993  
FXHW52 PHFO 300114  
SRDHFO  
 
COLLABORATIVE NEARSHORE SWELL AND WIND FORECAST FOR OAHU  
NWS/NCEI HONOLULU HI  
314 PM HST FRI MAY 29 2020  
 
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 3 N 9 2 4 DOWN 10-14 E DOWN  
05/29 2 SSW 18 3 5 UP  
 
SAT 3 NNE 13 4 6 UP LOW 9-13 E SAME  
05/30 2 SSW 16 3 5 SAME LOW  
2 SSE 11 2 4 UP LOW  
 
SUN 3 NNE 11 3 5 DOWN LOW 9-13 E SAME  
05/31 2 SSW 14 3 5 DOWN LOW  
2 SSE 11 2 4 SAME LOW  
 
MON 3 NNE 9 2 4 DOWN LOW 7-10 E DOWN  
06/01 2 SSW 14 3 5 DOWN LOW  
2 SSE 10 1 3 DOWN LOW  
 
TUE 2 NNE 9 1 2 DOWN LOW 7-10 E SAME  
06/02 3 S 18 7 10 UP LOW  
2 SSE 10 1 3 SAME LOW  
 
WED 3 NW 11 3 5 UP LOW 11-16 E UP  
06/03 4 S 16 8 12 SAME LOW  
2 SSE 10 1 3 SAME 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 IN 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...SPRING CONDITIONS WITH SURF FROM NORTHERN AND SOUTHERN  
HEMISPHERE'S MID LATITUDE SOURCES.  
 
DETAILED...  
MID FRIDAY ON NORTHERN SHORES HAS DECLINING BREAKERS FROM 350-010  
DEGREES AT LEVELS BELOW THE MAY AVERAGE. THE PRESENT EVENT IS  
PREDICTED TO FADE LATE FRIDAY WITH A NEW NNE EPISODE FILLING IN  
SATURDAY.  
 
THE N PACIFIC MID LATITUDES HAVE BEEN RELUCTANT TO GIVE IN TO SUMMER  
WITH AN ACTIVE CYCLONIC PATTERN IN MAY KEEPING MORE DAYS THAN NORMAL  
NEAR TO ABOVE AVERAGE. THE TREND IS EXPECTED TO HOLD INTO THE EARLY  
DAYS OF JUNE, AFTER WHICH SUMMERY CONDITIONS WRESTLE CONTROL.  
 
A FAST-MOVING LOW PRESSURE NNW OF HAWAII 5/25 REACHED THE GULF OF  
ALASKA 5/27. THE NEAR AVERAGE SURF LOCALLY FRIDAY 5/29 IS IN DECLINE  
FROM THE EARLY STAGE WHEN THE FETCH WAS WITHIN 900 NM TO OUR NNW TO  
N. THE PACIOOS/CDIP WAIMEA, OAHU BUOY SHOWS THIS EVENT PEAKED LOCALLY  
WEDNESDAY NIGHT AND HAS BEEN SLOWLY DROPPING INTO FRIDAY AS THE  
DIRECTION VEERED FROM NEAR 320 TO 360 DEGREES.  
 
THE LOW PRESSURE SYSTEM OCCLUDED SOUTH OF KODIAK, ALASKA 5/27. THERE  
WAS A DONUT-SHAPED PATTERN TO THE WAVE MODEL OUTPUT OF SEAS FROM THE  
SYMMETRIC, SLOW-MOVING LOW. THE STRONGEST WINDS AIMED AT HAWAII TO  
GALES OVER A NARROW FETCH BEYOND 1600 NM AWAY WERE ON 5/27. THE  
SYSTEM WEAKENED TO NEAR GALE BY 5/28 AND SUB GALE 5/29. IT SHOULD  
MAKE FOR A SMALL, LONG-LIVED EVENT.  
 
WAVE WATCH III TRENDS THE SURF UP OFF OAHU AT DAWN ON SATURDAY,  
THOUGH HEIGHTS SHOULD REMAIN BELOW AVERAGE UNTIL MID DAY FROM 000-020  
DEGREES. THE EVENT SHOULD PEAK SATURDAY NIGHT WITH HEIGHTS HOLDING  
NEAR AVERAGE SUNDAY, THEN FALLING BELOW AVERAGE MONDAY. THE EVENT  
COULD LINGER NEAR THE TINY BRACKET ON TUESDAY FROM THE SAME  
DIRECTION.  
 
A NEW LOW PRESSURE FORMED EAST OF THE KURIL ISLANDS THURSDAY NIGHT.  
MODELS SHOW THE LOW CENTER TRACKING EAST, PASSING THE DATE LINE  
SATURDAY 5/30, AND OCCLUDING SOUTH OF KODIAK BY MONDAY 6/1. THE BEST  
SURF POTENTIAL FOR HAWAII IS WHEN THE FETCH STRETCHES EAST OF THE  
DATE LINE 5/30-31 WITH BEST AIM AT HAWAII OVER THE 320-340 DEGREE  
BAND. ONCE THE CENTER IS EAST OF THE LONGITUDES OF HAWAII, THE AIM IS  
MOSTLY WEST TO EAST AIMING SEAS AT NW AMERICA. THIS EVENT IS NOT  
EXPECTED TO GIVE A N TO NNE EVENT LIKE THE ONE DUE THIS WEEKEND  
5/30-31.  
 
