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Pacific Storm and Surf Forecast
Updated: May 18, 2008 12:38 PM
Buoys: Northern CA - Southern CA - Hawaii - Gulf of Alaska - Pacific Northwest
Buoy Forecast:
Northern CA - Southern CA - Hawaii - Gulf of Alaska - Pacific Northwest
Pacific Links:  Atmospheric Models - Buoy Data - Current Weather - Wave Models
Forecast Archives: Enter Here
A chronology of recent Mavericks Underground forecasts. Once you enter, just click on the HTML file forecast you want to review (e.g. 073199.html equals July 31, 1999). To view the maps that correspond to that forecast date, select the html file labeled 073199 maps.html
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Swell Potential Rating = 1.5 - California & 1.5 - Hawaii
Using the 'Summer' Scale
(See Swell Category Table link at bottom of page)
Probability for presence of largest swells in near-shore waters of NCal, SCal or Hawaii.    
Issued for Week of Monday 5/19 thru Sun 5/25
Swell Potential Rating Categories
5 = Good probability for 3 or more days of Significant swell
4 = Good probability for 1-2 days of Significant swell
3 = Good probability for 3 or more days of Intermediate/Advanced swell
2 = Good probability for  1-2 days of
Intermediate/Advanced swell
1 = Good probability for 3 or more days of Impulse or Windswell
0 = Low probability for 1-2 days of Impulse or Windswell   

Windswell Expected for Central CA
Southeast Swell Likely for SCal & HI


New Swell Classification Guidelines

Significant: Swell 8 ft @ 14 secs or greater (11+ ft faces) for 8+ hours (greater than double overhead)
Advanced: Swell and period combination capable of generating faces 1.5 times overhead to double overhead (7-10 ft)
Intermediate: Swell and period combination generating faces at head high to 1.5 times overhead (4-7 ft)
Impulse/Windswell: Swell and period combination generating faces up to head high (1-4 ft) or anything with a period less than 11 secs.

On Sunday (5/18) Northern CA surf was 1-2 ft overhead and somewhat clean with fog in control, cooling things down. South facing breaks in Santa Cruz were chest high and socked in. Central California surf (Morro Bay) was chest to head high and pretty hacked early. Surf in Southern CA from Santa Barbara to just north of LA was chest high with a few bigger sets at top spots and clean. The LA Area southward to Orange County was waist to chest high and clean. South Orange County down into San Diego best breaks were chest high and clean early. The North Shore of Oahu was chest to head high and even a little more and clean. The South Shore was flat. The East Shore was waist high.

North/Central California continued seeing fun sized swell generated by a gale that was in the Gulf of Alaska earlier in the week, but with fog in control now. Southern California was also getting a nice piece of this same swell, wrapping in from the north to exposed breaks but without the fog and cold. Hawaii's North Shore was also still getting good short-period sideband energy from this same gale, providing something to ride for everyone.The East Shore was effectively flat. The South Shore had no swell.

For the next few days North and Central California to see the Gulf swell swell drift down to nothing by Tuesday, then locally generated windswell and very poor conditions to move in for mid-week. Some size expected from the windswell though, with improving conditions forecast late in the workweek. Southern CA to see some southern hemi swell pushing into exposed breaks from a southeasterly direction starting late Monday and building into Wednesday, then hanging on till the end of the week. North windswell to be wrapping in to helping to break up the lines a bit. The North Shore of Oahu to see the little northwest swell come to a close later Monday with virtually nothing behind it until maybe Sunday (5/25) and only tiny windswell then. The South Shore to see a little of that some southeast swell that Southern CA is to get, arriving late Monday and peaking Thursday. No windswell expected on the East Shore. The southern hemi to remain quiet for the next 7 days. So is the North Pacific. See details below...

Current marine weather and wave analysis.cgius forecast conditions for the next 72 hours

North Pacific

Sundays jetstream charts (5/18) for the North Pacific remained unbelievably decent for the time of year with energy was flowing flat off Japan over the dateline to a point north of Hawaii in the 120-140 kt range then lifting gently northeast and pushing into British Columbia at 100 kts. No defined troughs were present providing no real support for low pressure development, but the basic building blocks were there if such a trough were to form. Over the next 72 hours the jet to become energized with a trough forming over the western dateline region Tuesday (5/20) with 160 kts winds flowing under it providing some support, but a strong ridge is to build east of it in the Gulf of Alaska with equally strong winds flowing over it, likely setting up a blocking high pressure ridge off the US West Coast. Beyond 72 hours the dateline trough is to get very steep if not pinched off by late Wednesday (5/22) limiting it's potential to support surface level low pressure development while the ridge in front of it holds solid starting to edge into the US West Coast Thursday, but not quite making it. In fact a back door flow is to push over Southern CA late in the week, possibly setting up a short blast of desert heat there. Remnants of the dateline trough to hold into Friday, then fall apart, with the whole jet looking pretty weak after that.

