Weather Service Report


552 
FXHW60 PHFO 290137
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST MON JUL 28 2014

.SYNOPSIS...
HIGH PRESSURE FAR NORTHEAST OF THE STATE WILL MAINTAIN MODERATE TO 
LOCALLY FRESH TRADE WINDS ACROSS THE ISLANDS. SHOWERS CARRIED BY THE 
TRADES WILL AFFECT MAINLY WINDWARD AND MAUKA AREAS FOR THE NEXT 
SEVERAL DAYS. A SURGE IN MOISTURE FROM THE SOUTHEAST COULD BRING AN 
INCREASE IN SHOWERS AND MORE HUMID CONDITIONS LATE IN THE WEEK. 

&&

.DISCUSSION...
WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROUGH NORTH OF THE 
STATE...WITH A RIDGE TO THE SOUTHEAST. AT THE SURFACE...HIGH 
PRESSURE IS LOCATED FAR NORTHEAST OF THE STATE...WITH A TROUGH FAR 
TO THE NORTH. 00Z SOUNDINGS SHOW INVERSIONS RANGING FROM 4KFT AT 
LIHUE TO 6KFT AT HILO. THE HILO INVERSION IS ALSO WEAKER...WITH A 
SECONDARY INVERSION NEAR 12KFT. PRECIPITABLE WATERS ARE ALSO 
1.34-1.44 INCHES RESPECTIVELY...WHICH IS NEAR NORMAL FOR THIS TIME 
OF YEAR. EARLY AFTERNOON MIMIC TOTAL PRECIPITABLE WATER IMAGERY 
SHOWS A POCKET OF MOISTURE NEAR THE BIG ISLAND...WITH DRIER AIR 
ACROSS THE SMALLER ISLANDS AND WELL UPSTREAM TO THE NORTHEAST AND 
EAST. 

SHOWERS HAVE BEEN LIMITED THIS AFTERNOON...WITH ONLY A FEW GAGES ON 
THE BIG ISLAND PICKING UP MEASURABLE RAINFALL OVER THE LAST 6 
HOURS. THE AREA OF CLOUDS OVER THE EASTERN HALF OF THE STATE THIS 
MORNING HAS THINNED OUT DURING THE AFTERNOON...AND DRIER AIR 
UPSTREAM WILL BE SPREADING ACROSS THE ISLANDS TONIGHT. HAVE LOWER 
POPS A BIT TONIGHT TO ACCOUNT FOR THE DRIER AND MORE STABLE 
CONDITIONS. 

THE SURFACE HIGH WILL REMAIN NEARLY STATIONARY FAR NORTHEAST OF THE 
STATE THROUGH MUCH OF THE WEEK. WHILE THE HIGH DOES NOT 
STRENGTHEN...WE ARE ALREADY STARTING TO SEE A TIGHTENING OF THE 
PRESSURE GRADIENT ACROSS THE ISLANDS DUE TO LOW PRESSURE WELL TO OUR 
SOUTH. OVERALL WE EXPECT A TYPICAL TRADE WIND SETUP WITH SHOWERS 
FOCUSED MAINLY ACROSS WINDWARD AND MAUKA AREAS...AT LEAST FOR THE 
FIRST HALF OF THE WEEK. GFS FORECAST SOUNDINGS SHOW INVERSION 
HEIGHTS DIPPING EVEN LOWER FOR THE NEXT DAY OR TWO...AS WE HAVE 
ALREADY STARTED TO SEE AT LIHUE THIS AFTERNOON. WITH NO NOTICEABLE 
SOURCES OF MOISTURE IMMEDIATELY UPSTREAM...THIS WILL HELP TO LIMIT 
RAINFALL CHANCES FOR THE NEXT COUPLE DAYS. WINDS MAY BE LOCALLY 
BREEZY AT TIMES. 

BY THE END OF THE WEEK...WE MAY SEE A SURGE IN TROPICAL MOISTURE 
FROM THE SOUTHEAST THAT COULD BRING AN INCREASE IN SHOWERS AND MUGGY 
CONDITIONS. EXTENDED MODELS OVER THE LAST FEW DAYS HAVE BEEN BACK 
AND FORTH WITH TIMING AND HOW FAR NORTH TO BRING THE MOISTURE...SO 
IT IS DIFFICULT TO NAIL DOWN SPECIFICS AT THIS POINT. HOWEVER...THEY 
SEEM TO BE CONVERGING ON A SOLUTION THAT WOULD BRING AN INCREASE IN 
TROPICAL MOISTURE TO BIG ISLAND LATE THURSDAY/FRIDAY...WHICH WOULD 
THEN SPREAD ACROSS THE REST OF THE STATE DURING THE WEEKEND. 

&&

.AVIATION...
THE ISOLATED TCU WITH TOPS BETWEEN 150 AND 180 KFT ALONG THE LEE 
SLOPES OF MAUNA KEA AND MAUNA LOA SHOULD BEGIN WEAKEN WITH SUNSET. 
ELSEWHERE...WEATHER OVER ISLANDS WILL REMAIN RATHER BENIGN INTO THIS 
EVENING AND TONIGHT. BRIEF PASSING SHOWERS MAY BRING ISOL MVFR 
CONDITIONS...MAINLY FOR WINDWARD AND MAUKA AREAS. MODERATE TO 
LOCALLY GUSTY TRADE WINDS ARE FORECAST TO CONTINUE THROUGH THE 
PERIOD. AIRMET TANGO IS IN EFFECT FOR LOW LEVEL TURB IN THE LEE OF 
THE TERRAIN. OTHERWISE...THERE ARE NO OTHER AIRMETS. 

&&

.MARINE...
AN ASCAT PASS FROM THIS MORNING SHOWED A WIDE AREA OF 25 KNOT WINDS 
THROUGH THE ALENUIHAHA CHANNEL...WITH SOME 25 KNOT BARBS NEAR SOUTH 
POINT AS WELL. MODELS SHOW THE GRADIENT GRADUALLY TIGHTENING OVER 
THE NEXT COUPLE DAYS AS LOW PRESSURE PASSES FAR SOUTH OF THE AREA. 
THEREFORE THE CURRENT SMALL CRAFT ADVISORY FOR THE TYPICALLY WINDIER 
AREAS NEAR MAUI AND THE BIG ISLAND WILL LIKELY REMAIN IN EFFECT AT 
LEAST THROUGH WEDNESDAY. 

A SERIES OF SMALL SOUTHERLY SWELLS WILL BRING BELOW TO NEAR NORMAL 
SURF FOR SOUTH FACING SHORES. A LARGER SWELL FILLING IN FRIDAY 
AFTERNOON SHOULD BRING NEAR TO ABOVE NORMAL SURF FOR SOUTH FACING 
SHORES BY SATURDAY. SHORT PERIOD TRADE WIND SWELL WILL CONTINUE 
ACROSS EAST FACING SHORES...POSSIBLY INCREASING A BIT THROUGH THE 
WEEK AS TRADES STRENGTHEN. NO OTHER SIGNIFICANT SWELLS ARE EXPECTED 
FOR THE NEXT SEVERAL DAYS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 6 PM HST WEDNESDAY FOR MAALAEA BAY- 
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG 
ISLAND SOUTHEAST WATERS.

&&

$$

PUBLIC/MARINE...BRAVENDER
AVIATION...EATON



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