108 
FXHW60 PHFO 100630
AFDHFO

 AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST MON JUN 9 2014

.SYNOPSIS...
LOCALLY BREEZY TRADE WINDS WILL PREVAIL ACROSS THE MAIN HAWAIIAN 
ISLAND CHAIN DURING THE NEXT SEVERAL DAYS...WITH LOW CLOUDS AND 
PASSING TRADE SHOWERS FAVORING WINDWARD AND MAUKA AREAS...ESPECIALLY 
DURING NIGHTS AND MORNINGS. A SLIGHTLY DRIER AIR MASS MAY SPREAD 
ACROSS THE ALOHA STATE FROM FRIDAY THROUGH THE WEEKEND.

&&

.DISCUSSION...
THE TIGHT PRESSURE GRADIENT SOUTH OF A 1031 MB SURFACE HIGH CENTERED 
NEAR 39N 145W...OR ABOUT 1450 MILES NORTHEAST OF HONOLULU... 
CONTINUES TO MAINTAIN GUSTY TRADE WINDS ACROSS THE MAIN HAWAIIAN 
ISLANDS EARLY THIS EVENING. THIS HIGH IS MOVING TOWARD THE 
SOUTHWEST AT ALMOST 25 MPH. ALOFT...WATER VAPOR IMAGERY INDICATES A 
MID- TO UPPER-LEVEL LOW IS CENTERED NEAR 25.5N 155W...OR ABOUT 350 
MILES NORTH NORTHEAST OF HONOLULU. THIS FEATURE HAS BEEN DRIFTING 
SLOWLY NORTHEASTWARD.

THE COVERAGE OF LOW CLOUDS AND SHOWERS IS RATHER MEAGER ACROSS MOST 
AREAS OF THE ALOHA STATE AT SUNSET THIS EVENING BASED ON SATELLITE 
IMAGERY AND RADAR REFLECTIVITY DATA. THE EARLY AFTERNOON SOUNDINGS 
FROM LIHUE AND HILO SHOWED A SLIGHTLY BETTER DEFINED INVERSION 
BETWEEN 7 AND 8 THOUSAND FEET...COMPARED WITH THE PAST SEVERAL DAYS. 
THE PRECIPITABLE WATER /PW/ VALUES WERE ABOUT 1.3 INCHES AT LIHUE 
AND HILO. SATELLITE DERIVED PW IMAGERY DEPICTS THE LEADING EDGE OF 
AN AREA OF SLIGHTLY HIGHER LOW-LEVEL MOISTURE LESS THAN 100 MILES 
EAST OF HILO. THIS AREA OF SOMEWHAT ENHANCED MOISTURE WILL LIKELY 
MOVE INTO THE EASTERN HALF OF THE MAIN HAWAIIAN ISLAND CHAIN LATER 
TONIGHT. THE RELATIVELY CLOSE PROXIMITY OF THE MID- TO UPPER-LEVEL 
LOW NORTHEAST OF THE AREA MAY PROVIDE A SLIGHT INCREASE IN LOW 
CLOUDS AND TRADE SHOWERS OVER WINDWARD AND MAUKA AREAS OF THE BIG 
ISLAND AND PARTS OF MAUI COUNTY LATER TONIGHT. THE AREA OF SOMEWHAT 
ENHANCED MOISTURE MAY EVENTUALLY SPREAD ACROSS THE REMAINDER OF MAUI 
COUNTY AND OAHU...AND EVENTUALLY KAUAI...ON TUESDAY. 

THERE HAS BEEN NO SIGNIFICANT CHANGE IN THE FORECAST SCENARIO 
THROUGH MID-WEEK. THE TIGHT PRESSURE GRADIENT SOUTH OF PERSISTENT 
HIGH PRESSURE LOCATED FAR NORTH AND NORTHEAST OF THE AREA WILL 
MAINTAIN BREEZY TRADE WINDS ACROSS MOST SECTIONS OF THE ALOHA STATE. 
THE LOW ALOFT WILL PERSIST NORTHEAST OF THE STATE ALSO...WHICH WILL 
LIKELY KEEP THE SUBSIDENCE INVERSION SLIGHTLY WEAKER AND SOMEWHAT 
MORE ELEVATED THAN NORMAL. THESE FORECAST ENVIRONMENTAL CONDITIONS 
COMBINED WITH NEAR TO SLIGHTLY ABOVE NORMAL PW VALUES WILL ALLOW 
TRADE SHOWERS TO REMAIN RELATIVELY ACTIVE ACROSS MOST WINDWARD AND 
MAUKA AREAS...ESPECIALLY DURING NIGHTS AND MORNINGS. SOME OF THESE 
SHOWERS WILL PUSH INTO LEEWARD AREAS OF SOME OF THE SMALLER ISLANDS 
DUE TO THE BREEZY LOW-LEVEL TRADE WIND FLOW...ESPECIALLY LATE AT 
NIGHT AND EARLY IN THE MORNING. A TYPICAL SUMMERTIME PATTERN IS 
EXPECTED TO PREVAIL ALONG SLOPES OF THE LEEWARD BIG ISLAND...WITH 
AFTERNOON / EARLY EVENING CLOUDS AND SHOWERS CLEARING OUT DURING THE 
LATE NIGHT AND MORNING HOURS.

