High Surf in Hawaii, November 15 to 17, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST THU NOV 15 2012

.SYNOPSIS...
MODERATE TO STRONG TRADE WINDS HAVE PROPELLED MODERATE SHOWERS ONTO
MOST WINDWARD SLOPES...AND COMPLETELY OVER SOME OF THE SMALLER
ISLANDS OVERNIGHT. HOWEVER...A DRIER AND MORE STABLE AIR MASS WILL
PREVAIL BY THIS AFTERNOON. WIND SPEEDS WILL DIMINISH OVER THE
WEEKEND...THOUGH OTHERWISE LITTLE FURTHER CHANGE IS EXPECTED UNTIL
TUESDAY OR WEDNESDAY.
&&

.DISCUSSION...
HAVE EXPANDED THE WIND ADVISORY TO INCLUDE THE AREA AROUND SOUTH
POINT ON THE BIG ISLAND...AND FOR LANAI. THE SHOWER BAND THAT MOVED
OVER THE ISLANDS OVERNIGHT AND THIS MORNING BROUGHT SOME LOCAL GUSTS
TO VARIOUS AREAS OF THE STATE...HOWEVER THE DRIVING MECHANISM FOR
THE WIND ADVISORY IS THE HIGH PRESSURE NORTH OF THE
ISLANDS...COMBINED WITH THE DRY AIRMASS EXPECTED TO MOVE OVER THE
ISLANDS BEHIND THE SHOWER BAND. IN ADDITION TO ADDING THE AREAS TO
THE WIND ADVISORY...THE ADVISORY HAS BEEN EXTENDED THROUGH FRIDAY
AFTERNOON. AS WE HEAD INTO FRIDAY...THE HIGH PRESSURE NORTH OF THE
STATE IS EXPECTED TO SINK SOUTHWARD JUST A BIT AND WEAKEN A
TOUCH...THE COMBINATION WILL KEEP THE PRESSURE GRADIENT OVER THE
ISLANDS SIMILAR TO TODAY...SO THE STRONGER WINDS WILL CONTINUE.

THE SHOWER BAND THAT MOVED OVER THE ISLANDS OVERNIGHT AND THIS
MORNING BROUGHT SOME RAIN TO MOSTLY WINDWARD AREAS. THE RAIN GAGE
NETWORK SHOWED SEVERAL WINDWARD GAGES ACROSS THE STATE RECEIVING A
QUARTER TO HALF AN INCH OF RAIN. THE SHOWER BAND HAS CLEARED MOST OF
THE ISLANDS AS OF 9 AM. DRIER AIR IS EXPECTED THROUGH THE REMAINDER
OF TODAY...AND THROUGH MUCH OF TOMORROW.

HEADING INTO THE WEEKEND...THE HIGH PRESSURE SYSTEM WILL CONTINUE TO
SINK SOUTH AND WEAKEN...SO LOOK FOR THE WINDS TO WEAKEN THROUGH THE
WEEKEND AND TURN A BIT MORE EASTERLY. ANOTHER BATCH OF MOISTURE
LOOKS TO BE CARRIED IN ON THE TRADES...ARRIVING SUNDAY NIGHT OR
MONDAY...WHICH WILL BRING MORE TYPICAL TRADE WIND SHOWERS TO
WINDWARD AND MAUKA AREAS FOR THE START OF THE WORK WEEK.

&&

.MARINE...
THE CURRENT NORTHWEST SWELL IS EXPECTED TO SLOWLY RISE
TODAY...PEAKING JUST BELOW ADVISORY LEVELS TONIGHT AND FRIDAY. THIS
SWELL WILL GRADUALLY LOWER SATURDAY AND SUNDAY. A SMALL SOUTH SWELL
IS EXPECTED TUESDAY AND WEDNESDAY. TRADE SWELL WILL CONTINUE
TO PRODUCE MODERATE SHORT-PERIOD SURF ALONG WINDWARD SHORES.

&&

.AVIATION...
AIRMET TANGO REMAINS FOR LL TURBULENCE. SFC WINDS OVER MOUNTAIN
RIDGES AND THRU VALLEYS WILL RANGE FROM 20 TO 30 KT FROM THE NE.
ENHANCED TRADE WIND SHOWERS WILL REMAIN OVER WINDWARD AREAS THIS
MORNING BEFORE DRYING OUT IN THE AFTERNOON. MVFR VISIBILITIES AND
CEILINGS ARE EXPECTED IN SHOWERS...MAINLY ACROSS WINDWARD SECTIONS.
STABLE...LESS SHOWERY...LOW CLOUDS WILL MOVE INTO WINDWARD AREAS
TONIGHT.

&&

.FIRE WEATHER...
A RED FLAG WARNING REMAINS IN EFFECT FOR MOSTLY LEEWARD AREAS OF THE
ISLANDS THIS AFTERNOON. DESPITE THE RAIN RECEIVED
OVERNIGHT...LEEWARD AREAS WOULD NEED A MORE PROLONGED BOUT OF RAIN
TO LOWER THE KBDI. BEHIND THE SHOWER BAND DRIER AIR IS EXPECTED TO
MOVE IN...WHICH WILL LOWER RELATIVE HUMIDITY VALUES THIS AFTERNOON.
THE DRIER AIR COMBINED WITH THE HIGH PRESSURE TO THE NORTH WILL ALSO
ALLOW WINDS TO INCREASE THIS AFTERNOON. THIS COMBINATION OF EVENTS
RAISES THE FIRE WEATHER THREAT FOR THIS AFTERNOON. SIMILAR
CONDITIONS ARE EXPECTED FRIDAY AFTERNOON...WHICH MAY REQUIRE THE RED
FLAG WARNING TO BE EXTENDED TO COVER THAT TIME PERIOD.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM NOON TODAY TO 6 PM HST THIS EVENING FOR
NIIHAU-KAUAI WINDWARD-KAUAI LEEWARD-OAHU SOUTH SHORE-WAIANAE
COAST-OAHU NORTH SHORE-OLOMANA-CENTRAL OAHU-WAIANAE MOUNTAINS-
MOLOKAI LEEWARD-LANAI-MAUI LEEWARD WEST-MAUI CENTRAL VALLEY-
LEEWARD HALEAKALA-KONA-SOUTH BIG ISLAND-KOHALA-BIG ISLAND
INTERIOR.

WIND ADVISORY TO 6 PM HST FRIDAY FOR BIG ISLAND NORTH AND
EAST-KOHALA-SOUTH BIG ISLAND-LANAI MAKAI-LANAI MAUKA.

SMALL CRAFT ADVISORY UNTIL 6 PM HST FRIDAY FOR KAIWI CHANNEL-
MAALAEA BAY-PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND
LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS.

&&

DISCUSSION/AVIATION/MARINE...M BALLARD
AVIATION...MORRISON