Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 300654
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST FRI AUG 29 2014

.SYNOPSIS...
GENTLE TRADE WINDS WILL PREVAIL ACROSS THE ALOHA STATE THROUGH THE
LABOR DAY HOLIDAY WEEKEND. THESE LIGHTER WINDS WILL ALLOW LOCAL
SEABREEZES TO DEVELOP ACROSS MOST INTERIOR AND LEEWARD SECTIONS EACH
AFTERNOON...PRODUCING LOCALIZED CLOUD BUILDUPS AND SOME SHOWERS.
LOCAL LAND BREEZES WILL BRING CLEARING SKIES OVER THESE SAME AREAS
AT NIGHT. THE WEAK TRADE WINDS WILL CONTINUE TO CARRY SOME LOW
CLOUDS AND BRIEF SHOWERS INTO WINDWARD AND MAUKA AREAS...ESPECIALLY
NIGHTS AND MORNINGS. A MORE TYPICAL TRADE WIND WEATHER PATTERN MAY
RETURN TO THE ISLANDS BY THE MIDDLE OF NEXT WEEK.

&&

.DISCUSSION...
THE PRESSURE GRADIENT SOUTH OF A 1025 MB SUBTROPICAL SURFACE HIGH
NEAR 40N 161W...OR MORE THAN 1300 MILES NORTH OF HONOLULU...
CONTINUES TO MAINTAIN THE LOW-LEVEL TRADE WIND FLOW ACROSS THE ALOHA
STATE EARLY THIS EVENING. THIS HIGH IS MOVING TOWARD THE EAST AT
ABOUT 10 MPH. THE REMNANT SURFACE TROUGH ASSOCIATED WITH FORMER
NORTHEASTERN PACIFIC TROPICAL CYCLONE LOWELL...WHICH IS LOCATED
ABOUT 700 MILES NORTH OF HILO...IS MOVING WESTWARD AT ABOUT 10 MPH.
SATELLITE IMAGERY ALSO INDICATES THERE IS A SMALL LOW CLOUD SWIRL...
APPARENTLY DENOTING A WEAK LOW-LEVEL TROUGH...CENTERED ABOUT 180
MILES EAST NORTHEAST OF HILO AND MOVING SLOWLY TOWARD THE WEST
SOUTHWEST.

LOOPS OF WATER VAPOR IMAGERY SHOW AN EAST NORTHEAST TO WEST
SOUTHWEST ORIENTED UPPER TROPOSPHERIC RIDGE NEAR THE BIG ISLAND. IN
ADDITION TO THIS FEATURE...THERE IS SIGNIFICANT SUBSIDENCE HIGH
ABOVE MOST OF THE ISLANDS. THE PRESENCE OF THE RIDGING AND THE
SINKING AIR ALOFT ARE MAINTAINING STABLE ATMOSPHERIC CONDITIONS
ACROSS THE MAIN HAWAIIAN ISLANDS THIS EVENING. THE PRECIPITABLE
WATER VALUES RANGED FROM 1.02 INCHES AT LIHUE TO 1.5 INCHES AT HILO
EARLIER THIS AFTERNOON. ALSO...ABOVE NORMAL TRADE WIND INVERSIONS
AROUND 10 THOUSAND FEET CONTINUE TO BE PRESENT IN THE SOUNDINGS.

THE FORECAST MODELS INDICATE THE SUBTROPICAL HIGH WILL REMAIN RATHER
WEAK AND FAR TO THE NORTH OF THE AREA THROUGH THE LABOR DAY HOLIDAY
WEEKEND. IN ADDITION...THE SURFACE TROUGH ASSOCIATED WITH THE
REMNANTS OF LOWELL...AS WELL AS THE LOW CLOUD SWIRL EAST NORTHEAST
OF THE BIG ISLAND...WILL BE NORTH OF THE ISLANDS BY SATURDAY. THE
PRESENCE OF THIS LOWER PRESSURE TO THE NORTH OF THE STATE SHOULD
CAUSE A SLACKENING OF THE PRESSURE GRADIENT. AS A RESULT...WE EXPECT
THE TRADE WINDS SPEEDS WILL CONTINUE TO WEAKEN. AT THE SAME TIME...
THE UPPER LEVEL RIDGING IN THE VICINITY OF THE ISLANDS SHOULD
MAINTAIN A RELATIVELY STABLE ATMOSPHERIC REGIME OVER THE STATE.

