High Surf in Hawaii, March 14 to 17, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
953 AM HST FRI MAR 14 2014

.SYNOPSIS...
A WEAKENING FRONT WILL PASS THROUGH ENHANCING SHOWERS LATE TODAY AND
TONIGHT...BEFORE SURGING HIGH PRESSURE MOVES IN SATURDAY AND
SUNDAY. WINDY CONDITIONS WILL ENVELOPE THE AREA FOR THE
WEEKEND...BEFORE MORE TYPICAL TRADE WIND WEATHER RETURNS FOR NEXT WEEK.

&&

.DISCUSSION...
A QUIET MORNING THUS FAR ACROSS THE STATE WITH TRADE WIND WEATHER
IN FIRM CONTROL. MORNING SOUNDINGS INDICATE INVERSIONS DOWN TO
NEAR 5000 FEET OVER THE WESTERN HALF OF THE STATE WITH HIGHER
INVERSIONS NEAR THE BIG ISLAND AND MAUI. IN RESPONSE TO THESE
HIGHER INVERSIONS SHOWER ACTIVITY IS MORE ENHANCED NEAR MAUI AND
THE BIG ISLAND THIS MORNING. RAINFALL REPORTS INDICATE AMOUNTS ARE
RELATIVELY LIGHT...WITH MAX VALUES IN THE 0.10 TO 0.30 RANGE OVER
THE PAST 12 HOURS GENERALLY OVER WINDWARD BIG ISLAND. SATELLITE
IMAGERY INDICATES A WEAKENING LEFT-OVER FRONT IS LOCATED ABOUT 150
MILES NORTHWEST OF KAUAI. WATER VAPOR IMAGERY IS INDICATING A WEAK
TROUGH OF LOW PRESSURE NORTH OF THE STATE. THIS TROUGH IS FORECAST
TO DRIFT EASTWARD NEAR THE STATE LATER TODAY AND OVERNIGHT. THE
PRESENCE OF THE LEFT-OVER FRONT AND THE TROUGH WILL HELP TO
ENHANCE SHOWERS SOMEWHAT OVER WINDWARD AREAS.

THE MAIN WEATHER FEATURE IMPACTING OUR WEATHER OVER THE NEXT
SEVERAL DAYS IS A STRONG AREA OF HIGH PRESSURE NOW CENTERED FAR TO
THE NORTHWEST. SATELLITE DERIVED WINDS FROM THE ASCAT INSTRUMENT
ARE INDICATING A SWATH OF NORTH TO NORTHEAST WINDS ALONG THE
EASTERN PERIPHERY OF THE HIGH WITH VALUES BETWEEN 20 TO 35 KNOTS.
FORECAST MODELS HAVE BEEN CONSISTENT IN MIGRATING THE HIGH
EASTWARD AND MOVING THE STRONG WINDS OVER THE STATE. THIS WILL
GENERATE A PERIOD OF WINDY CONDITIONS FOR MOST AREAS WITH ADVISORY
AND WARNING LEVEL WINDS PROBABLE. EXACERBATING THE SITUATION WILL
BE STRONG LOW LEVEL INVERSIONS AS THE HIGH BUILDS SOUTHWARD AND
EASTWARD. THESE LOW INVERSIONS WILL COMPRESS THE WINDS BETWEEN THE
INVERSION AND THE MOUNTAINS LEADING TO A HIGH PROBABILITY OF
LEEWARD ACCELERATION. A HIGH WIND WATCH IS IN EFFECT FOR MOST
LEEWARD AREAS ALONG WITH NIIHAU AND LANAI FOR SATURDAY AFTERNOON
THROUGH SUNDAY. WINDS WILL BE FAVORING A NORTHEAST DIRECTION AND
WILL LIKELY BE THE STRONGEST TRADE WINDS SEEN IN THE STATE SINCE
JANUARY OF 2013. RESIDENTS AND VISITORS ALIKE WITH OUTDOOR PLANS
SHOULD EXPECT STRONG WINDS AND POTENTIAL ISSUES WITH
POWERLINES...ROOFS...AND BROKEN TREE BRANCHES. A SPECIAL WEATHER
STATEMENT HAS ALSO BEEN ISSUED TO HIGHLIGHT THE POTENTIAL IMPACTS
FOR THE WEEKEND.

