712 FXHW60 PHFO 031342 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 338 AM HST MON DEC 3 2012 .SYNOPSIS... HIGH CLOUDS OVER THE ALOHA STATE WILL DECREASE TODAY AND MOVE EAST OF THE AREA BY THIS AFTERNOON. A WEAKENING COLD FRONT JUST TO THE NORTHWEST OF THE ISLANDS REMAINS NEARLY STATIONARY AND WILL CONTINUE TO BRING PASSING SHOWERS OVER NIIHAU AND KAUAI TODAY. SCATTERED SHOWERS MAY DEVELOP OVER THE REST OF THE ISLANDS LATER TODAY WITH RAIN IN GENERAL REMAINING LIGHT TO MODERATE. WINDS ARE EXPECTED TO DECREASE OR EVEN BECOME LIGHT ACROSS MUCH OF THE AREA LATER THIS AFTERNOON. ANOTHER COLD FRONT APPROACHES KAUAI FROM THE NORTHWEST ON TUESDAY AND BRINGS INCREASING SHOWERS...MAINLY WEST OF MAUI COUNTY THROUGH LATE WEDNESDAY. LIGHT TRADES ARE THEN EXPECTED TO RETURN FOR THE END OF THE WORK WEEK. && .DISCUSSION... A DECAYING FRONTAL BOUNDARY REMAINS NEARLY STATIONARY JUST NW OF KAUAI WITH A NARROW BAND OF MOSTLY LIGHT RAIN STILL AFFECTING KAUAI AND NIIHAU THROUGH THIS MORNING. THE FRONT WILL SLOWLY PUSH EASTWARD...BUT IT WILL WEAKEN EVEN FURTHER OR MAY EVEN DISSIPATE OR LIFT NORTH BEFORE REACHING OAHU. SFC RIDGING EAST OF THE STATE IS STILL EXTENDING INTO THE BIG ISLAND AND MAUI COUNTY...AND SHOULD REMAIN IN PLACE DURING THE NEXT COUPLE OF DAYS. MEANWHILE...AN UPPER LVL TROUGH EXTENDS SOUTH OF AN UPPER LOW NEAR 170W. THIS SYSTEM IS RESPONSIBLE FOR THE PERSISTING SW WINDS ALOFT AND THE MID/UPPER LVL CLOUD COVER THAT HAS KEPT MUCH OF THE AREA UNDER CLOUDY CONDITIONS THE LAST FEW DAYS. BUT THE CLOUD COVERAGE SHOULD GRADUALLY DECREASE TODAY AS THE FLOW ALOFT SWITCHES TO THE WEST AND PUSHES THE MAIN CANOPY OF CLOUDS FURTHER TO THE EAST OF THE ISLANDS. LATEST IR/WV IMAGERY IS INDEED SHOWING THE EDGE OF THE THICKER CLOUDS NOW PUSHING EAST OF MAUI COUNTY...AND THIS TREND SHOULD CONTINUE TODAY. THE REMAINING SHOWERS IN THE AREA WILL MOSTLY AFFECT NIIHAU AND KAUAI THROUGH THE MORNING HOURS. ELSEWHERE...ENOUGH MOISTURE WILL LINGER OVER THE AREA FOR SOME SCATTERED SHOWERS TO DEVELOP THROUGH THE DAY. RAIN IN GENERAL SHOULD REMAIN LIGHT TO MODERATE. THE STRONG SW FLOW ALOFT IS KEEPING WIND ADVISORY LEVELS AT THE MOUNTAIN SUMMITS UNTIL 6 AM HST THIS MORNING. THE SFC RIDGE OVER THE EASTERN PORTIONS OF THE ALOHA STATE IS TRYING TO SLOWLY PUSH NORTHWARD THROUGH TUESDAY WHILE THE TROUGH ALOFT TO THE WEST WILL LIFT OUT TO THE NE. LATEST MODEL RUNS DEVELOP A