At the surface today a neutral pressure pattern was in control of the North Pacific with no swell producing winds occurring. Trades were suppressed over the Hawaiian Islands too. Over the next 72 hours weak high pressure is to start building in the Gulf of Alaska and also west of Japan, but nothing inordinate. A weak surface low is set up almost over the Central Canadian coast Mon/Tues sinking south towards the PAcific Northwest, almost forming a pressure gradient with building high pressure in the Gulf late Tuesday, but again nothing of any real interest. But by Wednesday (5/21) the high is to build to 1032 mbs 800 nmiles west of San Francisco with remnants of the low moving over the same area, generating a fetch of north winds at 30 kts centered near Pt Conception. Short period windswell to start trying to build for Central CA.


North Pacific Animations: Jetstream - Surface Pressure/Wind - Sea Height - Surf Height


California Nearshore Forecast
On Sunday (5/18) a near neutral pressure pattern was in control offering a slight onshore/northwest flow but generally light (10 kts or less) over the entire state other than Pt Conception. High pressure to build only marginally on Monday with northwest winds 10 kts expected along most of the coast, less in the morning and in Southern CA. No changing into Tuesday either. On Wednesday low pressure inland and building high pressure at 1030 mbs centered 800 niles off Cape Mendocino to start the wind machine again, with 25 kt north winds forecast over all of Central CA on down over outer waters of South CA and building chop and windswell. That fetch to peak out Thursday (5/22) with a broad fetch of 35-40 kt winds forecast off Cape Mendo to almost Pt Conception and large windswell and chop in control. Local winds to improve on Friday as the gradient moves north with a eddy flow (southwest) likely from Pt Reyes southward down into Southern CA, continuing through the weekend.


No tropical systems of interest were occurring on Sunday (5/18).


South Pacific

On Sunday (5/18) the jetstream over the South Pacific was heavily .cgiit with most energy in the northern branch, not conducive to gale production. A ridging pattern remained in control of the southern branch di.cgiacing it well to the south, near the 70S latitude with no support for surface level low pressure development. Over the next 72 hours that same pattern is to hold, with only the region east of 120W showing any tendency towards a trough, and that is to be outside most of the California swell window. No hope in the Hawaiian swell window. Beyond 72 hrs no change is expected.

At the oceans surface no swell producing weather systems were indicated, and none forecast for the next 7 days.


Cutoff Low
A weak cutoff low developed in the far southeast Pacific late Sunday (5/11) and held through Tuesday (5/13) near 32S 117W (well north of usual) generating a tiny fetch of 40-45 kts southerly winds drifting to 32S 110W then up to 50 kts at 34S 106W Tuesday AM. Decent seas did not start being generated until Tuesday AM. At that time winds built to 50 kts at 32S 111W and held into Thursday (5/15) aimed north to northwest with seas 30 ft over a tiny area at 30S 108W (Tuesday), holding in the 28-29 ft range through Thursday but repositioned at 36S 105W. They were positioned about 3840-4080 nmiles south-southeast of Southern CA.

Very tiny southerly angled swell is likely pushing north towards Southern CA expected to arrive 6 days later with period at 16 secs (late Mon 5/19). Swell 2 ft @ 15-16 secs then (3 ft faces) building to 4 ft @ 14 secs on Wednesday (5/21) (5 ft faces) then slowly fading from there. Swell Direction: 175 degrees

Swell might also start pushing into Hawaii late Monday (5/19) with swell 1.6 ft @ 15 secs (2.5 ft faces) building to maybe 3 ft @ 14-15 secs (4.0-4.5 ft faces) by Wednesday and holding into Thursday (5/22). Swell Direction: 140 degrees

This swell to be too southerly an angle to reach into most North and Central CA breaks except those with good southerly exposure.


South Pacific Animations: Jetstream - Surface Pressure/Wind - Sea Height - Surf Height




Marine weather and forecast conditions 3-10 days into the future

North Pacific

Beyond 72 hrs a very strong pressure gradient is to continue building over the California coast early Thursday (5/22) , with low pressure that was off Canada now inland over Nevada and high pressure at 1032 mbs off Cape Mendocino, generating 35 kt north winds from Cape Mendo down to Morro Bay and 30 kts north winds down off the Northern Baja coast. Windswell building. The gradient is to lift north and fade some, isolated to the Cape Mendocino region Friday and Saturday but still generating strong north winds at 35 kts there, producing short period windswell pushing down over Central and South CA.

On Saturday (5/24) low pressure is to try and form over the dateline with winds to 45 kts, but all if it is to be aimed due north towards the Aleutians with only a 24 hr fetch of 25-30 kts winds aimed towards Hawaii, maybe providing a tiny window for some windswell generation, but that's it.

