FXHW60 PHFO 191959 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 1000 AM HST WED SEP 19 2012 .SYNOPSIS... LIGHT TRADE WINDS WILL ALLOW DAYTIME SEA BREEZES AND NIGHTTIME LAND BREEZES TO FORM TODAY THROUGH FRIDAY. THE TRADES WILL BRING SHOWERS TO WINDWARD AREAS...MAINLY AT NIGHT...WHILE THE SEA BREEZES WILL BRING SHOWERS TO LEEWARD AREAS DURING THE AFTERNOONS. SOME OF THE SHOWERS WILL BE BRIEFLY HEAVY. HIGH PRESSURE WILL BUILD NORTH OF THE STATE...BRINGING STRONGER TRADE WINDS TO THE ISLANDS THIS WEEKEND. THE TRADES MAY BE WET ON SUNDAY. && .DISCUSSION... WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROUGH JUST NORTHEAST OF THE STATE...WITH AN IMPULSE DIGGING DOWN THE BACK SIDE OF IT. THIS SHORTWAVE IS CURRENTLY MOVING OVER MAUI COUNTY...HAVING HELPED TO ENHANCE SHOWERS OVER OAHU EARLIER IN THE MORNING. AT THE SURFACE HIGH PRESSURE IS LOCATED FAR NORTHEAST OF THE STATE...WITH A RIDGE EXTENDING ABOUT 450 MILES NORTH OF KAUAI. A COLD FRONT IS LOCATED ABOUT 700 MILES NORTHWEST OF KAUAI. 12Z SOUNDINGS FROM LIHUE AND HILO SHOW WEAK INVERSIONS OF 10-12KFT...AND PRECIPITABLE WATERS OF 1.3-1.4 INCHES. 16Z-18Z ACARS SOUNDINGS OUT OF HONOLULU ARE SIMILAR TO THE RAOBS AND ALSO SHOW SURFACE WINDS ARE OUT OF THE EAST...BUT LOW-LEVEL FLOW FROM 900MB-700MB OUT OF THE SOUTHEAST THE COLD FRONT NORTHWEST OF THE STATE WILL STALL AND WEAKEN...BUT NOT BEFORE ERODING THE RIDGE FROM THE WEST AND SHIFTING IT SOUTHWARD TOWARD THE STATE. THE PRESSURE GRADIENT ACROSS THE AREA HAS ALREADY WEAKENED...WITH THE PRESSURE DIFFERENCE BETWEEN BUOY 51000 TO THE NORTHEAST AND BUOY 51002 TO THE SOUTH HAVING DROPPED BY ABOUT A MILLIBAR OVER THE PAST 24 HOURS. THE GRADIENT WAS LIGHT ENOUGH FOR LAND BREEZES TO FORM LAST NIGHT AT MANY LOCATIONS...INCLUDING LIHUE/HONOLULU/KAHULUI. LOCALIZED SEA BREEZES ARE EXPECTED TODAY...WITH MORE WIDESPREAD SEA BREEZES ON THURSDAY. THE ATMOSPHERE IS SOMEWHAT MORE UNSTABLE THAN NORMAL DUE TO THE COLDER MID-LEVEL TEMPERATURES ASSOCIATED WITH THE TROUGH JUST NORTHEAST OF THE AREA. EARLY MORNING MIMIC TOTAL PRECIPITABLE WATER IMAGERY SHOWED THE MOIST AIRMASS WITH PW VALUES OF 1.4-1.6 EXTENDING OVER 500 MILES TO THE EAST OF THE BIG ISLAND. ONE CONCERN THOUGH IS THAT THE BULK OF THIS MOISTURE MAY STAY NORTHEAST OF THE STATE... BEING STEERED ACROSS WINDWARD WATERS BY THE LOW-LEVEL SOUTHEASTERLY FLOW. THE 12Z GFS AND TO A LESSOR EXTENT THE NAM DEPICT THIS SOLUTION...ALTHOUGH THE ECMWF AND CRAS SHOW GREATER MOISTURE OVER THE ISLANDS. GIVEN THAT THE PW VALUES NEAR KAUAI ARE ALREADY HIGH...WILL LEAN TOWARD THE HIGHER MOISTURE SOLUTION. WITH THE LIGHT TRADE WIND PATTERN...LEEWARD CLOUDS AND SHOWERS WILL BE MOST ACTIVE DURING THE AFTERNOON. WE MAY NEED TO UPDATE THIS MORNING TO INCREASE POPS/CLOUDS TO FEATURE MORE LEEWARD SHOWERS THIS AFTERNOON. THIS ACTIVITY WILL QUICKLY CLEAR OUT THIS EVENING AS OFFSHORE DRAINAGE FLOWS BEGIN TO REDEVELOP. SHOWERS ACROSS WINDWARD SECTIONS WILL BE MOST ACTIVE DURING THE NIGHT AND MORNING...WITH A SIGNIFICANT DECREASE DURING THE AFTERNOON. A SHORTWAVE IMPULSE HELPED TO ENHANCE SHOWERS OVER THE KOOLAUS THIS MORNING. HOWEVER... PERSISTENT SHOWERS MAY REDEVELOP TONIGHT UNDER THE LIGHT SOUTHEASTERLY LOW-LEVEL FLOW. WITH THE ELEVATED INVERSIONS AND AVAILABLE LOW-LEVEL MOISTURE...HEAVY RAINFALL IS POSSIBLE WITH THESE SHOWERS. HOWEVER...WITHOUT A FOCUSING MECHANISM...THE ACTIVITY SHOULD REMAIN ISOLATED ENOUGH TO NOT REQUIRE A FLASH FLOOD WATCH. THE SURFACE RIDGE STARTS TO REBUILD NORTH OF THE AREA ON FRIDAY... BUT REALLY