Area Forecast Discussion
Issued by NWS Honolulu, HI

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000
FXHW60 PHFO 260700
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
900 PM HST TUE NOV 25 2014

.SYNOPSIS...
A COOLER AND SOMEWHAT DRIER AIR MASS HAS SETTLED OVER THE ISLANDS
AND WILL LINGER FOR ANOTHER DAY OR TWO. DRY CONDITIONS WILL PREVAIL
ACROSS MOST OF THE STATE OVERNIGHT...BUT LINGERING LOW LEVEL MOISTURE
WILL CONTINUE TO GENERATE FREQUENT SHOWERS ACROSS THE WINDWARD BIG
ISLAND. A STRONG HIGH PRESSURE SYSTEM WILL SETTLE NORTH OF THE
ISLANDS THURSDAY...RESULTING IN BREEZIER TRADES FOR THE REST OF
THE WEEK AND INTO THE WEEKEND. A STABLE AIR MASS WILL KEEP TRADE
SHOWERS MOSTLY LIGHT AND CONFINED TO THE WINDWARD AND MAUKA AREAS.

&&

.DISCUSSION...
CLOUDS HAVE REMAINED ABUNDANT ACROSS WINDWARD SECTIONS OF THE
STATE THIS EVENING. THE SMALLER ISLANDS HAVE BEEN LARGELY DRY
WITH JUST SOME ISOLATED LIGHT SHOWERS OR PATCHES OF DRIZZLE
OVER WINDWARD AREAS...BUT THE WINDWARD BIG ISLAND HAS REMAINED
SOUPY WITH WIDESPREAD RAINFALL CONTINUING. AT THE SURFACE...A
1022 MB HIGH IS CENTERED ABOUT 550 MILES NORTHWEST OF KAUAI...WITH
A COLD FRONT ALONG 30N SEPARATING THIS HIGH FROM A LARGER 1025 MB
HIGH ABOUT 1300 MILES NORTHWEST OF KAUAI. THE 00Z HILO SOUNDING
INDICATES THAT A LOW LEVEL TROUGH CONTINUES TO LINGER OVER THE
CENTRAL PART OF THE STATE...WITH SW WINDS ABOVE 800 MB AND A
SOMEWHAT ELEVATED INVERSION BASED AROUND 7500 FEET. THE LIHUE
SOUNDING FOUND A LOWER INVERSION BASED NEAR 5500 FEET...AND A VERY
DRY PWAT VALUE OF 0.89 INCHES.

LITTLE CHANGE IS EXPECTED OVERNIGHT. THE WINDWARD BIG ISLAND
WILL REMAIN RATHER WET AS LOW LEVEL MOISTURE LINGERS IN THAT
AREA TO THE EAST OF THE DISSIPATING 850-700 MB TROUGH...AND A
FORECAST UPDATE WAS ISSUED EARLIER TO INCREASE POPS IN THAT AREA.
CLOUDS WILL REMAIN WIDESPREAD ACROSS THE OTHER WINDWARD AREAS...
BUT WOULD EXPECT ONLY ISOLATED TO WIDELY SCATTERED SHOWERS DUE TO
THE DRIER AIRMASS IN PLACE OVER THE SMALLER ISLANDS.

THE 850-700 MB TROUGH NEAR MAUI COUNTY SHOULD FINALLY WASH OUT ON
WEDNESDAY...ALLOWING THE STUBBORN STRATOCU WHICH HAS PLAGUED PARTS
OF THE STATE FOR THE PAST COUPLE OF DAYS TO BREAK UP IN THE
AFTERNOON. WOULD EXPECT SHOWER ACTIVITY TO DECREASE ACROSS THE
WINDWARD BIG ISLAND IN THE AFTERNOON AS WELL.

A STRONGER SURFACE HIGH IS THEN FORECAST TO BUILD SLOWLY EASTWARD
TO THE NORTH OF THE STATE BETWEEN 30N AND 40N FROM WEDNESDAY NIGHT
INTO THE WEEKEND. BREEZY CONDITIONS WILL BECOME MORE WIDESPREAD
OVER LAND AREAS DURING THIS TIME AS FRESH TO STRONG TRADE WINDS
PREVAIL. SHOWERS WILL BE MAINLY CONFINED TO WINDWARD AND MAUKA
AREAS THROUGH THE PERIOD...AND MOST COMMON DURING THE NIGHT AND
EARLY MORNING HOURS. WE MAY SEE A MODEST INCREASE IN WINDWARD
SHOWERS ON FRIDAY...WHEN THE REMNANTS OF AN OLD FRONTAL BOUNDARY
REACH THE STATE. BLENDED MODEL DATA KEEPS PWATS AROUND ONE
INCH...WHICH IS BELOW THE 25TH PERCENTILE FOR THIS TIME OF YEAR...
THROUGH THE NEXT SEVERAL DAYS. THEREFORE WOULD EXPECT RAINFALL
AMOUNTS TO REMAIN MOSTLY ON THE LIGHT SIDE EVEN OVER WINDWARD
AREAS. LONG RANGE MODELS DO NOT SHOW ANY INDICATIONS OF ANOTHER
FRONTAL PASSAGE ACROSS THE MAIN HAWAIIAN ISLANDS THROUGH EARLY
NEXT WEEK.

