High Surf in Hawaii, March 3 to 4, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST SUN MAR 3 2013

.SYNOPSIS...
A BREEZY TRADE WIND WEATHER PATTERN WILL PREVAIL OVER THE NEXT FEW
DAYS DUE TO RELATIVELY STRONG SURFACE HIGH PRESSURE FAR NORTH OF THE
ALOHA STATE. AN UPPER LEVEL TROUGH MOVING OVER THE STATE TUESDAY IS
EXPECTED TO PRODUCE A SLIGHT INCREASE IN TRADE SHOWERS FROM TUESDAY
THROUGH EARLY WEDNESDAY. EXPECT THE WINDS TO BECOME LIGHTER TOWARD
THE END OF THE NEW WORK WEEK AS A FRONT BEGINS TO APPROACH THE
ISLANDS FROM THE NORTHWEST.

&&

.DISCUSSION...
THE TIGHT PRESSURE GRADIENT SOUTH OF A 1033 MB SURFACE HIGH NEAR 36N
170W...OR ABOUT 1350 MILES NORTHWEST OF HONOLULU...IS PRODUCING
BREEZY TRADE WIND CONDITIONS ACROSS THE ISLAND CHAIN EARLY THIS
MORNING AS IT MOVES TOWARD THE EAST SOUTHEAST AT 20 TO 25 MPH.
ALOFT...NORTHEAST TO SOUTHWEST ORIENTED MIDDLE AND UPPER LEVEL
TROUGHING IS EVIDENT ABOUT 350 MILES EAST SOUTHEAST OF HILO. THERE
IS ALSO AN UPPER LEVEL RIDGE NEAR THE NORTHERN HAWAIIAN ISLANDS.
WATER VAPOR IMAGERY INDICATES THERE IS SIGNIFICANT SUBSIDENCE HIGH
ABOVE MOST OF THE MAIN HAWAIIAN ISLAND CHAIN. AS A RESULT...THE
ISLANDS ARE IN A RELATIVELY STABLE ENVIRONMENT WITH A TRADE WIND
INVERSION OF 6 THOUSAND FEET NEAR KAUAI...AND ABOUT 8 THOUSAND FEET
NEAR THE WINDWARD BIG ISLAND. THIS LOW-LEVEL INVERSION ALONG WITH
BELOW NORMAL MOISTURE VALUES IS LIMITING THE VERTICAL DEVELOPMENT OF
SHOWER BEARING CLOUDS ENTERING THE STATE. MOST OF THE CLOUDS UPWIND
OF THE ISLANDS APPEAR TO BE STABLE STRATOCUMULUS WITH ISOLATED LIGHT
TRADE SHOWERS MAINLY AFFECTING THE WINDWARD FACING SLOPES AND
BEACHES ON MAUI AND BIG ISLAND...AS WELL AS THE ADJACENT COASTAL
WATERS.

THE SURFACE HIGH FAR NORTHWEST OF THE ISLANDS WILL MOVE TO A
POSITION FAR NORTH OF THE ALOHA STATE BY MONDAY. THIS WILL KEEP THE
PRESSURE GRADIENT RATHER TIGHT ACROSS THE REGION RESULTING IN BREEZY
TRADE WINDS INTO THE FIRST FEW DAYS OF THE NEW WEEK. THE RIDGE ALOFT
IS ALSO EXPECTED TO REMAIN IN PLACE THROUGH TONIGHT. SO EXPECT A
RELATIVELY DRY TRADE WIND WEATHER PATTERN TO CONTINUE INTO EARLY
MONDAY.

AGAIN...THE FORECAST MODELS INDICATE THE UPPER LEVEL TROUGH WILL
PROPAGATE DOWN FROM THE NORTH OVER THE STATE FROM LATE MONDAY INTO
TUESDAY. THE PRESENCE OF THE COLD AIR ALOFT AND DYNAMIC LIFT
ASSOCIATED WITH THIS TROUGH ARE EXPECTED TO PRODUCE A SLIGHT
DESTABILIZATION OF THE ATMOSPHERE. THE RESULT WILL BE AN INCREASE IN
WINDWARD AND MAUKA SHOWERS...WITH THE BREEZY TRADE WINDS CARRYING A
FEW BRIEF SHOWERS OVER TO SOME LEEWARD AREAS OF THE SMALLER ISLANDS.

THE SURFACE HIGH WILL CONTINUE TO MOVE EASTWARD INTO THE MIDDLE OF
NEXT WEEK WITH ITS ASSOCIATED SURFACE RIDGE SHIFTING SLOWLY
SOUTHWARD TO A POSITION SLIGHTLY CLOSER TO THE STATE AS A FRONTAL
SYSTEM DEVELOPS FAR NORTHWEST OF KAUAI. THIS WILL CAUSE THE TRADE
WINDS TO GRADUALLY WEAKEN FROM CURRENT SPEEDS BY THE END OF THE NEW
WORK WEEK.

