949
FXHW52 PHFO 290053
SRDHFO
COLLABORATIVE NEARSHORE SWELL AND WIND FORECAST FOR OAHU
NWS/NCEI HONOLULU HI
253 PM HST MON DEC 28 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 NNW 12 4 6 DOWN 4-9 LV DOWN
12/28 6 E 9 5 7 SAME
TUE 11 NW 17 24 30 UP MED 9-13 E UP
12/29 6 E 9 5 7 SAME MED
WED 12 NW 16 26 32 SAME MED 9-13 E DOWN
12/30 6 E 8 4 6 DOWN MED
THU 9 NW 15 16 22 DOWN MED 17-21 ENE UP
12/31 14 NNW 17 32 40 UP LOW
7 E 8 4 7 UP LOW
FRI 12 NNW 15 24 30 DOWN LOW 19-23 ENE UP
01/01 9 ENE 7 5 8 UP LOW
SAT 7 NNW 13 10 14 DOWN LOW 19-23 E DOWN
01/02 9 ENE 8 6 8 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....
FLEXED WINTER SURF MUSCLE.
DETAILED...
MID MONDAY ON NORTHERN SHORES HAS DECREASING, SHORTER-PERIOD BREAKERS
OF 10-13 SECONDS FROM 330-360 DEGREES BELOW THE SEASONAL AVERAGE.
IMMINENT EXTRA-LONG PERIOD SWELL FROM 310-325 DEGREES SHOULD SLOWLY
RISE THE SURF INTO THE EVENING TO LEVELS ABOVE AVERAGE AFTER SUNDOWN.
A LOW-PRESSURE CELL BOMBED, MEANING RAPID DEEPENING OF THE CENTRAL
PRESSURE, 12/25-26 IN THE NW PACIFIC TO NEAR 940 MB NEAR 50N, 170E.
THIS ESTABLISHED A PARENT ALEUTIAN LOW PRESSURE PATTERN COVERING A
MASSIVE AREA FILLING THE BREADTH OF THE WESTERN TO CENTRAL NORTH
PACIFIC. HURRICANE-FORCE WINDS FAVORED THE AREA CLOSEST TO THE LOW
CENTER WITH A LONG FETCH OVER THE 310-325 DEGREE BAND. GALES TO
SEVERE GALES DEFINED ANOTHER LONG, WIDE, COINCIDING FETCH OVER THE
295-310 DEGREE BAND. THE FORMER FETCH HAD HIGHER SEAS TO NEAR 50 FEET
AS VALIDATED BY THE JASON SATELLITE EARLY SUNDAY WHILE THE LATTER,
MORE WNW, FETCH GREW SEAS WITHIN 25-35 FEET. THE CENTER OF THE PARENT
LOW SHIFTED ENE LATE SATURDAY INTO SUNDAY AS HIGHEST SEAS BEGAN
AIMING MORE NE OF HAWAII.
THE EXTREME BURST FROM 12/26 TO EARLY 12/27 ASSOCIATED WITH THE
FORMER FETCH ALLOWED WAVE PERIODS TO REACH WELL ABOVE 20 SECONDS IN
AN AREA ABOUT 1800 NM AWAY LATE SATURDAY. THE 25 SECOND WAVE ENERGY
CAN TRAVEL 900 NM A DAY. THAT MATCHES THE NOAA NW HAWAII MONDAY
MORNING 12/28 BUOY READINGS SHOWING TICKLES TO 26 SECOND AND MORE
SOLID ENERGY RISING WITHIN 20-25 SECONDS. THESE FORERUNNERS RACE WELL
AHEAD OF THE MAIN SWATH OF HIGH SWELL, AND SHOULD EQUATE TO A GRADUAL
RISE 12/28 PM ON OAHU. THE RISE SHOULD CONTINUE INTO TUESDAY AS
BREAKERS REACH EXTRA-LARGE HEIGHTS, MEANING HIGH ENOUGH TO TRIGGER
OUTER REEFS. THE LONGER-PERIOD SWELL FROM 310-325 SHOULD DOMINATE THE
BREAKERS, WITH THE 295-310 ENERGY PIGGY-BACKING ON BY THE AFTERNOON.
THE FIRST OF THE OFFSPRING, OR NEW LOW PRESSURE CELLS, FROM THE
PARENT ALEUTIAN LOW FORMED 12/27 MOSTLY SEEN AT UPPER LEVELS BY A
SHORT-WAVE TROUGH EMBEDDED SW OF THE BROAD CYCLONIC GYRE AND A
TIGHTENING OF THE SURFACE PRESSURE GRADIENT, HENCE, OCEAN SURFACE
WINDS BELOW IT.. THE JET HAS BECOME MORE ZONAL GOING INTO TO 12/28,
ALLOWING THE OFFSPRING TO RACE EAST. A FETCH OF GALES WITH POCKETS TO
SEVERE GALES SET UP FROM WELL WEST OF THE DATE LINE 12/27 OVER THE
305-325 DEGREE BAND AND HAS NOSED TO NEAR 1100 NM AWAY FROM HAWAII
EARLY MONDAY. JASON SHOWS SEAS WITHIN 20-24 FEET. THIS ENERGY SHOULD
ADD ON TO THE ORIGINAL PARENT SOURCE BY WEDNESDAY, KEEPING
EXTRA-LARGE BREAKERS CENTERED FROM NEAR 320 DEGREES BUT SPREAD FROM
295-340 DEGREES. HEIGHTS SHOULD DROP BY THURSDAY MORNING TO
MARGINALLY EXTRA-LARGE.