STRENGTHENS FROM SATURDAY INTO SUNDAY. FRIDAY LOOKS TO BE SOMEWHAT OF A TRANSITION DAY...WITH SEA BREEZES LINGERING ACROSS SHELTERED LEEWARD AREAS. TRADES RETURN FULLY ON SATURDAY...AND STRENGTHEN FURTHER ON SUNDAY. LOW-LEVEL MOISTURE THINS OUT ON SATURDAY...BUT THE GFS/ECMWF SHOW IT INCREASING AGAIN BY SUNDAY AS ANOTHER SURGE OF TROPICAL MOISTURE MOVES IN FROM THE EAST. && .AVIATION... WHILE VFR CONDITIONS SHOULD PREVAIL...BRIEF MOUNTAIN OBSCURATIONS AND MVFR CIGS AND VIS AROUND SHOWERS COULD IMPACT ANY AREAS AROUND HAWAII TODAY AND TONIGHT. EAST TO SOUTHEAST WINDS WILL BE LIGHT OVER THE NEXT COUPLE DAYS...BUT CONVECTIVE CURRENTS OVER THE ISLANDS MAY PRODUCE ISOLATED POCKETS OF LOW LEVELS TURBULENCE DURING APPROACHES AND TAKEOFFS. NO AIRMETS ARE CURRENTLY IN EFFECT GIVEN THE SPARSE COVERAGE...BUT WILL BE MONITORING FOR POSSIBLE ISSUANCES FOR AIRMET SIERRA AND TANGO. && .MARINE... SOUTH SOUTHWEST SWELLS WILL PRODUCE MODERATE SURF ALONG SOUTH FACING SHORES THROUGH TODAY...WITH SMALL SURF EXPECTED THE REST OF THIS WEEK. A LOW DEEPENING FAR NORTH NORTHWEST OF THE ISLANDS TODAY WILL SEND A NORTHWEST SWELL IN OUR DIRECTION. THIS SWELL IS EXPECTED TO REACH THIS ISLANDS BEGINNING LATE SATURDAY...AND COULD BOOST SURF TO ADVISORY LEVELS ALONG NORTH AND WEST FACING SHORES ON SATURDAY NIGHT/SUNDAY. WINDS AND SEAS WILL REMAIN BELOW ADVISORY THRESHOLDS THROUGH SATURDAY. THE TRADE WINDS WILL LIKELY STRENGTHEN TO 25 KT IN THE WINDIER AREAS AROUND THE BIG ISLAND AND MAUI BY SATURDAY NIGHT. IN ADDITION...THE BUILDING NORTHWEST SWELL MAY COMBINE WITH LOCAL WIND WAVES TO GENERATE COMBINED SEAS GREATER THAN 10 FEET ACROSS PORTIONS OF THE REMAINING COASTAL WATERS EXPOSED TO THE NORTHWEST SWELL. && .HFO WATCHES/WARNINGS/ADVISORIES... NONE. && $$ PUBLIC/MARINE...BRAVENDER AVIATION...FOSTER  FXHW60 PHFO 200200 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 400 PM HST WED SEP 19 2012 .SYNOPSIS... LIGHT TRADE WINDS WILL ALLOW DAYTIME SEA BREEZES AND NIGHTTIME LAND BREEZES TO FORM THROUGH FRIDAY. THE TRADES WILL BRING SHOWERS TO WINDWARD AREAS...MAINLY AT NIGHT...WHILE THE SEA BREEZES WILL BRING SHOWERS TO LEEWARD AREAS DURING THE AFTERNOONS. SOME OF THE SHOWERS WILL BE BRIEFLY HEAVY. HIGH PRESSURE WILL BUILD NORTH OF THE STATE...BRINGING INCREASING TRADE WINDS TO THE ISLANDS THIS WEEKEND. THE TRADES MAY BE WET ON SUNDAY. && .DISCUSSION... WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROUGH JUST NORTHEAST OF THE STATE...WITH AN IMPULSE DIGGING DOWN THE BACK SIDE OF IT. THIS SHORTWAVE IS CURRENTLY MOVING EAST OF MAUI COUNTY...AND IS HELPING TO ENHANCE THUNDERSTORMS OVER THE OFFSHORE WATERS NORTHEAST OF THE BIG ISLAND. AT THE SURFACE HIGH PRESSURE IS LOCATED FAR NORTHEAST OF THE STATE...WITH A RIDGE EXTENDING ABOUT 400 MILES NORTH OF KAUAI. A COLD FRONT IS LOCATED ABOUT 700 MILES NORTHWEST OF KAUAI. 00Z SOUNDINGS FROM LIHUE AND HILO SHOW WEAK INVERSIONS OF 8-10KFT... WHICH ARE SLIGHTLY LOWER THAN THIS MORNING. PRECIPITABLE WATERS ARE 1.2-1.3 INCHES...WHICH ARE ALSO DOWN A TENTH OF AN INCH FROM THIS MORNING. THE RAOBS AND RADAR VAD WIND PROFILES SHOW SURFACE WINDS OUT OF THE EAST...BUT LOW-LEVEL FLOW FROM 900MB-700MB OUT OF THE SOUTHEAST. THIS SOUTHEASTERLY FLOW IS MOST PRONOUNCED NEAR THE BIG ISLAND...DUE TO THE PRESENCE OF A SURFACE TROUGH OFFSHORE TO THE NORTHEAST. THE COLD FRONT NORTHWEST OF THE STATE WILL STALL AND WEAKEN...BUT NOT BEFORE ERODING THE RIDGE FROM THE WEST AND SHIFTING IT SOUTHWARD TOWARD THE STATE. THE PRESSURE GRADIENT ACROSS THE