576  
FXHW52 PHFO 190054  
SRDHFO  
 
COLLABORATIVE NEARSHORE SWELL AND WIND FORECAST FOR OAHU  
NWS/NCEI HONOLULU HI  
254 PM HST TUE FEB 18 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 2 NNW 11 2 4 DOWN 17-21 NNE SAME  
02/18 7 ENE 8 4 6 SAME  
2 SSW 15 3 5 SAME  
 
WED 3 NW 15 4 6 UP LOW 22-27 ENE UP  
02/19 10 ENE 8 6 8 UP LOW  
2 SSW 14 3 5 DOWN LOW  
 
THU 10 ENE 9 7 9 SAME LOW 22-27 ENE DOWN  
02/20 4 NNW 14 6 8 SAME LOW  
2 S 12 2 4 DOWN LOW  
 
FRI 3 NNW 11 3 5 DOWN LOW 17-21 E DOWN  
02/21 8 E 9 6 8 DOWN LOW  
2 S 11 1 3 SAME LOW  
 
SAT 5 NW 16 8 12 UP LOW 11-16 E DOWN  
02/22 6 ENE 9 5 7 DOWN LOW  
1 SSW 16 2 3 UP LOW  
 
SUN 4 NNW 14 6 8 DOWN LOW 7-10 SSE DOWN  
02/23 5 E 9 4 5 DOWN LOW  
1 S 15 2 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... MORE SPRING-LIKE CONDITIONS THIS WEEK WITH RETURN TO  
WINTER FOR NORTH SHORES IN THE LONG RANGE.  
 
DETAILED...  
MID TUESDAY ON NORTHERN SHORES HAS BREAKERS WELL BELOW THE  
SEASONAL AVERAGE FROM 315-030 DEGREES. A NEW EVENT IS DUE  
WEDNESDAY PM.  
 
A ZONAL JET STREAM SITUATED FURTHER NORTH THAN NORMAL OVER THE  
NORTH PACIFIC SINCE LAST WEEKEND IS EXPECTED TO HOLD TO THE END  
OF THIS WORK WEEK. A PAIR OF FAST-MOVING LOW PRESSURE SYSTEMS  
NORTH OF 45N ARE EXPECTED TO BRING MODERATE SURF.  
 
THE FIRST SYSTEM DEEPENED NEAR THE DATE LINE SUNDAY 2/16 WITH A  
COMPACT AREA OF GALES. IT MOVED EAST OF THE DATE LINE MONDAY 2/17  
AS THE HIGHEST SEAS AIMED NE OF HAWAII. THE SYSTEM IS EAST OF THE  
HAWAII SWELL WINDOW 2/18.  
 
SURF FROM THIS SOURCE IS PREDICTED TO FILL IN LOCAL WEDNESDAY 2/19  
AFTERNOON FROM 310-330 DEGREES. IT SHOULD PEAK OVERNIGHT A NOTCH  
BELOW THE SEASONAL AVERAGE, THEN SLOWLY DROP INTO FRIDAY FROM  
320-340 DEGREES. A NEW EVENT IS DUE LATE FRIDAY.  
 
THE SECOND IN THE SERIES OF SYSTEMS IN THE ZONAL JET TRACK HAS  
FORMED 2/18. IT IS STRONGER WITH SEVERE GALES OVER THE 300-315  
DEGREE BAND. MODELS SHOW IT RACING ENE PASSING EAST OF THE DATE  
LINE WEDNESDAY AND INTO THE GULF OF ALASKA THURSDAY. HIGHEST SEAS  
ALSO EXPECTED TO BE AIMED NE OF HAWAII.  
 
LONG-PERIOD FORERUNNERS ARE DUE LOCALLY NEAR SUNDOWN FRIDAY. THIS  
EVENT SHOULD PEAK NEAR THE SEASONAL AVERAGE ON SATURDAY FROM  
305-330 DEGREES. THE EVENT SHOULD FALL BELOW AVERAGE BY SUNDAY  
FROM 310-340 DEGREES.  
 
