Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 091407
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST TUE FEB 9 2016

.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL STAY OVER THE ISLANDS THROUGH
WEDNESDAY...BRINGING COOL AND DRY WEATHER WITH LIGHT WINDS.
GENTLE TRADE WINDS WILL RETURN DURING THE SECOND HALF OF THE WEEK AS
A HIGH PRESSURE PASSES NORTH OF THE STATE. AN APPROACHING FRONT FROM
THE NORTHWEST WILL RESULT IN WINDS TURNING MORE SOUTHEAST FOR THE
SMALLER ISLANDS OVER THE WEEKEND.

&&

.DISCUSSION...
WINDS HAVE EASED ACROSS THE ISLANDS OVERNIGHT AS A RIDGE BUILDS
OVER THE ISLANDS. MOSTLY FAIR WEATHER PREVAILS ACROSS THE
AREA...WITH ONLY FEW LOW CLOUDS ACROSS THE AREA. AIRMASS IS STABLE
AND RATHER DRY AS REVEALED BY EARLY MORNING LIHUE AND HILO
SOUNDINGS...SO THERE IS ALMOST NO PRECIPITATION REPORTED ACROSS THE
STATE. LATEST SATELLITE IMAGERY SHOWED MORE STABLE LOW CLOUDS HAVE
DEVELOPED IN THE ISLAND VICINITY...THOUGH THIS WILL HAVE MINIMAL
IMPACT TO THE WEATHER TODAY. THEREFORE EXPECT ANOTHER FAIR WEATHER
ACROSS THE STATE. LIGHT SYNOPTIC WINDS IN THE AREA WILL ALLOW
WIDESPREAD AFTERNOON SEA BREEZES AND NIGHTTIME LAND BREEZES TO
DEVELOP. AFTERNOON CLOUDS WILL FORM OVER THE ISLANDS...ESPECIALLY
OVER THE BIG ISLAND UNDER DAYTIME HEATING. LIMITED...IF
ANY...PRECIPITATION IS EXPECTED UNDER THE DRY AND STABLE ATMOSPHERE.

TEMPERATURES WILL STILL BE COOLER THAN NORMAL THROUGH WEDNESDAY
WITH DEW POINTS REMAINING IN THE 50/S BEFORE REBOUNDING IN THE
SECOND HALF OF THE WEEK. WITH THE DRY AIR AND THE EXPECTED LIGHT
WINDS...NIGHTTIME AND EARLY MORNING TEMPERATURE WILL LOWER
INTO THE UPPER 50/S FOR SOME LOCATIONS AT THE SEA LEVEL...WITH EVEN
COLDER TEMPS AT THE HIGHER ELEVATIONS.

THE RIDGE IS STILL FORECAST TO LIFT NORTH BY THURSDAY AS A HIGH
PRESSURE SYSTEM PASSES NORTH OF THE STATE. THIS WILL ALLOW LIGHT TO
MODERATE TRADE WINDS TO RETURN. FORECAST MODELS ALSO INDICATE A
SLIGHT INCREASE IN THE MOISTURE IN THE ISLAND VICINITY. LOOK FOR
TRADE WIND WEATHER IN THE LATER PART OF THE WEEK...WITH SOME PASSING
LOW CLOUDS AND SHOWERS AFFECTING MAINLY WINDWARD AREAS.

A COLD FRONT IS FORECAST TO APPROACH THE ISLANDS OVER THE WEEKEND
AND WILL RESULT IN DIMINISHING WINDS OVER THE SMALLER ISLANDS WITH
AFTERNOON SEA BREEZES LIKELY. LATEST FORECAST MODELS HINT THIS FRONT
WILL WEAKEN AND BECOME A SHEARLINE AS A STRONG HIGH PRESSURE BUILDS
BEHIND THIS FEATURE. THIS PENDING SYSTEM MAY BRING MORE WIDESPREAD
CLOUDS AND SHOWERS TO THE ISLANDS AS WELL AS MUCH STRONGER TRADE
WINDS EARLY NEXT WEEK.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL OVER THE AREA. NO AIRMETS ARE IN EFFECT
AND NONE ARE ANTICIPATED THROUGH TODAY.

&&

.MARINE...
A VERY LARGE NORTHWEST SWELL IS EXPECTED TONIGHT...PEAKING
WEDNESDAY...AND THEN SLOWLY SUBSIDE THURSDAY AND FRIDAY. MODEL
GUIDANCE STILL SHOWS PEAK SWELL HEIGHTS AT 16-18 FT BEGINNING
WEDNESDAY MORNING AND CONTINUING THROUGH THE AFTERNOON.
WELL ABOVE WARNING LEVEL SURF WILL BE PRESENT ALONG NORTH AND WEST
FACING SHORES OF MOST SMALLER ISLANDS LATE TONIGHT THROUGH THURSDAY.
SOME SWELL WILL ALSO WORK ITS WAY TO NORTH FACING SHORES ALONG THE
NORTHEAST COAST OF THE BIG ISLAND. MOREOVER...THERE IS ENOUGH OF A
WESTERLY COMPONENT TO THIS SWELL THAT IT WILL AFFECT THE WEST SHORES
OF THE BIG ISLAND LATER ON WEDNESDAY. FOR NOW...A HIGH SURF WARNING
IS POSTED EFFECTIVE 6 PM HST THIS EVENING FOR NORTH AND WEST FACING
SHORES OF NIIHAU KAUAI OAHU MOLOKAI AND NORTH FACING SHORES OF MAUI.
CONDITIONS SHOULD IMPROVE TO BELOW ADVISORY LEVELS BY FRIDAY EVENING.

COASTAL WAVE RUN-UP WILL BE SIGNIFICANT WITH THIS VERY LARGE
SWELL. THE GREATEST REACH WILL OCCUR DURING THE HIGH TIDES FROM
PREDAWN WEDNESDAY INTO THURSDAY MORNING. PREVIOUS LARGE NW SWELLS
HAVE SCOURED SAND FROM THE BEACHES ACROSS MUCH OF THE NORTH AND WEST
FACING COASTLINE. THE LACK OF SAND WILL ALLOW A GREATER WAVE RUN-UP
FOR THIS EVENT...AND ANY UPCOMING LARGE SWELLS RELATIVE TO EARLIER
IN THE SEASON WHEN MORE BEACH SAND WAS PRESENT.

A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE WINDWARD WATERS DUE
TO THE ELEVATED SEAS FROM THE CURRENT SUBSIDING NORTHWEST SWELL. AS
THE NEXT VERY LARGE NORTHWEST SWELL REACHES THE ISLANDS THIS
EVENING...THE COASTAL AREAL COVERAGE OF THE ADVISORY WILL BE
INCREASED.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF WARNING FROM 6 PM THIS EVENING TO 6 PM HST THURSDAY
FOR NIIHAU-KAUAI WINDWARD-KAUAI LEEWARD-WAIANAE COAST-OAHU NORTH
SHORE-OAHU KOOLAU-MOLOKAI-MAUI WINDWARD WEST-MAUI CENTRAL VALLEY-
WINDWARD HALEAKALA.

SMALL CRAFT ADVISORY UNTIL 6 PM HST THURSDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-OAHU WINDWARD WATERS-KAIWI CHANNEL-
MAUI COUNTY WINDWARD WATERS-ALENUIHAHA CHANNEL-BIG ISLAND
WINDWARD WATERS.

SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 PM HST THURSDAY
FOR KAUAI LEEWARD WATERS-KAUAI CHANNEL-OAHU LEEWARD WATERS.

&&

$$

AVIATION...DONALDSON
REST...HUI


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