Madden-Julian Oscillation Note: The MJO remains in the active phase with daily SOI values pretty negative as of 5/17, at -24. But that's only one days data, with the larger 30 day trend hovering more in the +5 range. But over all the 90 day trend is dropping quickly down from +20 in April to +5 as of today. This is interesting. Anomalous 850 mb westerly winds remain entrenched over nearly the entire equatorial Pacific with the core still hovering over the Philippines to nearly the dateline.It's to hold till about 5/27 , then dissipate as the inactive phase of the MJO is already starting to build in the Indian Ocean, poised for entry into the Pacific about June 1. No significant support for low pressure development likely, except in the West Pacific tropics if at all.


South Pacific

No swell producing winds are forecast.

Details to follow...


External Reference Material: El Nino Southern Oscillation (ENSO), Madden Julian Oscillation (MJO), Pacific Decadal Oscillation (PDO), Southern Oscillation Index (SOI), Kelvin Wave

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Local Interest

Time Zone Converter - Finally! By popular demand we've built and easy to use time convert that transposes GMT time to whatever time zone you are located. It's ion left hand column on every page on the site near the link to the swell calculator.

Mavericks Contest 2008: View all the action from the 2008 Maverick Surf Contest from Powelines Productions here:

Half Moon Bay Surfers - Attention: There¹s a movement afoot to dredge sand out of the Pillar Point (i.e. Half Moon Bay) Harbor and dump it just south of the jetty, so it will r.cgienish all sand that¹s disappeared between the harbor and HMB. The guy who¹s spearheading the project, Brian Overfelt, has already received a positive preliminary reading from the local harbor commissioners. He¹s making a formal presentation to the Monterey Bay National Marine Sanctuary¹s advisory council this coming Friday (2/15) at Our Lady of Pillar church in Half Moon Bay. (It's on Kelly Ave, just east of the Coast Highway, across the street from Cunha Intermediate School.) starting at 9 AM. More details here:

Need Chiropractic Help? Visit our friends at Darrow Chiropractic. Not only will Dr. Darrow fix you up, he might give you some big wave surfing tips too! See more here:

Grib File Switchover: The old grib1 format wave model datafiles that have been the mainstay of the National Weather service for years now are scheduled to be retired on 1/26. We switched over to the new grib2 files starting with the 00z run of Thurs 1/17. All appears to be running fine. There is no functional change to the content of the models, just that files we receive are now smaller due to improved compression of grib2. But this sets us up to start processing new higher resolution files and building new products in the months ahead. So in all it's a good maintenance level change.

Sharkwater: There's a new feature film called Sharkwater that is hitting theaters November 2nd. Sharkwater is an award winning documentary (22 international film awards including the UN and Cannes) that broke box office records in Canada, opening to bigger numbers than any documentary in history save Fahrenheit 911 and Supersize Me. It is a conservation film that demonstrates that the biggest influence on the air we breathe, and global warming is life in the oceans except life in the oceans is being wiped out. Shark populations have dropped 90% in the last 30 years alone, and the oceans continue to be destroyed because nobody knows that it's happening Learn more here:

Bluewater Gold Rush: The first and only chronicle of the California sea urchin dive fishery. Diving, surfing, comedy, and tragedy on and under the waves of California. "A quintessential tale of California ... dramas of adventure and loss on and under the sea" We read it and it's a great story about the bloom of the urchin diving boom in the 70's and the few lucky souls who were right there when it took off. An easy read that's hard to put down. The trials and success of a 'real' California dream right down to it's core. Check it out here:

Submit your story to 'Surfings Greatest Misadventures: Vol. 2': DEADLINE: January 15th, 2008 Casagrande Press is seeking stories, articles, and essays on the general subject of surfing misadventure for publication in Surfings Greatest Misadventures: Volume 2. We are looking for nonfiction, first-person surf stories of bad judgment calls, pranks, comical/ironic episodes, disaster, attacking predators, misfortune, injury, loss of wit or limb, panic, critical conditions, contest meltdowns, everyday fears, surf trips gone wrong or the out-of-water episodes that surround surfing. We are looking for well-written stories that tell a good tale, reflect a culture, and develop the depth of the characters involved. We also like stories that have a tight narrative tension and a payoff at the end. Open to writers and surfers of any level. There is no fee to submit a story. We will consider previously published stories. To see more info on the first book visit Submit online at

Waveriders Gallery: Check out this collection of high quality artwork all related to waves and the ocean. Surf Paintings, Photography, Posters, Books, Boards and exhibits all produced by a variety of top artists provide a beautiful selection of pieces to chose from. Take and look and see some of the stunning work available from these artists.

Stormsurf Google Gadget - Want Stormsurf content on your Google Homepage? It's si.cgie and free. If you have Google set as your default Internet E.cgiorer Homepage, just click the link below and a buoy forecast will be added to your Google homepage. Defaults to Half Moon Bay CA. If you want to select a different location, just click on the word 'edit', and a list of alternate available locations appears. Pick the one of your choice. Content updates 4 times daily. A great way to see what waves are coming your way! .xml

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Surf Height-Swell Height Correlation Table


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