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Pacific Storm and Surf Forecast
Updated: May 20, 2008 7:55 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   

South Swell Hits Exposed CA Breaks
Significant Wind Event Right Behind


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 Tuesday (5/20) Northern CA surf was chest high and pretty lumpy and foggy early. South facing breaks in Santa Cruz were up to 1 ft overhead at the most exposed break, though most were less. Central California surf (Morro Bay) was chest high and textured mid-day. Surf in Southern CA from Santa Barbara to just north of LA was waist to chest high with a few bigger sets at top spots and a bit breezy, though still reasonably clean. The LA Area southward to Orange County was head high to 2 ft overhead at to spots and textured but not too bad. South Orange County down into San Diego best breaks were head high and textured early. The North Shore of Oahu was maybe waist high. The South Shore was chest high and coming up. The East Shore was knee high.

North/Central California was seeing a little windswell but the dominant swell was coming from the southeast (160 degrees) from a storm that was off Chile a week before. It was only wrapping into select breaks, those with excellent southern exposure. Southern California was seeing much more of this southern hemi swell. Hawaii's North Shore was effectively flat, though a little windswell was hitting making for something to stand up on. The East Shore was effectively flat. The South Shore was flat.

For Wednesday North and Central California to continue seeing energy from the southern hemi swell for those breaks with exceptions southeast exposure, then fading fast as the swell moves out of the swell window (it's amazing anything from it is getting in at all even now). Otherwise large and wind whipped northerly windswell to be the name of the game, best later in the workweek once winds start to subside. One note: After re-looking at the Jason-1 satellite data from last week we did find one satellite pass that went directly over the Chilean storm Tues 5/13 at 18Z, registering a solid average reading of 37 ft with one peak reading to 40 ft, far higher than the 32 ft reflected by the wave model and covering a far greater area. This accounts for the larger than expected surf. We apologize for not spotting this sooner and incorporating it into the forecast. Southern CA to continue seeing southern hemi swell pushing into exposed breaks from a southeasterly direction, peaking early Wednesday, then hanging on while losing size till the end of the week. North windswell to be wrapping in later Wednesday and beyond. The North Shore of Oahu to be flat for the foreseeable future.The South Shore to see more of that southeast swell that Southern CA is getting, peaking late Wednesday into early 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

Tuesdays jetstream charts (5/20) for the North Pacific remained decent for the time of year with energy flowing southeast off the Kuril Islands into a trough over the dateline at near 170 kts there, then ridging northeast equally as strong apexing in the Northern Gulf of Alaska before sinking into another mini-trough centered directly over the Oregon coast. Good support for low pressure development in both troughs with high pressure likely under the ridge in-between. Over the next 72 hours the jet to become even stronger in the dateline trough with winds to 190 kts early Wednesday but kinda pinched off, limiting it's potential to support low pressure development at the oceans surface. Likewise the ridge to the east is to build even more in the Gulf of Alaska with equally strong winds flowing over it, building a blocking high pressure ridge off the US West Coast. The ridge is to really take over through Friday, though the trough is to still be there, just not nearly as dominant. Beyond 72 hours the dateline trough is to fade out while the ridge peaks on Saturday pushing all the way up into Alaska before dissipating. A weak flow to follow but there's signs that the jet might start re-energizing Tuesday of next week (4/27) with a new trough building off the Kuril's and a weaker one north of Hawaii. For the time of year, this is really pretty impressive. Suspect the currently roaring active phase of the MJO might be contributing to this pattern.

At the surface today high pressure at 1028 mbs was building just 600 nmiles off Cape Mendocino with a second one at 1032 mbs just west of the dateline. Low pressure was working it's way inland over Washington with a second one in-between the two highs over the Aleutians. In all no swell producing fetch was indicated, though north winds were starting to build pushing down the Pacific Northwest and California coasts. Over the next 72 hours the big story is to be wind over California nearshore waters attributable to a weak surface low pressure moving from over the Central Canadian coast to just inland of the San Francisco Bay area, while high pressure offshore builds to 1032 mbs 800 nmiles west of San Francisco, generating a fetch of north winds at 30-35 kts centered over Central CA Wednesday moving north and building to 35-40 kts centered near Pt Arena on Thursday (5/22). 20 ft seas forecast Thursday building to 23 ft early Friday off Monterey Bay, then steadily decaying into early Saturday. Solid raw local windswell to start trying to build for Central CA Wednesday pushing 11 ft @ 9-10 secs Thursday hanging at 9 ft @ 10 secs Friday into early Saturday (7+ ft faces).

