FXHW60 PHFO 131953 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 1000 AM HST WED MAY 13 2015 .SYNOPSIS... LOCALLY BREEZY TRADE WINDS WILL CONTINUE THROUGH THE WEEK...THEN RAMP UP A BIT OVER THE WEEKEND. CLOUDS AND SHOWERS WILL FAVOR WINDWARD AND MAUKA AREAS...ESPECIALLY DURING THE NIGHT AND EARLY MORNING...WITH SOME SHOWERS PASSING ACROSS LEEWARD AREAS OF THE SMALLER ISLANDS. THE LEE SIDE OF THE BIG ISLAND WILL ALSO SEE CLOUDS AND SHOWERS EACH AFTERNOON. && .DISCUSSION... WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL LOW OVER THE EASTERN HALF OF THE STATE...WITH A RIDGE TO THE NORTHWEST AND NORTH. THE SUBTROPICAL JET IS LOCATED NEAR THE BIG ISLAND...AND EXTENDS WELL TO THE EAST. AT THE SURFACE...HIGH PRESSURE IS LOCATED FAR NORTH-NORTHEAST OF THE STATE...WITH A RIDGE PASSING SEVERAL HUNDRED MILES TO OUR NORTHWEST. A COLD FRONT IS LOCATED FAR TO THE NORTHWEST. 12Z SOUNDINGS FROM LIHUE AND HILO SHOWED RELATIVELY WEAK AND ELEVATED INVERSIONS AROUND 9KFT....AND PRECIPITABLE WATERS OF 1.01 AND 1.22 INCHES RESPECTIVELY. EARLY MORNING MIMIC TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE POCKET OF MOISTURE NEAR THE BIG ISLAND EXTENDING ACROSS THE WINDWARD COASTAL WATERS...WITH DRIER AIR UPSTREAM TO THE NORTHEAST AND EAST. ANOTHER BAND OF HIGHER MOISTURE IS LOCATED ABOUT 200 MILES NORTHEAST OF THE STATE. HIGH CLOUDS ASSOCIATED WITH THE SUBTROPICAL JET HAVE SHIFTED EAST OF THE BIG ISLAND...REVEALING THE AREA OF LOW CLOUDS COVERING WINDWARD SECTIONS. RAINFALL AMOUNTS HAVE BEEN GREATEST OVER THE BIG ISLAND... WITH UP TO AN INCH IN THE PAST 12 HOURS IN SEVERAL LOCATIONS. WINDWARD SHOWERS WILL DIMINISH BY AFTERNOON DUE TO A COMBINATION OF TYPICAL DIURNAL TRENDS ENHANCED BY DRIER AIR ADVECTING IN FROM THE NORTHEAST. THE ELEVATED INVERSIONS BENEATH THE UPPER LOW WILL ALLOW FOR GREATER CLOUD DEPTH WITH CLOUDS THAT FORM ACROSS LEEWARD SECTIONS OF THE BIG ISLAND. WE HAD ONE REPORT OF HEAVY RAIN FROM HONAUNAU YESTERDAY AFTERNOON...AND SIMILAR BRIEF HEAVY SHOWERS ARE POSSIBLE ACROSS THE KONA SLOPES THIS AFTERNOON AS WELL. THE SURFACE HIGH NORTH-NORTHEAST OF THE STATE WILL MOVE SOUTHEAST AND WEAKEN OVER THE NEXT FEW DAYS AS A FRONT PASSES WELL TO OUR NORTH. SURFACE PRESSURES AT AIRPORTS ACROSS THE STATE HAVE CONTINUED TO DROP...AND ARE DOWN ABOUT 1MB IN THE PAST 24 HOURS. HOWEVER AS THE HIGH WEAKENS FURTHER FROM 1031MB TO 1025MB THROUGH THURSDAY...IT WILL SHIFT CLOSER TO THE STATE. THE GRADIENT ACROSS THE ISLANDS HAS ONLY DROPPED OFF SLIGHTLY...AND WINDS WILL REMAIN LOCALLY BREEZY. THE 12Z MODELS SHOW THE UPPER LOW OVER THE STATE QUICKLY SHIFTING EASTWARD AND FILLING OVER THE NEXT DAY OR TWO. HOWEVER...AN UPPER TROUGH WILL LINGER BACK ACROSS THE ISLANDS...AND FORECAST SOUNDINGS SHOW INVERSIONS REMAINING WEAK AND ELEVATED THROUGH THE WEEKEND. MODEL CROSS SECTIONS SHOW VARYING LEVELS OF MOISTURE DEPTH...TIED INTO POCKETS OF MOISTURE EMBEDDED IN THE