000 FXHW60 PHFO 091340 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 400 AM HST THU FEB 9 2012 .SYNOPSIS... MODERATE NORTHERLY WINDS WILL BECOME NORTHEASTERLY BY FRIDAY...AS SHOWERS ALONG NORTH SLOPES OF MOST ISLANDS SHIFT TOWARD NORTHEAST SLOPES. BY EARLY NEXT WEEK...SHOWERS WILL DIMINISH WHILE WINDS WEAKEN AND BECOME MORE SOUTHEASTERLY. WETTER TRADE WINDS ARE EXPECTED BY LATE NEXT WEEK. && .DISCUSSION... OBSERVATIONS AROUND THE MAIN HAWAIIAN ISLANDS REPORTED MODERATE NORTHERLY TO NORTHEASTERLY WINDS. CLOUD MOTIONS VISIBLE IN SATELLITE IMAGES...TOGETHER WITH PRESSURE TRENDS...SUPPORTED AN EASTWARD SHIFT BY THE REFORMING SUBTROPICAL HIGH TO THE NORTH...SO SURFACE WINDS SHOULD BECOME MORE NORTHEASTERLY THROUGH THE SHORT RUN. THE FRONTAL CLOUD BAND TO THE SOUTH OF THE STATE GREW INDISTINCT... WHILE STABLE STRATOCUMULI PREVAILED IN THE POSTFRONTAL AIR MASS. OVERALL CLOUD COVER HAS BEEN INCREASED IN THE OFFICIAL FORECAST FOR THIS MORNING...BUT SUBSIDENCE ON THE LEE SIDES OF THE ISLANDS WILL PRODUCE CLEARER SKIES THERE. WITH PRECIPITABLE WATER VALUES EXTREMELY LOW...EVEN SUBSTANTIAL OROGRAPHIC FORCING WILL STRUGGLE TO PRODUCE MUCH PRECIPITATION TODAY. DRIZZLE AND VERY LIGHT RAIN WILL NOT NECESSARILY BE ABSENT FROM NORTH SLOPES...JUST NOT ADDING UP TO MUCH. AS WINDS TURN TO A MORE TYPICAL DIRECTION OVER THE NEXT 12 TO 18 HOURS...THESE SHOWERS WILL SHIFT ACCORDINGLY. INTENSITY AND ACCUMULATION ALSO WILL INCREASE TOWARD CLIMATOLOGY AS THE AIR MASS MODIFIES OVER THE WEEKEND. ALOFT...A BROAD TROUGH AND ITS ASSOCIATED POOL OF COLD AIR WERE LOCATED RIGHT OVER THE STATE. IF NOT FOR THE COOL...DRY AIR AT THE SURFACE...THE AIR MASS WOULD BE QUITE UNSTABLE. FROM THIS MORNING INTO THE WEEKEND...SOLUTIONS PREDICT THE GREATER PART OF THE MID-LEVEL TROUGH TO MOVE AWAY TO THE NORTHEAST...BUT A PORTION OF THE COLD POOL TO CUT OFF TO THE SOUTHWEST AS WEAK RIDGING BUILDS IN OVER THE STATE ITSELF. THUS...STABILITY WILL INCREASE GRADUALLY... THOUGH PRECIPITABLE WATER LIKELY WILL TRUMP STATIC STABILITY ALONG WINDWARD SLOPES THROUGH THE WEEKEND. FROM SUNDAY INTO THE MIDDLE OF NEXT WEEK...DIFFLUENCE IN THE SOUTHEASTERLY FLOW AT THE SURFACE OVER THE ISLANDS WILL PRODUCE INCREASING SUBSIDENCE AND DRYING AS THE SUBTROPICAL RIDGE STARTS TO SHIFT EVEN FURTHER EAST AHEAD OF A NEW APPROACHING FRONT. AS THE FRONT ITSELF APPROACHES AROUND THE MIDDLE OF NEXT WEEK... SHOWERS COULD INCREASE SLIGHTLY AHEAD OF IT IF THE PREVAILING FLOW BECOMES MORE CONVERGENT. HOWEVER...GUIDANCE FAVORS CONTINUED DRY CONDITIONS OVERALL. EVEN THE FRONT IS EXPECTED TO DISINTEGRATE BEFORE ARRIVING...LEAVING ONLY A MASS OF MOISTURE THAT WILL MOVE IN ON INCREASING TRADE WINDS LATE NEXT WEEK. && .MARINE... THE CURRENT NORTHWEST SWELL HAS STARTED A SLOW DECLINE. WHILE SURF WILL BEGIN TO LOWER...IT WILL REMAIN ABOVE WARNING LEVEL IN PLACES THROUGH THIS EVENING...AND OVER THE ADVISORY LEVEL INTO FRIDAY. AS THE SWELL DIMINISHES...IT ALSO WILL TURN TO A MORE NORTH-NORTHWESTERLY DIRECTION...CAUSING THE SMALLER ISLANDS TO BLOCK THE SWELL FROM THE KONA SIDE OF THE BIG ISLAND. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR ALL HAWAIIAN WATERS FOR THE COMBINATION OF WINDS AND SEAS. THIS ADVISORY LIKELY WILL BE NEEDED FOR THE ENTIRE AREA INTO FRIDAY. BY THE WEEKEND...SEAS WILL DIMINISH...BUT WINDS WILL REMAIN STRONG OVER THE TYPICALLY WINDIER LOCATIONS AROUND MAUI COUNTY AND THE BIG ISLAND. && .HFO WATCHES/WARNINGS/ADVISORIES... HIGH SURF WARNING UNTIL 6 PM HST THIS EVENING FOR NORTH AND WEST FACING SHORES OF NIIHAU KAUAI OAHU AND MOLOKAI AND NORTH FACING SHORES OF MAUI. HIGH SURF ADVISORY UNTIL 6 PM HST THIS EVENING FOR WEST FACING SHORES OF THE BIG ISLAND. SMALL CRAFT ADVISORY UNTIL 6 AM HST FRIDAY FOR ALL HAWAIIAN WATERS. && $$ RYSHKO