Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 060614
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
814 PM HST TUE MAY 5 2015

.SYNOPSIS...
MODERATE TO FRESH TRADE WINDS WILL CONTINUE THROUGH THURSDAY...
THEN INCREASE ON FRIDAY...AND REMAIN STRONG THROUGH THE WEEKEND
AND INTO NEXT WEEK. CLOUDS AND SHOWERS WILL BE MOST ACTIVE OVER
WINDWARD SLOPES AND COASTS DURING NIGHTS AND MORNINGS...ALTHOUGH
A FEW SHOWERS WILL BE BLOWN OVER INTO LEEWARD AREAS AT TIMES.

&&

.DISCUSSION...
SCATTERED SHOWERS ARE PRESENT ACROSS PORTIONS OF THE HAWAIIAN
COASTAL WATERS...BUT MOST LAND AREAS HAVE REMAINED DRY DURING THE
PAST FEW HOURS. MODERATE TO FRESH TRADES CONTINUE ACROSS THE STATE...
DRIVEN BY A 1032 MB SURFACE HIGH CENTERED ABOUT 1400 MILES NE OF PHNL.
A NON-DESCRIPT PATTERN PREVAILS ALOFT...WITH GENERALLY ZONAL FLOW
OVER THE REGION. MIMIC-TPW SATELLITE IMAGERY SHOWS A RELATIVELY
DRY AND HOMOGENEOUS AIRMASS AROUND THE STATE...WITH DEEP TROPICAL
MOISTURE CONFINED WELL SOUTH OF THE BIG ISLAND...AND A STRIPE OF
SOMEWHAT HIGHER MOISTURE ALONG A WEAK FRONT FAR TO THE NW OF KAUAI.
A SMALL POCKET OF SLIGHTLY ENHANCED MOISTURE IS MOVING INTO THE
COASTAL WATERS EAST OF MAUI...AND IS MARKED BY AN AREA OF SHOWERY
LOW CLOUDS. THE 00Z SOUNDINGS DEPICT SOMEWHAT ELEVATED INVERSIONS
BASED BETWEEN 8K AND 10K FEET...WITH NEAR NORMAL PWATS RANGING
FROM 1.14 TO 1.32 INCHES.

OVERNIGHT INTO WEDNESDAY MORNING...THE AREA OF SLIGHTLY HIGHER
MOISTURE AND SHOWERY LOW CLOUDS STILL APPEARS ON TRACK TO REACH
MAUI AFTER MIDNIGHT...THEN SPREAD ACROSS OAHU AND KAUAI WEDNESDAY
MORNING. SHOWERS SHOULD INCREASE ACROSS WINDWARD COASTS AND SLOPES...
WITH THE ELEVATED INVERSIONS AND FRESH TRADES ALLOWING SOME SHOWERS
TO CARRY OVER INTO SELECTED LEEWARD AREAS...ESPECIALLY THOSE JUST
TO THE LEE OF THE HIGHER TERRAIN. MAY NUDGE HIGHER RAIN CHANCES
AND CLOUDS A BIT FURTHER INTO SOME LEEWARD AREAS FOR LATE TONIGHT
INTO WEDNESDAY MORNING. OTHERWISE...THE EXISTING FORECAST APPEARS
TO BE ON TRACK.

LITTLE CHANGE IS EXPECTED THROUGH THURSDAY...WITH MODERATE TO FRESH
TRADES CONTINUING. HIGH PRESSURE FAR NE OF THE STATE WILL SLOWLY
WEAKEN AS A FRONT MOVES ACROSS THE NORTH PACIFIC...BUT MODELS SHOW
THE LOCAL PRESSURE GRADIENT OVER THE ISLANDS REMAINING MORE OR
LESS CONSTANT. A NEW HIGH WILL BUILD NORTH OF THE STATE FRIDAY
INTO THE WEEKEND...WHICH SHOULD INCREASE TRADE WIND FLOW FURTHER.
SHOWERS AND CLOUDS SHOULD REMAIN MOST PREVALENT ACROSS WINDWARD
COASTS/SLOPES DURING THE NIGHT AND MORNING HOURS. PATCHES OF
SLIGHTLY ENHANCED MOISTURE EMBEDDED IN THE TRADES WILL INCREASE
WINDWARD SHOWERS AT TIMES...AND THE BRISK TRADES ALONG WITH
CONTINUED RELATIVELY HIGH INVERSIONS WILL PROBABLY CARRY SOME OF
THESE SHOWERS OVER INTO SOME LEEWARD AREAS. MODEL CONSENSUS
DEPICTS A MID LEVEL TROUGH DEVELOPING NEARBY OVER THE WEEKEND...
AND ASSOCIATED MID LEVEL COOLING COULD CAUSE THE INVERSION TO RISE
A BIT MORE AND LEAD TO INCREASED TRADE WIND SHOWERS. OVERALL...DO
NOT EXPECT ANY MAJOR CHANGES TO THE ONGOING TRADE WIND PATTERN
THROUGH AT LEAST EARLY NEXT WEEK.

