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Pacific Storm and Surf Forecast
Updated: May 16, 2010 6:01 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
Swell Potential Rating = 4.0 - California & 2.0 - 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 5/17 thru Sun 5/23
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   

Small Southern Hemi Pulse for CA Mid-Week
Stronger Swell Forecast to Follow


New Swell Classification Guidelines (Winter)

Significant: Winter - Swell 8 ft @ 14 secs or greater (11+ ft faces) for 8+ hours (greater than double overhead). Summer - Head high or better.
Advanced: Winter - Swell and period combination capable of generating faces 1.5 times overhead to double overhead (7-10 ft) Summer - Chest to head high.
Intermediate: Winter - Swell and period combination generating faces at head high to 1.5 times overhead (4-7 ft). Summer - Waist to chest high.
Impulse/Windswell: Winter - Swell and period combination generating faces up to head high (1-4 ft) or anything with a period less than 11 secs. Summer - up to waist high swell. Also called 'Background' swell.

Wave Model Issue: Starting last Tues (5/11) NOAA changed the format of the way they distribute the raw wave model data. This resulted in Stormsurf missing many of the model updates. We've were able to put a temporary solution in.cgiace that provided some images, but it was inconsistent. As of Sunday (5/16) we believe we have a fully workable solution i.cgiemented and hopefully the models will continue to update consistently. We'll be monitoring and i.cgiementing incremental changes as required to stabilize the situation. Regardless, the actual content of the models has not changed, only the format of how it's delivered (which means no change to whatever methodology our viewers have developed over the years to calculate local surf height at your break). Thanks for your patience.

On Sunday (5/16) North and Central California was getting very small south angled southern hemi swell with waves waist to chest high and top spots maybe seeing some head high sets and clean. This is way less than expected and did not warrant a significant class swell rating. Southern California was getting the same swell with thigh to maybe waist high sets up north and clean. Down south it was chest to maybe head high with top spots 1 ft overhead on the sets and looking better. Hawaii's North Shore was effectively flat and clean with trades in effect. The East Shore was getting waist high east windswell and chopped. The South Shore had some thigh high tradewind generated wrap-around sets and clean. 

The forecast for North and Central CA is for southern hemi swell to be fading from waist high early Monday. Nothing till the next southern hemi swell arrives late Wed (5/19) building into Thursday at maybe waist high or so, with head high northwest windswell moving in at the same time. Southern California is to see southern hemi swell fading from chest high Monday at top spots. Nothing till the next small southern hemi swell arrives on Wednesday afternoon to waist high building to chest high on Thursday. The North Shore of Oahu is to see no rideable swell for the next week. The East Shore to see east tradewind generated windswell at waist high Monday dropping out, then back at waist high on Wednesday and maybe 6 inches more Thursday. The South Shore to see a very southerly pulse of southern hemi swell on Tuesday to waist to chest high and fading some on Wednesday. More very south angled swell to arrive on Thursday at waist high and holding. We're really in a summer pattern now.

The models continue suggesting that a decent gale is to set up in the Northwestern Gulf dropping southeast Mon-Thurs (5/20) with 35 kt winds and up to 21 ft seas late Tues into Wed (5/19). Some rideable northwest windswell could result mainly for Central CA, but don't count on it.  Down south a small gale formed northeast off New Zealand on Tues/Wed (5/12) with 30 ft seas and possible swell for Hawaii and the US West Coast mid-week.  And a far stronger system is in the deep southeast Pacific on Fri-Sun (5/16) with seas pushing 44 ft aimed pretty well to the north. Possible larger swell for mainly the US West Coast next weekend and beyond if all stays on track. 


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

North Pacific

On Sunday (5/16) the North Pacific jet was more or less consolidated tracking from a trough just off Japan down at 30N pushing east-northeast up into a strong ridge over the dateline (winds at 170 kts), then dropping into a reasonable trough off the US West coast while loosing wind energy. Limited support for gael development in the trough off the US West Coast. Over the next 72 hours the same basic pattern is expected to hold, just all shifting to the east some. If anything the trough off the US west coast is to build, looking pretty good late Tuesday with 140 kt winds pushing into it. Good odds for surface level gael development there. Beyond 72 hours that trough is to get some reinforcing energy injected into it with winds back to 150 kts providing more support for gael development into Thurs (5/20) before it pushes into North CA on Fri (5/21).  The weak trough that was off Japan is to push to the dateline and fade offering nothing of interest in regards to gale formation.     

