000 FXHW60 PHFO 241400 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 400 AM HST TUE NOV 24 2009 .SYNOPSIS... A SURFACE RIDGE LOCATED NORTH OF THE ALOHA STATE WILL MAINTAIN MODERATE TRADES THROUGH THIS AFTERNOON. A NEW SURFACE HIGH PASSING FAR NORTH OF THE ISLANDS WILL BRING A NOTICEABLE INCREASE IN TRADE WIND SPEEDS FROM LATER TONIGHT THROUGH FRIDAY. SHOWERS CARRIED BY THE TRADES WILL REMAIN FOCUSED ACROSS WINDWARD AND MAUKA SECTIONS OF THE ISLANDS...BUT EXPECT A FEW TRADE SHOWERS TO BE CARRIED LEEWARD ON SOME OF THE SMALLER ISLANDS BY MID-WEEK. && .DISCUSSION... THE WESTERN END OF A SURFACE RIDGE IS LOCATED ABOUT 340 MILES NORTH OF HONOLULU. THIS NEARLY STATIONARY SURFACE RIDGE IS SLOWLY ERODING FROM THE WEST AS A NEARBY SURFACE FRONT PUSHES DOWN FROM THE NORTHWEST. THE PRESSURE GRADIENT SOUTH OF THE RIDGE IS MAINTAINING MODERATE TRADE WIND SPEEDS ACROSS THE STATE TODAY. SATELLITE IMAGERY AND RADAR REFLECTIVITY DATA INDICATE THAT RATHER TRANQUIL WEATHER CONDITIONS CONTINUE ACROSS MOST OF THE STATE EARLY THIS MORNING. THERE WAS A SLIGHT INCREASE IN THE COVERAGE OF LOW CLOUDS AND SHOWERS OVER THE WINDWARD COASTAL WATERS FROM OAHU TO THE BIG ISLAND OVERNIGHT. HOWEVER...RAINFALL TOTALS AT MOST LAND STATIONS WERE VERY LIGHT. FOR EXAMPLE...THE LARGEST RAINFALL TOTALS FOR THE 12 HOUR PERIOD ENDING AT 200 AM HST THIS MORNING BY ISLAND WERE...0.11 INCHES AT WAINIHA AND MOUNT WAIALEALE ON KAUAI...0.01 INCHES AT WAIMANALO ON OAHU...0.03 INCHES AT PUU KUKUI ON MAUI...AND 0.23 INCHES AT MOUNTAIN VIEW ON THE BIG ISLAND. THE SURFACE FRONT...WHICH WAS MENTIONED ABOVE...IS EXPECTED TO WEAKEN RAPIDLY AND BEGIN TO DISSIPATE LATER TONIGHT WHEN IT REACHES A POINT ABOUT 200 MILES NORTH OF KAUAI. AT THE SAME TIME...A 1031 MB SURFACE HIGH IS FORECAST TO BE FAR NORTH NORTHWEST OF THE STATE. THEREFORE...EXPECT THE PRESSURE GRADIENT SOUTH OF THIS HIGH TO TIGHTEN ENOUGH TO INCREASE OUR TRADE WINDS TO MODERATE TO FRESH SPEEDS TONIGHT. THESE STRONGER TRADES WILL LIKELY CONTINUE INTO FRIDAY AS THE HIGH STRENGTHENS AND MOVES SLOWLY TOWARD THE EAST NORTHEAST AND STRENGTHENS ALONG A TRACK FAR NORTH OF THE HAWAIIAN ISLANDS. BASED ON THE PRESENT GUIDANCE...IT APPEARS THAT THURSDAY...THANKSGIVING DAY...MAY HAVE THE STRONGEST TRADES. SUSTAINED WINDS SPEEDS...ALONG WITH HIGHER GUSTS...MAY INCREASE TO NEAR THE WIND ADVISORY THRESHOLD OF 30 MPH IN SOME OF THE TYPICALLY WINDIER LOCATIONS