AREA HAS ALREADY WEAKENED...WITH THE PRESSURE DIFFERENCE BETWEEN BUOY 51000 TO THE NORTHEAST AND BUOY 51002 TO THE SOUTH HAVING DROPPED BY ABOUT A MILLIBAR OVER THE PAST 24 HOURS. THE GRADIENT HAS BEEN WEAK ENOUGH FOR LOCALIZED SEA BREEZES TO FORM AT SHELTERED LEEWARD AREAS TODAY. LAND BREEZES ARE EXPECTED AGAIN TONIGHT ACROSS MUCH OF THE AREA... SIMILAR TO WHAT OCCURRED LAST NIGHT...WITH MORE WIDESPREAD SEA BREEZES EXPECTED FOR THURSDAY. THE ATMOSPHERE IS SOMEWHAT MORE UNSTABLE THAN NORMAL DUE TO THE COLDER MID-LEVEL TEMPERATURES ASSOCIATED WITH THE TROUGH JUST NORTHEAST OF THE AREA. EARLY AFTERNOON AMSU/SSMI BLENDED TOTAL PRECIPITABLE WATER IMAGERY MATCHES WITH THE KAUAI SOUNDING...BUT WAS TOO MOIST COMPARED TO THE HILO SOUNDING. EVEN IF THE AMOUNTS ARE SLIGHTLY HIGH...SATELLITE IMAGERY SHOWED THE MOIST AIRMASS WITH EXTENDING NEARLY 400 MILES TO THE EAST OF THE BIG ISLAND. ONE POSSIBILITY THOUGH IS THAT THE BULK OF THIS MOISTURE MAY STAY NORTHEAST OF THE STATE...BEING STEERED ACROSS WINDWARD WATERS BY THE LOW-LEVEL SOUTHEASTERLY FLOW. THE GFS AND TO A LESSOR EXTENT THE NAM DEPICT THIS SOLUTION...ALTHOUGH THE ECMWF AND CRAS SHOW GREATER MOISTURE OVER THE ISLANDS. GIVEN THAT CLOUDS CONTINUE TO ROTATE INTO MAUI COUNTY...WILL LEAN TOWARD THE MOIST SOLUTION WITH HIGHER POPS FOR TONIGHT. RAINFALL WILL BE FOCUSED ACROSS WINDWARD SECTIONS... WITH THE CLOUDS AND SHOWERS ACROSS LEEWARD AREAS CLEARING OUT BY SUNSET. WITH AN EVEN LIGHTER GRADIENT EXPECTED FOR THURSDAY...SEA BREEZES WILL BE MORE WIDESPREAD THAN TODAY. THESE WILL FOCUS SHOWERS ACROSS THE INTERIOR AND LEEWARD SECTIONS DURING THE AFTERNOON. THE ACTIVE SHOWERS ACROSS WINDWARD SECTIONS SHOULD LINGER INTO THE MORNING BEFORE DECREASING SIGNIFICANTLY DURING THE AFTERNOON. WITH THE SOMEWHAT ELEVATED INVERSION AND ADDITIONAL LOW-LEVEL MOISTURE UPSTREAM...HEAVY RAINFALL IS ALSO POSSIBLE WITH THESE SHOWERS. HOWEVER...WITHOUT A FOCUSING MECHANISM...THE ACTIVITY SHOULD REMAIN ISOLATED ENOUGH TO NOT REQUIRE A FLASH FLOOD WATCH. THE SURFACE RIDGE STARTS TO REBUILD NORTH OF THE AREA ON FRIDAY... BUT REALLY STRENGTHENS FROM SATURDAY INTO SUNDAY. FRIDAY LOOKS TO BE SOMEWHAT OF A TRANSITION DAY...WITH SEA BREEZES LINGERING ACROSS SHELTERED LEEWARD AREAS. TRADES RETURN FULLY ON SATURDAY...AND STRENGTHEN FURTHER ON SUNDAY. LOW-LEVEL MOISTURE THINS OUT ON SATURDAY...BUT THE GFS/ECMWF SHOW IT INCREASING AGAIN BY SUNDAY AS ANOTHER SURGE OF TROPICAL MOISTURE MOVES IN FROM THE EAST. && .AVIATION... EAST TO SOUTHEAST WINDS WILL BE LIGHT OVER THE NEXT COUPLE DAYS. VFR CONDITIONS SHOULD PREVAIL...BUT BRIEF MOUNTAIN OBSCURATIONS AND MVFR CIGS AND VIS AROUND SHOWERS COULD IMPACT ANY AREAS AROUND HAWAII. CONVECTIVE CURRENTS OVER THE ISLANDS MAY PRODUCE ISOLATED POCKETS OF LOW LEVELS TURBULENCE DURING APPROACHES AND TAKEOFFS...AND WILL BE A PRIMARY CONCERN WHILE DAYTIME HEATING OF THE LAND IS OCCURING. NO AIRMETS ARE CURRENTLY IN EFFECT GIVEN THE SPARSE COVERAGE OF TURBULENCE AND MOUNTAIN OBSCURATIONS...BUT WILL BE MONITORING FOR POSSIBLE ISSUANCES OF AIRMET SIERRA AND TANGO. && .MARINE... THE CURRENT SOUTHERLY SWELL WILL SLOWLY FADE THROUGH THE END OF THE WEEK. A SMALL NORTHWEST SWELL WILL FILL IN FRIDAY/SATURDAY...BEFORE A LARGER ONE ARRIVES OVER THE WEEKEND. A LOW DEEPENING FAR NORTH NORTHWEST OF THE ISLANDS WILL GENERATE THIS SWELL...WHICH IS EXPECTED TO REACH THIS ISLANDS BEGINNING LATE SATURDAY. THIS SWELL IS EXPECTED TO BOOST SURF TO ADVISORY LEVELS ALONG NORTH AND WEST FACING SHORES ON SATURDAY NIGHT/SUNDAY. WINDS