Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 272004
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1005 AM HST FRI MAR 27 2015

.SYNOPSIS...
MODERATE TO LOCALLY FRESH TRADE WINDS WILL CONTINUE OVER THE WEEKEND
AND EARLY NEXT WEEK...BEFORE DIMINISHING TUESDAY AND WEDNESDAY.
MOSTLY DRY WEATHER WILL CONTINUE THROUGH SATURDAY...WITH AN INCREASE
IN WINDWARD SHOWERS EXPECTED ON SUNDAY AND MONDAY...ESPECIALLY ON
KAUAI AND OAHU. A DISTURBANCE PASSING NORTH OF THE ISLANDS ON
TUESDAY WILL WEAKEN THE TRADE WINDS AND BRIEFLY DESTABILIZE THE
ATMOSPHERE...WITH ISOLATED HEAVY SHOWERS POSSIBLE...AGAIN MAINLY
OVER KAUAI AND OAHU. THE DISTURBANCE WILL MOVE EAST OF THE AREA ON
WEDNESDAY AND THURSDAY...WITH TYPICAL TRADE WIND WEATHER EXPECTED.
ANOTHER DISTURBANCE DEVELOPING NORTH OF THE AREA MAY WEAKEN THE
TRADE WINDS AGAIN TOWARD THE END OF NEXT WEEK.

&&

.DISCUSSION...
MODERATE TO LOCALLY FRESH TRADE WINDS ARE BEING SUPPLIED BY A 1030
MB SURFACE HIGH FAR NE OF THE ISLANDS...AND AN ASSOCIATED RIDGE
ABOUT 500 MILES N OF THE ISLANDS. A RIDGE ALOFT IS SUPPORTING A
STABLE ATMOSPHERE...AND NOW THAT MOISTURE ASSOCIATED WITH A
DISSIPATED FRONT HAS CLEARED THE AREA...A MOSTLY DRY TRADE WIND
WEATHER PATTERN IS IN PLACE OVER THE ISLANDS. STABLE LOW CLOUDS ARE
BANKED UP ALONG WINDWARD SLOPES...BUT ONLY ISOLATED LOCALIZED
SHOWERS WERE OBSERVED EARLIER THIS MORNING.

A MOSTLY DRY TRADE WIND WEATHER PATTERN IS EXPECTED THROUGH
SATURDAY...AS A MID LEVEL RIDGE REMAINS OVERHEAD...AND TRADE WINDS
GRADUALLY DIMINISH AS THE SURFACE RIDGE N OF THE ISLANDS RETREATS
EASTWARD. A NEW HIGH BUILDING NW OF THE AREA ON SUNDAY WILL PUSH
REMNANT FRONTAL MOISTURE TOWARD THE ISLANDS FROM THE N ON SUNDAY
AND MONDAY. ALTHOUGH THIS MOISTURE MAY NOT MAKE IT AS FAR S AS THE
ISLANDS...WEAKLY CONVERGENT LOW LEVEL FLOW WILL LEAD TO INCREASED
TRADE WIND SHOWERS OVER KAUAI AND OAHU LATE SUNDAY INTO MONDAY.

THE TRADE WIND FLOW COULD BE DISRUPTED AROUND TUESDAY AS A
PROGRESSIVE MID-LEVEL TROUGH PASSES N OF THE ISLANDS...AND INDUCES
THE FORMATION OF A SURFACE TROUGH NEAR THE ISLANDS. THE TROUGHS MAY
BRING SOME INSTABILITY...AND COMBINED WITH THE LINGERING MOISTURE
NEAR KAUAI AND OAHU...MAY LEAD TO LOCALIZED ISOLATED DOWNPOURS. BEST
CHANCES FOR THIS HAPPENING MAY BE WITH SEA BREEZE CONVERGENCE OVER
ISLAND INTERIORS ON TUESDAY. ALTHOUGH WINDS WILL REMAIN ON THE LIGHT
SIDE THROUGH WEDNESDAY...THE DEPARTING TROUGH SHOULD BE FAR ENOUGH
AWAY SUCH THAT THE ISLAND ATMOSPHERE WILL BEGIN TO STABILIZE. TRADE
WINDS SHOULD REBUILD LATE WEDNESDAY/THURSDAY AS THE SURFACE TROUGH
DISSIPATES.

TRADE WINDS MAY WEAKEN AGAIN TOWARD THE END OF NEXT WEEK AS ANOTHER
TROUGH ALOFT INDUCES SURFACE TROUGHING NEAR THE ISLANDS ONCE AGAIN.

&&

.AVIATION...
PREDOMINANTLY VFR CONDITIONS ARE EXPECTED AT ALL TERMINALS THROUGH
28/18Z. NO AIRMETS ARE IN EFFECT AND NONE ARE ANTICIPATED THROUGH
THE REMAINDER OF THE DAY.

&&

.MARINE...
AN OVERNIGHT SCATTEROMETER PASS PROVIDED GROUND TRUTH FOR THE MARINE
ZONES CURRENTLY INCLUDED IN THE SMALL CRAFT ADVISORY /SCA/...WITH
THE SCA SLATED TO EXPIRE AT 6 PM THIS EVENING. ALTHOUGH TRADE WINDS
ARE IN THE PROCESS OF GRADUALLY EASING...LATEST GUIDANCE INDICATES
25 KT WINDS CONTINUING OVER WATERS N AND S OF THE BIG ISLAND
OVERNIGHT. AS THE CURRENT FORECAST GRIDS ALSO INDICATE WINDS NEAR
CRITERIA...THE SCA HAS BEEN EXTENDED THROUGH 6 AM SATURDAY FOR THESE
ZONES. ALTHOUGH A SLIGHT INCREASE IN WIND SPEEDS IS EXPECTED
SUNDAY/MONDAY...THE EXPECTATION IS THAT WINDS WILL REMAIN BELOW SCA
SPEEDS BEFORE WINDS DIMINISH TUESDAY INTO WEDNESDAY.

NOT MUCH SURF TO SPEAK OF CURRENTLY...AS LINGERING SSW AND NNW
SWELLS FADE AWAY THROUGH SATURDAY. A LONG-PERIOD NW SWELL WILL BUILD
AND PEAK ON SUNDAY...WITH PEAK SURF HEIGHTS NEARING ADVISORY LEVELS
ALONG EXPOSED N AND W SHORES. THIS SWELL WILL GRADUALLY DIMINISH IN
HEIGHT AND PERIOD THROUGH TUESDAY. AT ITS PEAK...THIS SWELL WILL
BRING COMBINED SEAS CLOSE TO...BUT REMAINING BELOW...THE 10 FT
THRESHOLD FOR SCA ISSUANCE. SWELLS ARRIVING FROM THE S WILL BE LOW
IN MAGNITUDE...BUT SUFFICIENTLY LARGE TO KEEP SOME SURF ALONG S
FACING SHORES THROUGH THE PERIOD.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 6 AM HST SATURDAY FOR ALENUIHAHA
CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS.

SMALL CRAFT ADVISORY UNTIL 6 PM HST THIS EVENING FOR KAUAI
NORTHWEST WATERS-KAUAI CHANNEL-KAIWI CHANNEL-MAALAEA BAY-PAILOLO
CHANNEL.

&&

$$

DISCUSSION/MARINE...BIRCHARD
AVIATION...JELSEMA




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