646  
FXHW52 PHFO 270101  
SRDHFO  
 
COLLABORATIVE NEARSHORE SWELL AND WIND FORECAST FOR OAHU  
NWS/NCEI HONOLULU HI  
301 PM HST FRI MAY 26 2017  
 
THIS COLLABORATIVE FORECAST WILL BE UPDATED MONDAY THROUGH FRIDAY AT  
300 PM WHEN PAT CALDWELL IS AVAILABLE/  
 
FORECAST SWL DMNT DMNT H H HGT WIND WIND SPD  
DATE HGT DIR PD 1/3 1/10 TEND PROB SPD DIR TEND  
 
1 PM 4 NNE 8 3 4 SAME 9-13 NE DOWN  
05/26 3 SSW 18 6 8 UP  
 
SAT 3 NNE 7 1 3 DOWN LOW 4-6 VRB SAME  
05/27 5 SSW 15 8 10 DOWN MED  
 
SUN 3 NE 11 3 5 UP LOW 4-6 VRB SAME  
05/28 4 SSW 14 6 8 DOWN MED  
 
MON 3 NE 10 3 5 DOWN LOW 4-6 VRB SAME  
05/29 2 SSW 14 3 5 DOWN LOW  
 
TUE 4 NNW 12 5 7 UP LOW 9-13 E UP  
05/30 2 S 13 2 4 DOWN LOW  
 
WED 4 NNW 11 5 7 DOWN LOW 13-19 E UP  
05/31 6 E 6 2 4 UP LOW  
1 S 18 2 4 UP LOW  
 
LEGEND:  
SWL HGT OPEN OCEAN SWELL HEIGHT MEASURED FROM TROUGH TO CREST  
IN FEET LOCATED 20 NAUTICAL MILES OFFSHORE  
DMNT DIR DOMINANT DIRECTION TYPICALLY +/-10 DEGREES IN 16 COMPASS  
POINTS  
DMNT PD DOMINANT PERIOD IN SECONDS  
H1/3 SIGNIFICANT WAVE HEIGHT IN THE SURF ZONE  
H1/10 AVERAGE HEIGHT OF THE HIGHEST ONE-TENTH WAVES IN THE SURF  
ZONE  
HGT TEND HEIGHT TENDENCY OF SWELL (VALID VALUES: UP/DOWN/SAME)  
PROB PROBABILITY OF OCCURRENCE (VALID VALUES: HIGH/MED/LOW)  
WIND SPD OPEN WATER WIND SPEED MEASURED IN KNOTS LOCATED  
20 NAUTICAL MILES OFFSHORE  
WIND DIR WIND DIRECTION IN 16 COMPASS POINTS  
SPD TEND WIND SPEED TENDENCY (VALID VALUES: UP/DOWN/SAME)  
 
SURF HEIGHTS WILL VARY BETWEEN DIFFERENT BEACHES AND AT THE SAME  
BEACH AT DIFFERENT BREAK AREAS.  
 
DISCUSSION:  
SUMMARY...  
ACTIVE SPRING SURF PATTERN.  
 
DETAILED...  
MID FRIDAY ON NORTHERN SHORES HAS BELOW MAY MONTHLY AVERAGE BREAKERS  
FROM 000-030 DEGREES. HEIGHTS SHOULD DROP ON SATURDAY.  
 
SHORT-PERIOD N TO NE WINDSWELL GENERATED BY FRESH TO STRONG  
BREEZES BETWEEN A HIGH PRESSURE CELL TO THE N OF HAWAII AND A WEAK  
LOW NEAR 38N...150W 5/23-25 WAS THE SOURCE FOR THE SMALL BREAKERS  
FOR SELECT ZONES THAT FAVOR THIS DIRECTION 5/25-26. THIS EVENT  
SHOULD FADE OUT ON SATURDAY INTO SUNDAY.  
 
WAVE ENERGY FROM WNW TO N IS NEAR NIL AND SHOULD REMAIN QUIET THROUGH  
MONDAY.  
 
STRONG TO NEAR GALE BREEZES BETWEEN THE WEAK LOW PRESSURE NE OF  
HAWAII 5/23-25 AND STRONG HIGH PRESSURE BETWEEN THE LOW AND ALASKA  
IS EXPECTED TO DELIVER A SHORTER-PERIOD SWELL EVENT FROM 40-50  
DEGREES BUILDING SUNDAY AND DROPPING MONDAY.  
 
MODELS SHOW A LARGE AREA OF WEAK LOW PRESSURE MOVING EAST FROM THE  
DATELINE 5/27 ALONG 40N TO A POSITION NORTH OF HAWAII 5/28. A  
LONG FETCH OF NEAR GALES IS MODELLED TO AIM MOSTLY AT TARGETS NE  
OF HAWAII. IT SHOULD BE CLOSE ENOUGH FOR ANGULAR SPREADING TO GIVE  
BREAKERS NEAR TO A NOTCH ABOVE THE MAY AVERAGE BUILDING TUESDAY  
AND DROPPING WEDNESDAY FROM 330-360 DEGREES.  
 