AND SEAS WILL REMAIN BELOW ADVISORY THRESHOLDS THROUGH SATURDAY. THE TRADE WINDS WILL LIKELY STRENGTHEN TO 25 KT IN THE WINDIER AREAS AROUND THE BIG ISLAND AND MAUI BY SATURDAY NIGHT. IN ADDITION...THE BUILDING NORTHWEST SWELL MAY COMBINE WITH LOCAL WIND WAVES TO GENERATE COMBINED SEAS GREATER THAN 10 FEET ACROSS PORTIONS OF THE REMAINING COASTAL WATERS EXPOSED TO THE NORTHWEST SWELL. && .HFO WATCHES/WARNINGS/ADVISORIES... NONE. && $$ PUBLIC/MARINE...BRAVENDER AVIATION...FOSTER  FXHW60 PHFO 120146 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 400 PM HST FRI JAN 11 2013 .SYNOPSIS... WINDS WILL WEAKEN TONIGHT AS A TROUGH MOVES ACROSS THE STATE FROM THE EAST...AND WILL REMAIN LIGHT THROUGH THE WEEKEND. THE LIGHT WINDS WILL ALLOW FOR LOCAL AFTERNOON SEA BREEZES AND NIGHTTIME LAND BREEZES. CLOUDS AND SHOWERS WILL FAVOR INTERIOR AND LEEWARD SECTIONS OF THE ISLANDS EACH AFTERNOON THIS WEEKEND. SHOWERS WILL INCREASE EARLY NEXT WEEK ACROSS THE WESTERN ISLANDS AS A WEAKENING FRONT APPROACHES THE STATE. && .DISCUSSION... WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL LONGWAVE TROUGH OVER AND TO THE EAST OF THE STATE. EMBEDDED WITHIN THE TROUGH ARE A PAIR OF SHORTWAVES...LOCATED NEAR KAUAI/OAHU AND OVER 300 MILES NORTHEAST OF THE BIG ISLAND. AT THE SURFACE...A TROUGH IS LOCATED LESS THAN 150 MILES SOUTH-SOUTHEAST OF HILO. A STRONG HIGH IS LOCATED FAR NORTHEAST OF THE STATE. A DISSIPATING STATIONARY FRONT IS OVER 400 MILES NORTHWEST OF KAUAI...WHILE A STRONGER COLD FRONT IS FAR TO THE NORTHWEST. 00Z SOUNDINGS FROM HILO AND LIHUE SHOW AN OTHERWISE UNSTABLE AIRMASS WITH NO EFFECTIVE INVERSION. PRECIPITABLE WATERS RANGE FROM 0.94 AT LIHUE TO 1.15 AT HILO. EARLY AFTERNOON MIMIC TOTAL PRECIPITABLE WATER IMAGERY SHOWS GREATER MOISTURE UPSTREAM...WITH PW VALUES UP TO 1.7 INCHES WITHIN 100 MILES OF THE BIG ISLAND. THE SURFACE TROUGH SOUTHEAST OF THE BIG ISLAND IS EXPECTED TO MOVE NORTHWESTWARD OVER THE ISLANDS TONIGHT...EVENTUALLY WEAKENING TO OUR WEST ON SATURDAY. PERSISTENT THUNDERSTORMS ARE OCCURRING OVER THE EASTERN OFFSHORE WATERS...BUT THE EASTWARD PROGRESS OF THIS AREA HAS STARTED TO SLOW...AND SHOULD BEGIN TO SHIFT NORTHWARD THIS EVENING. ADDITIONAL DEEP CONVECTION HAS DEVELOPED ACROSS WINDWARD COASTAL WATERS OF MAUI COUNTY AND THE BIG ISLAND ALONG AN OUTFLOW BOUNDARY FROM THE MAIN COMPLEX TO THE EAST. ADDITIONAL DEEP CONVECTION IS LOCATED ACROSS LEEWARD SLOPES OF HALEAKALA...AND LEEWARD AND SOUTHEAST SECTIONS OF THE BIG ISLAND. THIS LEEWARD ACTIVITY WILL WEAKEN THIS EVENING WITH THE LOSS OF HEATING...BUT WINDWARD SHOWERS MAY CONTINUE. THERE IS SOME UNCERTAINTY AS TO HOW THE PATTERN WILL EVOLVE OVERNIGHT. THE GFS-LAMP IMPLIES THAT LAND BREEZES WILL WIN OUT WITH WINDWARD BIG ISLAND CLEARING OUT...WHILE THE 12Z CRAS INDICATES THAT THE EASTERN CONVECTION WILL SPREAD WESTWARD ACROSS THE BIG ISLAND. GIVEN THAT THE MAIN CONVECTION SHOULD MOVE NORTHWARD AND THAT MANY LOCATIONS CLEARED OUT LAST NIGHT...WILL LEAN TOWARD THAT PATTERN AGAIN FOR TONIGHT. KEPT HIGHER POPS FOR WINDWARD SECTIONS THROUGH THE EVENING...THEN DIMINISHING OVERNIGHT. MODEL CROSS SECTION SHOW AN INCREASE IN MOISTURE DEPTH TONIGHT INTO SATURDAY...MAINLY NEAR AND TO THE NORTHEAST OF THE BIG ISLAND... ASSOCIATED WITH THE SURFACE TROUGH. WHILE THE FREEZING LEVEL ON THE HILO SOUNDING IS OVER 13KFT...THE WETBULB ZERO HEIGHT IS BELOW 10KFT. AS CLOUDS INITIALLY REACH SUMMIT LEVEL...THEY COULD BE SHALLOW ENOUGH TO RESULT IN LIGHT FREEZING PRECIPITATION. DURING HEAVIER CONVECTIVE