| Current Conditions | ||
| Temp |  | 10.2 C |
| RH | | 25 % |
| Wind | | E 15 mph |
| Road | | Open |
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Hawaiian Islands Synoptic Discussion and Guidance 965 FXHW60 PHFO 232005 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 1005 AM HST WED JUL 23 2014 .SYNOPSIS... DRIER AND LOCALLY BREEZY TRADE WIND WEATHER WILL PREVAIL ACROSS THE STATE THROUGH THURSDAY...WITH TRADE WINDS DIMINISHING SLIGHTLY AS WE HEAD INTO THE WEEKEND. ONLY BRIEF WINDWARD SHOWERS ARE EXPECTED THE NEXT COUPLE OF DAYS...WITH A CHANCE THAT WINDWARD SHOWERS WILL INCREASE TOWARDS THE LATER PART OF THE WEEKEND AND INTO EARLY NEXT WEEK. && .DISCUSSION... CURRENTLY...MODERATE TO LOCALLY STRONG TRADE WINDS OVER THE ISLANDS ARE BEING SUPPORTED BY A 1032 MB HIGH CENTERED ABOUT 1500 MILES TO THE N. THE ISLAND AIR MASS IS IN THE PROCESS OF DRYING OUT...WITH SURFACE DEW POINTS DOWN ABOUT 7-8 DEGREES F OVER THE PAST 24 HOURS...AND DRIER AIR IMMEDIATELY UPSTREAM. WHILE EARLY MORNING SOUNDINGS SHOW A SUBSIDENCE INVERSION IN PLACE BETWEEN 7 AND 8 KFT...THEY ALSO INDICATE A FAIR AMOUNT OF INSTABILITY/CAPE ABOVE ABOUT 12 KFT. LATEST VISIBLE IMAGERY SHOWS A FAIRLY TYPICAL DISTRIBUTION OF LOW CLOUDS OVER THE ISLANDS AND NEAR SHORE WATERS THIS MORNING...EXCEPT THE LOWER WINDWARD AND LEEWARD SLOPES OF THE BIG ISLAND ARE A LITTLE CLOUDIER THAN NORMAL. THE FORECAST CALLS FOR MID AND UPPER LEVEL RIDGING TO BECOME BETTER DEVELOPED OVER THE ISLANDS IN THE SHORT TERM...AS DRIER AIR MOVES IN FROM THE E. THIS WILL LEAD TO A FAIRLY TYPICAL AND BREEZY TRADE WIND PATTERN INTO FRIDAY...WITH BRIEF WINDWARD SHOWERS FAVORING NIGHTS AND MORNINGS...AND TYPICAL AFTERNOON CLOUDS AND SHOWERS OVER THE BIG ISLAND LEEWARD SLOPES. WITH THE INSTABILITY ALOFT NOTED IN OVERNIGHT SOUNDINGS...THERE IS A CHANCE TODAY THAT WE SEE A REPEAT OF YESTERDAY AFTERNOON...WHEN THUNDERSTORMS AND HEAVY SHOWERS DEVELOPED OVER INTERIOR AND LEEWARD SLOPES OF THE BIG ISLAND. WILL BE UPDATING THE FORECAST TO INCREASE AFTERNOON POPS AND SKY COVER IN THAT AREA... BUT WILL BE OMITTING THE THUNDERSTORM THREAT. THE TRADE WIND-SUPPLYING HIGH TO THE N IS FORECAST TO WEAKEN AND SLIDE E LATE THURSDAY INTO FRIDAY...WITH TRADE WINDS GRADUALLY DIMINISHING IN RESPONSE. ALTHOUGH A WEAKNESS IN THE RIDGE PREVAILS N OF THE ISLANDS INTO NEXT WEEK...GLOBAL FORECAST MODELS ARE ANTICIPATING THAT A WEAK TROPICAL SYSTEM WILL PASS WELL S OF THE ISLANDS THIS WEEKEND AND EARLY NEXT WEEK. WHILE ANY INCIPIENT SYSTEM IS NOT EXPECTED TO THREATEN THE ISLANDS...IT/S PRESENCE COULD TIGHTEN THE LOCAL PRESSURE GRADIENT AND PRODUCE STRONGER TRADE WINDS THAN CURRENTLY FORECAST. A SLIGHT INCREASE IN TRADE SHOWERS IS POSSIBLE OVER THE WEEKEND AND EARLY NEXT WEEK AS RIDGING ALOFT GIVES WAY TO WEAK TROUGHING...AND LOW LEVEL MOISTURE INCREASES FROM THE ESE SUNDAY AND MONDAY. TYPICAL TRADE WIND WEATHER ON TUESDAY MAY GIVE WAY TO WETTER CONDITIONS WEDNESDAY AND THURSDAY AS MORE TROPICAL MOISTURE POTENTIALLY ADVECTS IN FROM THE ESE. && .MARINE... A SMALL CRAFT ADVISORY /SCA/ REMAINS IN EFFECT FOR THE TYPICALLY WINDY WATERS AROUND THE BIG ISLAND AND MAUI DUE TO FRESH TO LOCALLY STRONG TRADE WINDS. WINDS ARE EXPECTED TO DIMINISH BELOW SCA SPEEDS FROM FRIDAY INTO THE WEEKEND...ALTHOUGH THERE IS THE OUTSIDE CHANCE A TROPICAL SYSTEM PASSING WELL S OF THE ISLANDS KEEPS THE LOCAL GRADIENT TIGHTER THAN CURRENTLY EXPECTED...WHICH WOULD LEAD TO STRONGER TRADE WINDS. NO SIGNIFICANT SWELLS ARE EXPECTED THROUGH THE UPCOMING WEEK. SMALL LONG-PERIOD BACKGROUND SWELL FROM THE SSW AND SHORT-PERIOD SWELL FROM THE SE REPRESENT THE SWELL SOURCES FROM THE S HEMISPHERE... WHILE SHORT PERIOD WIND WAVES FROM THE E REPRESENT THE ONLY SOURCE OF SWELL FROM THE N HEMISPHERE. && .AVIATION... MODERATE AND GUSTY TRADE WINDS WILL CONTINUE THROUGH THE PERIOD. AIRMET TANGO IS POSTED FOR LOW LEVEL TURB IN THE LEE OF THE TERRAIN FOR ALL ISLANDS BELOW 8 KFT. OVERALL...ISLAND TERMINALS WILL REMAIN PREDOMINATELY VFR. TRADES WILL CARRY PASSING SHOWERS...MAINLY AFFECTING WINDWARD AND MAUKA AREAS. SOME SHOWERS MAY PRODUCE BRIEF MVFR CONDITIONS. && .HFO WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY THROUGH 6 PM HST THURSDAY FOR THE PAILOLO AND ALENUIHAHA CHANNELS...MAALAEA BAY AND WATERS SOUTH OF THE BIG ISLAND. && $$ DISCUSSION/MARINE...BIRCHARD AVIATION...EATON Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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