TRADES. BASED ON THE 12Z GFS TIMING...THE BAND OF MOISTURE MENTIONED ABOVE SHOULD REACH THE ISLANDS ON THURSDAY AFTERNOON/EVENING. A SIMILAR AND CONSISTENT PATTERN IS EXPECTED THROUGH THE UPCOMING WEEKEND. MODERATE TO LOCALLY FRESH TRADES WILL CONTINUE...WITH THE SURFACE RIDGE REMAINING NORTH OF 30N. A NEW HIGH WILL BUILD NORTHEAST OF THE STATE BY THE WEEKEND...HELPING TO ENHANCE WINDS ONCE AGAIN. POCKETS OF MOISTURE EMBEDDED IN THE TRADES WILL BRING PERIODS OF SHOWERS...THOUGH EXACT TIMING OF THESE SMALL SCALE FEATURES WILL REMAIN DIFFICULT. SHOWERS WILL AFFECT MAINLY WINDWARD SECTIONS...BUT WITH A NUMBER OF SHOWERS BRIEFLY SPREADING LEEWARD OF THE SMALLER ISLANDS AS WELL. && .AVIATION... VAD WIND PROFILES AND AMDAR REPORTS ARE SHOWING SUSTAINED WINDS BETWEEN 15 AND 20 KT WITH OCCASIONAL WINDS UP TO 25 KT WITHIN THE LAYER. THE EARLY MORNING SOUNDINGS FROM LIHUE AND HILO PUT A WEAK INVERSION AROUND 9 KFT. WITH THE WIND CONDITIONS RIGHT AT THE THRESHOLD LEVEL AND EXPECTED TO STAY THERE UNTIL AT LEAST THURSDAY...AIRMET TANGO FOR LOW LEVEL TURB WILL REMAIN POSTED FOR AREAS OVER AND SOUTH THROUGH WEST OF THE TERRAIN. EARLY MORNING SHOWERS PROMPTED AN AIRMET SIERRA OVER WINDWARD BIG ISLAND. THESE SHOWERS...PRODUCING TEMPO MVFR TO ISOL IFR WILL SCATTER OUT INTO THE AFTERNOON AND THE AIRMET WILL LIKELY BE CANCELLED. THROUGHOUT THE DAY...ALL WINDWARD AREAS SHOULD EXPECT PASSING SHOWERS WITH POSSIBLE TEMPO MVFR EMBEDDED. OTHERWISE...VFR WILL PREVAIL. CONDITIONS ALONG WINDWARD AREAS WILL DETERIORATE LATE TONIGHT AS A PATCH OF SHOWERY CLOUDS...APPROX 200 NM UPSTREAM...APPROACHES THE ISLANDS. THE UPPER LEVEL LOW IS CENTERED JUST NORTHEAST OF PHOG AND THE UPPER LEVEL JET HAS MOVED FAR ENOUGH TO THE EAST TO LIMIT HIGH CLOUDS OVER THE ISLANDS. AIRMET TANGO REMAINS POSTED FOR UPPER LEVEL TURB BETWEEN FL270 AND FL390. HOWEVER...MOST SIGNIFICANT TURB IS LIKELY TO BE A FEW HUNDRED MILES NORTHEAST OF THE ISLANDS. THE UPPER LEVEL LOW IS FORECAST TO MOVE EAST...PUSHING THE JET AND THE CHANCE FOR TURB FURTHER FROM THE ISLANDS BY LATE TONIGHT. && .MARINE... THE SMALL CRAFT ADVISORY FOR THE TYPICALLY WINDER ZONES NEAR MAUI AND THE BIG ISLAND IS NOW IN EFFECT THROUGH THURSDAY NIGHT...WHILE THE KAIWI CHANNEL IS STILL EXPERIENCING STRONG ENOUGH WINDS TO JUSTIFY KEEPING IT UNDER THE ADVISORY THROUGH TONIGHT. A MODERATE NORTHWEST SWELL WILL ARRIVE LATE THURSDAY/EARLY FRIDAY... WITH A SERIES OF SMALL TO MODERATE NORTHWEST SWELLS CONTINUING INTO EARLY NEXT WEEK. SURF ALONG EAST FACING SHORES WILL REMAIN ROUGH AND CHOPPY...THOUGH BETWEEN THE DECREASE IN WINDS AND SHRINKING OF THE UPSTREAM FETCH THERE WILL BE A DOWNWARD TREND IN SURF HEIGHTS. SOUTH SHORES WILL SEE SMALL SWELLS THROUGH MUCH OF THE WEEK...WITH A SLIGHTLY LARGER SWELL ARRIVING LATE THURSDAY/FRIDAY AND CONTINUING INTO THE WEEKEND. && .HFO WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY UNTIL 6 AM HST THURSDAY FOR KAIWI