ON LAND...SUCH AS NEAR SOUTH POINT AND ALONG RIDGES AND DOWNSLOPING SECTIONS OF THE KOHALA DISTRICTS ON THE BIG ISLAND. THE TRADES WILL WEAKEN TO MODERATE SPEEDS FROM LATE FRIDAY THROUGH SATURDAY WHEN THE HIGH MOVES OFF TO THE NORTHEAST. THE TRADES WILL LIKELY INCREASE AGAIN BY SUNDAY WHEN YET ANOTHER HIGH PASSES BY FAR TO THE NORTH OF THE STATE. SHOWERS CARRIED BY THE TRADES WILL REMAIN FOCUSED MAINLY ACROSS WINDWARD AND MAUKA SECTIONS OF THE STATE THROUGH THE END OF THIS WEEK. A WEAK UPPER LEVEL TROUGH MOVING TO A POSITION OVER THE WESTERN END OF THE STATE MAY ENHANCE THE SHOWER COVERAGE SLIGHTLY BY LATE WEDNESDAY AND THANKSGIVING DAY. AT THE SAME TIME...THE STRONGER TRADES MAY ALSO CARRY A FEW OF THESE SHOWERS OVER TO SOME LEEWARD SECTIONS OF THE SMALLER ISLANDS. NOTE...NO HEAVY RAINFALL IS EXPECTED AT LEAST THROUGH SATURDAY. && .MARINE... A COMPLEX STORM SYSTEM MOVING ACROSS THE NORTHERN PACIFIC OCEAN HAS AIMED A NEW VERY LARGE NORTHWEST SWELL TOWARD THE ISLAND CHAIN. THIS LARGE OPEN OCEAN SWELL IS EXPECTED TO ARRIVE IN THE ISLANDS TONIGHT...WITH SURF HEIGHTS FORECAST TO RISE ABRUPTLY BY LATE TONIGHT AND CONTINUING THROUGH WEDNESDAY. THE FORECAST SURF HEIGHTS RESULTING FROM THIS SWELL WILL LIKELY REQUIRE A HIGH SURF WARNING ALONG NORTH AND WEST FACING SHORES OF KAUAI...OAHU...AND MOLOKAI...AS WELL AS NORTH FACING SHORES OF MAUI. BASED ON THE FORECAST SWELL DIRECTION OF 320 DEGREES...DO NOT ANTICIPATE SURF HEIGHTS REACHING THE HIGH SURF ADVISORY THRESHOLD ALONG NORTH OR WEST FACING SHORES OF THE BIG ISLAND DUE TO SHADOWING BY THE SMALLER ISLANDS. A MARINE WEATHER STATEMENT HAS BEEN UPDATED THIS MORNING WITH ADDITIONAL INFORMATION ABOUT THIS SWELL AND ITS POTENTIAL IMPACT ON THE WATERS ADJACENT TO THE HAWAIIAN ISLANDS. THIS NORTHWEST SWELL WILL SLOWLY DECREASE AFTER WEDNESDAY...BUT SURF HEIGHTS WILL LIKELY REMAIN NEAR OR ABOVE THE ADVISORY THRESHOLD ALONG NORTH AND WEST FACING SHORES OF THE SMALLER ISLANDS THROUGH THURSDAY. THE NEW LARGE NORTHWEST SWELL...ALONG WITH INCREASING TRADE WIND SPEEDS...WILL LIKELY REQUIRE THE ISSUANCE OF A SMALL CRAFT ADVISORY...SCA...FOR MOST HAWAIIAN COASTAL WATERS...INCLUDING THE CHANNELS...FOR TUESDAY NIGHT. ONCE THIS SCA IS ISSUED...WHICH WILL LIKELY BE LATER THIS MORNING...IT IS EXPECTED TO REMAIN IN EFFECT FOR MOST MARINE ZONES THROUGH THURSDAY NIGHT OR FRIDAY. && .HFO WATCHES/WARNINGS/ADVISORIES... NONE. && $$ HOUSTON