WINDS WILL REMAIN ELEVATED THROUGH SUNDAY...WITH THE PEAK
APPEARING TO BE OVERNIGHT SATURDAY INTO LATE SUNDAY MORNING. THE
HIGH WILL MIGRATE FAR ENOUGH TO THE EAST TO REDUCE THE PRESSURE
GRADIENT AND THE WINDS INTO THE FIRST PART OF NEXT WEEK. MORE
TYPICAL TRADE WIND FLOW IS ANTICIPATED FOR THE REMAINDER OF NEXT WEEK.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL THROUGH TONIGHT...AS MODERATE TRADE
WINDS DELIVER A FEW SHOWERS TO WINDWARD COASTS AND SLOPES. A
PARTICULARLY PERSISTENT CLUMP OF SHRA IS AFFECTING WINDWARD MAUI
THIS MORNING...WHERE AIRMET SIERRA IS CURRENTLY IN EFFECT FOR TEMPO
MOUNTAIN OBSCURATION. THESE CLOUDS AND SHRA SHOULD BE DIMINISHING IN
COVERAGE SHORTLY...ALLOWING THE AIRMET TO BE CANCELLED.

BUILDING TRADE WINDS WILL BECOME ESPECIALLY STRONG OVER THE
WEEKEND...LIKELY LEADING TO THE ISSUANCE OF AIRMET TANGO FOR TURB
TO THE S AND W OF THE MOUNTAINS...SUSTAINED SURFACE WINDS NEAR 30
KT...AND POSSIBLY REQUIRING A SIGMET FOR ISOL SEVERE TURB BY LATE
SATURDAY. MVFR WIND CONDITIONS WILL HIGHLIGHT THE AREA FORECAST FOR
THE BULK OF THE WEEKEND.

&&

.MARINE...
SURF REPORTS INDICATE THAT A BUILDING NORTH-NORTHWEST SWELL IS
BEGINNING TO ARRIVE ACROSS THE STATE. THE SWELL IS EXPECTED TO
RISE TO ADVISORY LEVELS BY THIS AFTERNOON. A SMALL CRAFT ADVISORY
IS IN EFFECT ACROSS THE COASTAL WATERS DUE TO THE ARRIVING SWELL.

STRONG NORTHEAST WINDS ASSOCIATED WITH BUILDING HIGH PRESSURE AT
THE SURFACE ON SATURDAY AND SUNDAY HAVE PROMPTED A GALE WATCH. GALE
FORCE WINDS ARE EXPECTED IN MANY OF THE CHANNELS OVER THE
WEEKEND...MAKING FOR VERY ROUGH AND DANGEROUS SEAS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON
FOR NIIHAU-KAUAI LEEWARD-OAHU SOUTH SHORE-WAIANAE COAST-MOLOKAI
LEEWARD-LANAI-KAHOOLAWE-MAUI LEEWARD WEST-MAUI CENTRAL VALLEY-
LEEWARD HALEAKALA-KOHALA.

HIGH SURF ADVISORY UNTIL 6 AM HST SUNDAY FOR MOST NORTH AND WEST
FACING SHORES.

GALE WATCH FROM SATURDAY MORNING THROUGH LATE SUNDAY NIGHT FOR
KAUAI CHANNEL-KAIWI CHANNEL-MAALAEA BAY-PAILOLO CHANNEL-
ALENUIHAHA CHANNEL-BIG ISLAND WINDWARD WATERS-BIG ISLAND LEEWARD
WATERS-BIG ISLAND SOUTHEAST WATERS.

SMALL CRAFT ADVISORY UNTIL 6 AM HST SATURDAY FOR ALL HAWAIIAN
WATERS-

&&

DISCUSSION/MARINE...CANTIN
AVIATION...BIRCHARD