CHANNEL. SMALL CRAFT ADVISORY UNTIL 6 AM HST FRIDAY FOR MAALAEA BAY- PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS. && $$ DISCUSSION/MARINE...BRAVENDER AVIATION...EATON  FXHW60 PHFO 140157 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 400 PM HST WED MAY 13 2015 .SYNOPSIS... LOCALLY BREEZY TRADE WINDS WILL CONTINUE THROUGH THE WEEK...AND RAMP UP A BIT OVER THE WEEKEND. CLOUDS AND SHOWERS WILL FAVOR WINDWARD AND MAUKA AREAS...ESPECIALLY DURING THE NIGHT AND EARLY MORNING... WITH SOME SHOWERS PASSING ACROSS LEEWARD AREAS OF THE SMALLER ISLANDS. THE LEE SIDE OF THE BIG ISLAND WILL ALSO SEE CLOUDS AND SHOWERS EACH AFTERNOON. && .DISCUSSION... WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL LOW OVER THE EASTERN HALF OF THE STATE...WITH A RIDGE TO THE NORTHWEST AND NORTH. THE SUBTROPICAL JET IS LOCATED NEAR THE BIG ISLAND...AND EXTENDS WELL TO THE EAST. AT THE SURFACE...HIGH PRESSURE IS LOCATED FAR NORTH-NORTHEAST OF THE STATE...WITH A RIDGE PASSING SEVERAL HUNDRED MILES TO OUR NORTHWEST. A COLD FRONT IS LOCATED FAR TO THE NORTHWEST. 00Z SOUNDINGS SHOW AN INVERSION NEAR 7KFT AT LIHUE AND WEAK INVERSIONS NEAR 7KFT AND 13KFT AT HILO. PRECIPITABLE WATERS ARE 0.92 AND 1.03 INCHES RESPECTIVELY. LATE MORNING MIMIC TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE EARLIER MOISTURE BAND MOVING PAST THE STATE...WITH AN AREA OF DRIER AIR EXTENDING ABOUT 100-150 MILES NORTHEAST OF THE STATE. ANOTHER BAND OF HIGHER MOISTURE IS LOCATED JUST BEYOND THIS AREA. WINDWARD CLOUDS AND SHOWERS THINNED OUT A BIT THIS AFTERNOON AS DRIER AIR MOVED OVER THE STATE...AND THIS WILL CONTINUE THROUGH THE EVENING. RAINFALL WAS LIMITED ACROSS MOST AREAS...WITH THE EXCEPTION BEING LEEWARD BIG ISLAND. THE ELEVATED INVERSIONS BENEATH THE UPPER LOW DID ALLOW FOR GREATER CLOUD DEPTH AND SHOWER COVERAGE ACROSS LEEWARD BIG ISLAND...AND WE RECEIVED A COUPLE BRIEF HEAVY RAIN REPORTS. SHOWERS ACROSS LEEWARD BIG ISLAND WILL DIMINISH QUICKLY WITH SUNSET THIS EVENING...AND WINDWARD SHOWERS WILL PICK UP OVERNIGHT AS THE NEXT BAND OF MOISTURE REACHES THE STATE. THE SURFACE HIGH NORTH-NORTHEAST OF THE STATE WILL MOVE SOUTHEAST AND WEAKEN OVER THE NEXT FEW DAYS AS A FRONT PASSES WELL TO OUR NORTH. SURFACE PRESSURES AT AIRPORTS ACROSS THE STATE HAVE CONTINUED TO DROP...AND ARE DOWN ABOUT 1MB IN THE PAST 24 HOURS. HOWEVER AS THE HIGH WEAKENS FURTHER FROM 1031MB TO 1025MB THROUGH THURSDAY...IT WILL SHIFT CLOSER TO THE STATE. THE GRADIENT ACROSS THE ISLANDS HAS ONLY DROPPED OFF SLIGHTLY...AND WINDS WILL REMAIN LOCALLY BREEZY. 