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000
FXHW60 PHFO 161354
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST SUN JUN 16 2013

.SYNOPSIS...
MODERATE TO LOCALLY FRESH TRADE WINDS WILL CONTINUE ACROSS THE ALOHA
STATE FOR THE FIRST FEW DAYS OF THE NEW WORK WEEK. TRADE SHOWERS ARE
FORECAST TO BECOME SOMEWHAT MORE ACTIVE OVER WINDWARD AND MAUKA
AREAS THROUGH TUESDAY DUE TO AN UPPER LEVEL TROUGH IN THE VICINITY
OF THE STATE. A FEW TRADE SHOWERS MAY AFFECT LEEWARD SECTIONS OF
SOME OF THE SMALLER HAWAIIAN ISLANDS...ESPECIALLY DURING THE EARLY
MORNING AND LATE NIGHT HOURS.

&&

.DISCUSSION...
THE RELATIVELY TIGHT PRESSURE GRADIENT SOUTH OF SURFACE HIGH
PRESSURE FAR NORTH OF THE ALOHA STATE IS MAINTAINING MODERATE TO
LOCALLY FRESH TRADE WINDS ACROSS THE ISLANDS EARLY THIS MORNING.
ALOFT...A WEAK MID-TROPOSPHERIC TROUGH LOCATED NEAR THE SOUTHERN END
OF THE STATE IS PROPAGATING SLOWLY TOWARD THE WEST NORTHWEST. THERE
IS ALSO AN UPPER TROPOSPHERIC TROUGH DIGGING SOUTHEASTWARD TOWARD
KAUAI AND OAHU FROM THE NORTHWEST. THE PRESENCE OF THESE TWO
FEATURES IN THE VICINITY OF THE ISLANDS HAS INTRODUCED SLIGHTLY
COOLER AIR ALOFT IN THE MIDDLE AND UPPER LEVELS OF THE ATMOSPHERE.
AS A RESULT...THE EARLY MORNING BALLOON SOUNDINGS FROM KAUAI AND THE
BIG ISLAND SHOW TRADE WIND INVERSIONS IN PLACE AROUND 7000 FEET.

THE SOUNDINGS AND SATELLITE DERIVED PRECIPITABLE WATER /PW/ VALUES
SHOW SLIGHTLY BELOW NORMAL VALUES OF 1.1 TO 1.3 INCHES IN THE
VICINITY OF THE STATE...WITH PW VALUES OF LESS THAN 1 INCH A SHORT
DISTANCE EAST OF THE BIG ISLAND. THEREFORE...EVEN THOUGH THE
ATMOSPHERE IS SLIGHTLY UNSTABLE...THE SUPPLY OF LOW-LEVEL MOISTURE
REMAINS RATHER MEAGER EARLY THIS MORNING. SATELLITE IMAGERY AND
RADAR REFLECTIVITY DATA SHOW SCATTERED TO BROKEN LOW CLOUDS WITH
EMBEDDED SHOWERS...MAINLY ALONG WINDWARD FACING SLOPES AND BEACHES
OF THE ISLAND CHAIN.

THE FORECAST MODELS SHOW SURFACE HIGH PRESSURE WILL REMAIN FAR NORTH
OR NORTH NORTHEAST OF THE ISLANDS FOR THE NEXT FEW DAYS...WHICH WILL
MAINTAIN THE MODERATE TO LOCALLY FRESH LOW-LEVEL TRADE WIND FLOW
ACROSS THE ISLAND CHAIN INTO MID-WEEK. THE MODEL GUIDANCE ALSO
INDICATES THE MID-LEVEL TROUGH WILL CONTINUE TO SLIDE WEST
NORTHWESTWARD IN THE VICINITY OF THE STATE THROUGH MONDAY NIGHT...
WHILE THE AXIS OF THE UPPER LEVEL TROUGH WILL REMAIN JUST TO THE
WEST OF KAUAI THROUGH TUESDAY. THESE FEATURES ALOFT SHOULD CONTINUE
TO SLIGHTLY ENHANCE THE LOW CLOUDS AND SHOWERS CARRIED BY THE
LOW-LEVEL TRADE WIND FLOW...ESPECIALLY ALONG WINDWARD FACING AND
MAUKA SECTIONS DURING THE NIGHTS AND MORNINGS...EARLY THIS WEEK. THE
TRADES WILL ALSO CARRY A FEW LIGHT SHOWERS OVER TO LEEWARD SECTIONS
OF SOME OF THE SMALLER ISLANDS...ESPECIALLY LATE AT NIGHT AND EARLY
IN THE MORNING. THE KONA SIDE OF THE BIG ISLAND WILL SEE A RATHER
TYPICAL TRADE WIND WEATHER PATTERN OF CLOUD BUILD UPS AND ISOLATED
SHOWERS EACH AFTERNOON...WITH CLEARING CONDITIONS AT NIGHT FOLLOWED
BY MOSTLY SUNNY MORNINGS. SINCE THE PW VALUES WILL REMAIN LOW...NO
SERIOUS HEAVY RAIN OR FLOODING PROBLEMS ARE ANTICIPATED.

