRAFT ADVISORY /SCA/ REMAINS IN EFFECT THROUGH TUESDAY
EVENING FOR ALL HAWAIIAN WATERS AS A NEW NORTHWEST SWELL WILL BOOST
COMBINED SEAS TO SCA LEVELS.

SURF HEIGHTS WILL REACH THE HIGH SURF ADVISORY CRITERIA TODAY ALONG
MOST NORTH AND WEST FACING SHORES OF THE SMALLER ISLANDS...AND ALONG
NORTH AND EAST FACING SHORES OF THE BIG ISLAND. A HIGH SURF ADVISORY
IS NOW IN EFFECT FOR THESE AREAS THROUGH TUESDAY EARLY MORNING.

&&

.AVIATION...
AIRMET TANGO FOR LOW LEVEL TURBULENCE FOR SOUTH THROUGH WEST OF
MOUNTAINS CONTINUES ACROSS THE STATE.

THE BLANKET OF LOW CLOUDS STREAMING TOWARDS THE ISLANDS ARE SHALLOW
AND STABLE. HENCE...VFR CONDITIONS WILL PREVAIL AT ALL TERMINALS
THROUGHOUT THE FORECAST PERIOD WITH THE POSSIBILITY OF BRIEF MVFR
CONDITIONS OVER WINDWARD SLOPES DUE TO SHOWERS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY THROUGH 600 AM HST TUESDAY MORNING FOR NORTH AND
WEST FACING SHORES OF KAUAI...NIIHAU...OAHU AND MOLOKAI...FOR NORTH
FACING SHORES OF MAUI...AND ALONG NORTH AND EAST FACING SHORES OF
THE BIG ISLAND.

SMALL CRAFT ADVISORY IN EFFECT THROUGH 600 PM HST TUESDAY FOR ALL
HAWAIIAN COASTAL WATERS.

&&

DISCUSSION/MARINE...REYNES
AVIATION...FUJI