Area Forecast Discussion
Issued by NWS Honolulu, HI

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000
FXHW60 PHFO 281949
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
949 AM HST THU AUG 28 2014

.SYNOPSIS...
TRADE WINDS WILL WEAKEN TODAY...WITH LOCAL SEA BREEZES DEVELOPING
THIS AFTERNOON. TRADES WILL BECOME LIGHT FROM FRIDAY THROUGH THE
WEEKEND AND INTO EARLY NEXT WEEK...ALLOWING MORE WIDESPREAD
AFTERNOON SEA BREEZES AND NIGHTTIME LAND BREEZES TO DEVELOP OVER
LEEWARD AND INTERIOR AREAS. AFTERNOON AND EVENING CLOUDS AND
SHOWERS WILL DEVELOP OVER LEEWARD AND INTERIOR SECTIONS...FOLLOWED
BY NIGHTTIME CLEARING...WHILE PASSING LOW CLOUDS WILL AFFECT THE
WINDWARD AREAS AT TIMES. STRONGER TRADE WINDS MAY RETURN BY THE
MIDDLE OF NEXT WEEK.

&&

.DISCUSSION...
RADAR LOOPS DEPICT WIDELY SCATTERED RAIN SHOWERS ACROSS THE
WINDWARD COASTAL WATERS...WHILE RAIN GAUGES HAVE MEASURED JUST
LIGHT ACCUMULATIONS ACROSS SOME WINDWARD AREAS DURING THE PAST
SEVERAL HOURS. SURFACE ANALYSIS SHOWS AN EAST-WEST HIGH PRESSURE
RIDGE FAR TO THE NORTH OF THE STATE ALONG 40N...WITH A REMNANT LOW
FROM FORMER EAST PACIFIC TROPICAL CYCLONE LOWELL NEAR 31N 143W.
TRADES ARE BEGINNING TO WEAKEN ACROSS THE STATE...ALTHOUGH THE 12Z
LIHUE SOUNDING AND MORE RECENT 88D VWP DATA STILL SHOW TRADE WINDS
AROUND 15 KNOTS IN THE LOW LEVELS. THE SOUNDINGS SHOW NEAR TO
SLIGHTLY BELOW PWATS OF 1.2 TO 1.3 INCHES IN PLACE...WHILE MIMIC-
TPW SATELLITE IMAGERY DEPICTS A POCKET OF SOMEWHAT HIGHER PWATS
AROUND 1.5 INCHES APPROACHING THE STATE FROM THE NORTHEAST.
RELATIVELY STABLE CONDITIONS ARE IN PLACE...WITH A MID/UPPER LEVEL
RIDGE CENTERED TO THE SOUTH OF HAWAII EXERTING ITS INFLUENCE OVER
THE STATE.

THROUGH THE REST OF TODAY...IT APPEARS THAT TRADES WILL BE WEAK
ENOUGH TO ALLOW FOR SEABREEZES TO DEVELOP ACROSS SOME LEEWARD
AREAS...BUT STRONG ENOUGH TO PREVENT A COMPLETE SWITCHOVER TO
A CONVECTIVE PATTERN. WOULD EXPECT A HYBRID PATTERN WITH SOME
PASSING SHOWERS CONTINUING WINDWARD...AND WIDELY SCATTERED SHOWERS
DEVELOPING LEEWARD/INTERIOR DURING THE AFTERNOON. WILL UPDATE THE
FORECAST SHORTLY TO TWEAK POPS AND SKY COVER.

FROM FRIDAY THROUGH THE WEEKEND...THE NORTHEAST PACIFIC HIGH WILL
REMAIN WEAKER THAN NORMAL...DUE TO A COMBINATION OF A PAIR OF
REMNANT LOWS MOVING SLOWLY WESTWARD ALONG 30N (FORMER EAST
PACIFIC TROPICAL CYCLONES LOWELL AND MARIE) AND A WEAK COLD FRONT
MOVING SLOWLY EASTWARD FROM THE INTERNATIONAL DATELINE. THIS
SYNOPTIC REGIME WILL ALLOW FOR LIGHT TRADE WINDS TO PREVAIL ACROSS
THE STATE...WITH A CONVECTIVE SEABREEZE PATTERN LIKELY TO DEVELOP
ACROSS INTERIOR AND LEEWARD AREAS EACH AFTERNOON. WOULD EXPECT
CLOUDS AND SCATTERED SHOWERS ACROSS INTERIOR/LEEWARD IN THE
AFTERNOONS AND EARLY EVENINGS...WITH SOME CLOUDS AND PASSING
SHOWERS STILL REMAINING OVER WINDWARD AREAS AS WELL. LAND BREEZES
SHOULD CLEAR OUT THE REMAINDER OF THE SMALLER ISLANDS DURING THE
NIGHTTIME HOURS. MID/UPPER LEVEL RIDGING SHOULD MAINTAIN A FAIRLY
STABLE REGIME... BUT THERE WILL BE A COUPLE OF AREAS OF SOMEWHAT
HIGHER MOISTURE (PWATS AROUND 1.5 INCHES) MOVING THROUGH THE STATE
DURING THE WEEKEND. ISOLATED HEAVIER DOWNPOURS WILL BE POSSIBLE
EACH AFTERNOON...WHEN SLOW MOVING SHOWERS WILL BE MOST LIKELY TO
DEVELOP ALONG THE SEABREEZES.