At the surface on Sunday (5/16) a very weak low pressure system was off the Pacific Northwest repressing high pressure and making for a light local wind pattern. Some form of the high pressure system remained just north of Hawaii generating trades as 15 kts there, but overall lighter than days and weeks past. A gale that was off Japan raced northeast and was starting to re-developing in the Northwestern Gulf of Alaska on Sunday AM (5/16) with 35 kt northwest winds at 52N 163W. Seas building. Over the next 72 hours that gale is to be dropping southeast with seas up to 20 ft Sunday PM at 50N 158W then fading some,. only to regenerate Monday evening with 35 kt west winds at 48N 162W and seas rebuilding. By Tuesday AM (5/18) 30 kts west winds are forecast at 45N 155W aimed well up the 295 degree path to Central CA.  Seas forecast at 19 ft at 47N 161W that location and pushing east with 21 ft seas on Wednesday AM at 45N 151W and holding into the evening at 43N 144W. The gale is to be dissolving after that while pushing into Oregon on late Thurs (5/20). Possible swell for Oregon down into Central CA.

Also a rather vigorous gale was just off Japan on Thurs (5/13) with 35 kt west winds and 26 ft seas, but a long ways away from even Hawaii. At this time no real swell is expected to push into Hawaii, just maybe some 2 ft @ 14 secs energy (3 ft faces) on Tues (5/18) from 305 degrees.


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


California Nearshore Forecast
On Sunday (5/16) a light wind regime was in control of California waters courtesy of low pressure trying to hang on off the North CA coast. It is to hang on and push east with possible south winds at 5 kts Monday then going calm on Tuesday (5/18).  A stronger gale is forecast building in the Gulf of Alaska pushing up to the North CA coast later Tuesday into Wednesday suppressing winds locally.  But as soon as that low pressure system moves out of the area, high pressure is forecast moving back in with north winds on the increase, likely by mid-Thursday (5/20). After that a steady north wind pattern is forecast building in Friday even to Southern CA and continuing Saturday and Sunday (5/23) with winds to 25 kts just off the coast focused on Pt Conception.   


South Pacific

On Thursday AM (5/13) the models indicate another broad and decent strength gale was forming in the deep Central Pacific with 45 kt southwest winds at 58S 162W pushing pretty quickly east.  By evening a large fetch of 40-45 kt south -southwest winds are to be positioned at 53S 150W generating 35 ft seas at 53S 150W.  On Friday AM a solid area of 40-45 kt south winds are forecast at 55S 150W aimed right up the 196 degree path to Southern CA with sideband swell up the 178 degree path to Hawaii.  36 ft seas are forecast at 50S 145W.  In the evening stronger 45-50 kt south-southwest winds are to build over a larger area again aimed well to the north at 59S 140W over the same area as before producing a large area of 36 ft seas at 53S 140W.  That fetch is to hold and lift a bit north Sat AM (5/15) with 45 kt south winds at 57S 135W pushing up the 188 degree path to CA with 44 ft seas at 55S 135W.  Fetch is hold solid in the evening at 52S 130W with 46 ft seas at 51S 131W. 40-45 kt southwest winds to fade on Sunday AM (5/16) with 44 ft seas fading at 46S 124W.  

If all this comes to pass some decent degree of south angled southern hemi swell would seem likely for California with sideband energy into Hawaii. Will monitor. 


New Zealand Gale
A gale formed under New Zealand on Mon (5/10) with a small area of 40 kt west-southwest winds producing 30 ft seas. By Tuesday AM the gale was taking a more northeasterly track but with only 35 kt winds at 50S 160W resulting in 30 ft seas at 49S 160W.  In the evening 35-40 kt south winds continued at 43S 157W and pushing even more to the northeast with up to 32 ft seas at 45S 156W on the 203 degree track to California and in the middle of the Tahitian swell shadow relative to CA. The gale was fading and tracking even better to the north on Wed AM (5/12) with a small area of 35 kt winds and barely 30 ft seas at 42S 151W pushing up the same heading relative to CA and shadowed. This system faded after that. 

Given the weak wind speeds, the 30 ft sea estimate put forth by the models seems like a best case scenario. Still some degree of limited support for small scale swell is possible in CA. But Hawaii looks to be better positioned, with energy pushing unshadowed up the 180-185 degree tracks. And Tahiti will do even better, especially considering the close proximity of this system (1400 nmiles out).  

Hawaii: Expect swell arrival in Hawaii on Tuesday (5/18) with pure swell 2 ft @ 17 secs (3.0-3.5 ft faces) and holding.  Swell to continue on Wednesday (5/19) at 2.0-2.3 ft @ 14 secs (3.0 ft faces) and fading as the day progresses.  Swell Direction:  185 degrees.  

