SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
315 AM HST THU MAY 16 2019
315 AM HST THU MAY 16 2019
Surf along south facing shores will be 3 to 5 feet today, lowering to 2 to 4 feet Friday.
Surf along north facing shores will be 2 feet or less through Friday.
Surf along west facing shores will be 2 to 4 feet today, lowering to 2 to 3 feet Friday.
Surf along east facing shores will be 2 to 3 feet through Friday.
Outlook through Thursday May 23: The current south swell will continue to slowly fade through Friday. A small reinforcement out of the southwest is possible today into Friday. A slightly larger series of southwest and south swells are expected over the weekend through the middle of next week. Small surf will continue along east and north facing shores through Friday. Over the weekend, a small northwest swell is expected to give a boost to north shore surf, while an increase in trade wind swell brings an increase in surf to east facing shores. The trade wind swell will hang on into the middle of next week, keeping some surf in place along east facing shores. The northwest swell will quickly fade early next week, with surf returning to very small levels.
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.
This collaborative forecast will be updated Monday through Friday at 300 PM when Pat Caldwell is available.
|SWL HGT||Open ocean swell height measured from trough to crestin feet located 20 nautical miles offshore|
|DMNT DIR||Dominant direction typically +/-10 degrees in 16 compasspoints|
|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 surfzone|
|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 located20 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:. Small weekend surf for north and south side.
DETAILED:. Mid Wednesday on northern shores has near flat conditions. Similar status is predicted for Thursday.
A band of low pressure centered near 42N has been shifting eastward from the Kuril Islands since 5/12. The head of the fetch of strong breezes with small pockets to near gales reached the Date Line late Tuesday 5/14. The jet stream has become zonal 5/15 and is modelled to steer the system rapidly east out of the Hawaii swell window by late 5/16.
Shorter-period surf from 305-320 degrees is expected to build locally Saturday afternoon. It should peak early Sunday near the May average then slowly drop into Monday as the direction veers within 315-340 degrees.
Mid Wednesday on eastern shores has minimal east side surf. Similar conditions are predicted for Thursday.
See the latest NWS State Forecast Discussion for details on the local trades.
The trade wind pattern that has formed over the Hawaiian Islands 5/15 does not extend far to the NE and is of magnitude too low for surf from windswell. Low conditions should hold into Saturday.
By early next week 5/19-20, the high center is modelled to shift eastward and a longer fetch of trades is predicted to build. This should trend the surf up slightly, though still below average 5/19-20.
Mid Wednesday on southern shores has breakers from 175-195 degrees near to a notch above the summer average. Similar surf is likely for Thursday.
A fetch of gales south of French Polynesia 5/7-8 had direct aim at Hawaii. NOAA southern buoys 51002 and 51004 showed an uptick in 13-15s wave energy in the wee hours 5/15. The PacIOOS/CDIP Barbers Pt., Oahu, and Lanai buoys showed a slight downward trend Wednesday morning 5/15. The increase is due locally Wednesday late afternoon from 175-185 degrees. It should at least keep similar surf for Thursday. This event should drop below average by Friday.
Severe gale to storm-force westerly winds near 60S within 110-120E, or south of western Australia, set up a large area of seas greater than 30 feet 5/8-9. The winds weakened as the system moved east with mostly gales south of Tasmania 5/10. Long-period swell from this remote source about 6000 nm away is near the great circle ray 210-220 degree to Hawaii. This will likely be the dominant background surf this weekend, with tiny to small breakers continuing from 140-180 degrees.
A low formed in the central Tasman Sea 5/10-11 with pockets to severe gales. This could add small breakers locally by late 5/19 holding into 5/20.
The Tasman low pressure strengthened as it raced SE across New Zealand 5/12 to near 60S, 150W by 5/14. The pressure dropped to 936 mb with hurricane-force winds aimed at the Americas. ASCAT satellite showed a wide, long fetch aimed at Hawaii late 5/12 into early 5/13 over the 185-200 degree band. But the fast SE track of the low meant no captured fetch and minimal fetch duration. Thus only an average event is expected. The long-period onset stage is due Monday 5/20.
Into the long range, the new event should peak 5/21 near the summer average from 180-200 degrees. An active cyclonic pattern SW and SE of New Zealand began to set up 5/14-15. Multiple potent fetch areas within the 180-220 degree band are due to set up within 5/16-20, leading to overlapping events and peak days well above average locally within 5/22-29. Stay tuned for details as the events unfolded.
In the north Pacific, models still show potential from a low pressure areas NNW to N of Hawaii this weekend into mid next week that could make small surf locally mid next week and again for Memorial Day weekend. It is too early for specifics.
East side is predicted to build to near the by 5/22.
Long range forecasts are subject to low confidence.
This collaborative forecast will resume on Friday, May 17.
This forecast was produced through the collaborative efforts of NWS and NCEI. Please send suggestions to firstname.lastname@example.org 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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