Also a quick developing gale is forecast for the Northwestern Gulf Thurs/Fri (5/23) with 40-45 kts winds, but all aimed northeast towards Alaska offering no swell generation potential.


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


California Nearshore Forecast
On Tuesday (5/20) high pressure at 1028 mbs was building late off the North CA coast and expected to be forming a tight gradient with lower pressure moving inland. By Wednesday the gradient is to become acute with 30-35 kt north winds over nearshore waters from Cape Mendocino to off the Northern Baja Coast (though southern CA to remain mostly immune), then drifting north and becoming centered near Pt Arena Thursday with north winds to 40 kts there (and still 35 kts into Pt Conception). Large windchop developing with horrible surf conditions from Pt Conception northward except at protected breaks. Southern CA to likely see some indirect effects from this too. The gradient to start slacking Friday and winds pulling away from the coast with a eddy flow (southwest) likely from Pt Reyes southward down into Southern CA, continuing through the weekend. Effectively all windswell producing fetch is to be gone by mid-day Saturday (5/24). But a broader high to be building offshore with north winds starting up again by Monday from Pt Conception northward (15 kts) pushing 20 kts Tuesday, though Southern CA to remain protected.


No tropical systems of interest were occurring on Tuesday (5/20).


South Pacific

On Tuesday (5/20) the jetstream over the South Pacific remained heavily .cgiit with energy equally shared between the north and Southern branches. The southern branch (the main storm and swell producing region) remained di.cgiaced well to the south flowing flat west to east over the 65S latitude, offering no support for low pressure development. Over the next 72 hours that same pattern is to hold, with only the region east of 110W showing any tendency towards a trough, and that is to be outside even the California swell window. No hope in the Hawaiian swell window. Beyond 72 hrs no significant change is expected, though the flow is to inch a bit more to the north, possibly cracking the door open a notch a week out if a trough were to form.

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. Seas were modeled at 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. But a more careful inspection of Jason-1 satellite data revealed that at 18Z the satellite made a pas directly over the fetch and registered a solid 15 reading average of 36.7 ft with one peak reading to 40 ft, far higher than the 32 ft reflected by the wave model and covering a far greater area.

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 building to 4.6 ft @ 14 secs on Wednesday (5/21) (6.5 ft faces) then slowly fading from there. Swell Direction: 165-175 degrees

Swell to push into Hawaii late Monday (5/19) building to 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 more high pressure is forecast for the Gulf of Alaska generating northerly winds pushing down the Cape Mendocino corridor Mon/Tues (5/27) but only in the 25 kt range offering limited potential for local windswell generation for Central CA.

Also Mon/Tues (5/27) a pair of weak low pressure systems are to try and form, one off Japan and the second north of Hawaii over the dateline with winds to 35 kts aimed somewhat down the great circle paths to Hawaii. Will believe it when it happens.

Madden-Julian Oscillation Note: The MJO remains in the active phase, and strongly so with daily SOI values pretty negative as of 5/20, at -48, making it 5 days in a row heading downward, with the larger 30 day trend now hovering at 0. The 90 day trend is dropping quickly too, down from +20 in April to +7 as of today. This is interesting in that it is the first time the 30 day average has been at 0 or less since July of 2007, when it was coming out of the weak 2006 El Nino. Anomalous 850 mb westerly winds remained entrenched over nearly the entire equatorial Pacific with the core still hovering from the Philippines to the dateline, and expected to hold till about 5/2r , then start dissipating as the inactive phase of the MJO builds into the Pacific from the Indian Ocean near June 1. No significant support for low pressure development likely from this pulse of the active phase of the MJO, except in the West Pacific tropics if at all. but of more interest is to see if this pulse of the MJO helps to wipe cool waters associated with La Nina out of the central equatorial Pacific, possibly opening the door just a nudge towards El Nino.


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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