SHOWERS...THE MOISTURE SHOULD BE DEEP ENOUGH FOR ICE NUCLEATION...WITH HEAVIER BURSTS OF SNOW BEING POSSIBLE. THE CURRENT FORECAST HAS A CHANCE OF A MIX OF FREEZING RAIN AND SNOW...WHICH SHOULD COVER THIS SITUATION. THERE IS ENOUGH UNCERTAINTY WITH THE AMOUNT OF PRECIPITATION THAT MIGHT REACH THE SUMMIT THAT A WINTER WEATHER ADVISORY IS NOT APPLICABLE. IF THE POTENTIAL FOR WINTER BECOME MORE CERTAIN...WE MAY NEED TO ISSUE AN ADVISORY FOR THE SUMMITS. BY SATURDAY WINDS WILL WEAKEN FURTHER AND TURN SOUTHEASTERLY BEHIND THE TROUGH...PUTTING THE SMALLER ISLANDS IN A BLOCKED FLOW DOWNSTREAM OF THE BIG ISLAND. THE LIGHT WINDS WILL ALLOW FOR LOCALIZED CIRCULATIONS...WITH ONSHORE SEA BREEZES DURING THE DAY AND OFFSHORE LAND BREEZES AT NIGHT. THIS PATTERN WILL FOCUS CLOUDS AND SHOWERS ACROSS THE INTERIOR AND LEEWARD SECTIONS OF THE ISLANDS DURING THE AFTERNOON AND EVENING...WITH CLEARING OVERNIGHT. THERE REMAINS ENOUGH INSTABILITY TO KEEP A SLIGHT CHANCE OF THUNDERSTORMS FOR SATURDAY AFTERNOON ACROSS LEEWARD MAUI AND BIG ISLAND. BY SUNDAY MID-LEVEL TEMPERATURES START TO WARM...WHICH WILL LIMIT THE INSTABILITY AND CONSEQUENTLY THUNDER POTENTIAL. HOWEVER WITH WEAK LOW-LEVEL INVERSIONS...WE COULD STILL SEE HEAVIER BURSTS OF RAIN WITH THE AFTERNOON SHOWERS. BY EARLY NEXT WEEK...THE FRONT CURRENTLY FAR NORTHWEST OF THE STATE WILL HAVE REACHED THE ISLANDS. THE MAIN UPPER LEVEL SUPPORT WITH THIS FEATURE WILL STAY NORTH OF THE STATE...WITH THE PORTION OF THE BOUNDARY AT OUR LATITUDE STARTING TO WEAKEN. THIS WEAKENING FRONT IS EXPECTED TO REACH KAUAI ON MONDAY...THEN DISSIPATE ACROSS OAHU AND MAUI COUNTY BY MONDAY NIGHT/TUESDAY. SHOWERS ARE EXPECTED TO INCREASE IN PREFRONTAL CONVERGENCE AHEAD OF THE FRONT...ACROSS KAUAI LATE SUNDAY AND SUNDAY NIGHT AND OAHU ON MONDAY. BEHIND THE FRONT...A RELATIVELY WEAK HIGH WILL MOVE IN NORTHWEST OF THE STATE. WE SHOULD RETURN TO A MORE NORTHEASTERLY TRADE WIND PATTERN...BUT WIND SPEEDS WILL BE ON THE LIGHT SIDE THROUGH THE REMAINDER OF THE FORECAST PERIOD. && .MARINE... THE STRONG HIGH FAR NORTHEAST OF THE STATE WILL MAINTAIN A LARGE FETCH OF STRONG WINDS OF 30-35 KNOTS POINTED AT THE STATE. THESE WINDS EXTEND FROM JUST UPSTREAM OF THE ISLANDS TO OVER 1500 MILES EAST AND NORTHEAST. THE WINDS ARE CONTRIBUTING TO THE EASTERLY TRADE SWELL WITH A LONGER THAN NORMAL PERIOD NEAR 11 SECONDS. WAVE HEIGHTS AT THE NEARSHORE BUOYS EAST OF THE BIG ISLAND...MAUI...AND OAHU ARE STARTING TO SHOW AN INCREASE IN WAVE HEIGHTS. SURF HEIGHTS WILL BUILD FOR TONIGHT AND SATURDAY...THEN SLOWLY START TO DIMINISH FROM SUNDAY THROUGH THE FIRST PART OF THE WEEK. THE INCREASE IN THE SWELL TONIGHT DOES CORRESPOND WITH A 2.5 FOOT HIGH TIDE LATE NIGHT...WHICH COULD ENHANCE THE COASTAL IMPACTS FOR EXPOSED WINDWARD COASTS SATURDAY MORNING. HIGH SURF IS EXPECTED TO CONTINUE INTO SUNDAY BEFORE DIMINISHING EARLY NEXT WEEK. OTHERWISE...A REINFORCING LONG-PERIOD NORTHWEST SWELL ARRIVING SUNDAY NIGHT WILL GRADUALLY BUILD...AND MAY PRODUCE SURF JUST BELOW THE HIGH SURF ADVISORY THRESHOLDS ALONG NORTH AND WEST FACING SHORES OF SOME OF THE SMALLER ISLANDS STARTING TUESDAY. SURF WILL REMAIN ELEVATED ALONG NORTH AND WEST FACING SHORES AT LEAST THROUGH MID-WEEK. A LARGER AND LONGER-PERIOD NORTHWEST SWELL IS POSSIBLE LATE IN THE WEEK. && .AVIATION... VFR CONDITIONS WILL PREVAIL OVER LEEWARD TERMINALS WITH TEMPO MVFR AT PHTO...AND ISOL MVFR AT PHLI. TEMPO MVFR EXPECTED ALONG WINDWARD SLOPES IN CLD AND SHRA. SLIGHT CHANCE OF THUNDERSTORMS OVER THE SLOPES OF THE BIG ISLAND