SECOND UPPER LVL TROUGH AROUND 170W ON TUESDAY...BRINGING BACK STRONG SW WINDS ALOFT AND INCREASING HIGH CLOUD COVER AGAIN ACROSS THE MAIN HAWAIIAN ISLANDS. AN ASSOCIATED FRONTAL BOUNDARY APPROACHES KAUAI FROM THE NW ALSO ON TUESDAY AS A COUPLE OF CLOSED LOWS ROTATE AROUND THE AFOREMENTIONED TROUGH. RAIN CHANCES WILL AGAIN INCREASE TUE THROUGH WED...BUT THE AIRMASS OVER THE AREA SEEMS TO REMAIN STABLE ENOUGH TO KEEP CHANCES OF THUNDERSTORM ACTIVITY LOW. HOWEVER...THE SITUATION WILL BE CLOSELY MONITORED IN CASE CONDITIONS CHANGE SIGNIFICANTLY IN UPCOMING MODEL GUIDANCE. FOR THE SECOND HALF OF THE WORK WEEK...LIGHT TRADE WINDS AND GENERALLY PARTLY CLOUDY SKIES SHOULD RETURN ACROSS MUCH OF THE AREA WITH LOW CLOUDS AND SHOWERS FAVORING WINDWARD AND MAUKA SECTIONS. THEN MODELS SUGGEST THE POSSIBLE ARRIVAL OF ANOTHER FRONTAL BOUNDARY FROM THE NORTHWEST DURING THE WEEKEND. && .MARINE... A LARGE NORTHWEST SWELL WILL KEEP HIGH SURF CONDITIONS THROUGH LATER THIS AFTERNOON...THUS A HIGH SURF ADVISORY REMAINS IN EFFECT FOR NORTH AND WEST FACING SHORES OF NIIHAU KAUAI AND MOLOKAI...AND NORTH FACING SHORES OF OAHU UNTIL 6 PM HST TODAY. ALSO...A SMALL CRAFT ADVISORY IS IN EFFECT FOR ALL KAUAI WATERS... INCLUDING KAUAI CHANNEL...UNTIL 6 PM HST TODAY. CONDITIONS SHOULD THEN BEGIN SUBSIDING ON THIS EVENING. && .AVIATION... SOME OF THE TAF SITES ARE REPORTING MVFR/IFR CIGS THIS MORNING... WITH LIFR CIGS RECENTLY REPORTED AT PHNY...WITH THE LOW CLOUD BASES DUE TO A SATURATED AIR MASS. LOW CLOUD BASES ARE EXPECTED TO RISE AFTER SUNRISE THIS MORNING...WITH ONLY ISOLATED MVFR CIG/VIS EXPECTED THEREAFTER. THIS WILL MAINLY BE NEAR KAUAI...WHERE A NE-SW ORIENTED BAND OF SHRA WILL PERSIST BEFORE GRADUALLY WEAKENING LATER TODAY. AIRMET TANGO REMAINS IN EFFECT FOR MOD TURB BLW 150 TO THE N AND E OF THE MTN OF ISLANDS FROM MAUI TO KAUAI AS LATEST RADAR VAD WIND PROFILES INDICATE WSW WINDS UP TO 30 KT IN THE LOWER LEVELS. GUIDANCE SHOWS THESE WINDS DIMINISHING BY LATE TODAY. && .HFO WATCHES/WARNINGS/ADVISORIES... HIGH SURF ADVISORY UNTIL 6 PM HST TODAY FOR NIIHAU-KAUAI WINDWARD-KAUAI LEEWARD-OAHU NORTH SHORE-OAHU KOOLAU-MOLOKAI. WIND ADVISORY UNTIL 10 AM HST MONDAY FOR HALEAKALA SUMMIT-BIG ISLAND SUMMITS. SMALL CRAFT ADVISORY UNTIL 6 PM HST MONDAY FOR KAUAI NORTHWEST WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL. && $$ DISCUSSION/MARINE...REYNES AVIATION...BIRCHARD