Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 210146
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST THU NOV 20 2014

.SYNOPSIS...
TRADE WIND WEATHER SHOULD CONTINUE INTO THE START OF THE WEEKEND DUE
TO HIGH PRESSURE TO THE NORTHEAST OF THE ISLANDS. EXPECT SHOWERS TO
REMAIN FOCUSED OVER THE WINDWARD AND MAUKA AREAS OF THE ISLANDS. THE
SECOND HALF OF THE WEEKEND WILL SEE A FRONT APPROACH FROM THE
NORTHWEST...WHICH WILL TURN WINDS LIGHT AND SOUTHERLY. THE FRONT IS
EXPECTED TO BEGIN MOVING DOWN THE ISLAND CHAIN SUNDAY NIGHT AND
MONDAY...BRINGING SHOWERS TO THE ISLANDS. BEHIND THE FRONT...EXPECT
WINDS TO INCREASE OUT OF THE NORTH.

&&

.DISCUSSION...
ISOLATED MIDDAY CONVECTION DID FIRE OVER THE INTERIOR OF THE BIG
ISLAND...AS THE LOW LEVEL MOISTURE MOVED OVER THE ISLANDS FROM EAST
TO WEST. THIS AFTERNOON WE/RE STARTING TO SEE THE CLOUDS AND SHOWERS
OVER THE BIG ISLAND BEGIN TO FADE AS THAT MOISTURE MOVES TO THE WEST
AND THINS OUT.

HIGH PRESSURE TO THE NORTHEAST OF THE ISLANDS IS EXPECTED TO REMAIN
NEARLY STATIONARY INTO SATURDAY...SO EXPECT A TRADE WIND FLOW TO
CONTINUE...HOWEVER WINDS SHOULD DECREASE SOME OVERNIGHT AND FRIDAY
AS THE PRESSURE GRADIENT OVER THE ISLAND RELAXES.

THE GFS AND ECMWF BOTH ARE IN PRETTY GOOD AGREEMENT WITH THE
HANDLING OF THE NEXT FRONTAL SYSTEM. BOTH MODELS SHOW THE FRONT
APPROACHING THE ISLANDS FROM THE NORTHWEST ON SUNDAY...REACHING
KAUAI AND OAHU SUNDAY NIGHT. THEN AS IT MOVES TOWARDS MAUI COUNTY
MONDAY...IT STARTS TO WEAKEN. HAVE MADE SOME MODIFICATIONS TO THE
POP AND RELATED GRIDS FOR SUNDAY THROUGH MONDAY NIGHT AS A
RESULT...WITH A MORE DEFINITIVE BAND OF SHOWERS MAKING ITS WAY TO
KAUAI AND OAHU.

AHEAD OF THE FRONT...WINDS WILL TURN SOUTHERLY AND BE ON THE WEAK
SIDE. BEHIND THE FRONT...THE WINDS ARE EXPECTED TO TURN TO THE NORTH
AND INCREASE. WHILE THE GRIDS DO CURRENTLY ADDRESS THESE NORTHERLY
WINDS...HOW DRY THE AIRMASS IS BEHIND THE FRONT WILL PLAY A FACTOR
INTO HOW STRONG THE WINDS ARE.

LONGER RANGE...THE WINDS SHOULD THEN BECOME MORE TRADE LIKE BY
MIDWEEK...WITH SHOWERS RETURNING TO THE TYPICAL WINDWARD AND MAUKA
AREAS.

&&

.AVIATION...
THUNDERSTORM ACTIVITY HAS DECREASED OVER THE BIG ISLAND. THE AREA OF
ENHANCED MOISTURE AND THE WEAK SURFACE TROUGH CONTINUE TO TRACK
WESTWARD. AREAS OF THE BIG ISLANDS CAN EXPECT CONDITIONS TO CONTINUE
TO IMPROVE INTO THE EVENING. LEEWARD AND SE COASTAL WATERS MAY HAVE
LINGERING CLOUDS AND SHOWERS WITH ISOL TCU TOPS BETWEEN 20 AND 25
KFT. ANOTHER BATCH OF MOISTURE LOOKS TO BE HEADING TOWARD THE BIG
ISLAND EARLY FRIDAY MORNING. THIS WILL ACT TO INCREASE CLOUD COVER
AND SHOWERS...ESPECIALLY FOR WINDWARD BIG ISLAND EARLY IN THE
MORNING.
AIRMET SIERRA MAY BE NEED AT THAT TIME.

TRADE WINDS HAVE EASED SLIGHTLY AND VAD WIND PROFILES ARE NOW
SHOWING MOSTLY E WINDS BETWEEN 10 AND 15 KT. THEREFORE...AIRMET
TANGO
FOR LOW LEVEL TURB HAS BEEN DROPPED. TRADE WINDS ARE EXPECTED TO
CONTINUE FRIDAY BEFORE VEERING SE SATURDAY AND SUNDAY AS A FRONT
APPROACHES FROM THE NW.

OTHERWISE...VFR CONDITIONS SHOULD PREVAIL...WITH ONLY TEMPO MVFR
CONDITIONS IN PASSING SHOWERS...MAINLY FOR WINDWARD AND MOUNTAIN
AREAS.

&&

.MARINE...
WINDS TODAY REMAINED NEAR SMALL CRAFT ADVISORY /SCA/ LEVELS NEAR THE
KAIWI CHANNEL...BUT ARE ON THE DOWNWARD TREND...SO HAVE DROPPED THE
ADVISORY FOR KAIWI CHANNEL WITH THIS PACKAGE. THE SCA REMAINS POSTED
FOR THE REMAINING WINDIER WATERS INTO FRIDAY NIGHT. WINDS WILL
LIKELY PICK UP AGAIN BEHIND THE FRONT...WHICH COULD MEAN MORE SCA
EARLY NEXT WEEK.

NORTHWEST SWELLS ARE EXPECTED TO CONTINUE THROUGH SATURDAY NIGHT
BRINGING MODEST SURF LEVELS. A SLIGHTLY LARGER SWELL IS EXPECTED TO
ARRIVE SUNDAY...WHICH COULD BRING NEAR ADVISORY LEVEL SURF TO NORTH
AND WEST FACING SHORES OF THE SMALLER ISLANDS THROUGH MONDAY. THIS
SWELL COMBINED WITH THE NORTHERLY WINDS BEHIND THE FRONT COULD BRING
SCA CONDITIONS TO VARIOUS WATERS.

ELSEWHERE...ROUGH SURF DUE TO TRADE WIND GENERATED WAVES ALONG EAST
FACING SHORES IS EXPECTED TO REMAIN BELOW THE HIGH SURF ADVISORY
CRITERIA THROUGH TONIGHT. SURF WILL GRADUALLY DECLINE ALONG EAST
FACING SHORES FROM FRIDAY THROUGH THIS WEEKEND AS THE TRADE WINDS
DIMINISH.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL MIDNIGHT HST FRIDAY NIGHT FOR MAALAEA
BAY...THE WATER SOUTH OF THE BIG ISLAND...AND THE PAILOLO AND
ALENUIHAHA CHANNELS.

&&

$$

DISCUSSION/MARINE...M BALLARD
AVIATION...EATON





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