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FXHW60 PHFO 040129
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
330 PM HST TUE NOV 3 2009
SYNOPSIS
A DEVELOPING TROUGH WEST OF KAUAI WILL FOCUS SHOWERS OVER WINDWARD
PORTIONS OF KAUAI AND OAHU THROUGH TONIGHT...BEFORE DIMINISHING ON
WEDNESDAY AS THE TROUGH MOVES FURTHER AWAY TO THE WEST. OTHERWISE...
WE CAN EXPECT BREEZY TRADE WINDS TO CONTINUE THROUGH MOST OF THE
WORK WEEK...WITH WINDS DIMINISHING AND BECOMING SOUTHEASTERLY OVER
THE WEEKEND. THE BREEZY TRADES WILL DELIVER A FEW PASSING WINDWARD
SHOWERS...BUT THEIR INTENSITY AND COVERAGE WILL BE LIMITED AS THE
ISLAND ATMOSPHERE WILL BE STABLE FROM WEDNESDAY INTO THE WEEKEND.
DISCUSSION
THE CURRENT FORECAST CONTINUES TO REFLECT A RATHER DRAMATIC
DEPARTURE FROM WHAT HAD BEEN ADVERTISED OVER THE PAST COUPLE OF
DAYS...AS A FRONTAL BOUNDARY NW OF KAUAI IS NO LONGER EXPECTED TO
MOVE DOWN THE ISLAND CHAIN...BRINGING A SIGNIFICANTLY COOLER/DRIER
AIR MASS TO THE ISLANDS. INSTEAD...THE ISLANDS WILL REMAIN TO THE S
OF THIS BOUNDARY...AND THUS DEW POINTS WILL REMAIN IN THE UPPER
60/S...WITH LITTLE CHANGE TO THE CURRENT AIR MASS.
THE FORECAST NOW CALLS FOR A DEVELOPING SURFACE WAVE ALONG THE
NEARBY FRONTAL BOUNDARY TO TRACK W...IN CONJUNCTION WITH IT/S MID-
AND UPPER-LEVEL SUPPORT...WHICH IS CLEARLY DEFINED IN WATER VAPOR
IMAGERY AS A DEVELOPING CUT-OFF LOW ALOFT NEAR 24N 165W. AS THIS
SURFACE TROUGH SHARPENS JUST W OF KAUAI THROUGH TONIGHT...TRADE
WINDS WILL BE STRONGER OVER THE NW PORTION OF THE ISLAND CHAIN...AND
THE ASSOCIATED TIGHTENING OF THE SURFACE GRADIENT WILL SUPPORT
LOW-LEVEL CONVERGENCE...AND SHOWER DEVELOPMENT...IN THE SAME GENERAL
AREA.
AS THE LOW ALOFT PROGRESSIVELY TRACKS W OVER THE NEXT SEVERAL
DAYS...IT/S INDUCED SURFACE TROUGH WILL FOLLOW SUIT...AND STRONG
TRADE WINDS NEAR KAUAI WILL DIMINISH SOMEWHAT ON WEDNESDAY.
MEANWHILE...A STRONG SURFACE HIGH FAR TO THE NW WILL WEAKEN WHILE
REMAINING STATIONARY INTO WEDNESDAY NIGHT...AND WILL THEN BUILD E
WELL N OF THE ISLANDS. THIS WILL SUPPORT A MODERATE TO FRESH TRADE
WIND FLOW OVER THE ISLANDS INTO THE WEEKEND. WITH AN UPPER RIDGE
FORECAST TO DEVELOP OVER THE ISLANDS LATER WEDNESDAY...AND INTO THE
WEEKEND...TRADE WIND SHOWERS WILL BE LIMITED IN THEIR COVERAGE AND
INTENSITY. THE HIGH WILL CONTINUE TO TRACK E OVER THE WEEKEND...AND
WINDS OVER THE ISLANDS WILL VEER TO THE SE. THE SURFACE RIDGE MAY
MOVE OVER THE ISLANDS ON MONDAY AND TUESDAY IN ADVANCE OF AN
APPROACHING FRONT.
MARINE
THE OAHU SURF FORECAST /SRFHFO/ CONTAINS A DETAILED LOOK AT EXPECTED
SURF AND SWELL CONDITIONS OVER THE NEXT COUPLE OF DAYS...AND CAN BE
LOOSELY APPLIED TO THE OTHER MARINE AREAS. A SMALL CRAFT ADVISORY
/SCA/ IS CURRENTLY IN EFFECT FOR MOST WATERS AROUND KAUAI AND
OAHU...WITH COMBINED SEAS AT OR ABOVE 10 FEET. STRONG N/NE WINDS
JUST NW OF THE FRONTAL BOUNDARY NW OF KAUAI ARE RESPONSIBLE FOR THE
ELEVATED SEAS...AND SURF OBSERVATIONS FROM NORTH SHORE KAUAI THIS
MORNING INDICATED SURF ABOVE ADVISORY LEVELS. THUS...A HIGH SURF
ADVISORY /HSA/ WAS ISSUED FOR NORTH FACING SHORES OF KAUAI COUNTY
THIS MORNING. SEAS ARE ALREADY DROPPING AT BUOY 51001 AND THE SURF
IS EXPECTED TO DROP BELOW ADVISORY LEVELS EARLY WEDNESDAY.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY FOR KAUAI NORTHWEST WATERS-KAUAI WINDWARD
WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-OAHU WINDWARD WATERS.
HIGH SURF ADVISORY NORTH FACING SHORES OF KAUAI AND NIIHAU THROUGH
TONIGHT.
BIRCHARD
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