THE SURFACE HIGH WILL EVENTUALLY SHIFT EASTWARD AND REBUILD FAR
NORTHEAST OF HAWAII EARLY THIS WEEK...PRODUCING A SLIGHT BOOST IN
TRADE WIND SPEEDS. AT THE SAME TIME...EXPECT MID / UPPER LEVEL
RIDGING TO START BECOMING REESTABLISHED OVER THE STATE...WHICH WILL
GRADUALLY MAKE THE ATMOSPHERE MORE STABLE. THIS WILL LIKELY REDUCE
THE COVERAGE OF LOW CLOUDS AND TRADE SHOWERS DURING THE MIDDLE AND
LATE PART OF THE NEW WORK WEEK. AS THE SURFACE HIGH CONTINUES TO
DRIFT EASTWARD...THE TRADE WINDS WILL ALSO GRADUALLY DECREASE FROM
LATE WEDNESDAY INTO THURSDAY. EXPECT A TRADE WIND WEATHER PATTERN TO
REMAIN IN PLACE FROM FRIDAY INTO NEXT WEEKEND BASED ON THE LATEST
FORECAST GUIDANCE.

&&

.AVIATION...
AS THE TRADE WIND WEATHER PATTERN CONTINUES...EXPECT TO SEE SOME
BRIEF PERIODS OF MVFR CONDITIONS IN THE USUAL AREAS ALONG WINDWARD
AND MAUKA SECTIONS OF THE ISLANDS. OTHERWISE...ANTICIPATE VFR
CONDITIONS WILL PREVAIL MOST OF THE TIME...ESPECIALLY OVER THE
LEEWARD SIDES OF THE STATE.

&&

.MARINE...
MODERATE TO LOCALLY FRESH TRADES AND ROUGH ELEVATED SEAS WILL
CONTINUE TO REQUIRE A SMALL CRAFT ADVISORY /SCA/ REMAIN POSTED FOR
THE TYPICAL WINDY WATERS ADJACENT TO THE BIG ISLAND AND THE ISLANDS
OF MAUI COUNTY...AT LEAST THROUGH TUESDAY AFTERNOON. THE SCA WILL
LIKELY NEED TO BE EXTENDED INTO TUESDAY NIGHT...AND POSSIBLY
WEDNESDAY...FOR THE SAME WATERS BASED ON THE PRESENT FORECAST.

EAST FACING SHORES OF THE ISLANDS WILL CONTINUE TO HAVE CHOPPY
MODERATE-SIZED TRADE WIND GENERATED SURF THIS WEEK. NO SIGNIFICANT
SWELLS ARE EXPECTED...INCLUDING FROM SOUTHERN HEMISPHERE
SOURCES...SO SURF WILL REMAIN ON THE SMALL SIDE FOR ALL OTHER
BEACHES AND NEAR SHORE REEFS OF THE ALOHA STATE FROM TODAY THROUGH
FRIDAY. SMALL...LONG PERIOD SOUTH SWELLS WILL MAINTAIN SMALL
BACKGROUND SURF ALONG SOUTH FACING SHORES OF THE ISLANDS THIS WEEK.

&&

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

&&

$$

HOUSTON