Southern California:  Expect swell arrival on Wednesday afternoon (5/19) with pure swell 1.6 ft @ 18 secs (2.5-3.0 ft faces) peaking Thursday at 2.3 ft @ 16-17 secs (3.5-4.0 ft faces).  Swell Direction: 208 degrees

North California:  Expect swell arrival late Wednesday afternoon (5/19) with pure swell 1.6 ft @ 18 secs (2.5-3.0 ft faces) peaking Thursday at 2.0 ft @ 16-17 secs (3.0-3.5 ft faces).  Residuals at 2 ft @ 14-15 secs on Friday (5/21). Swell Direction: 205 degrees


Possible Swell #5S (California)
On Thursday AM (5/13)
the models indicate another broad and decent strength gale was forming in the deep Central Pacific with 45 kt southwest winds at 58S 162W pushing pretty quickly east.  By evening a large fetch of 40-45 kt south -southwest winds was positioned at 53S 150W generating 35 ft seas at 55S 152W.  On Friday AM a solid area of 40-45 kt south winds continued at 50S 147W aimed right up the 196 degree path to Southern CA with sideband swell up the 178 degree path to Hawaii.  36 ft seas were modeled at 50S 147W.  In the evening stronger 45-50 kt south-southwest winds built over a larger area again aimed well to the north at 59S 140W over the same area as before producing a large area of 39 ft seas at 55S 145W.  That fetch held and lifted a bit north Sat AM (5/15) with 45 kt south winds at 57S 135W pushing up the 188 degree path to CA with 44 ft seas at 55S 135W.  Fetch held solid in the evening at 52S 130W with 43 ft seas at 52S 132W. 40-45 kt southwest winds were fading on Sunday AM (5/16) with 40 ft seas fading at 46S 127W. Residual 37 ft seas are forecast Sunday evening at 43S 119W and moving out of the CA swell window, though much fetch is still forecast pushing towards Chile.  

If all this comes to pass some decent degree of south angled southern hemi swell would seem likely for California with sideband energy into Hawaii. Will monitor. 

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 high pressure is to return to the East Pacific later on Thursday (5/20) as low pressure starts to fade. The usual pressure gradient along the Central CA coast is forecast with 25 kt north winds on Friday pushing 30 kts over the weekend. Locally generated short period north windswell expected in the usual locations. Trades to fire up over the HAwaiian Islands too later Thurs and be in full force Saturday (5/22) with east windswell on the upswing.

MJO/ENSO Update (reference): As of Sunday (5/16) the Southern Oscillation Index (SOI) was hanging around neutral territory. The daily SOI was at 15.95.  The 30 day average was up to 8.19 with the 90 day average up to 2.37.  A massive upward trend started in early March, peaked at the end of April, and is now loosing ground. This looks like the transition from El Nino to a neutral state.  

Wind anomalies at the 850 mb level (approx 5000 ft up) as defined by models suggest light easterly anomalies filling the entire equatorial Pacific basin, indicating the Inactive Phase is still in control. It is scheduled to push hard east and be exiting over Central America 5/25. This signals the end of El Nino and eliminates any support for gale development. The Active Phase continues brewing behind it filling the Indian Ocean as of 5/15.  It is to reach the dateline on 5/25, then slowly fading while pushing east towards Central America, but still influencing a large area of the North Pacific on 6/4. Maybe some support for gale development from this Active Phase of the MJO when it happens. But it will be pretty late in the season to see much if any impact.    

At this point we believe that El Nino will not hang on for another year, and that rather we'll fall back into at least a neutral pattern if not a La Nina Pattern (where the Inactive Phase takes control). Of other interest will be whether the Iceland Volcano will spew enough high level fine particle dust and aerosols into the atmosphere to produce a reflective effect, dropping surface temperature and pushing us into a multi-year La Nina.  This is a very real concern.  

Sea Surface Temp anomaly data (5/13) indicated no dramatic change from previous weeks, with warmer than normal waters consolidated on the equator with a new pocket of warmer water off Ecuador and the Galapagos Islands, fading some south of Hawaii (almost down to normal levels) and then regrouping the in the West Pacific. A massive buildup of warmer than normal waters is occurring in the Atlantic, of concern to hurricane forecasters there. We'll see if upper level winds support development of hurricane activity though. Suspect residual upper level shear from El Nino will have an impact well into the summer there.

Below the surface on the equator no Kevin Wave activity was present and if anything colder than normal water was building over the dateline and pushing east. Not good.. 

