Area Forecast Discussion
Issued by NWS Honolulu, HI

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000
FXHW60 PHFO 071955
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
955 AM HST TUE JUL 7 2015

.SYNOPSIS...
TRADE WINDS WILL GRADUALLY INCREASE THROUGH WEDNESDAY AS
HIGH PRESSURE BUILDS FAR NORTH OF THE STATE. LOW CLOUDS AND
PASSING SHOWERS WILL FAVOR WINDWARD AND MAUKA AREAS AND MAY REACH
THE LEE AREAS OF THE SMALLER ISLANDS AS THE WINDS STRENGTHEN. A
TROPICAL DISTURBANCE TO THE EAST SOUTHEAST OF THE STATE MAY
IMPACTS OUR WEATHER ON FRIDAY INTO THIS WEEKEND.

&&

.DISCUSSION...
TRADE WIND WEATHER CONTINUES ACROSS THE ISLANDS LATE THIS MORNING...WITH
PASSING LOW CLOUDS AND SHOWERS AFFECTING MAINLY WINDWARD AND MAUKA AREAS.
VISIBLE SATELLITE IMAGERY SHOWS AN AREA OF LOW CLOUDS WITH LIGHT
TO MODERATE SHOWERS IMPACTING THE WINDWARD SIDE OF THE BIG ISLAND
AND MAUI. THESE CLOUDS WILL SPREAD WESTWARD WITH THE TRADE WINDS
AS THE DAY PROGRESSES AND BRING INCREASED CLOUDINESS AND SHOWERS
TO THE WINDWARD SIDES OF MOLOKAI OAHU AND KAUAI THIS EVENING AND WEDNESDAY.
EARLY MORNING SOUNDINGS AT HILO SHOW A WEAK MIDLEVEL INVERSION IN
PLACE WITH PRECIPITABLE WATER /PW/ VALUE OF 1.37 INCHES. AT LIHUE
THIS MORNING...THE ATMOSPHERE IS A BIT MORE DRIER AND STABLE WITH
A PW OF 1.19 INCHES.

SUBTROPICAL HIGH PRESSURE FAR NORTH OF THE STATE IS DRIVING THE
TRADE WINDS ACROSS THE HAWAIIAN ISLANDS. ANTICIPATING THE HIGH
PRESSURE TO STRENGTHEN SLIGHTLY THROUGH WEDNESDAY AND MAINTAIN ON
THURSDAY. TRADE WINDS WILL STRENGTHEN TO FRESH BREEZES TONIGHT AND
TOMORROW AND COULD PUSH OCCASIONAL SHOWERS ONTO THE LEEWARD SIDES
OF THE SMALLER ISLANDS TONIGHT AND WEDNESDAY. HOWEVER...MOST OF
CLOUDS AND SHOWERS WILL FOCUS OVER THE WINDWARD SLOPES UNDER A
TRADE WIND REGIME.

THE FORECAST GETS A BIT MORE COMPLICATED AFTER THURSDAY WITH SEVERAL
SCENARIOS THAT COULD DEVELOP DEPENDING UPON THE PROGRESSION OF
TROPICAL DISTURBANCE 96E LOCATED 1300 MILES EAST-SOUTHEAST OF THE
BIG ISLAND AT THIS TIME. FORECAST MODELS SHOW THIS FEATURE TRACKING
TOWARDS THE WEST-NORTHWEST FROM NOW THROUGH THIS WEEKEND. AS 96E
IS STILL IN ITS DEVELOPING STAGES...NHC IS NOT ISSUING TRACK AND
INTENSITY FORECASTS AT THIS TIME.