MID FRIDAY ON EASTERN SHORES HAS LOW WAVE ENERGY FROM 50-90  
DEGREES. SURF FROM THIS DIRECTIONAL BAND SHOULD REMAIN LOW ON  
SATURDAY.  
 
MORE N TO NE EXPOSURES ARE EXPECTED TO TREND AFOREMENTIONED FOR  
5/28-29.  
 
EASTERLY TRADES ARE MODELLED TO RETURN TUESDAY. A SLOW INCREASE IN  
WINDSWELL IS EXPECTED THOUGH REMAINING BELOW AVERAGE.  
 
MID FRIDAY ON SOUTHERN SHORES HAS RISING BREAKERS FROM 185-200  
DEGREES AT LEVELS ABOVE THE SUMMER AVERAGE. HEIGHTS ARE EXPECTED  
TO BE LARGER ON SATURDAY.  
 
A COMPLEX PATTERN OF LOW PRESSURE IN THE NEW ZEALAND VICINITY  
5/17-21 HAD STRONGEST WINDS TO THE S TO SE OF NEW ZEALAND 5/18-19.  
THE LIMITING FACTOR FOR THE SOURCE WAS PROXIMITY TO NEW ZEALAND  
WHICH MADE THE FETCH WIDTH NARROW. A CAPTURED FETCH WAS SET UP AS  
POST-FRONTAL WINDS PUSHED PARALLEL TO NEW ZEALAND TO THE NNE  
5/19-21...WITH NEAR GALES REACHING INTO THE SUBTROPICS. THE  
COMBINED FETCH LENGTH FROM 65S TO NEAR 30N WAS NEAR 2000 NM.  
 
THE PACIOOS/CDIP AMERICAN SAMOA BUOY SHOWED PEAK WAVE ENERGY IN  
THE 15-17 SECOND BAND TUESDAY MORNING WITH A DOWNWARD TREND INTO  
WEDNESDAY. THIS IS THE PULSE THAT HAS BEEN STEADILY RISING AT THE  
NOAA SOUTHERN HAWAII BUOYS 51002-4 FRIDAY MORNING 5/26. THIS  
EVENT WILL LIKELY PEAK OVERNIGHT INTO SATURDAY MORNING.  
 
THE AMERICAN SAMOA BUOY SHOWED THE 13-14S BAND HOLDING STEADY  
WEDNESDAY THROUGH THURSDAY WITH A SHARP DROP OFF BY FRIDAY. SURF  
LOCALLY SHOULD HOLD ABOVE AVERAGE INTO SUNDAY WITH A DOWNWARD  
TREND FROM 185-200 DEGREES. HEIGHTS SHOULD FALL TO NEAR SUMMER  
AVERAGE LEVELS BY MONDAY 5/29 AND FADE TO BACKGROUND ON TUESDAY  
5/30.  
 
SEE THE SPECIAL WEATHER STATEMENT (SPSHFO) REGARDING COASTAL  
FLOODING FOR THE HIGHER HIGH TIDES DURING THE LATE AFTERNOONS TO  
EARLY EVENINGS 5/26-28.  
 
A BROAD...STORM-FORCE SYSTEM NEAR 60S AND A COMPACT GALE NEAR 30S  
AT THE EASTERN EDGE OF THE HAWAII SWELL WINDOW S OF FRENCH  
POLYNESIA 5/24-25 AIMED HIGHEST SEAS TOWARD THE AMERICAS. ANGULAR  
SPREADING COULD DELIVER SURF LOCALLY. INCONSISTENT FORERUNNERS  
FROM 170-185 DEGREES ARE DUE ON WEDNESDAY AFTERNOON 5/31.  
 
INTO THE LONG RANGE...SURF SHOULD BE NEAR THE SUMMER AVERAGE 6/1-2  
FOR SSE TO S EXPOSURES.  
 
SMALL...SHORT-PERIOD NNW TO N SURF IS POSSIBLE LATE NEXT WEEK.  
 
BREAKERS FROM TRADE WINDSWELL SHOULD APPROACH THE AVERAGE 6/2-3  
FROM 70-90 DEGREES.  
 
LONG RANGE FORECASTS ARE SUBJECT TO MAJOR REVISIONS.  
 
THIS COLLABORATIVE FORECAST WILL RESUME ON TUESDAY...JUNE 13.  
 
THIS FORECAST WAS PRODUCED THROUGH THE COLLABORATIVE EFFORTS OF  
NWS AND NCEI. PLEASE SEND SUGGESTIONS TO W-HFO.WEBMASTER@NOAA.GOV  
OR CALL THE WARNING COORDINATION METEOROLOGIST AT 808-973-5275.  
 
ADDITIONAL RESOURCES:  
SEE /IN LOWERCASE/ HTTP://WWW.PRH.NOAA.GOV/HNL/PAGES/MARINE.PHP  
 

 
 
NWS FORECASTER AND NCEI PAT CALDWELL  
 
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