000 
FXHW60 PHFO 280130
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST THU AUG 27 2009

.SYNOPSIS...
DRY TRADE WIND WEATHER WILL PERSIST THROUGH THIS WEEKEND WITH 
GENTLE TO MODERATE TRADE WINDS FLOWING ACROSS THE ISLANDS. SHOWERS 
WILL BE CONTAINED TO MAINLY THE WINDWARD AND MOUNTAIN PORTIONS OF 
THE ISLANDS WITH A SPRINKLE POSSIBLE IN LEEWARD AREAS. STRONGER 
TRADE WINDS ARE POSSIBLE LATE NEXT WEEK AS A HIGH PRESSURE SYSTEM IS 
FORECAST TO FORM FAR NORTHEAST OF THE ISLANDS.

&&

.DISCUSSION...
DRY TRADE WIND WEATHER IS EXPECTED AS GENTLE TO MODERATE TRADE WINDS 
FLOW ACROSS THE HAWAIIAN ISLANDS. VISIBLE SATELLITE IMAGERY SHOWS 
NOTHING MORE THAN STABLE STRATOCUMULUS CLOUDS PASSING OVER THE 
REGION. RADAR AND OBS SITES THROUGHOUT THE DAY HAVE SHOWN SOME WEAK 
SHORT LIVED SHOWERS ON WINDWARD AND MOUNTAIN SIDES OF THE ISLANDS 
WITH LITTLE ACCUMULATIONS. THIS PATTERN SHOULD REMAIN IN PLACE AS 
GFS SHOWS LOW PRECIPITABLE WATER VALUES THROUGH MONDAY. GFS 500 MB 
TEMPERATURES NEVER GO BELOW -8 DEGREES CELSIUS WHICH MEANS THE 
ATMOSPHERE SHOULD REMAIN STABLE THROUGH THE FORECAST PERIOD. AS A 
RESULT...LIGHT SHOWERS WILL PERSIST MAINLY ON THE WINDWARD AND 
MOUNTAIN SIDES OF MOST ISLANDS THROUGH MONDAY. 

THE GFS AND NAM BRING A TRAILING BAND OF MOISTURE FROM DISSIPATING 
HILDA LATE TONIGHT AND FRIDAY...BUT A SIGNIFICANT INCREASE IN 
RAINFALL SEEMS UNLIKELY DUE TO THE STABLE CONDITIONS IN PLACE. AS A 
COMPROMISE WE BRUSHED THE BIG ISLAND AND WATERS SOUTH OF THE BIG 
ISLAND WITH SOME HIGHER POPS THROUGH FRIDAY NIGHT. GFS SHOWS 
MOISTURE ADVECTION AND A HIGHER INVERSION NEXT TUESDAY WHICH COULD 
INCREASE SHOWER ACTIVITY AND HEAVINESS.   

SURFACE PRESSURE CHANGES AT OBSERVATION SITES THROUGHOUT THE STATE 
OF HAWAII SHOW DECREASING PRESSURE TRENDS FROM 24 HOURS AGO. THIS 
INDICATES WEAKENING TRADE WINDS IN THE SHORT TERM. ALSO...A SERIES 
OF DISSIPATING FRONTS TO THE FAR NORTH WILL WEAKEN THE SUBTROPICAL 
RIDGE THROUGH TOMORROW. THIS WILL KEEP TRADE WINDS IN THE MODERATE 
STRENGTH CATEGORY THROUGH THE WEEKEND INTO NEXT WEEK. GFS AND ECMWF 
MODELS SUGGEST A NEW SURFACE HIGH PRESSURE SYSTEM WILL FORM FAR 
NORTH OF THE ISLANDS LATE NEXT WEEK WHICH WOULD BRING STRONGER 
TRADES BACK TO THE ISLANDS.  

TROPICAL DEPRESSION HILDA CONTINUES TO WEAKEN AND IS NOT EXPECTED TO 
IMPACT THE STATES WEATHER. 

&&

.MARINE...
NO SIGNIFICANT SURF IS EXPECTED FROM TROPICAL DEPRESSION HILDA. 
HOWEVER...A PAIR OF OUT OF SEASON MODERATE NORTH SWELLS SHOULD 
ARRIVE FRIDAY AND SUNDAY...KEEPING SURF ALONG NORTH SHORES WELL 
ABOVE THE SUMMERTIME NORM THROUGH TUESDAY.

.HFO WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

HARRISON/WROE