PAT CALDWELL

Hazards

No high surf advisory or warnings.

Forecast

Surf along north facing shores will be 5 to 7 feet tonight, lowering to 3 to 5 feet on Wednesday. Surf along west facing shores will be 3 to 5 feet tonight, lowering to 2 to 4 feet on Wednesday. Surf along east facing shores will be 2 to 4 feet, with occasional higher sets, through Wednesday. Surf along south facing shores will be 2 to 4 feet tonight, lowering to 1 to 3 feet on Wednesday.

Outlook

Outlook through Tuesday May 30: the current northwest swell will continue to subside through Wednesday. While the current south swell will slowly diminish through Wednesday, a new south southwest swell is expected to arrive Friday and to continue through most of the upcoming holiday weekend. This new swell is expected to reach advisory levels, and will coincide with high astronomical tides, which will likely result in minor coastal flooding due to wave run-up along the south facing shores. The greatest chance of run-up will be near the high tide times from Wednesday afternoon through Sunday night. Surf heights are forecast heights of the face or front of waves. The surf forecast is based on the significant wave height, the average height of the one third largest waves, at the locations of the largest breakers. Some waves may be more than twice as high as the significant wave height. Expect to encounter rip currents in or near any surf zone.

About Collaborative Surf

THIS COLLABORATIVE FORECAST WILL BE UPDATED MONDAY THROUGH FRIDAY AT 300 PM WHEN PAT CALDWELL IS AVAILABLE/

Collaborative Surf Table

FORECAST
DATE
SWL
HGT
DMNT
DIR
DMNT
PD
H
1/3
H
1/10
HGT
TEND

PROB
WIND
SPD
WIND
DIR
SPD
TEND
1PM
05/22
4NNW1268SAME17-21ENEUP
6ENE613UP
2SSW1435SAME
TUE
05/23
4NNW1057DOWNMED19-23ENESAME
8ENE734UPLOW
2S1435SAMELOW
WED
05/24
3N1035DOWNMED13-19ENEDOWN
7ENE724DOWNLOW
2S1324DOWNLOW
THU
05/25
3NNE924DOWNLOW9-13ENEDOWN
2S1213DOWNLOW
1SSW2035UPLOW
FRI
05/26
3NNE813SAMELOW4-6VRBSAME
3SSW18610UPMED
SAT
05/27
3NNE813SAMELOW4-6VRBSAME
4SSW16810SAMEMED

Collaborative Surf Table Legend

LEGEND:

SWL HGTOPEN OCEAN SWELL HEIGHT MEASURED FROM TROUGH TO CRESTIN FEET LOCATED 20 NAUTICAL MILES OFFSHORE
DMNT DIRDOMINANT DIRECTION TYPICALLY +/-10 DEGREES IN 16 COMPASSPOINTS
DMNT PDDOMINANT PERIOD IN SECONDS
H1/3SIGNIFICANT WAVE HEIGHT IN THE SURF ZONE
H1/10AVERAGE HEIGHT OF THE HIGHEST ONE-TENTH WAVES IN THE SURFZONE
HGT TENDHEIGHT TENDENCY OF SWELL (VALID VALUES: UP/DOWN/SAME)
PROBPROBABILITY OF OCCURRENCE (VALID VALUES: HIGH/MED/LOW)
WIND SPDOPEN WATER WIND SPEED MEASURED IN KNOTS LOCATED20 NAUTICAL MILES OFFSHORE
WIND DIRWIND DIRECTION IN 16 COMPASS POINTS
SPD TENDWIND SPEED TENDENCY (VALID VALUES: UP/DOWN/SAME)

Disclaimer

SURF HEIGHTS WILL VARY BETWEEN DIFFERENT BEACHES AND AT THE SAME BEACH AT DIFFERENT BREAK AREAS.