A SMALL EVENT IS PREDICTED TO BUILD FROM 315-330 DEGREES TUESDAY  
NIGHT. IT SHOULD PEAK ABOVE THE JUNE AVERAGE BUT NEAR THE MAY AVERAGE  
WEDNESDAY NIGHT FROM 320-340 DEGREES. THE EVENT SHOULD BE  
SHORT-LIVED.  
 
MID FRIDAY ON EASTERN SHORES HAS BREAKERS FROM 30-90 DEGREES NEAR AN  
EAST SIDE MINIMUM. LOW CONDITIONS SHOULD HOLD ON SATURDAY.  
 
SEE THE LATEST NWS STATE FORECAST DISCUSSION REGARDING THE MODERATE  
TRADE WIND PATTERN LOCALLY FOR THE WEEKEND.  
 
THE AXIS OF SURFACE HIGH PRESSURE 5/29 IS ZONAL, OR WEST TO EAST,  
NEAR 28 N FROM WELL NNW TO WELL NNE OF HAWAII. THIS POSITION IS  
CLOSER TO HAWAII THAN NORMAL FOR THE SEASON, AND AS A RESULT THE  
LOCAL TRADES AND WIND SWELL ARE BELOW AVERAGE. PACIOOS/CDIP MOKAPU  
BUOY OFF EAST OAHU 5/29 SHOWS ONLY 4 FEET AT 6 SECONDS. THE SHORT  
WAVE-PERIOD REFLECTS THE SHORT FETCH OF THE GENTLE TO MODERATE TRADES  
UPSTREAM OF OAHU.  
 
MODELS DO SHOW A SHORT-LIVED BUMP OF 3 FEET AT 8 SECONDS FROM 45  
DEGREES BUILDING MONDAY AND DROPPING TUESDAY. IT WAS FORMED FROM  
FRESH TO STRONG TRADES 5/26-28 OVER 1000 NM NE OF HAWAII. IT COULD  
MAKE FOR TINY TO SMALL BREAKERS. IN GENERAL, LOW CONDITIONS SHOULD  
HOLD ON THE EAST SIDE THROUGH THE PERIOD.  
 
MORE NORTHERLY EXPOSURES SHOULD TREND AFOREMENTIONED 5/30-6/2.  
 
MID FRIDAY ON SOUTHERN SHORES HAS SLOWLY RISING BREAKERS NEAR THE  
SUMMER AVERAGE FROM A MIX OF TASMAN AND SE NEW ZEALAND SOURCES OUT OF  
180-220 DEGREES. HEIGHTS ARE EXPECTED TO HOLD ABOUT THE SAME INTO  
SATURDAY.  
 
A STRONG, AUSTRAL, LOW-PRESSURE PATTERN WITH CENTRAL PRESSURE BELOW  
950 MB TRACKED EAST ALONG 60S 5/20-22 FROM SW TO SE OF NEW ZEALAND.  
IT FILLED THE SOUTHERN TASMAN SEA WITH SEAS OVER 30 FEET 5/20. THE  
TASMAN COMPONENT OUT OF 208-220 DEGREES HAS ARRIVING LOCALLY 5/29. IT  
SHOULD PEAK LATE FRIDAY 5/29 AND SLOWLY DROP FROM THIS DIRECTION ON  
THE WEEKEND.  
 
THE AUSTRAL LOW PRESSURE GREW SEAS OVER 35 FEET JUST S TO SE OF NEW  
ZEALAND 5/21-22 AIMED HIGHEST AT THE AMERICAS. THE LONG-PERIOD SWELL  
TRAINS ROLLED UNDER THE PACIOOS/CDIP AMERICAN SAMOA BUOY 5/25-27. IT  
SHOWED MODERATE, LONG-PERIOD ENERGY IN THE 16-20S BAND SIMILAR TO THE  
SOURCE THAT DELIVERED THE MEMORIAL DAY WEEKEND SWELL LOCALLY. THIS  
GIVES BETTER CONFIDENCE THAT THE SURF SHOULD HOLD NEAR AVERAGE INTO  
THE WEEKEND FROM 180-220 DEGREES WITH A DOWNWARD TREND SUNDAY 5/31.  
 
STRONG TRADES EAST OF THE TUAMOTU ISLANDS 5/23-27 COULD ADD SOME  
SOUTHERN HEMISPHERE WIND SWELL OF 10-12S OUT OF 140-160 DEGREES  
LOCALLY STARTING SATURDAY 5/30 AND HOLDING THROUGH MID WEEK NEXT  
WEEK.  
 
