FXHW60 PHFO 072012 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 1012 AM HST SAT DEC 7 2013 .SYNOPSIS... A WEAK RIDGE OF HIGH PRESSURE BUILDING OVER THE ISLANDS WILL KEEP WINDS LIGHT FOR THE NEXT FEW DAYS...LEADING TO AN INCREASE IN HAZE AND HUMIDITY. AN UPPER LEVEL LOW SOUTH OF THE ALOHA STATE COULD LEAD TO A FEW DOWNPOURS ON THE BIG ISLAND LATER THIS WEEKEND. LIGHT WINDS WILL GIVE WAY TO TRADES AGAIN ON TUESDAY AS HIGH PRESSURE BUILDS NORTH OF THE STATE. && .DISCUSSION... SATELLITE IMAGERY SHOWS THAT THE LOW LEVEL FLOW HAS ALREADY VEERED FROM EASTERLY TO SE. THE MODELS ARE IN GOOD AGREEMENT THAT THE FLOW WILL VEER EVEN MORE TO LIGHT KONA WINDS THIS AFTERNOON. LOW CLOUD MOTION IS CURRENTLY FROM THE SE AT ABOUT 14 KT NEAR KAUAI... AND IF THIS SPEED HOLDS AS THE WIND SHIFTS S...THIS WILL PROBABLY BE TOO STRONG TO ALLOW FOR MUCH AFTERNOON CLOUDINESS OR CONVECTION OVER THE SMALLER ISLANDS. WILL CONTINUE TO WATCH TRENDS AND MAY NEED TO UPDATE THE AFTERNOON FORECAST TO LOWER SKY COVER AND POPS. AN UPPER LEVEL LOW ABOUT 750 MILES S OF THE BIG ISLAND IS EXPECTED TO SHIFT SLOWLY N THIS WEEKEND. THE MIMIC AND POES IMAGERY SHOW THE DEEPER MOISTURE AND INSTABILITY ASSOCIATED WITH THIS LOW ARE ABOUT 100 MILES OR SO SOUTHEAST OF THE BIG ISLAND AND EDGING NORTHWARD. THIS SURGE IN DEEPER MOISTURE ALONG WITH SE LOW LEVEL BACKGROUND FLOW COULD LEAD TO A FEW DOWNPOURS IN THE KAU DISTRICT BY SUNDAY...AND HAVE ADDED THIS POSSIBILITY TO THE FORECAST. SOME INCREASE IN MOISTURE IS EXPECTED EVEN FOR THE SMALLER ISLANDS SUN- MON WHICH SHOULD INCREASE THE COVERAGE OF SHOWERS COMING UP FROM THE SOUTH ON THE KONA WINDS. MID LEVEL RIDGING BUILDS OVER THE STATE ON TUESDAY WITH SURFACE HIGH PRESSURE MOVING BY TO OUR N TUE-WED. THIS WILL RETURN THE TRADE WINDS...AND CLEAR OUT THE HAZE AND HUMIDITY. A FAIRLY TYPICAL DISTRIBUTION OF MAINLY NIGHT AND MORNING SHOWERS FOR WINDWARD AND MAUKA AREAS IS EXPECTED. ANOTHER BRIEF WEAKENING OR INTERRUPTION OF THE TRADES SEEMS LIKELY ON THU AS A FRONT PASSING BY TO THE N BREAKS DOWN THE HIGH TEMPORARILY...BUT A NEW STRONGER HIGH MOVES IN N OF THE ISLANDS TOWARD NEXT WEEKEND. 12Z GUIDANCE MAINTAINS THE TREND FIRST STARTED IN THE 06/12Z ECMWF RUN AND THE 07/00Z GFS SHOWING TRADES INSTEAD OF SE WINDS LATE IN THE WEEK. && .AVIATION... MAINLY VFR IS EXP FOR THE TERMINALS THRU THE PD. AFTN CLD/SHRA WITH ISOL MVFR CIGS WILL FOCUS ALONG INTERIOR AND SOME MT SECTIONS FROM 07/22Z-08/04Z. SE BIG ISLAND SLOPES AND ADJ WTRS MAY SEE TEMPO MVFR CONDITIONS DUE TO SHRA/RA BY 08/00Z SPREADING TO WINDWARD MAUI AFT 08/04Z. BKN-OVC CI WILL PERSIST OVR FAR SE BIG ISLAND ADJ WTRS. && .MARINE... THE COMBINATION OF S OR SE WINDS AND NW SWELL WILL MAKE IT ROUGH FOR BOATERS...BUT COULD SEE VERY CLEAN CONDITIONS FOR EXPERIENCED SURFERS ON N FACING SHORES IF THE SEA BREEZES DO NOT OVERPOWER THE SYNOPTIC BACKGROUND FLOW. ANOTHER PULSE DUE ON SUNDAY WILL MAINTAIN ADVISORY CONDITIONS...AND WAVEWATCH III GUIDANCE CONTINUES TO SHOW A MODERATE SWELL LASTING WELL INTO MIDWEEK. WINDS WILL REMAIN BELOW SMALL CRAFT ADVISORY /SCA/ LEVELS THROUGH AT LEAST MONDAY...BUT THE COMBINATION OF THE BUILDING NNW SWELL AND LINGERING HIGHER WIND WAVES IS PRODUCING COMBINED SEAS AROUND 10 FT AT BUOY 51101 AND THE HANALEI BUOY. AS A RESULT...AN SCA HAS BEEN ISSUED THROUGH THE AFTERNOON FOR KAUAI WATERS. EXPECT BORDERLINE CONDITIONS THROUGH THE WEEKEND...POSSIBLY SPREADING TO THE REST OF THE STATE. && .HFO WATCHES/WARNINGS/ADVISORIES... HIGH SURF ADVISORY UNTIL 6 PM HST SUNDAY FOR NIIHAU-KAUAI WINDWARD-KAUAI LEEWARD-OAHU NORTH SHORE-OAHU KOOLAU-MOLOKAI-MAUI WINDWARD WEST-MAUI CENTRAL VALLEY-WINDWARD HALEAKALA. SCA UNTIL 6 PM HST THIS EVENING FOR KAUAI NORTHWEST WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS. && $$ DISCUSSION/MARINE...R BALLARD AVIATION...DEJESUS