High Surf Warning 14, NWS Honolulu, HI

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE HONOLULU HI
915 PM HST SAT DEC 19 2015

.UPDATE...
A WIND ADVISORY AND A WINTER WEATHER ADVISORY HAVE BEEN ISSUED FOR
THE BIG ISLAND SUMMITS...AND THE WATCH/WARNING/ADVISORY SECTION
BELOW HAS BEEN UPDATED.

&&

.SYNOPSIS...
HIGH PRESSURE NORTH-NORTHEAST OF THE ISLANDS WILL SUPPORT TRADE
WINDS OVER THE ISLANDS FOR MOST OF THE NEXT WEEK. WINDS WILL BE
ESPECIALLY STRONG AND GUSTY THROUGH MONDAY...AND A WIND ADVISORY IS
IN EFFECT FOR THE ENTIRE STATE. AN UPPER-LEVEL DISTURBANCE COMBINED
WITH MOISTURE ASSOCIATED WITH AN OLD FRONT WILL CAUSE THE TRADE WIND
FLOW TO BE ESPECIALLY WET STATEWIDE TONIGHT. AS THE DISTURBANCE
MOVES SOUTH OF THE BIG ISLAND...SHOWERS WILL BE ESPECIALLY ACTIVE
OVER WINDWARD BIG ISLAND SUNDAY. ANOTHER BOUT OF ACTIVE TRADE WIND
SHOWERS IS EXPECTED STATEWIDE FROM SUNDAY NIGHT INTO WEDNESDAY AS
THE DISTURBANCE MOVES NORTH. WEAKER TRADE WINDS AND FEWER SHOWERS
ARE EXPECTED FOR THE SECOND HALF OF THE WEEK.

&&

.DISCUSSION...
NEARLY STATIONARY STRONG HIGH PRESSURE CENTERED ABOUT 900 MILES NE
OF THE ISLANDS IS SUPPLYING STRONG AND GUSTY TRADE WINDS. A WIND
ADVISORY REMAINS IN EFFECT STATEWIDE...DUE TO WIND GUSTS NEAR 50
MPH. CONCURRENTLY...ENHANCED MOISTURE ASSOCIATED WITH AN OLD FRONT
IS ORIENTED E-W ACROSS THE ISLAND CHAIN WHILE A SHARPENING E-W
ORIENTED TROUGH ALOFT IS STRADDLING THE ISLAND CHAIN. THIS
COMBINATION IS LEADING TO LOCALLY HEAVY TRADE SHOWERS THAT ARE
EASILY SPREADING LEEWARD ON THE SMALLER ISLANDS...WITH RADAR WIND
PROFILES INDICATING 30 TO 40 MPH E WINDS EXTENDING AS HIGH AS 12
THOUSAND FEET. COLD MID-LEVEL TEMPERATURES ASSOCIATED WITH THE
TROUGH HAVE ERODED THE INVERSION TO THE EXTENT THAT THUNDERSTORMS
WERE OBSERVED JUST N OF KAUAI AND OAHU WITHIN THE MOISTURE BAND
EARLIER TODAY.

THE ONGOING FORECAST INDICATES A SLIGHT CHANCE OF THUNDERSTORMS OVER
KAUAI AND OAHU AND ADJACENT WATERS THIS EVENING. HOWEVER THE
MOVEMENT OF THE TROUGH AND MOISTURE POOL IS SUCH THAT THE CHANCE OF
THUNDERSTORMS APPEARS TO BE SHIFTING S TOWARD THE BIG ISLAND AND
MAUI FOR LATER TONIGHT AND SUNDAY...WHILE SHOWERS WILL GRADUALLY
DIMINISH OVER THE ISLANDS FROM KAUAI TO MOLOKAI. A FORECAST UPDATE
WILL BE ISSUED SHORTLY TO INDICATE THIS POTENTIAL...AND TO INCLUDE
INCREASED PRECIPITATION CHANCES OVER BIG ISLAND SUMMITS TONIGHT AND
TOMORROW. WITH TEMPERATURES BELOW FREEZING ON THE BIG ISLAND
SUMMITS...CHANCES OF FREEZING RAIN APPEARS TO BE GREAT ENOUGH TO
WARRANT THE RE-ISSUANCE OF A WINTER WEATHER ADVISORY. WINDS OVER THE
SUMMITS OF THE BIG ISLAND AND HALEAKALA ARE EXPECTED TO INCREASE
THROUGH SUNDAY...AND REMAIN STRONG THROUGH MONDAY. WINDS MAY
POTENTIALLY REACH WARNING LEVELS...AS THE TROUGH ALOFT BECOMES A
CLOSED LOW S OF THE BIG ISLAND...AND A STRONG HIGH ALOFT REMAINS DUE
N OF THE ISLANDS. WINDS OVER THE BIG ISLAND SUMMITS HAVE ALREADY
INCREASED TO THE POINT THAT THE WIND ADVISORY WILL BE EXPANDED
SHORTLY TO INCLUDE THIS ZONE.

THE MOISTURE BAND IS FORECAST TO SHIFT S TO NEAR THE BIG ISLAND ON
SUNDAY AS THE CUT OFF LOW DEVELOPS JUST TO THE S. THIS IS EXPECTED
TO FUEL LOCALLY HEAVY DOWNPOURS ON THE BIG ISLAND THROUGH SUNDAY...
WHILE THE SMALLER ISLANDS SEE A REDUCTION IS SHOWERS AS A SLIGHTLY
COOLER AND DRIER AIR MASS PREVAILS IN THE WAKE OF THE REMNANT
FRONTAL BAND. THIS MODEST DRYING IS FORECAST TO BE SHORT-LIVED...
WITH THE ENHANCED MOISTURE BAND FORECAST TO SPREAD BACK UP TOWARD
THE SMALLER ISLANDS EARLY MONDAY THROUGH TUESDAY AS THE DISTURBANCE
ALOFT ALSO SHIFTS SLIGHTLY N.

