Wind Advisory 16, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST TUE FEB 16 2010

.SYNOPSIS...
LIGHT TO MODERATE TRADE WINDS WILL DIMINISH TODAY. STRONGER
NORTHERLY WINDS WILL ARRIVE TONIGHT...BEFORE TURNING INTO WET TRADES
BY WEDNESDAY. FROM THURSDAY INTO THE WEEKEND...BOTH TRADES AND
SHOWERS WILL DIMINISH AGAIN SLOWLY. WINDWARD SHOWERS MAY INCREASE
SLIGHTLY BY NEXT MONDAY.

&&

.DISCUSSION...
LOCAL OBSERVATIONS AROUND THE MAIN HAWAIIAN ISLANDS REPORTED LIGHT
TO MODERATE TRADE WINDS. GAUGES TALLIED LITTLE RAIN ACROSS THE
STATE...WITH MOST ACCUMULATION OCCURRING ALONG WINDWARD SHORES FROM
OAHU TO THE BIG ISLAND. THE LIHUE SOUNDING SHOWED A DRY AIR MASS
UNDER A VERY LOW INVERSION BASE. AT HILO...THE MIXED LAYER ALSO WAS
DRIER THAN USUAL...BUT LESS SO...AND THE INVERSION BASE HAD RISEN TO
NEAR THE TYPICAL HEIGHT OVERNIGHT.

ALOFT...A DEEP TROUGH TO THE NORTHEAST EXTENDED TOWARD THE STATE...
BUT PERSISTENT RIDGING TO THE SOUTH KEPT THE TROUGHING SHALLOW
LOCALLY. STILL...EVEN WEAK TROUGHING WILL PROVIDE SOME SUPPORT FOR
THE FADING FRONT APPROACHING FROM THE NORTHWEST. LIKEWISE...
INCREASING LOW CLOUD COVER TO THE EAST OF THE ISLANDS HINTED AT
MOISTURE CONVERGENCE AHEAD OF THE FRONT.

GUIDANCE PREDICTS THIS FRONT TO DISPLACE THE SUBTROPICAL RIDGE ONTO
THE STATE AND WEAKEN IT FURTHER THIS MORNING...REDUCING THE TRADES
SLIGHTLY...AND PERHAPS TURNING THE PREVAILING WINDS SOUTHEASTERLY
BRIEFLY. THE UPPER SUPPORT PROBABLY WILL NOT PROVE SUFFICIENT TO
KEEP THE FRONT FROM DISINTEGRATING BEFORE REACHING THE STATE.
HOWEVER...MOISTURE FROM ITS REMNANTS...TOGETHER WITH ANY CONVERGED
AHEAD OF THE FEATURE...WILL MOVE ASHORE ON STRENGTHENING TRADES FROM
TONIGHT INTO WEDNESDAY AS THE SUBTROPICAL RIDGE REBUILDS...LEADING
TO WET TRADES ACROSS MOST WINDWARD SLOPES...AND PROBABLY A FEW
SHOWERS LEEWARD AS WELL.

WINDS HAVE PICKED UP ACROSS THE BIG ISLAND SUMMITS...AND THE RSM
SUPPORTS FURTHER INCREASES TODAY. THE FORECAST HAS BEEN ADJUSTED TO
INCLUDE THIS EFFECT...BUT A WIND ADVISORY MAY BE NEEDED FOR THE
SUMMITS BY TONIGHT. SIMILARLY...STRONGER WINDS BEHIND THE FRONT
LIKELY WILL REQUIRE A SMALL CRAFT ADVISORY FOR WATERS AROUND KAUAI
TONIGHT...AND THESE CONDITIONS WILL SPREAD SOUTHEAST WITH TIME.

FROM WEDNESDAY ON...TRADES WILL PERSIST THROUGH THE WEEKEND...THOUGH
MOST SOLUTIONS SUGGEST A STEADY DECREASE IN WIND SPEED WITH TIME AS
THE RIDGE SLOWLY SHIFTS CLOSER TO THE ISLANDS. ANOTHER FEEBLE FRONT
DISINTEGRATING NORTH OF THE AREA BY SUNDAY NIGHT MAY PROVIDE A
SECOND BURST OF MOISTURE FOR SLIGHTLY WETTER TRADES INTO EARLY NEXT
WEEK. GUIDANCE PREDICTS YET ANOTHER...STRONGER FRONT TO APPROACH THE
STATE BY NEXT TUESDAY...TURNING WINDS SOUTHEASTERLY AGAIN...BUT
SOLUTIONS STILL DIFFER ON THE TIMING AND INTENSITY OF THIS EFFECT...
SO THE CURRENT SCENARIO OF WEAK TRADES SEEMS APPROPRIATE.

&&

.MARINE...
DEVELOPING LOWS IN THE GULF OF ALASKA WILL PROVIDE A LENGTHENING
FETCH DIRECTED TOWARD THE MAIN HAWAIIAN ISLANDS...PRODUCING THE NEXT
BIG SWELL THAT SHOULD PUSH SURF ABOVE THE HIGH SURF ADVISORY
CRITERIA ALONG NORTH SHORES FROM THIS EVENING THROUGH THURSDAY...AND
POSSIBLY INTO FRIDAY. THIS SWELL WILL ARRIVE FROM A MORE NORTHERLY
DIRECTION THAN USUAL...SO IT MAY REACH SOME EASTERN SHORES WITH
NORTHERN EXPOSURE...BUILDING SURF UP TOWARD THE SURF ADVISORY
THRESHOLD...WHICH IS ONLY 8 FEET ALONG EAST SHORES.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

RYSHKO