Over the entire Equatorial Pacific trades were blowing all the way to almost the Philippines, but only in the normal range. Perhaps a slight push to the west was occurring, but nothing extraordinary. This looks like the normal Springtime transition typical for this time of the year. 

El Nino is effectively gone and slowly loosing it's grip on the global atmospheric weather pattern. Still some lingering impact is to continue into the Summer of 2010 enhancing the storm track in the South Pacific some. A slow transition to a normal state is expected through Nov 2010. 

See more details in the new  El Nino update.


South Pacific

Beyond 72 hours the models indicate no additional swell producing fetch of interest 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

Stormsurf Hi-Res Coastal Precipitation Models Upgraded Though a bit late in the season, on 3/20 we i.cgiemented the same basic technology used in our new snow/ski models into the coastal hi-res precipitation models. So now you can not only determined whether rain is forecast for your area, but also snow. And not just light, medium or heavy snow like most sites, but the exact snowfall amount (in inches) for each 3 hr frame of the animation. Here's a sa.cgie, but now this approach is used in all our precipitation models.

Stormsurf Precip Models Upgraded! On 2/20 we upgraded some of the broader precipitation models driven by the hi-def GFS model to include snow fall. The algorithm used is similar to the recently released snow models for the Southwest US in that the areas where snow is expected are identified and the exact amount of snow forecast over a 3 hr window is e.cgiicitly color coded. For East and West Coast US interests the following links provide good exa.cgies:
West Coast:
East Coast:

Stormsurf Weather Models have all been upgraded! Over the New Years break we installed all new and upgraded weather models. Also new are experimental snow models for the Southwest US. Take a look here:

Read about Eric Nelson and Curt Myers, the makers of Ride-On and other Big Wave Surf Movies here:

Ride On! Powerlines new big wave epic is now available on DVD. Get the entire big wave story of the 2008-2009 season here:

Click here to learn more about Casa Noble Tequila! Casa Noble Tequila If you are looking for an exquisite experience in fine tequila tasting, one we highly recommend, try Case Noble. Consistently rated the best tequila when compared to any other. Available at BevMo (in California). Read more here:

Interview With Stormsurf:  The crew at worked with Stormsurf on a feature about why surfers should be able to read wave charts themselves. They are firm believers that a little learning can go a long way to help your surfing.  This is a great article to help convince your friends that they can benefit from being able to read the data themsleves rather than just relying on the forecasts of others.  See the full thing here:  Create Your Own Surf Forecast with Stormsurf

North California Surf Report Works Again: After an extended downtime we finally got the North California Surf Report working again. Thanks for your patience. See it here:

Shark Video: Our friend Curt Myers of Powerlines productions shot this footage of 2 great whites munching on a whale carcass off Devils Slide (south of San Francisco) on Thursday. Kind of interesting to watch. Check it here: (Fixed link)

Wave Model Upgrade Status Report: At this point we believe the installation of the new wave models is complete, with no problems being reported, the server stabilizing and the much requested return of the old style hemispheric Surf Height models now operational (again) and running side-by-side along the new ones. We thank you for your patience and input as we went though this process.  Your feedback helps guide our efforts and ultimately results in a better product for everyone.  Now we're off to start providing better menus to some wave model products most of you probably haven't uncovered yet (site specific graph and text forecasts), updateing the wave model FAQs and then upgrading the Weather Models.  

New Wave Model Facts: Click HERE to read more about the new wave models. Important info.

Stormsurf Wave Models Updated: On Friday (2/6) we installed the latest upgrade to our wavemodels. A year in the works, this upgrade essentially is a total re-write of every wave model product we produce. They now take advantage of the new Version 3 of the Wavewatch wavemodel. This version runs at a much higher resolution, specifically 0.0 X 0.5 degrees for the global grib with local products at 0.1667 X 0.1667 degrees, and it uses the hi-res GFS model for wind speeds. And of even more interest, the model now identifies primary swell and windwave variables. As such we now have new model images which displays this data. Also we've included out special 3D topographic land masks into all models. In all it makes for a radical step forward in wave model technology. We'll be upgrading minor components (FAQ, new menu pages etc) for a few weeks to come, but all the basics are available for your use now. Check it out here:

Story About Stormsurf: The folks at SurfPulse (and specifically author Mike Wallace) have written up a really nice article about Stormsurf, complete with some good pics. Learn about how we came to be and a little of where we are going. Check it out here:

Stormsurf Video: Just for fun - here's a clip about Stormsurf that ran on Bay Area TV a while back. Thought you might enjoy it:

Time Zone Converter 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.

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:

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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