&&

.AVIATION...
MODERATE TO FRESH TRADE WINDS WILL CONTINUE THROUGH WEDNESDAY.
AIRMET TANGO FOR LOW LEVEL TURB OVER AND S THRU W OF THE TERRAIN
WILL REMAIN POSTED UNDER THE BRISK WINDS.

ANOTHER AREA OF LOW CLOUDS REACHED WINDWARD BIG ISLAND EARLIER THIS
EVENING. CLOUDS WILL SPREAD TO THE REST OF THE ISLANDS THROUGH
THE REST OF THE EVENING INTO EARLY WEDNESDAY MORNING...BRINGING
BRIEF MVFR CEILING CONDITION MAINLY TO WINDWARD AREAS. SOME OF THE
LOW CLOUDS MAY REACH THE LEE AREAS OF THE SMALLER ISLANDS.
REGARDLESS...EXPECT MAINLY VFR CONDITIONS TO PREVAIL FOR THE
SITES.

&&

.MARINE...
A SMALL CRAFT ADVISORY /SCA/ REMAINS IN EFFECT THROUGH FRIDAY FOR
THE TYPICALLY WINDIER MARINE ZONES AROUND MAUI COUNTY AND THE BIG
ISLAND. THE SCA FOR THESE AREAS WILL ALMOST CERTAINLY NEED TO BE
EXTENDED THROUGH THE WEEKEND AS A NEW HIGH BUILDS N OF THE
ISLANDS...WITH NEAR GALE FORCE WINDS ANTICIPATED IN SOME OF THE
CHANNELS. THE SCA MAY ALSO NEED TO BE EXPANDED TO OTHER MARINE
ZONES THIS WEEKEND.

THE TRADE WINDS WILL MAINTAIN ELEVATED SHORT PERIOD SURF ALONG
E FACING SHORES THROUGH THE NEXT SEVERAL DAYS...THOUGH HEIGHTS
SHOULD REMAIN BELOW ADVISORY LEVELS. WAVE WATCH GUIDANCE
INDICATES LARGEST WAVES ALONG E FACING SHORES WILL OCCUR THIS
WEEKEND. AN EXPECTED LONG-PERIOD SSW SWELL IS CURRENTLY ARRIVING
IN HAWAIIAN COASTAL WATERS...WITH BUOYS AROUND THE ISLANDS
INDICATING INCREASING LONG PERIOD ENERGY THIS EVENING. SWELL IS
EXPECTED TO CONTINUE BUILDING OVERNIGHT...PEAK ON WEDNESDAY...AND
THEN GRADUALLY LOWER INTO THE WEEKEND AS SEVERAL SMALLER PULSES OF
SWELL ARRIVE FROM THE S HEMISPHERE. A HIGH SURF ADVISORY HAS BEEN
ISSUED FOR S FACING SHORES OF ALL ISLANDS. IT IS WORTH NOTING THAT
THE LOW RESPONSIBLE FOR THIS SWELL IS NOT RELATED TO THE LOWS THAT
RECENTLY SENT DAMAGING SURF TO A LARGE PORTION OF THE AMERICAS.
OTHERWISE...A TINY N SWELL WILL LINGER INTO WEDNESDAY...WITH A
SLIGHTLY LARGER NNW SWELL EXPECTED FROM THURSDAY INTO SATURDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY FROM 4 AM WEDNESDAY TO 10 AM HST THURSDAY FOR
SOUTH FACING SHORES OF NIIHAU KAUAI OAHU MOLOKAI MAUI KAHOOLAWE AND
THE BIG ISLAND.

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

&&

$$

DISCUSSION/MARINE...JACOBSON
AVIATION...HUI






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