12Z/18Z MODELS SHOW THE UPPER LOW OVER THE STATE QUICKLY SHIFTING EASTWARD AND FILLING OVER THE NEXT DAY OR TWO. HOWEVER...AN UPPER TROUGH WILL LINGER BACK ACROSS THE ISLANDS...AND FORECAST SOUNDINGS SHOW INVERSIONS REMAINING WEAK AND ELEVATED THROUGH THE WEEKEND. MODEL CROSS SECTIONS SHOW VARYING LEVELS OF MOISTURE DEPTH...TIED INTO POCKETS OF MOISTURE EMBEDDED IN THE TRADES. BASED ON THE 18Z GFS TIMING...THE BAND OF MOISTURE MENTIONED ABOVE SHOULD REACH THE ISLANDS TONIGHT AND AFFECT US THROUGH THURSDAY MORNING. A SIMILAR AND CONSISTENT PATTERN IS EXPECTED THROUGH THE UPCOMING WEEKEND. MODERATE TO LOCALLY FRESH TRADES WILL CONTINUE...WITH THE SURFACE RIDGE REMAINING NORTH OF 30N. A NEW HIGH WILL BUILD NORTHEAST OF THE STATE BY THE WEEKEND...HELPING TO ENHANCE WINDS ONCE AGAIN. POCKETS OF MOISTURE EMBEDDED IN THE TRADES WILL BRING PERIODS OF SHOWERS...THOUGH EXACT TIMING OF THESE SMALL SCALE FEATURES WILL REMAIN DIFFICULT. SHOWERS WILL AFFECT MAINLY WINDWARD SECTIONS...BUT WITH A NUMBER OF SHOWERS BRIEFLY SPREADING LEEWARD OF THE SMALLER ISLANDS AS WELL. && .AVIATION... MODERATE AND GUSTY TRADE WINDS WILL CONTINUE INTO THURSDAY. AIRMET TANGO FOR LOW LEVEL TURB OVER AND SOUTH THROUGH WEST OF THE TERRAIN WILL REMAIN POSTED. LEEWARD BIG ISLAND...INCLUDING KAU AND NORTH AND SOUTH KONA DISTRICTS HAVE SEEN CLOUD BUILD UPS AND SHOWERS THIS AFTERNOON. SOME SHOWERS ARE CARRYING MVFR CIGS AND VIS WITH TCU TOPS REACHING 15 KFT. THESE SHOWERS WILL SUBSIDE AND SCATTER OUT WITH SUNSET. WINDWARD AREAS ON ALL ISLANDS CONTINUE TO SEE PASSING SHOWERS. AN ENHANCED BAND OF MOISTURE WILL ADVECT INTO THE WINDWARD AREAS OF THE ISLANDS LATE TONIGHT. HEAVY DOWNPOURS WITH TEMPO MVFR AND POSSIBLE ISOL IFR ARE LIKELY WITHIN THIS BAND...ESPECIALLY OVER THE EASTERN ISLANDS AS AN UPPER LEVEL LOW PASSES JUST EAST OF PHOG. MOUNTAIN OBSCURATION AIRMETS WILL LIKELY BE NEEDED LATER. THE UPPER LEVEL LOW MENTIONED ABOVE AND THE SUB TROPICAL JET SOUTH AND EAST OF IT WILL CONTINUE TO MOVE EAST. ANY UPPER LEVEL TURB MENTIONED IN EARLIER PRODUCTS HAS SINCE BEEN REMOVED...MOST SIGNIFICANT TURB ASSOCIATED WITH THE SUB TROPICAL JET WILL BE SEVERAL HUNDRED OF MILE NORTHEAST OF THE ISLANDS. && .MARINE... THE SMALL CRAFT ADVISORY FOR THE TYPICALLY WINDER ZONES NEAR MAUI AND THE BIG ISLAND REMAINS IN EFFECT THROUGH THURSDAY NIGHT...AND WILL LIKELY BE EXTENDED FURTHER THROUGH THE WEEKEND. THE MORNING ASCAT PASS MISSED US...BUT THE HIGH RESOLUTION WRF FROM UH STILL INDICATES 25 KNOTS OF WIND POSSIBLE THROUGH THE KAIWI CHANNEL...AND THEY WILL REMAIN IN THE ADVISORY THROUGH TONIGHT. A MODERATE NORTHWEST SWELL WILL ARRIVE LATE THURSDAY/EARLY FRIDAY... WITH A SERIES OF SMALL TO MODERATE NORTHWEST SWELLS CONTINUING INTO EARLY NEXT WEEK. SURF ALONG EAST FACING SHORES WILL REMAIN ROUGH AND CHOPPY WITH LITTLE CHANGE EXPECTED THROUGH THE WEEKEND. SOUTH SHORES WILL SEE SMALL SWELLS THROUGH MUCH OF THE WEEK...WITH A SLIGHTLY LARGER SWELL ARRIVING LATE THURSDAY/FRIDAY AND CONTINUING INTO THE WEEKEND. && .HFO WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY UNTIL 6 AM HST THURSDAY FOR KAIWI CHANNEL. SMALL CRAFT ADVISORY UNTIL 6 AM HST FRIDAY FOR MAALAEA BAY- PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS. && $$ DISCUSSION/MARINE...BRAVENDER AVIATION...EATON