Collaborative Surf Discussion

Discussion: summary: North side holding into mid week with south side rising late in the week. Detailed: Mid Monday on has breakers from 320-340 degrees at heights above the may monthly average. Heights should remain above average on Tuesday. A long-lived, broad area of low pressure moved slowly east from the dateline along 40°N 5/18-21 as peak winds slowly weakened. Strongest winds aimed NE of Hawaii. There was a short-lived spell of 13-15 second wave period energy late 5/21 locally as measured by the pacioos/cdip Waimea buoy. The energy is dominant in the 10-12 second band mid Monday 5/22. The primary fetch aimed at Hawaii was of strong to near gale winds over the 320-340 degree band, closest on 5/20 about 800 nm out. Fresh to strong breezes over the 330-360 degree band nosed even closer to within a few hundred miles while the tail of the fetch was beyond 1200 nm away. This should make for a long-lived episode as the dominant direction veers from NNW to N then to NNE. Heights should slowly trend down Tuesday from 320-350 degrees, dropping to near the average on Wednesday from 330-360 degrees. Small, short-period surf from 000-030 degrees should continue Thursday into Saturday. Mid Monday on has breakers below the trade windswell average. Heights are increasing. Surface high pressure near 40°N, 170°W 5/22 is moving east and strengthening. Models show an upper level trough pinching off into an eddy near 40°N, 145°W on Tuesday, which would keep a broad area of flat pressure gradient to the E to NE of Hawaii out 1000 nm miles. The local gradient is expected to tighten over Oahu 5/22-23 though the upstream fetch is predicted to be too short to allow a growth in the dominant wave period, and in turn, keep breakers below average. Windswell from 50-70 degrees should trend down Wednesday to near nil by Thursday. Dominant windswell for Thursday to Saturday should be from 000-50 degrees. Mid Monday on has breakers near the summer average from 180-200 degrees. Similar surf is likely for Tuesday. The local swell event of the past weekend is receiving a mild reinforcement on 5/22. The latter was from a low pressure in the far southern mid-latitudes SE of New Zealand 5/14-16 that got stronger as it tracked east of the Hawaii swell window. Angular spreading should keep surf near the summer average locally on Tuesday, with a downward trend from 175-190 degrees Wednesday. Low, long period swell from the Tasman sea, 208-220 degrees could add to the summer background level surf heights Wednesday into Thursday. The highest south swell episode so far this season is due late in the week. It is predicted to be above average, but at levels commonly seen during Hawaiian summers for the typical peak days. A complex low pressure pattern unfolded over, S, and E of New Zealand 5/17-21. The central pressure 5/18-19 reached its lowest value below 950 mb, though the complexities of the pressure distribution made the strongest winds over a compact area near the center well SE of New Zealand, with weak area of winds for the fetch aimed at Hawaii. Just to the W to NW of the weak area, another strong area of winds occurred. This is the primary source for the event. The severe gales on the westernmost portion of the low pressure area grew seas within 30-35 feet for a maximum 5/19. It was reported that waves were measured to 64 feet by a buoy SSE of New Zealand. However, this was the estimate of the theoretical maximum wave height, not the significant wave height, which was measured within 30-35 feet just as modelled by the Wave Watch III, ww3. A captured fetch was set up over the 190-200 degree band hugging the E side of New Zealand as surface winds gradually weakened behind a NNE pushing front, which reached as strong to near gales into the subtropics NE of New Zealand 5/21. The fetch width was limited by New Zealand. This reduces the size potential. The pacioos/cdip american samoa buoy 5/22 has registered the forerunners in the 16-22 second band. Ww3 shows the peak of the event at this location late Monday into Tuesday. This will allow fine-tuning of the Oahu surf forecast on Wednesday. As with most remote source events, the ramp up time of breakers locally takes about a day as inconsistent, long-period forerunners arrive. This spin-up is expected mid Thursday into mid Friday. The event should trend up steadily above average Friday afternoon, and peak within Friday evening to Saturday evening. Above average mean sea level surrounding Oahu, spring tides, and the above average surf should result in greater than normal landward reach of the wave swash zone coinciding with the late afternoon higher high tides 5/26-27. Into the long range, the south swell should slowly trend down Sunday 5/28 to levels to near average levels by Monday 5/29 from 180-200 degrees. No surf beyond tiny to small is expected from the mid latitudes of the north Pacific. Trade windswell is expected to be well below average 5/28-29. Long range forecasts are subject to low confidence. This collaborative forecast will resume on Wednesday, May 24. 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.

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NWS FORECASTER AND NCEI PAT CALDWELL

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