THE LIGHT TO GENTLE TRADE WINDS WILL LIKELY LEAD TO A DIURNAL
CONVECTIVE PATTERN OF LOCAL AFTERNOON SEABREEZES AND NIGHTTIME
LANDBREEZES THIS WEEKEND. THIS WEATHER PATTERN TYPICALLY PRODUCES
LOCALIZED CLOUD BUILD UPS WITH ISOLATED SHOWERS ACROSS SOME INTERIOR
AND LEEWARD AREAS OF THE ISLAND CHAIN EACH AFTERNOON. AT THE SAME
TIME...THE WEAK LOW-LEVEL TRADE FLOW MAY CONTINUE TO TRANSPORT SOME
LOW CLOUDS AND BRIEF SHOWERS INTO WINDWARD FACING SLOPES AND HIGHER
TERRAIN...ESPECIALLY DURING NIGHTS AND EARLY MORNINGS. AT NIGHT...
THE LAND BREEZES SHOULD CLEAR SKIES OVER MOST OF THE REMAINDER OF
THE SMALLER ISLANDS. NOTE THAT THE ARRIVAL OF THE SMALL LOW CLOUD
SWIRL MAY PROVIDE SOME LOCAL INCREASE IN MOISTURE OVER SOME OF THE
ISLANDS SATURDAY OR SATURDAY NIGHT.

THE GENTLE TRADE WIND WEATHER PATTERN WILL LIKELY CONTINUE AT LEAST
THROUGH LABOR DAY. THE FORECAST MODELS APPEAR TO INDICATE THE TRADE
WINDS MAY RETURN TO MODERATE SPEEDS DURING THE MIDDLE AND LATER PART
OF NEXT WEEK. THIS WILL LIKELY BRING A RETURN TO A MORE TYPICAL
TRADE WIND WEATHER PATTERN ACROSS THE STATE.

&&

.AVIATION...
LIGHT TRADES WILL CONTINUE OVERNIGHT WITH SOME LOCAL LAND BREEZES.
ISOLATED SHOWERS MAY BRING ISOLATED MVFR CONDITIONS...BUT OVERALL
VFR CONDITIONS ARE EXPECTED TO PREVAIL. LIGHT TRADES SATURDAY MAY
ALLOW FOR SOME AFTERNOON SEA BREEZES...BUT AGAIN VFR CONDITIONS ARE
EXPECTED TO PREVAIL. NO AIRMETS ARE IN EFFECT.

&&

.MARINE...
ABOVE NORMAL SURF PRODUCED BY THE CURRENT SOUTH SWELL CONTINUES TO
REQUIRE A HIGH SURF ADVISORY ALONG SOUTH FACING SHORES OF THE MAIN
HAWAIIAN ISLAND CHAIN EARLY THIS EVENING. THE BARBERS POINT BUOY
CONTINUES TO SHOW A SIGNIFICANT WAVE HEIGHT OF 4 TO 5 FEET WITH A
PERIOD OF AROUND 14 SECONDS FROM AN AZIMUTH OF 190 DEGREES. GUIDANCE
FROM THE WAVE WATCH III MODEL SUGGESTS THIS ELEVATED SURF WILL
CONTINUE THROUGH SATURDAY NIGHT. AS A RESULT...THE HIGH SURF
ADVISORY REMAINS IN EFFECT THROUGH 6 AM HST SUNDAY. LOOKING
AHEAD...ANOTHER REINFORCING SOUTH SWELL IS FORECAST TO ARRIVE ON
SUNDAY...WITH YET ANOTHER VERY LONG-PERIOD SOUTH SWELL FORECAST TO
ARRIVE ON TUESDAY...AND CONTINUE FROM WEDNESDAY THROUGH THURSDAY.
SURF MAY REMAIN NEAR OR ABOVE THE HIGH SURF ADVISORY CRITERIA ALONG
SOUTH FACING SHORES THROUGH THE MIDDLE OF NEXT WEEK.

THE LIGHT TRADE WINDS WILL KEEP WINDS WELL BELOW THE SMALL CRAFT
ADVISORY CRITERIA INTO EARLY NEXT WEEK.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 AM HST SUNDAY FOR SOUTH FACING SHORES OF
NIIHAU...KAUAI...OAHU...MOLOKAI...LANAI...KAHOOLAWE...MAUI  AND THE
BIG ISLAND.

&&

$$

DISCUSSION/MARINE...HOUSTON
AVIATION...MBALLARD







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