THE LATEST GUIDANCE FROM THE LONG-RANGE FORECAST MODELS CONTINUES TO 
SHOW HIGH PRESSURE FAR NORTH OF THE AREA WILL MAINTAIN A MODERATE TO 
LOCALLY BREEZY TRADE WIND WEATHER PATTERN THROUGH THE NEXT SEVEN 
DAYS...AND BEYOND. THE GUIDANCE ALSO SUGGESTS A DRIER AIR MASS WILL 
SPREAD FROM EAST TO WEST ACROSS THE ALOHA STATE FROM FRIDAY AND 
THROUGH THE WEEKEND. IN FACT...PW VALUES MAY DROP CLOSER TO ONE 
INCH. A LINGERING MID/UPPER LEVEL TROUGH ALSO APPEARS TO REMAIN IN 
RELATIVELY CLOSE PROXIMITY TO THE ISLANDS. AS A RESULT...THE TRADE 
WIND SUBSIDENCE INVERSION MAY REMAIN SOMEWHAT INHIBITED...SO SOME 
LOW CLOUDS AND LIMITED SHOWERS WILL CONTINUE TO BE POSSIBLE...MAINLY 
DURING NIGHT AND MORNINGS OVER WINDWARD AND MAUKA SECTIONS. 
HOWEVER...EXPECT MOST LEEWARD SECTIONS TO REMAIN RATHER DRY. 

&&

.AVIATION...
MODERATE TRADES WINDS CONTINUE OVER THE ISLANDS. THE AREA OF 
INCREASED MOISTURE RIDING IN ON THE TRADES IS STARTING TO APPROACH 
THE BIG ISLAND. SHOWERS EMBEDDED IN THIS AREA ARE LIKELY TO BRING 
PERIODS OF MVFR CIGS/VIS TO THE WINDWARD AREAS OF THE BIG ISLAND... 
TONIGHT AND EARLY TUESDAY MORNING WITH MOISTURE SPREADING TO 
WINDWARD MAUI LATE TONIGHT. AN AIRMET FOR MOUNTAIN OBSCURATION CAN 
NOT BE RULED OUT LATER TONIGHT. ELSEWHERE ON THE SMALLER 
ISLANDS...BRIEF MVFR CONDITIONS ARE EXPECTED WITH PASSING SHOWERS 
BEING CARRIED BY THE TRADES...MAINLY FOR WINDWARD AREAS. 
OTHERWISE...VFR CONDITIONS ARE EXPECTED. 

AIRMET TANGO CONTINUES FOR MECHANICAL TURBULENCE TO THE LEE OF THE 
MOUNTAINS DUE TO THE MODERATE TRADES BLOWING OVER THE ISLANDS.

&&

.MARINE...
FRESH TO LOCALLY STRONG TRADE WINDS WILL PERSIST THROUGH THE REST OF 
THIS WEEK AND INTO THE WEEKEND. AS A RESULT...WINDS IN THE TYPICALLY 
WINDY WATERS ADJACENT TO THE ISLANDS IN MAUI AND HAWAII COUNTIES 
CONTINUE TO MEET SMALL CRAFT ADVISORY /SCA/ CRITERIA. THIS SCA 
CURRENTLY REMAINS IN EFFECT THROUGH WEDNESDAY AFTERNOON. THE 
FORECAST MODELS INDICATE THERE WILL LIKELY BE LITTLE SIGNIFICANT 
CHANGE IN TRADE WIND SPEEDS FOR THROUGH THIS WEEKEND...SO THE SCA 
WILL PROBABLY BE REQUIRED FOR THESE SAME WINDY WATERS FOR THE REST 
OF THIS WEEK.

A RELATIVELY LONG-PERIOD SOUTH SOUTHWEST SWELL...WITH A SWELL HEIGHT 
OF 3 FEET AND A WAVE PERIOD OF 14 TO 15 SECONDS...IS GENERATING 
MODERATE-SIZED SURF ALONG MOST SOUTH FACING SHORES OF THE STATE 
EARLY THIS EVENING. THIS SOUTH SOUTHWEST SWELL IS EXPECTED TO BE 
REINFORCED FROM LATE TUESDAY INTO WEDNESDAY...WITH MODERATE-SIZED 
SURF CONTINUING ALONG SOUTH FACING SHORES. HOWEVER...WE DO NOT 
ANTICIPATE THAT A HIGH SURF ADVISORY WILL BE REQUIRED BASED ON THE 
LATEST GUIDANCE. AS THE SOUTH SWELL FADES TOWARD THE END OF THE WORK 
WEEK...EXPECT SURF HEIGHTS TO GRADUALLY DIMINISH ALONG SOUTH FACING 
THURSDAY AND FRIDAY...WITH SMALL SURF CONTINUING NEXT WEEKEND. 
ELSEWHERE...TYPICAL SHORT-PERIOD TRADE WIND WAVES COMBINED WITH A 
SMALL NORTHEAST SWELL WILL CONTINUE TO PRODUCE MODERATE-SIZED CHOPPY 
SURF ALONG EAST FACING BEACHES AND REEFS THROUGH THE END OF THIS 
WEEK.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 6 PM HST WEDNESDAY FOR MAALAEA BAY...THE 
WATERS SOUTH OF THE BIG ISLAND...AND THE PAILOLO AND ALENUIHAHA 
CHANNELS.

&&

$$

DISCUSSION/MARINE...HOUSTON
AVIATION...EATON