Big Picture
BIG Picture updated 515pm, Sunday, March 23
Monday, March 24th – Tuesday, April 1st
Light winds and gorgeous weather through the week and weekend…
Sea breezes were widespread on Sunday afternoon due to light (5-10mph) Easterly trades. The light local wind regime was caused by a front passing north of the islands and washing out. It should be similar on Monday. By Tuesday, a disturbance will deepen 1,300 nautical miles WNW of Hawaii and then pass to the north through midweek. This feature will bring light to moderate (5-15mph) E-ESE flow on Tuesday followed by light SE wind on Wednesday. Morning land breezes and afternoon sea breezes will be common. On Thursday, the system will track further north, which will enable a weak ridge of high pressure to form overhead. Light to near moderate E-ESE wind will return on Thursday and Friday. Another system will form well WNW of Hawaii over the weekend. While confidence is lower, these light winds will likely persist through the weekend. Models then differ significantly on the strength and location of the system: the GFS model indicates light Kona winds for early next week while the ECMWF model maintains some trade wind flow.
Most of the period should be drier than normal. There could be a slight increase in showers from Tuesday to Thursday due to a system passing to the north.
Surf Outlook –
North Shore and West Shores: Near XL surf to start, but much smaller into the foreseeable future…
Recent/Now (LARGE-EXTRA LARGE): Surf was 8-10’ Hawaiian scale by 3pm and 10-12’ by 5pm (and triggering the outer reefs) on a rapidly rising, 18 second period NW swell. The source was a storm that emerged from Honshu Mar 18 and traveled NE Mar 19-20. It gained hurricane-force winds (60-75mph) as it turned straight eastward before reaching the Aleutian Islands Mar 20. Unfortunately, satellite altimeter passes missed the highest seas, which likely approached or slightly exceeded 40’. Extra-long period forerunners of 21-23 seconds arrived overnight Saturday. As of this writing, the NW buoys reached 12’ at 17 seconds. This should equate to a Waimea Bay buoy peak of 10-11’ of swell at 17 seconds after dusk and a local overnight peak of 12-15’ (25’ faces). Surf at dawn Monday should be 10-12’+ and drop to 8-10’+ in the afternoon, 5-7’ early Tuesday, 2-4’ early Wednesday, and 1-2’ early Thursday as the swell angle turns NNW.
Next (SMALL-MODERATE): Fetch winds associated with the system weakened to 35-45mph as it slowly crossed the dateline Mar 21-22. By Mar 23, it approached the Gulf of Alaska, and the fetch angled from the north to the south from the eastern Aleutian Islands. Wind speeds eased to 25-35mph and will persist into Mar 31. Short to medium period forerunners of 12-13 seconds from the North should arrive overnight Thursday. Surf should rise to and hold at 2-4’ on Friday and drop to 2-3’ early Saturday and 1-2’ early Sunday. It should be similar on Monday and bump up to 1-2’+ on Tuesday.
Finally: On Mar 23, a weakening system entered the far NW corner of the North Pacific with winds of 30-40mph aimed at Hawaii. It will continue to weaken into Mar 24. Moderate period energy of 14-15 seconds from the NW should arrive late Friday evening. Surf should slowly rise to 1-2’ by late Saturday and slowly drop to below 2’ on Sunday.
Outlook: The transition season will really show itself this period as high pressure builds over the west-central North Pacific. This will keep swell energy from the WNW-NW small and favor swell from the N-NNE for the first week of Apr. It is too early to provide any specifics.
South Shores: Several small bumps in surf later this week into next weekend…
Recent/Now/Next: Surf on Sunday was 1-occ. 2’ on a small 12-13 second period SW-SSW swell. The source was a weak trough that passed over the Tasman Sea Mar 16 and directed 30-40mph winds to the NNE. Surf should drop to 1-1.5’ on Monday and Tuesday.
Next: A rather large system hugged the northern coast of Antarctica and passed well south of Australia. It had a large area of 40-50mph winds pointed to the NE Mar 16-17. 18-20 second period energy from the SW could reach Hawaii on Tuesday. Surf could bump up to 1-near 2’ on Wednesday.
Next: A compact storm deepened from well SE of New Zealand and gained a small area of storm-force winds Mar 19-20. The storm merged with a trough, which substantially increased the fetch length towards the north Mar 20-21. 18-19 second period energy from the SSW-S should arrive overnight Wednesday. Surf should rise to 1-occ. 2’ by late Thursday and peak at 1-2’ occ. + on Friday. Heights should drop to 1-occ. 2’ on Saturday.
Next: A fast-moving, powerful system raced south of New Zealand Mar 20 with a large area of 50-60mph winds aimed mostly zonally. It weakened as it approached the central South Pacific region. The high winds will support very long period forerunners of 20-21 seconds from the SSW, which should arrive on Friday. Surf should rise to 1-occ. 2’ early Saturday and 1-2’ occ. + on Sunday. It should drop to 1-occ. 2’ on Monday.
Finally: A compact system followed closely behind on Mar 22-23 and will aim a short, wide fetch of 35-45mph winds to the NNE as it tracks across the South Pacific Mar 23-24. It should keep moderate period swell from the SSW-S in place on Monday and Tuesday with surf of 1-occ. 2’.
Outlook:
East Shores: Low wind swell but a bump in North swell late this week…
Recent/Now/Next/Finally: Surf on Sunday was 1-2’ on a dropping East trade wind swell. Surf should be barely 2’ from Monday to Thursday, maintained only by enhanced trades well upstream of the islands. A small North swell should boost surf to 1-2’+ on Friday and Saturday. It should drop to 1-barely 2’ on Sunday as the North swell fades.
Outlook: The trade wind swell will likely be small to tiny through the first few days of Apr. There could be a surge in NE trades towards the end of the first week of the new month, and wind swell could increase. The potential for more significant N-NE ground swells is heightened heading towards the second week of Apr. Stay tuned…
The next SNN Big Picture will be issued on Sunday, March 30.
Forecaster Jonathan Huynh
Surf Climatology HERE