A NEW AUSTRAL MID LATITUDE PATTERN UNFOLDED 5/25-28 THAT SHOULD BRING  
SURF IN HAWAII ABOVE AVERAGE NEXT WEEK. AT THE JET STREAM LEVEL,  
LONG-WAVE PATTERN FORMED WITH A BROAD RIDGE NEAR NEW ZEALAND AND A  
BROAD TROUGH SOUTH OF FRENCH POLYNESIA. AT THE SURFACE, A SEVERE-GALE  
LOW PRESSURE 5/25 NEAR 60S TO THE SE OF NEW ZEALAND TRACKED NE TO  
NEAR 45S SOUTH OF FRENCH POLYNESIA 5/27. THE TRACK SET UP A CAPTURED  
FETCH WITH HIGHEST SEAS AIMED NEAR TO JUST EAST OF HAWAII. JASON  
ALTIMETER MEASURED LARGE AREA OF SEAS OVER 30 FEET 5/27. THE SYSTEM  
MOVED EAST OF THE HAWAII SWELL WINDOW 5/28-29.  
 
THE ONSET STAGE IS DUE LOCALLY MONDAY PM 6/1 WITH A SLOW,  
INCONSISTENT RISE INTO MID TUESDAY. THE EVENT SHOULD CLIMB ABOVE  
AVERAGE BY MID TUESDAY FROM 175-190 DEGREES. THE EVENT IS PREDICTED  
TO PEAK WELL ABOVE AVERAGE WITHIN LATE TUESDAY TO MID WEDNESDAY.  
 
AS USUAL, THE HIGHEST SWATH OF SWELL IS EXPECTED TO NEAR MISS HAWAII  
TO THE EAST. THIS GIVES LARGER ERROR BARS FOR THE LOCAL SURF  
ESTIMATE. STAY TUNED TO THE LATEST UPDATES OF THE NWS SURF FORECAST  
PRODUCTS 6/2-3 ONCE THE SWELL TRAINS ROLL UNDER THE SOUTHERN NOAA  
BUOYS AND ALLOW MORE CONFIDENT BREAKER HEIGHT ESTIMATES.  
 
AS USUAL, ALSO FOR SOUTH SWELLS, IS THE INTERMITTENT NATURE OF HIGH  
ENERGY SPURTS AND LOW ENERGY LULLS, AS CAN BE EASILY SEEN IN THE  
30-MINUTE MEASURING CYCLES BY THE PACIOOS/CDIP BUOYS AS A JITTERY UP  
AND DOWN SIGNAL WITHIN THE OVERALL LONG-TERM TREND. THE TABLE ABOVE  
HIGHLIGHTS THE MOST ENERGETIC ENVELOPES OF A GIVEN FORECAST DAY, OR  
ACTIVE SPURTS WITH LARGER AND MORE FREQUENT SETS. LULLS OF MINIMAL  
SURF TEND TO OCCUR MORE FREQUENTLY AND PRONOUNCED FOR SOURCES THAT  
ARE FURTHER AWAY, SUCH AS THE 4000 NM TRAVEL ON AVERAGE FOR SOUTH  
SWELLS IN HAWAII. THIS MAKES SOUTH SWELLS IN HAWAII MORE PRONE TO  
THE LOW ENERGY ENVELOPES (LULLS), WHICH CAN GIVE A FALSE SENSE OF  
SECURITY AND INCREASE HAZARD.  
 
INTO THE LONG RANGE, THE S SWELL SHOULD HOLD ABOVE AVERAGE 6/4 AND  
DROP NEAR AVERAGE 6/5 FROM 170-190 DEGREES. A FAST-MOVING, SEVERE  
GALE SE OF NEW ZEALAND 5/29-30 COULD KEEP NEAR AVERAGE SURF CENTERED  
ON 6/7 FROM 180-200 DEGREES.  
 
THE SMALL NW TO NNW EVENT ARRIVING 6/3 SHOULD SLOWLY DROP 6/4 AS THE  
DIRECTION VEERS TOWARD N. IT SHOULD FADE OUT 6/5. IN THE NORTH  
PACIFIC TO THE NW TO N OF HAWAII, SUMMERY CONDITIONS ARE PREDICTED  
6/1-3, THAT SHOULD LEAD TO MINIMAL WNW TO NNE SURF LOCALLY FOR THE  
WEEKEND OF 6/6-7.  
 
EAST SIDE IS MODELLED TO SLOWLY INCREASE WITHIN 6/4-5 BUILDING TO  
NEAR AVERAGE 4/6 FROM 40-90 DEGREES.  
 
LONG RANGE FORECASTS ARE SUBJECT TO HIGH UNCERTAINTY.  
 
THE NEXT COLLABORATIVE FORECAST WILL BE UPDATED MONDAY, JUNE 1.  
 
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 HTTPS://WWW.WEATHER.GOV/HFO/MARINE  
 

 
 
NWS FORECASTER AND NCEI PAT CALDWELL  
 
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