THE UPPER LEVEL TROUGH WILL MOVE SOUTHEAST AWAY FROM THE STATE BY
LATE WEDNESDAY AS ANOTHER RIDGE ALOFT BUILDS IN OVER THE REGION FROM
THE WEST. THIS SHOULD MAKE THE ATMOSPHERE MORE STABLE...WITH REDUCED
TRADE SHOWER COVERAGE AND INTENSITY EXPECTED. AS WE HEAD INTO NEXT
WEEKEND...A BROAD UPPER LEVEL TROUGH WILL BE ADVANCING TOWARD THE
STATE FROM THE NORTHWEST. THIS WILL PUSH THE UPPER LEVEL RIDGE SOUTH
OF THE STATE.

ALSO TOWARD THE END OF THE WEEK...THE WESTERN END OF THE SURFACE
RIDGE WILL CONTINUE PUSHING SOUTHWARD CLOSE TO THE STATE AS THE
FRONT ADVANCES TOWARD THE REGION. THE SURFACE WINDS WILL CONTINUE TO
BECOME LIGHTER AS THEY BEGIN TO VEER FROM A SOUTHEASTERLY
DIRECTION...ESPECIALLY OVER THE WESTERN END OF THE ISLAND CHAIN. BY
NEXT WEEKEND...THE FRONT IS FORECAST TO BE LOCATED NORTHWEST OF
KAUAI WITH LIGHT EAST TO SOUTHEAST WINDS OVER THE ISLANDS. IF THE
WINDS BECOME LIGHT ENOUGH...LOCAL NIGHTTIME LAND AND AFTERNOON SEA
BREEZES ARE LIKELY TO DEVELOP ALSO. MOISTURE ASSOCIATED WITH THE
APPROACHING FRONT WILL LIKELY REMAIN NORTHWEST OF KAUAI ON
SATURDAY...SO NO SIGNIFICANT PREFRONTAL SHOWERS ARE EXPECTED AT THIS
TIME.

&&

.MARINE...
A SMALL CRAFT ADVISORY /SCA/ REMAINS IN EFFECT THROUGH THIS
AFTERNOON FOR ALL HAWAIIAN WATERS DUE TO STRONG TRADE WINDS AND
ELEVATED SEAS. THE SCA HAS BEEN EXTENDED THROUGH TONIGHT FOR THE
TYPICALLY WINDY WATERS ADJACENT TO THE ISLANDS OF MAUI COUNTY AND
THE BIG ISLAND...INCLUDING THE KAIWI CHANNEL. A NEW NORTHWEST SWELL
ARRIVING MONDAY NIGHT WILL ONCE AGAIN BOOST COMBINED SEAS OVER MOST
HAWAIIAN WATERS. AS A RESULT...EXPECT A SCA TO BE ISSUED ONCE AGAIN
FOR MOST OF THE REMAINING HAWAIIAN WATERS.

A HIGH SURF ADVISORY REMAINS IN EFFECT THROUGH TONIGHT FOR EAST
FACING SHORES OF MOST ISLANDS DUE TO THE ELEVATED EASTERLY TRADE
WIND SWELL. THESE WIND WAVES ARE EXPECTED TO GRADUALLY DIMINISH...SO
THE HIGH SURF ADVISORY IS EXPECTED TO BE LOWERED SOME TIME ON
MONDAY.

THE HIGH SURF ADVISORY HAS BEEN CANCELLED FOR NORTH AND SOME WEST
FACING SHORES. A NEW LONG PERIOD NORTHWEST SWELL ARRIVING LATE
SUNDAY NIGHT WILL LIKELY CAUSE SURF HEIGHTS TO REACH THE HIGH SURF
ADVISORY CRITERIA ALONG MOST NORTH AND WEST FACING SHORES OF THE
SMALLER ISLANDS FROM MONDAY AFTERNOON INTO TUESDAY.

&&

.AVIATION...
AIRMET TANGO REMAINS IN EFFECT FOR MODERATE LOW-LEVEL TURBULENCE
BELOW 8 KFT SOUTH THROUGH WEST OF THE MOUNTAINS OVER ALL ISLANDS
DUE TO THE ROBUST TRADE WINDS.

VFR CONDITIONS WILL LIKELY PREVAIL THROUGH TODAY...WITH BRIEF MVFR
CIGS POSSIBLE...MAINLY ALONG WINDWARD FACING SLOPES.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 600 AM HST MONDAY FOR EAST FACING SHORES OF
KAUAI...OAHU...MOLOKAI...MAUI AND THE BIG ISLAND NORTH.

WIND ADVISORY UNTIL 600 PM HST THIS EVENING FOR HALEAKALA SUMMIT.

SMALL CRAFT ADVISORY UNTIL 600 AM HST MONDAY FOR MAALAEA BAY...THE
WATERS SOUTH OF THE BIG ISLAND...AND THE KAIWI...PAILOLO AND
ALENUIHAHA CHANNELS.

SMALL CRAFT ADVISORY UNTIL 600 PM HST THIS EVENING FOR ALL REMAINING
HAWAIIAN WATERS.

&&

HOUSTON