&&

.MARINE...
NORTHWEST SWELL HAS FINALLY STARTED TO SUBSIDE THIS EVENING AT
BOTH BUOY 51101 AND WAIMEA BAY. THE HIGH SURF ADVISORY REMAINS
IN EFFECT FOR NORTH AND WEST FACING SHORES OF KAUAI...AND FOR
NORTH FACING SHORES OF OAHU AND MAUI COUNTY OVERNIGHT. GIVEN
CURRENT TRENDS AND WAVEWATCH GUIDANCE...IT SEEMS LIKELY THAT
THIS ADVISORY WILL BE DROPPED AS SCHEDULED EARLY WEDNESDAY
MORNING.

A NEW NNE SWELL...GENERATED BY A GALE LOW 1400 MILES NORTH
NORTHEAST OF OAHU...IS DUE TO ARRIVE IN THE ISLANDS STARTING
WEDNESDAY AFTERNOON AND PEAKING WEDNESDAY NIGHT. THIS SWELL
COMBINED WITH BUILDING WIND WAVES DUE TO INCREASING TRADE WINDS
WILL CAUSE ROUGH SURF TO DEVELOP ON EAST FACING SHORES...ESPECIALLY
THOSE WITH A NORTHERN EXPOSURE. ADVISORY LEVEL SURF MAY OCCUR
ACROSS SOME OF THE EAST FACING SHORES WEDNESDAY NIGHT INTO EARLY
THURSDAY. SURF WILL BE INCREASING ACROSS NORTH FACING SHORES AS
WELL...BUT IS CURRENTLY EXPECTED TO REMAIN JUST BELOW ADVISORY
LEVELS. THE NNE SWELL WILL ALSO CAUSE A CONCERN FOR HARBOR SURGES
INTO KAHULUI AND HILO HARBORS WEDNESDAY NIGHT.

THE TUESDAY MORNING ASCAT PASS ONCE AGAIN MISSED MOST OF THE
HAWAIIAN COASTAL WATERS...BUT BASED ON RECENT LAND-BASED
OBSERVATIONS HAVE DECIDED TO EXPAND THE SMALL CRAFT ADVISORY /SCA/
TO COVER MAALAEA BAY AND ALENUIHAHA CHANNEL FOR THE OVERNIGHT
PERIOD. THE LINGERING NW SWELL COMBINED WITH WIND WAVES IS STILL
GENERATING COMBINED SEAS NEAR 10 FEET ACROSS A NUMBER OF
ADDITIONAL MAINLY WINDWARD ZONES AS WELL...AND THE SCA ALSO
REMAINS POSTED OVERNIGHT IN THOSE AREAS.

WITH THE NW SWELL SUBSIDING LATE TONIGHT...A MORE TYPICAL SCA
CONFIGURATION IS LIKELY FOR WEDNESDAY...DUE TO STRONG WINDS IN
THE NORMALLY WINDY AREAS AROUND MAUI COUNTY AND THE BIG ISLAND...
AS WELL AS THE KAIWI CHANNEL. THE SCA WILL LIKELY NEED TO EXPAND
ONCE AGAIN WEDNESDAY NIGHT...WHEN THE NEW NNE SWELL COMBINED WITH
INCREASING TRADES WILL PUSH COMBINED SEAS ABOVE 10 FEET ACROSS
SEVERAL ADDITIONAL MARINE ZONES.

&&

.AVIATION...
WITH LOW LEVEL WINDS FROM THE NORTH TO NORTHEAST...LOW CLOUDS...
SOME WITH ACCOMPANYING SHOWERS...ARE MAINLY CONCENTRATED OVER NORTH
CLOCKWISE THROUGH EAST SECTIONS OF THE ISLES. THIS IS WHERE MVFR
CONDITIONS ARE OCCURRING...AT LEAST FROM TIME TO TIME. ON THE BIG
ISLAND...THOUGH...MVFR HAS BEEN MORE PERSISTENT.  ELSEWHERE...VFR
IS THE RULE.

AN AIRMET FOR MOUNTAIN OBSCURATION REMAINS IN EFFECT FOR THE
NORTHEAST QUADRANT OF THE BIG ISLAND.  AN AIRMET FOR LOW LEVEL
TURBULENCE...SOUTH THROUGH WEST OF THE MOUNTAINS...WILL LIKELY BE
POSTED AT SOME POINT WEDNESDAY AS TRADE WINDS RAMP UP.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 AM HST WEDNESDAY FOR NORTH AND WEST
FACING SHORES OF NIIHAU AND KAUAI AND FOR NORTH FACING SHORES OF
OAHU MOLOKAI AND MAUI.

SMALL CRAFT ADVISORY FROM 6 AM WEDNESDAY TO 6 AM HST THURSDAY
FOR BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS.

SMALL CRAFT ADVISORY UNTIL 6 AM HST THURSDAY FOR KAIWI CHANNEL-
MAALAEA BAY-PAILOLO CHANNEL-ALENUIHAHA CHANNEL.

SMALL CRAFT ADVISORY UNTIL 6 AM HST WEDNESDAY FOR KAUAI
NORTHWEST WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-
KAUAI CHANNEL-OAHU WINDWARD WATERS-MAUI COUNTY WINDWARD WATERS.

&&

$$

DISCUSSION/MARINE...JACOBSON
AVIATION...KINEL






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