MID TUESDAY ON EASTERN SHORES HAS BREAKERS FROM 60-90 DEGREES AT  
LEVELS ABOVE THE TRADE WINDSWELL AVERAGE. AN INCREASE IS EXPECTED  
FOR WEDNESDAY.  
 
SURFACE HIGH PRESSURE NNW OF HAWAII 2/18 IS MOVING EAST. THE 1032  
MB HIGH IS PREDICTED TO BE DUE NORTH OF HAWAII WEDNESDAY NEAR 35N.  
IT IS MODELLED TO CONTINUE MOVING EAST INTO FRIDAY.  
 
THE UPSTREAM FETCH OF FRESH TO STRONG TRADES 2/18-19 IS MODELLED  
TO SLOWLY GROW IN LENGTH. THIS SHOULD TREND SURF UP LOCALLY UNDER  
ROUGH CONDITIONS INTO FRIDAY. LOCAL WINDS ARE MODELLED TO DECREASE  
INTO THE WEEKEND, THOUGH THE UPSTREAM SOURCE OF FRESH TO STRONG  
TRADES INTO 2/21 SHOULD KEEP ACTIVE SURF INTO SUNDAY AS HEIGHTS  
TREND DOWN TO NEAR THE AVERAGE FROM 60-90 DEGREES.  
 
MID TUESDAY ON SOUTHERN SHORES HAS SMALL BREAKERS FROM 180-200  
DEGREES ABOVE THE WINTER AVERAGE. SIMILAR SURF IS PREDICTED FOR  
WEDNESDAY.  
 
A LONG-LIVED AREA OF LOW PRESSURE SE OF NEW ZEALAND 2/7-11 WAS  
MOSTLY IN THE LOW TO MODERATE GALE RANGE. THIS EVENT PICKED UP  
LOCALLY OVER THE PAST WEEKEND AND IS STILL HOLDING ABOUT THE SAME  
ON TUESDAY DURING THE INCONSISTENT SETS. LIKELY ONE MORE DAY  
ABOUT THE SAME WITH A SLOW DOWNWARD TREND OF MARGINAL BACKGROUND  
CONDITIONS INTO FRIDAY FROM 170-200 DEGREES.  
 
A STORM-FORCE SYSTEM AIMED HIGHEST AT THE AMERICAS TO THE S TO SE  
OF NEW ZEALAND 2/13-14. ANGULAR SPREADING COULD BRING LOW, LONG-  
PERIOD SURF LOCALLY THIS WEEKEND 2/22-23 FROM 180-200 DEGREES,  
LOWER THAN THE RECENT EVENT.  
 
INTO THE LONG RANGE, A LOW PRESSURE GAINED STRENGTH AT THE EASTERN  
EDGE OF THE HAWAII SWELL WINDOW S OF FRENCH POLYNESIA 2/16-17.  
ANGULAR SPREADING COULD BRING ANOTHER LOW EVENT LOCALLY NEXT  
TUESDAY 2/25 LASTING A FEW DAYS.  
 
IN THE NORTH PACIFIC, MODELS SHOW A LOW PRESSURE OCCLUDING NEAR  
45N, 175E THIS SATURDAY 2/22 WITH STORM- TO HURRICANE-FORCE WINDS.  
THE SYSTEM IS EXPECTED TO SLOWLY DRIFT EAST AND WEAKEN 2/23-24.  
THIS SHOULD RETURN NORTH SHORE TO WINTER CALIBER SURF STARTING  
2/25 FROM 305-325 DEGREES. HINTS OF A SIMILAR EVENT ABOUT 3 DAYS  
BEHIND.  
 
EAST SIDE IS PREDICTED TO DROP BELOW AVERAGE 2/24-26.  
 
LONG RANGE FORECASTS ARE SUBJECT TO MAJOR REVISIONS.  
 
THIS COLLABORATIVE FORECAST WILL RESUME ON FRIDAY, 2/21.  
 
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  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HI Page Main Text Page