AND LEEWARD HALEAKALA EARLY THIS EVENING...AND AGAIN ON SATURDAY AFTERNOON. A TROUGH ALOFT MOVING FROM WEST TO EAST IS INCREASING UPPER LEVEL TURBULENCE...AND WILL REMAIN OVER THE STATE INTO SATURDAY. && .HFO WATCHES/WARNINGS/ADVISORIES... HIGH SURF ADVISORY UNTIL 600 PM HST SATURDAY FOR EAST FACING SHORES OF KAUAI...OAHU...MOLOKAI...MAUI AND THE BIG ISLAND. SMALL CRAFT ADVISORY UNTIL 600 PM HST SATURDAY FOR ALL HAWAIIAN WATERS...EXCEPT THE MAUI COUNTY LEEWARD WATERS AND MAALAEA BAY. && $$ DISCUSSION/MARINE...BRAVENDER AVIATION...MORRISON  FXHW60 PHFO 070139 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 400 PM HST WED NOV 6 2013 .SYNOPSIS... LIGHT WINDS WILL CONTINUE THROUGH THURSDAY NIGHT...WITH AFTERNOON CLOUDS AND SHOWERS LIKELY OVER THE INTERIOR OF THE ISLANDS AGAIN TOMORROW. HIGH PRESSURE BUILDING NORTH OF THE ISLANDS THROUGH THE WEEKEND WILL BRING A WET TRADE WIND PATTERN TO THE ISLANDS INTO THE START OF THE NEW WORK WEEK. LIGHT TO MODERATE TRADES SATURDAY WILL INCREASE TO MODERATE TO FRESH TRADES BY MONDAY. && .DISCUSSION... A SURFACE TROUGH NEAR MOLOKAI AND A DISSIPATING FRONTAL BOUNDARY NEAR KAUAI ARE EXPECTED TO MERGE TONIGHT...AND THE MODELS SHOW THE RESULTING BOUNDARY TO CONTINUE TO WEAKEN THROUGH FRIDAY. THESE BOUNDARIES HAVE WEAKENED THE TRADE WIND FLOW OVER THE ISLANDS. AS EXPECTED CLOUDS AND SHOWERS FORMED OVER THE INTERIOR OF THE ISLANDS THIS AFTERNOON WITH THE LIGHT WINDS THAT ALLOWED FOR SEA BREEZES. THE GFS HAS THE REMAINS OF THE BOUNDARY PASSING OVER THE ISLANDS TOMORROW...WHICH WILL CONTINUE THE LIGHT WIND FLOW. SATELLITE PRECIPITABLE WATER ESTIMATES SHOW SIMILAR VALUES OVER AND UPSTREAM OF THE ISLANDS. THE MODELS ARE IN GOOD AGREEMENT WITH HIGHER POPS TOMORROW AFTERNOON THAN TODAY...WITH THE CRAS BEING THE WETTEST. HAVE BOOSTED POPS STARTING WITH TOMORROW AFTERNOON TRENDING THEM TOWARDS THE CRAS DUE TO THE RESULTS OF TODAY. HIGH PRESSURE CONTINUES TO BUILD NORTH OF THE ISLANDS THROUGH THE END OF THE WEEK...AND WILL CONTINUE TO ATTEMPT TO BRING TRADE WINDS BACK TO THE ISLANDS. SOME AREAS COULD SEE SOME LIGHT TRADES ON FRIDAY...WITH MORE WIDESPREAD LIGHT TO MODERATE TRADES FOUND STATEWIDE SATURDAY. HIGH PRESSURE IS EXPECTED TO BRING MODERATE TO FRESH TRADE WINDS TO THE ISLANDS INTO THE START OF THE NEW WORK WEEK. INCREASED LOW LEVEL MOISTURE IS EXPECTED TO CONTINUE INTO THE START OF THE NEW WORK WEEK...WHICH WOULD KEEP A WET TRADE WIND PATTERN OVER THE ISLANDS. && .MARINE... AS WINDS INCREASE THIS WEEKEND AND EARLY NEXT WEEK...SMALL CRAFT CONDITIONS ARE POSSIBLE. A MODERATE NORTH SWELL WILL PEAK ON THURSDAY THEN DROP TO SMALL LEVELS FOR FRIDAY...FOLLOWED BY A MODERATE NORTHWEST SWELL THIS WEEKEND. A LARGE...SHORT-PERIOD NORTHEAST SWELL IS EXPECTED THIS WEEKEND ALONG WITH A SHARP INCREASE IN TRADE WINDS. && .AVIATION... LGT/VAR WINDS PREVAIL THIS AFTERNOON. AFTERNOON SEA BREEZES ARE PRODUCING SHRA/+RA OVER INTERIOR SECTIONS...MAINLY OAHU. A SHALLOW SHEARLINE WILL ALSO PRODUCE ADDITIONAL -SHRA/-DZ ON KAUAI AND ADJ WTRS THIS AFTERNOON...SPREADING EWD THRU TONIGHT. SHRA/BR WILL SHIFT BACK TO WINDWARD TERRAIN AFT 07/04Z. ANOTHER ROUND OF LGT WINDS AND AFTERNOON TCU/+RA EXPECTED THU 07/22Z-08/03Z. AIRMET SIERRA REMAINS IN EFFECT FOR THE WINDWARD BIG ISLAND. THIS MAY CONTINUE WELL INTO THE EVENING HOURS. THE JET STREAM ALF IS PRODUCING CHOP AOA FL320 AFFECTING MAINLY HIGH LVL TRAFFIC SO AIRMET TANGO WILL ALSO REMAIN POSTED UNTIL FURTHER NOTICE. && .HFO WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION/MARINE...M