THE LIGHT TRADE WIND PATTERN SEEMS LIKELY TO CONTINUE INTO
EARLY NEXT WEEK...AS THE EAST PACIFIC RIDGE REMAINS RELATIVELY
WEAK AND FAR TO THE NORTH...WITH A WEAK REMNANT LOW MOVING SLOWLY
WESTWARD BETWEEN THE RIDGE AND HAWAII. WOULD EXPECT A CONTINUED
SEABREEZE/LAND BREEZE PATTERN ACROSS LEEWARD/INTERIOR SECTIONS...
WITH SOME CLOUDS AND PASSING SHOWERS PERSISTING WINDWARD. TRADES
MAY INCREASE TO MODERATE LEVELS TOWARD THE MIDDLE AND LATER PART
OF NEXT WEEK...WHICH WOULD BRING A RETURN TO TYPICAL TRADE WIND
WEATHER ACROSS THE STATE.

&&

.AVIATION...
A RELATIVELY DRY AND STABLE AIRMASS OVER THE ISLANDS MEANS VFR
CONDITIONS ARE EXPECTED TO PREVAIL TODAY. LIGHT TRADE WINDS MAY
ALLOW FOR SOME LOCAL SEA BREEZES THIS AFTERNOON...WHICH COULD
BRING A FEW CLOUDS OVER THE INTERIOR OF THE ISLANDS AT THAT TIME.
OTHERWISE...EXPECT A FEW CLOUDS OVER THE WINDWARD AND MOUNTAIN
AREAS. NO AIRMETS ARE EXPECTED AT THIS TIME.

&&

.MARINE...
LATEST DATA FROM THE NEAR SHORE BUOYS JUST EAST OF OAHU AND NORTH
OF MAUI STILL SHOWS NO SIGN OF THE ANTICIPATED LONG PERIOD
EASTERLY SWELL...WHICH ORIGINATED FROM FORMER EAST PACIFIC
HURRICANE MARIE. HOWEVER...THERE IS SOME LONG PERIOD SWELL ENERGY
STARTING TO APPEAR AT BUOY 51004...LOCATED 205 NM SE OF HILO.
ALTHOUGH THE TIMING NOW SEEMS LIKELY TO BE A BIT SLOWER THAN
PREVIOUSLY FORECAST...WE STILL EXPECT THIS SWELL TO BEGIN BUILDING
ACROSS THE NEARSHORE WATERS DURING THE AFTERNOON AND INTO TONIGHT...
WITH ADVISORY LEVEL SURF ACROSS EAST FACING SHORES POSSIBLE LATER
THIS AFTERNOON...BECOMING LIKELY TONIGHT THROUGH FRIDAY. WHILE
SURF HEIGHTS ARE NOT EXPECTED TO BE EXCEPTIONALLY HIGH...LONG
PERIOD SWELL ENERGY FROM THE EAST IS SOMEWHAT UNUSUAL...RESULTING
IN NORMALLY SHELTERED WINDWARD LOCALES SEEING LARGER LONG PERIOD
WAVES AND STRONG CURRENTS.

LATEST DATA FROM THE NEAR SHORE BUOY JUST SOUTHWEST OF OAHU
INDICATE THAT THE EXPECTED SOUTH SWELL HAS ARRIVED...AND MORNING
SURF OBS FROM THE OAHU SOUTH SHORE DO INDICATE ELEVATED SURF NEAR
ADVISORY LEVELS. THIS SWELL IS FORECAST TO BUILD A BIT MORE THROUGH
THE REST OF TODAY INTO TONIGHT...WITH ADVISORY LEVEL SURF EXPECTED
ALONG SOUTH FACING SHORES THROUGH FRIDAY. STRONG CURRENTS WILL
DEVELOP IN SOME AREAS DUE THE INTERACTION BETWEEN THE LONG PERIOD
EAST AND SOUTH SWELLS. THE SURF FROM BOTH SWELLS WILL SLOWLY
DECLINE DURING THE WEEKEND.

AS TRADE WINDS CONTINUE TO DIMINISH...SMALL CRAFT ADVISORY
CRITERIA WINDS OF 25 KT OR GREATER ARE NOT EXPECTED THROUGH THE
REST OF THIS WEEK AND THE HOLIDAY WEEKEND. HOWEVER...THE LONG
PERIOD EASTERLY AND SOUTHERLY SWELL MENTIONED ABOVE COULD BRING
CONFUSED SEAS TO AREAS EXPOSED TO BOTH SWELLS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 AM HST SATURDAY FOR NIIHAU-KAUAI
WINDWARD-KAUAI LEEWARD-OAHU SOUTH SHORE-WAIANAE COAST-OAHU
KOOLAU-OLOMANA-MOLOKAI-LANAI MAKAI-KAHOOLAWE-MAUI WINDWARD WEST-
MAUI LEEWARD WEST-MAUI CENTRAL VALLEY-WINDWARD HALEAKALA-LEEWARD
HALEAKALA-KONA-SOUTH BIG ISLAND-BIG ISLAND NORTH AND EAST.

&&

$$

DISCUSSION/MARINE...JACOBSON
AVIATION...M BALLARD






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