THE NEXT OFFSPRING HAS FORMED NEAR 35N, 160E 12/28 AND IS MODELLED TO
BECOME RAMBUNCTIOUS AS IT REACHES THE DATE LINE EARLY TUESDAY WITH
HURRICANE-FORCE WINDS. THE TRACK THEN TURNS MORE NE AS IT CONTINUES
TO DEEPEN, REACH NEAR 45N, 160W EARLY WEDNESDAY. THE REDUCTION IN
SURF POTENTIAL DUE TO THE FAST TRACK WILL BE WELL OFFSET BY THE
EXTREME WINDS ACTING UPON EXISTING HIGH SWELL OVER THE 310-330 DEGREE
BAND. SEAS OVER 30 FEET ABOUT 1000 NM AWAY SPELLS POTENTIAL FOR THE
PEAK OF THE EVENT LOCALLY TO GIANT SURF, DEFINED BY LESS FREQUENT,
THOUGH COMMON, HIGHER SETS TOPPING 40 FEET FACE IN ZONES OF HIGH
REFRACTION ON OUTER REEFS. CLOSER SOURCES RESULT IN RAPID RISE AND
FALL OF EVENTS LOCALLY. THE CHRISTMAS TREE TIME SERIES SIGNATURE IS
MODELLED TO BE CENTERED ON THURSDAY NIGHT. HEIGHTS SHOULD REMAIN
EXTRA LARGE FRIDAY FROM 305-345 DEGREES AND DROP TO LEVELS A NOTCH
ABOVE THE SEASONAL AVERAGE BY SATURDAY FROM 305-360 DEGREES.
STAY TUNED TO NATIONAL WEATHER SERVICE UPDATES FOR FINE-TUNE FROM
BUOY READINGS FOR TIMING AND MAGNITUDE AS THE OVERLAPPING EVENTS
UNFOLD. ALSO NOTE THE NWS STATEMENT REGARDING THE COINCIDING SPRING
TIDES AND UPROARIOUS SURF FOR NEAR DAWN, ABOVE AVERAGE COASTAL WAVE
RUN-UP WITHIN 12/29-1/1.
MID MONDAY ON EASTERN SHORES HAS ABOVE AVERAGE SURF FROM THE TRADE
WIND BELT OF 70-90 DEGREES. HEIGHTS SHOULD BE SIMILAR ON TUESDAY.
SEE THE LATEST NWS STATE FORECAST DISCUSSION REGARDING THE TREND IN
LOCAL WINDS AND SKIES.
SURFACE HIGH PRESSURE NEAR 1028 MB NEAR 30N, 140W HAS SET UP A LONG
FETCH OF STRONG BREEZES WITH POCKETS TO NEAR GALES WITHIN 135-155W
12/27-28. JUST FROM THE WAVES ALREADY ON THE TRADE WIND SWELL
CONVEYOR BELT, ABOVE AVERAGE SURF IS LIKELY TO HOLD INTO WEDNESDAY
FROM 70-90 DEGREES WITH A SLOW DOWNWARD TREND 12/30-31.
A NEW SURFACE HIGH PRESSURE CELL IN MODELLED TO BECOME ESTABLISHED
NORTH OF THE ISLANDS 12/31 WITH A SLOW EASTWARD DRIFT INTO THE
WEEKEND. THIS SHOULD TURN UP THE LOCAL TRADES AS A NEW TRADE WIND
SWELL GROWS, MAINTAINING ABOVE AVERAGE SURF UNDER ROUGH CONDITIONS
12/31-1/2 FROM 50-90 DEGREES.
MID MONDAY ON SOUTHERN SHORES HAS BREAKERS BACK DOWN IN HAWAIIAN
WINTER MODE OF NEAR NIL. MORE OF THE SAME IS LIKELY ON TUESDAY.
IT APPEARS THE LAST QUARTERS INTO THE SOUTHERN HEMISPHERE WAVE
MACHINE HAVE BEEN DROPPED, WHICH GAVE THE OUT-OF-SEASON BREAKERS
LOCALLY LAST WEEK. AUSTRAL SUMMER MODE BECAME ESTABLISHED LAST WEEK
IN THE MIDLATITUDES. FROM LATE DECEMBER TO EARLY MARCH, ODDS ARE
HIGHER FOR SURF ON SOUTH SHORES FROM EAST OR WEST THAN FROM SOUTH.
INTO THE LONG RANGE, EAST SIDE SHOULD HOLD ABOVE AVERAGE 1/3 THEN
SLOWLY TREND DOWN TO NEAR AVERAGE 1/4-6 FROM 60-90 DEGREES.
MODELS SHOW A NEW BOMBING LOW PRESSURE TO 936 MB OVER THE WESTERN
ALEUTIANS BY 12/31. THIS SUGGESTS RISING, LONG-PERIOD SURF 1/3-4
POTENTIALLY TO EXTRA-LARGE FROM 305-325 DEGREES.
LONG RANGE FORECASTS ARE SUBJECT TO LOW CONFIDENCE.
THE LAST COLLABORATIVE FORECAST WILL BE UPDATED WEDNESDAY, DECEMBER
30.
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
PLEASE SEE
WEATHER.GOV/MEDIA/NOTIFICATION/PDF2/PNS20-87SRD_DISCONTINUATION.PDF
FOR MORE DETAILS ON THE DISCONTINUATION OF THIS PRODUCT.
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