BALLARD AVIATION...DEJESUS  FXHW60 PHFO 081347 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 400 AM HST FRI NOV 8 2013 .SYNOPSIS... HEAVY SHOWERS WILL REMAIN A POSSIBILITY TODAY ON KAUAI...AND THIS AFTERNOON ON OAHU. EXPECT LIGHT TO MODERATE TRADES TO RETURN TODAY...AND INCREASE OVER THE WEEKEND...WITH FRESH TO STRONG TRADE WINDS SUNDAY AND MONDAY. AN APPROACHING FRONT WILL BRING ENHANCED SHOWERS TO THE ISLANDS SATURDAY NIGHT THROUGH SUNDAY NIGHT...WITH MORE WIDESPREAD CHANCES OF LOCALLY HEAVY RAINFALL. && .DISCUSSION... AN AREA OF HEAVY RAIN MOVED OVER KAUAI SHORTLY AFTER MIDNIGHT FROM THE SOUTH. OVER THE LAST HOUR OR SO...ADDITIONAL RAIN HAS FORMED AND MOVED ONSHORE OF THE GARDEN ISLE. THE CRAS AND NAM MODELS BOTH PICKED UP BETTER ON THE ADDITIONAL POPS OVER KAUAI FOR TODAY COMPARED TO THE GLOBAL AND OTHER MODELS. HAVE BEEFED UP POPS FOR KAUAI FOR ALL DAY TODAY AS A RESULT OF THE MODEL DEPICTION AND THE CURRENT RADAR IMAGERY. NOT SURPRISING THE CRAS AND NAM ALSO BOTH SHOW A MORE UNSTABLE ATMOSPHERE OVER KAUAI THAN THE OTHER MODELS. HAVE ADDED THE CHANCE FOR LOCALLY HEAVY RAINFALL FOR KAUAI ALL DAY...AND FOR THE AFTERNOON ON OAHU. THE LIHUE 12Z SOUNDING HAS 2.02 INCHES OF PRECIPITABLE WATER /PW/...BUT AS THERE WERE HEAVY SHOWERS IN THE AREA AT THE TIME OF THE LAUNCH...THIS IS LIKELY ON THE HIGH END. HILO HAD 1.69 INCHES OF PW AND SHOWS A MORE STABLE ATMOSPHERE. THE OVERALL PHILOSOPHY REMAINS THE SAME. AN UPPER LOW NORTH OF THE ISLANDS WILL STICK AROUND TODAY...AND CONTINUE TO PRODUCE THUNDERSTORMS NORTHEAST OF THE ISLANDS...AND IS HELPING TO DESTABILIZE THE AIRMASS OVER KAUAI...AND TO A LESSER EXTENT OAHU. THE SURFACE TROUGH NEAR THE ISLANDS IS WEAKENING...WHICH SHOULD ALLOW FOR SOME TRADES TO BUILD BACK IN TODAY. A SURFACE LOW NORTHEAST OF THE ISLANDS IS WEAKENING...BUT MODELS REMAIN IN GOOD AGREEMENT WITH IS RESURGENCE SATURDAY...AND WITH IT ASSOCIATED FRONT REACHING TOWARDS THE ISLANDS OVER THE WEEKEND. COMBINED WITH THE BROAD UPPER LEVEL TROUGH THAT REMAINS OVERHEAD...AN INCREASE IN SHOWER ACTIVITY IS EXPECTED. SATURDAY NIGHT AND SUNDAY...AS THE LOW MOVES TO THE EAST AND HIGH PRESSURE NORTH OF THE ISLANDS STRENGTHENS...TRADE WINDS ARE EXPECTED TO BE ON THE RISE. THIS SPELLS WET TRADES PARTICULARLY FOR WINDWARD LOCATIONS...BUT THE STRONG WINDS AND UNSTABLE AIRMASS WILL ALLOW SHOWERS TO REACH AND FORM OVER LEEWARD AREAS. AT THIS TIME WE HAVE LOCALLY HEAVY RAINFALL IN PORTIONS OF THE FORECAST STARTING SATURDAY AFTERNOON AND PERSISTING FOR ABOUT 24 HOURS. THE ECMWF HAS THE COLDEST TEMPERATURES FORECAST AT 500 MB...GETTING AS COLD AS -12 C OVER KAUAI SUNDAY. THE GFS AND NOGAPS ARE CLOSER TO -10 C. NORMAL FOR THIS TIME OF YEAR IS ABOUT -8 C. BOTH OVERNIGHT SOUNDINGS HAD NEAR NORMAL 500 MB TEMPERATURES. AS WE HEAD INTO THE NEW WORK WEEK...THE PRESSURE GRADIENT OVER THE ISLANDS SHOULD WEAKEN...SO EXPECT THE STRONG TRADES TO WEAKEN MONDAY AND TUESDAY. THE SECOND HALF OF THE WEEK LOOKS LIKE ADDITIONAL SHOWERS WILL WORK THEIR WAY IN...AS THE FRONT COULD RETROGRADE BACK ACROSS THE ISLANDS. && .MARINE... THE CURRENT MODERATE NORTH SWELL WILL BE FOLLOWED BY A MODERATE NORTHWEST SWELL THIS WEEKEND. A LARGE...SHORT-PERIOD NORTHEAST SWELL IS EXPECTED THIS WEEKEND ALONG WITH A SHARP INCREASE IN TRADE WINDS. A SIGNIFICANT NORTHERLY SWELL WILL ARRIVE LATE ON TUESDAY AND BUILD TO NEAR ADVISORY LEVELS ON WEDNESDAY. AS TRADES INCREASE THIS WEEKEND...A SMALL CRAFT ADVISORY WILL LIKELY BE POSTED OVER MOST...IF NOT ALL...COASTAL WATERS. GALE FORCE