MODELS SHOW THE LOW ASSOCIATED WITH 96E TRACKING PARALLEL AND
NORTH OF THE ISLAND CHAIN FROM FRIDAY THROUGH THE WEEKEND WHILE
WEAKENING TO AN OPEN TROPICAL WAVE. IF THIS SCENARIO PLAYS
OUT...WE ANTICIPATE THE TRADE WINDS QUICKLY WEAKENING LATE
THURSDAY OR EARLY FRIDAY AS THE LOW MOVES BETWEEN US AND THE
SUBTROPICAL HIGH. 96E WILL ALSO PUSH VERY MOIST TROPICAL AIR OVER
HAWAII WHICH WILL MAKE CONDITIONS VERY HUMID THIS WEEKEND. HEAT
INDICIES COULD PEAK AT NEARLY 100 DEGREES IN SOME LOW LYING
COASTAL AREAS. THE MOISTURE...AND INSTABILITY TRIGGERED BY 96E
COULD RESULT IN LOCALIZED ACTIVE SHOWERS AND THUNDERSTORMS AT
TIMES FRIDAY THROUGH SUNDAY. A MORE SOUTHERLY TRACK OF THIS
SYSTEM WILL BRING MORE WIND IMPACTS AND LESS HUMIDITY...AND WE
CANNOT BE COMPLETELY CONFIDENT WITH WHICH SCENARIO WILL ACTUALLY
PLAY OUT.

TRADE WINDS WILL BUILD BACK IN EARLY NEXT WEEK AS THE SYSTEM MOVES
AWAY FROM THE AREA.

&&

.AVIATION...
MODERATE AND GUSTY TRADE WINDS WILL INCREASE TO FRESH LEVELS BY
WEDNESDAY. AIRMET TANGO REMAINS POSTED FOR LOW LEVEL TURB SOUTH
THROUGH WEST OF THE TERRAIN...AND WILL LIKELY STAY UP AT LEAST INTO
FRIDAY.

CLOUDS AND SHOWERS WILL CONTINUE TO FAVOR THE WINDWARD AND MOUNTAIN
AREAS. AN ENHANCED AREA OF LOW CLOUDS IS SPREADING WEST FROM THE BIG
ISLAND AND REACHING EAST MAUI AS OF 20Z. CLOUD TOPS WILL GENERALLY
RANGE FROM 8 TO 10 THOUSAND FEET. THIS AREA OF LOW CLOUDS IS
FORECAST TO BE NEAR KAUAI LATER THIS EVENING. IT WILL LIKELY LOWER
CIGS AND INCREASE CLOUDS AND SHOWERS ALONG WINDWARD AND MOUNTAIN
AREAS AS IT MOVES WEST. THE POSSIBILITY OF AIRMET SIERRA FOR
MOUNTAIN OBSCURATIONS CAN NOT BE RULED OUT...AND WILL MONITOR
CONDITIONS AND ISSUE IF NECESSARY. OTHERWISE...VFR SHOULD PREVAIL.

&&

.MARINE...
SURF ASSOCIATED WITH THE CURRENT SOUTHERLY SWELLS WILL REMAIN ABOVE
ADVISORY HEIGHTS THROUGH WEDNESDAY...THUS THE HIGH SURF ADVISORY FOR
SOUTH FACING SHORES CONTINUES. THE CURRENT SOUTHERLY SWELLS WILL
DECLINE ON THURSDAY. REINFORCING SOUTHWEST SWELLS ARE EXPECTED TO
BOOST SURF HEIGHTS AGAIN ALONG SOUTH FACING SHORES FROM FRIDAY
THROUGH THIS WEEKEND...THOUGH SURF HEIGHTS ALONG SOUTH FACING
SHORES ARE EXPECTED TO STAY BELOW ADVISORY LEVEL.

A SMALL CRAFT ADVISORY /SCA/ IS IN EFFECT THROUGH WEDNESDAY FOR
THE TYPICAL WINDY COASTAL ZONES AROUND MAUI COUNTY AND THE BIG
ISLAND DUE TO THE WINDS. THE SCA WILL LIKELY NEED TO BE EXTENDED INTO
THURSDAY AS THE PRESSURE GRADIENT ACROSS HAWAII TIGHTENS DUE TO
THE PRESENCE OF TROPICAL DISTURBANCE 96E NEARING THE HAWAIIAN
ISLANDS. LOW CONFIDENCE FOR WIND IMPACTS FRIDAY INTO THIS WEEKEND.

&&

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

SMALL CRAFT ADVISORY UNTIL 6 PM HST WEDNESDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.

&&

$$

DISCUSSION/MARINE...FOSTER
AVIATION...EATON




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