THE TROUGH ALOFT WILL WEAKEN AND LIFT NE AS THE WEEK PROGRESSES...
WITH THE SURFACE HIGH TO THE NE DOING THE SAME. THIS IS EXPECTED TO
LEAD TO A WEAKER TRADE WIND REGIME FOR THE SECOND HALF OF THE
UPCOMING WEEK...WITH FEWER SHOWERS. FOR CHRISTMAS DAY...A FAIRLY
TYPICAL TRADE WIND WEATHER PATTERN IS EXPECTED. ALTHOUGH TOO EARLY
FOR MUCH CONFIDENCE...LATEST GFS FORECAST DEPICTS A SHARP TROUGH
ALOFT DRIVING THE DEVELOPMENT OF A SURFACE TROUGH NEAR THE ISLANDS
FOR NEXT WEEKEND.

&&

.AVIATION...
THE GUSTY LOW-LEVEL TRADE WINDS FLOW WILL CONTINUE THROUGH SUNDAY.
AS A RESULT...AIRMET TANGO REMAINS IN EFFECT FOR STRONG SUSTAINED
WINDS OVER MOUNTAIN RIDGES...THROUGH VALLEYS AND ACROSS THE ADJACENT
WATERS OF ALL ISLANDS. ALSO...EXPECT MODERATE LOW-LEVEL TURBULENCE
BELOW 10 KFT SOUTHWEST OF THE HIGHER TERRAIN ON ALL ISLANDS.

A BAND OF LOW CLOUDS AND SHOWERS ASSOCIATED WITH A FORMER FRONT IS
BEING TRANSPORTED OVER THE ISLANDS BY THE TRADES. THIS BAND IS
PRODUCING MOUNTAIN OBSCURATION AND REDUCED VISIBILITIES MAINLY OVER
HIGHER TERRAIN ON THE WINDWARD SIDES OF MOST ISLANDS. THEREFORE...
AIRMET SIERRA FOR TEMPO MTN OBSC REMAINS IN EFFECT FOR KAUAI...
OAHU...MOLOKAI...AND MAUI. THIS AIRMET MAY NEED TO BE EXTENDED TO
THE WINDWARD SIDES OF THE BIG ISLAND LATER TONIGHT.

&&

.MARINE...
A STATEWIDE SMALL CRAFT ADVISORY /SCA/...WITH GALE WARNINGS IN THE
WINDIER AREAS...REMAINS IN EFFECT DUE TO THE ONGOING STRONG TRADE
WIND EVENT. THE STRONG SURFACE HIGH RESPONSIBLE FOR THESE CONDITIONS
WILL REMAIN NEARLY STATIONARY NNE OF THE ISLANDS WITH LITTLE CHANGE
IN STRENGTH OVER THE NEXT COUPLE OF DAYS. THEREFORE THE EXPECTATION
IS THAT COMBINED SEAS WILL REMAIN HIGH...RUNNING ABOUT 11 TO 13 FEET
IN EXPOSED WINDWARD AREAS...AND EVEN HIGHER IN THE CHANNELS...
THROUGH MONDAY. GRADUAL WEAKENING OF THE HIGH IS EXPECTED TUESDAY...
AND THEN AS THE HIGH WEAKENS FURTHER AND LIFTS N AROUND THE MIDDLE
OF THE WEEK...WINDS AND SEAS WILL DROP BELOW SCA LEVELS IN MOST
AREAS EXCEPT FOR THE WINDIER AREAS AROUND MAUI AND THE BIG ISLAND.

THE ROUGH SEAS DRIVEN TOWARD THE ISLANDS BY THE PERSISTENT HIGH WILL
MAINTAIN HIGH SURF ALONG E FACING SHORES OF THE ISLANDS...LIKELY
THROUGH TUESDAY...AND A HIGH SURF ADVISORY REMAINS IN EFFECT. OTHER
SURF SOURCES INCLUDE SMALL NW SWELLS AROUND TUESDAY AND THURSDAY...
WITH PEAK SURF HEIGHTS EXPECTED TO REMAIN BELOW ADVISORY LEVELS
ALONG N AND W FACING SHORES.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 6 PM HST SUNDAY FOR ALL AREAS.

WINTER WEATHER ADVISORY UNTIL NOON HST SUNDAY FOR BIG ISLAND
SUMMITS.

HIGH SURF ADVISORY UNTIL 6 PM HST MONDAY FOR EAST FACING SHORES OF
NIIHAU KAUAI OAHU MOLOKAI MAUI AND THE BIG ISLAND.

GALE WARNING UNTIL 6 PM HST MONDAY FOR ALENUIHAHA CHANNEL.

GALE WARNING UNTIL 6 PM HST SUNDAY FOR PAILOLO CHANNEL-BIG
ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS.

SMALL CRAFT ADVISORY UNTIL 6 PM HST MONDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-
OAHU WINDWARD WATERS-OAHU LEEWARD WATERS-KAIWI CHANNEL-MAUI COUNTY
WINDWARD WATERS-MAUI COUNTY LEEWARD WATERS-MAALAEA BAY- BIG ISLAND
WINDWARD WATERS.

&&

SYNOPSIS/DISCUSSION/MARINE...BIRCHARD
AVIATION...HOUSTON