WINDS ARE POSSIBLE SUNDAY AND MONDAY...PARTICULARLY OVER THE NORTHERN WATERS. EXPECT THE TRADES TO TAPER OFF MONDAY NIGHT AND TUESDAY. && .AVIATION... THE AIRMET FOR MTN OBSC OVR THE INTERIOR MTNS OF KAUAI WILL LIKELY BE EXTENDED FROM 16Z TO 18Z. OTHERWISE...THE PREVAILING FLYING COND IS VFR. THERE WILL STILL BE BRIEF MVFR CEILING AND VIS WITH THE WIDELY DISPERSED SHOWERS RIDING IN WITH THE TRADE WIND FLOW. THESE SHOWERS WILL BE FAVORING THE WINDWARD AND MOUNTAIN AREAS OF THE LARGER ISLANDS. COVERAGE OF THESE SHOWERS...HOWEVER...WILL NOT WARRANT AN AIRMET FOR MTN OBSC FOR THE MORNING HOURS. HVY SHRA MAY RESUME OVR INTERIOR KAUAI AND OAHU AFT 22Z WHICH MAY WARRANT AN AIRMET FOR MTN OBSC. TEMPO MOD TURB BTN FL330 AND FL400...IN ASSOCIATION WITH THE JET STREAM...WILL CONTINUE THROUGH 090400 UTC. && .HFO WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION/MARINE...M BALLARD AVIATION...LAU  FXHW60 PHFO 310641 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 830 PM HST THU JAN 30 2014 .SYNOPSIS... SOUTHERLY WINDS WILL CONTINUE OVER THE ISLANDS AHEAD OF AN APPROACHING FRONT. THE FRONT IS EXPECTED TO REACH KAUAI FRIDAY NIGHT...AND STALL NEAR OAHU SATURDAY. SHOWERS ARE EXPECTED TO CONTINUE THROUGH THE WEEKEND...AND THEN BE ENHANCED BY ANOTHER SYSTEM EARLY NEXT WEEK. && .DISCUSSION... IN THE NEAR TERM...DO NOT ANTICIPATE MANY CHANGES TO THE GRIDS AT THIS TIME. SOUTHERLY FLOW OVER THE ISLANDS WILL HELP TO KEEP MOISTURE OVER THE ISLANDS OVERNIGHT AND TOMORROW. SHOWERS ON THE BIG ISLAND ARE TAPERING OFF SOME SINCE THIS AFTERNOON/S ACTIVITY. WITH THE SOUTHERLY FLOW...MOISTURE WILL REMAIN IN THE AREA THAT COULD SPARK SOME MORE SHOWERS...BUT AGREE THAT THE TREND OVERNIGHT SHOULD BE DOWN. THE MODELS SHOW GOOD AGREEMENT THROUGH FRIDAY NIGHT...BOTH AT THE SURFACE AND IN THE UPPER LEVELS. A SURFACE LOW FAR NORTHWEST OF THE ISLANDS MOVES CLOSER TO THE ISLANDS...KEEPING SOUTHERLY WINDS OVER THE MAIN HAWAIIAN ISLANDS AHEAD OF THE SYSTEM. THE SURFACE FRONT ASSOCIATED WITH THE SYSTEM IS EXPECTED TO REACH KAUAI FRIDAY NIGHT...STALLING OUT OVER THE SMALLER ISLANDS ON SATURDAY. WITH THE FRONT STALLING OUT...SOUTHERLY WINDS AHEAD OF THE FRONT WILL HELP TO USHER IN MOISTURE...KEEPING SHOWERS NOT ONLY ALONG THE FRONT BUT OUT AHEAD OF THE FRONT. FROM SATURDAY ONWARDS...THE MODELS START TO DIVERGE IN THEIR HANDLING OF BOTH THE SURFACE AND UPPER LEVEL FEATURE. THE GFS AND UKMET ARE SIMILAR IN THEIR MORE AGGRESSIVE NATURE OF LIFTING THE LOW TO THE NORTH. THE ECMWF LAGS A BIT BUT ALSO LIFTS THE LOW NORTHWARD. THE CRAS IS IS THE SLOWEST...BUT KEEPS THE SAME GENERAL MOTION. THE SAME IS TRUE IN THE UPPER LEVELS. THE MODELS ARE IN GENERAL AGREEMENT WITH THE STRENGTH OF THE SYSTEM THROUGHOUT THE TIME PERIOD. A DEEP LAYER TROUGH IS EXPECTED TO INVIGORATE THE STALLED FRONT EARLY NEXT WEEK. THIS WILL KEEP THE POSSIBILITY OF UNSETTLED WEATHER OVER THE ISLANDS INTO THE MIDDLE OF THE WEEK. && .MARINE... THE NEXT NORTHWEST SWELL IS EXPECTED TO ARRIVE LATE SATURDAY NIGHT...WHICH WILL LIKELY BRING ADVISORY LEVEL SURF SUNDAY/MONDAY. UNTIL THEN...SEAS AND WINDS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVEL. && .AVIATION... VFR CONDITIONS WILL PREVAIL ACROSS THE MAIN HAWAIIAN ISLANDS THROUGH TONIGHT AND FRIDAY...ALTHOUGH RESIDUAL CLOUD COVER ACROSS LEEWARD SECTIONS OF THE BIG ISLAND MAY CAUSE TEMPORARY MVFR CONDITIONS THIS EVENING. NO AIRMETS ARE IN EFFECT AS OF 8 PM HST. && .HFO WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION/MARINE...M BALLARD AVIATION...POWELL