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000
FXHW60 PHFO 191755 AAA
AFDHFO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HONOLULU HI
800 AM HST SUN MAY 19 2013

.SYNOPSIS...
A SURFACE TROUGH WILL PRODUCE LIGHT SURFACE WINDS A CHANCE OF
LOCALLY HEAVY SHOWERS FROM OAHU TO THE BIG ISLAND TODAY. A WEAK
FRONT WILL BRING NORTH WINDS AND SOME CLOUDS AND SHOWERS TO KAUAI
TODAY. THE TROUGH GRADUALLY WEAKEN AS IT LINGER NEAR THE ISLANDS
THROUGH MID-WEEK. AS HIGH PRESSURE BUILD NORTHEAST OF THE AREA...
TRADE WINDS WILL SPREAD BACK OVER THE ISLANDS BY NEXT WEEKEND. HIGH
SURF WILL CONTINUE ALONG THE SOUTH SHORES INTO MONDAY AND WILL
REMAIN ELEVATED THROUGH MID-WEEK.

&&

.DISCUSSION...
A COMPLICATED WEATHER PATTERN PERSISTS OVER THE CENTRAL NORTH
PACIFIC. WATER VAPOR IMAGERY SHOWS A COLD UPPER LOW NORTH OF THE
ISLANDS DIGGING TO THE SOUTHEAST. MEANWHILE...AT THE SURFACE...A
NEARLY STATIONARY SURFACE TROUGH EXTENDS FROM NORTH NORTHEAST TO
SOUTH SOUTHWEST OVER MAUI. A WEAK COLD FRONT JUST NORTH OF KAUAI IS
MOVING SOUTH AT 10 TO 15 MPH.

CLOUDS ARE ISOLATED OVER MOST AREAS OF THE ISLANDS THIS MORNING
EXCEPT FOR BROKEN CLOUDS AND ISOLATED SHOWERS OVER THE NORTH SHORE
OF KAUAI AND ALONG THE EAST COAST OF THE BIG ISLAND. THERE ARE
SCATTERED MODERATE SHOWERS OVER WATER NORTH AND SOUTH OF MAUI COUNTY
AND OVERCAST CLOUDS AND NUMEROUS SHOWERS JUST SOUTHEAST OF THE BIG
ISLAND. THE SHOWERS EAST OF MAUI ARE MOVING FROM THE SOUTH WHILE
SHOWERS NEAR KAUAI ARE MOVING FROM THE NORTH. THE ATMOSPHERE OVER
THE ISLAND REMAINS UNSTABLE BECAUSE OF THE LOW ALOFT. BALLOON
SOUNDINGS FROM 200 AM SHOWED WEAK ELEVATION INVERSIONS AT 10000 FT
AT LIHUE AND 14000 FT AT HILO...WITH PRECIPITABLE WATER VALUES
OF 1.16 INCHES AT LIHUE AND 1.53 INCHES AT HILO. I HAVE UPDATED THE
FORECASTS TO SHOW FEWER CLOUDS AND LESS CHANCE OF SHOWERS THIS
MORNING.

THE TROUGH NEAR MAUI WILL ALLOW SEA BREEZES TO FORM OVER THE
ISLANDS FROM THE BIG ISLAND TO OAHU LATER TODAY...AND THERE WILL BE
ENOUGH INSTABILITY FOR LOCALLY HEAVY SHOWERS ON THOSE ISLANDS.
THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS ON THE BIG ISLAND.
THE WEATHER ON KAUAI WILL BE DIFFERENT. THE WEAK FRONT WILL MOVE
OVER KAUAI...BRINGING SOME CLOUDS AND SHOWERS BUT THE COOL
NORTHERLY FLOW BEHIND THE FRONT WILL MAKE THE ATMOSPHERE MORE STABLE
AND PREVENT THE SHOWERS FROM BECOMING HEAVY. THE WEAKENING FRONT
WILL BRING CLOUDS AND SHOWERS TO OAHU TONIGHT BEFORE DISSIPATING
NEAR MOLOKAI MONDAY MORNING.

THE SURFACE TROUGH WILL LINGER NEAR THE ISLANDS THROUGH MID-WEEK
ALLOWING DAYTIME SEA BREEZES AND NIGHTTIME LAND BREEZES TO PREVAIL.
THIS PATTERN WILL PRODUCE MOSTLY CLOUDY AFTERNOONS AND EVENINGS WITH
SHOWERS CONCENTRATED OVER INTERIOR AREAS AND PARTLY CLEARING DURING
THE OVERNIGHT HOURS.

LONG RANGE MODELS ARE IN GOOD AGREEMENT SHOWING THE TRADE WINDS
BECOMING WELL-ESTABLISHED BY FRIDAY...AND LOCALLY BREEZY NEXT
WEEKEND. THE CONVECTIVE PATTERN WILL END AND THE TRADES WILL BRING
FOCUS LIGHTER SHOWERS TO WINDWARD AND MAUKA AREAS. ANOTHER TROUGH
ALOFT MAY DIG DOWN OVER THE AREA NEXT WEEKEND AND MAY ENHANCE THE
TRADE WIND SHOWERS.


&&

.AVIATION...
AREAS OF MVFR VIS/CIG IN SHRA WILL PERSIST OVER COASTAL WATERS
AROUND MAUI COUNTY AND THE BIG ISLAND THIS MORNING WITH THE GREATEST
COVERAGE OF CLOUDS AND SHRA SE OF THE BIG ISLAND. THE LIGHT WINDS
WILL ALLOW WIDESPREAD SEA BREEZES TO DEVELOP FROM THE BIG ISLAND TO
OAHU THIS AFTERNOON...WITH CLOUDS AND +SHRA OVER INTERIOR AND
LEEWARD AREAS LEADING TO AREAS OF MVFR VIS/CIG. ISOL IFR CONDITIONS
ARE ALSO POSSIBLE IN AREAS OF +SHRA...AND IN ISOL +TSRA OVER BIG
ISLAND SLOPES THIS AFTERNOON. A WEAK COLD FRONT WILL BRING TEMPO
MVFR CONDITIONS TO THE N SIDE OF KAUAI.

&&

.MARINE...
WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY
LEVELS STATEWIDE THIS WEEK. A SERIES OF SWELLS WILL KEEP ELEVATED
SURF ALONG SOUTH FACING SHORES THROUGH MOST OF THE WEEK. SURF IS
EXPECTED TO REMAIN ABOVE THE ADVISORY THRESHOLD THROUGH AT LEAST
EARLY MONDAY MORNING. A MARINE WEATHER STATEMENT REMAINS POSTED FOR
WAVES BREAKING NEAR CHANNEL ENTRANCES AND POSSIBLE HARBOR SURGES.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 AM HST MONDAY FOR SOUTH FACING SHORES
OF ALL ISLANDS.


&&

$$
DONALDSON