Expires:No;;241092 FXHW60 PHFO 251955 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 955 AM HST WED NOV 25 2009 .SYNOPSIS... HIGH PRESSURE BUILDING NORTH OF THE ISLANDS WILL BRING INCREASED TRADE WINDS TODAY...REMAINING BREEZY INTO THE HOLIDAY WEEKEND. THE STRONGER TRADE WINDS WILL ALSO BRING AN UPTICK IN SHOWERS OVER WINDWARD AND MAUKA AREAS...ESPECIALLY FROM TONIGHT INTO FRIDAY. && .DISCUSSION... A WEAKENING COLD FRONT IS LOCATED ABOUT 250 MILES NNW OF KAUAI AND ITS SOUTHWARD PROGRESS HAS DIMINISHED CONSIDERABLE OVER THE PAST 12 HOURS. EAST OF THE ISLANDS...SCATTERED TO BROKEN LOW CLOUDS ARE APPROACHING THE ISLANDS IN A MODERATE TRADE WIND FLOW...BUT RADAR SHOWS LIMITED SHOWER COVERAGE WITHIN THESE CLOUDS. MORNING SOUNDINGS SHOW A STABLE AIR MASS OVER THE ISLANDS...SO LEEWARD LOCATIONS SHOULD SEE MOSTLY SUNNY SKIES WITH CLOUDS FOCUSING OVER WINDWARD AND MOUNTAIN AREAS. THE FORECAST FOR THANKSGIVING AND BEYOND REMAIN ON TRACK AND THE PREVIOUS DISCUSSION FOLLOWS... THE FRONTAL MOISTURE NORTHWEST OF KAUAI IS NOT EXPECTED TO REACH THE ISLANDS...AND WILL STALL ALONG 25N TODAY AND TONIGHT...AS HIGH PRESSURE FOLLOWING THE BOUNDARY MOVES QUICKLY EAST...AND ELIMINATES ANY SOUTHWARD MOMENTUM THE BOUNDARY CURRENTLY HAS. THE PASSAGE OF THE HIGH WILL ACT TO TIGHTEN THE LOW-LEVEL PRESSURE GRADIENT OVER THE ISLANDS...AND INCREASING TRADE WINDS ARE EXPECTED TODAY. TRADES ARE EXPECTED TO PEAK THURSDAY AND THURSDAY NIGHT BEFORE SLOWLY EASING AS WE HEAD INTO THE WEEKEND...AS THE HIGH TEMPORARILY ESTABLISHES ITSELF IN A CLIMATOLOGICAL POSITION FAR NORTHEAST OF THE ISLANDS. A MID-LEVEL RIDGE CURRENTLY OVER THE ISLANDS WILL GRADUALLY WEAKEN OVER THE NEXT 24 HOURS...AS A MID- AND UPPER-LEVEL TROUGH DROPPING DOWN FROM THE NORTHWEST SHARPENS OVER THE ISLANDS TONIGHT THROUGH FRIDAY...BEFORE DISSIPATING AND MOVING EAST THIS WEEKEND. EXPECT THAT THIS TROUGH WILL ACT TO SLIGHTLY DESTABILIZE THE ATMOSPHERE... RESULTING IN A DEEPER MARINE LAYER. THIS WILL LIKELY MEAN AN INCREASE IN THE NUMBER AND INTENSITY OF TRADE SHOWERS...WITH THE SHOWERS SPREADING SOME LIMITED MOISTURE LEEWARD IN THE INCREASED TRADE FLOW. THE EXTENDED PICTURE IS SIMILAR TO THAT EXPRESSED IN EARLIER DISCUSSIONS...AND SIMILAR TO THE CURRENT SCENARIO CURRENTLY UNFOLDING. ANOTHER FRONT WILL APPROACH FROM THE NORTHWEST SATURDAY NIGHT AND SUNDAY...WITH A FOLLOWING HIGH PASSING WELL NORTH OF THE ISLANDS ON SUNDAY AND MONDAY. WHILE MOISTURE ASSOCIATED WITH THE NEXT FRONT IS ALSO DEPICTED AS REMAINING NORTH OF THE ISLANDS... ANOTHER PROGRESSIVE MID-LEVEL TROUGH WILL PASS OVER THE ISLANDS FROM THE NORTHWEST...POSSIBLY ADDING TO THE VIGOR OF TRADE SHOWERS ON SUNDAY. THE DEPARTURE OF THE TROUGH TO THE EAST WILL MEAN FEWER SHOWERS MONDAY AND TUESDAY...BUT SURELY THIS FORECAST WILL NEED TO BE FINE TUNED AS THE WEEKEND NEARS. && .MARINE... THE ANTICIPATED LARGE NORTHWEST SWELL HAS ARRIVED. PEAK SWELL HEIGHTS AT THE CDIP WAIMEA BUOY SHOWS A RAPID RISE OVERNIGHT WITH SWELL HEIGHTS NOW LEVELING OFF BETWEEN 10 AND 11 FEET. SURF WILL CONTINUE TO RISE THIS MORNING ALONG NORTH AND WEST FACING SHORES OF MOST ISLANDS...AND A HIGH SURF WARNING REMAINS IN EFFECT FOR NORTH AND WEST FACING SHORES OF NIIHAU KAUAI OAHU AND MOLOKAI...AND FOR NORTH FACING SHORES OF MAUI. WITH BUOY OBS SHOWING THE SWELL COMING IN FROM 330-340 DEGREES... MOST OF THE ENERGY WILL BE BLOCKED FROM REACHING THE BIG ISLAND... BUT SOME INCREASE IN SURF IS EXPECTED ALONG THE KONA SIDE THIS AFTERNOON AND TONIGHT. A SMALL CRAFT ADVISORY IS IN EFFECT FOR BOTH THE LARGE NORTHWEST SWELL AND FOR INCREASING TRADE WINDS. && .HFO WATCHES/WARNINGS/ADVISORIES... HIGH SURF WARNING UNTIL 6 AM HST THURSDAY FOR NIIHAU-KAUAI WINDWARD-KAUAI LEEWARD-WAIANAE COAST-OAHU NORTH SHORE-OAHU KOOLAU-MOLOKAI-MAUI WINDWARD WEST-MAUI CENTRAL VALLEY-WINDWARD HALEAKALA. SMALL CRAFT ADVISORY UNTIL 6 PM HST FRIDAY FOR ALL HAWAIIAN WATERS- && $$ MORRISON/BIRCHARD