FXHW60 PHFO 260150
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
350 PM HST WED NOV 25 2009

.SYNOPSIS...
TRADE WINDS WILL REMAIN BREEZY THROUGH FRIDAY WITH INCREASING SHOWERS
FOCUSED OVER WINDWARD AND MAUKA AREAS. SOME SHOWERS WILL SPILL
OVER TO LEEWARD LOCATIONS OF THE SMALLER ISLANDS AS THE MOISTURE
GETS CARRIED OVER THE MOUNTAINS. WINDS AND SHOWERS WILL DIMINISH
ON SATURDAY...BEFORE BOTH INCREASE AGAIN SUNDAY AND MONDAY.

&&

.DISCUSSION...
THIS AFTERNOON/S RADAR IMAGERY HAS SHOWN INCREASING SHOWERS OVER
WINDWARD OAHU AND MOLOKAI...WITH MORE SCATTERED SHOWERS MOVING IN
OVER THE EASTERN COASTAL WATERS. VISIBLE SATELLITE IMAGERY SHOWS
AN AREA OF LOW SHOWERY CLOUDS EXTENDING 200 MILES EAST AND 100
MILES NORTH OF OAHU. THIS CLOUD FORMATION IS SOMETIMES CALLED A
SCREAMING EAGLE...AND IT IS EXPECTED TO BRING INCREASED SHOWERS
FROM MOLOKAI TO KAUAI TONIGHT AND THURSDAY...BEFORE MOVING WEST OF
KAUAI THURSDAY EVENING.

FRONTAL MOISTURE NOW LOCATED 200 MILES NORTHWEST OF KAUAI IS NOT
EXPECTED TO REACH THE ISLANDS...AS A HIGH PRESSURE MOVING IN FROM
THE WEST WILL PUSH THE FRONT QUICKLY EAST. THE HIGH WILL ACT TO
TIGHTEN THE LOW-LEVEL PRESSURE GRADIENT OVER THE ISLANDS...AND
KEEP TRADE WINDS AT THE FRESH TO STRONG LEVELS THROUGH FRIDAY.
ANOTHER FRONTAL BOUNDARY IS EXPECTED TO BE POSITIONED ABOUT 300
MILES NW OF KAUAI...LESSENING THE PRESSURE GRADIENT AND TRADE
WINDS OVER THE STATE ON SATURDAY. THIS BOUNDARY IS FORECAST TO BE
WHISKED AWAY QUICKLY TOWARD THE EAST WITH ANOTHER TRANSIENT HIGH
PRESSURE PUSHING IN FROM THE WEST. SUNDAY AND MONDAY...TRADE WINDS
WILL INCREASE BACK TO THE FRESH TO STRONG VARIETY AS THIS HIGH
INCREASES THE PRESSURE GRADIENT AGAIN OVER THE ISLANDS.
TUESDAY...WINDS WILL RELAX AS ANOTHER FRONTAL BOUNDARY APPROACHES
FROM THE NW.

THE FORECAST MODELS START TO WAIVER IN THEIR CONSENSUS SUNDAY AS
THE ECMWF DROPS A SHARP UPPER TROUGH OVER THE STATE...BRINGING MUCH
COLDER TEMPERATURES ALOFT AND DE-STABILIZING THE ATMOSPHERE. ON
THE OTHER HAND...THE GFS AND NOGAPS BOTH SHOW A MUCH WEAKER TROUGH
LOCATED JUST EAST OF THE STATE ON SUNDAY. THE ECMWF SOLUTION SEEMS
A LITTLE TOO FAR FETCHED COMPARED TO THE OTHER GLOBAL MODELS AND I
SUSPECT IT WILL ALIGN MORE WITH THE GFS AND NOGAPS IN THE NEXT FEW
MODEL RUNS. HOWEVER...EVEN WITH THE MORE CONSERVATIVE GFS
SOLUTION...THE RESULT WOULD BE A WET TRADE WIND REGIME. SO...HAVE
INCREASED POPS SUNDAY AND SUNDAY NIGHT INTO THE NUMEROUS TO LIKELY
RANGE FOR MOST WINDWARD AREAS WITH A SLIGHT UPTICK TO LEEWARD
POPS AS WELL. MONDAY AND TUESDAY...THE UPPER TROUGH SHOULD BE FAR
ENOUGH EAST PLACING THE STATE UNDER A MORE STABLE ATMOSPHERE...AND
DECREASING SHOWER COVERAGE ACROSS THE ISLANDS.

&&

.MARINE...
THE CURRENT LARGE NORTHWEST SWELL CONTINUES. PEAK SWELL HEIGHTS
OF 14 FEET AT THE CDIP WAIMEA BUOY OCCURRED ABOUT 2 PM EARLIER THIS
AFTERNOON. A HIGH SURF WARNING REMAINS IN EFFECT THROUGH TONIGHT
FOR AFFECTED SHORES. SURF WILL DROP SLOWLY TONIGHT AND WILL
GRADUALLY DIMINISH ON THANKSGIVING DAY INTO FRIDAY.

A SMALL CRAFT ADVISORY IS IN EFFECT FOR BOTH THE LARGE NORTHWEST
SWELL AND FOR INCREASING TRADE WINDS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF WARNING UNTIL 6 AM HST THURSDAY FOR NIIHAU-KAUAI 
WINDWARD-KAUAI LEEWARD-WAIANAE COAST-OAHU NORTH SHORE-OAHU 
KOOLAU-MOLOKAI-MAUI WINDWARD WEST-MAUI CENTRAL VALLEY-WINDWARD 
HALEAKALA.

SMALL CRAFT ADVISORY UNTIL 6 PM HST FRIDAY FOR ALL HAWAIIAN 
WATERS-

&&

$$

MORRISON