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Southern Hemi Swell Hitting CA! - Video Forecast HERE (5/19/24)
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Pacific Storm and Surf Forecast
Updated: May 22, 2010 3:17 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 & 0.5 - 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 5/24 thru Sun 5/30
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   

Southern Hemi Swell #5S Hitting CA
Maybe Another Small Pulse from Both North and South


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.

On Saturday (5/22) North and Central California had minimally whitecapped shoulder high northwest windswell with southern hemi swell building underneath from occasionally chest high. Southern California was getting wraparound northwest windswell at waist high.cgius up north with northwest wind on it early. Down south southern hemi swell was trying to move in at head high at top spots but pretty warbled by northwest windswell.  Hawaii's North Shore was flat and clean. The East Shore was getting head high.cgius tradewind generated east windswell and chopped. The South Shore was getting minimal background southern hemi swell with waves thigh high Sunday and dropping off after that with trades in control.  

The forecast for North and Central CA is for northwest windswell fading from head high Sunday while new southern hemi Swell #5S builds to 1-2 ft overhead, then fading from head high Monday and shoulder high Tuesday. Possible northwest swell to 1 ft overhead on later Tuesday. Southern California is to see southern hemi Swell #5S pushing 2 ft overhead Sunday then heading down from 1 ft overhead Monday and shoulder high early Tuesday with waist high background southern hemi swell holding for days beyond. 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 head high.cgius Sunday pushing 1-2 ft overhead on Monday and Tuesday before starting to drop off Wednesday. The South Shore to see south angled swell at waist thigh high Sunday then dropping Monday and gone for the rest of the week.

The models suggest a gale forming off British Columbia Sunday (5/23) with 22 ft seas then dropping straight south and fading through the workweek. POssible northwest swell for Central CA northward. Down south a cutoff low south of Tahiti is to develop some Mon/Tues (5/25) generating up to 35 ft seas aimed well to the north but over a small area. Possible southern hemi pulse to result. Then things to really quiet down after that.


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

North Pacific

On Saturday (5/22) the North Pacific jetstream was generally pretty weak in the west with a weak trough there, then started building at the dateline while ridging north and gaining energy with winds to 140 kts, dropping into a trough pushing into Northern CA. Limited support for gale development in that trough very close to the Pacific Northwest. Over the next 72 hours that trough is to hold right over the California coast while more energy builds into the jet, with the same basic configuration in control with the West Pacific holding ground with 140 kts winds flowing into it and the other trough redeveloping a bit more off the US West Coast. Both troughs to be easing east into Thursday (5/27) providing some support for gale development. Beyond 72 hours the jet is to fade with no real troughs or energy of interest occurring. 

At the surface on Saturday (5/22) high pressure was holding solid at 1032 mbs 1400 nmiles west of Central CA generating the usual pressure gradient along the coast and producing 25 kt northwest winds focused over the Pt Conception area. This was generating short period northwest windswell there. This high was also generating trades at 20 kts pushing into the Hawaiian Islands.  A weak low pressure system was pushing east over the top of the high from a position east of the dateline bound for the Eastern Gulf of Alaska. Over the next 72 hours more of the same is forecast with high pressure and brisk northwest winds continuing along the California coast enhancing the pressure gradient focused over Pt Conception into early Monday, then fading as the high retrogrades west shutting off the gradient with winds and windswell dying later Monday. The high is to also continue trades at 20+ kts pushing east into Hawaii generating east windswell there into Tuesday (5/25).  A solid gale is forecast forming in the Gulf of Alaska late Sat (5/22) with 35 kt west winds tracking east up to British Columbia, then stalling Monday.  Some fetch is to be aimed southeast towards US interests with seas forecast to 22 ft, likely setting up some degree of limited swell pushing down into Central CA and more for the Pacific Northwest. 


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


California Nearshore Forecast
On Saturday (5/22) high pressure was holding strong over the area with north winds and chop (making limited short period windswell) the norm. This same north wind pattern is forecast holding into Sunday then fading Monday as lower pressure moves into the area of the north. South winds, a front and light rain are forecast pushing down to Pt Conception by Tuesday (5/25). South winds to fade to calm Wednesday and hold into Friday (5/28) with light rain still in the forecast. But high pressure and more north winds are forecast taking hold for next weekend. 


South Pacific

On Thursday (5/20)
the models continued to indicate a ridge in the upper atmosphere pushing well to the south over the entire South Pacific offering no odds to support gale development.  A cutoff low was east of New Zealand tracking east and is forecast to get better organized on Monday resulting in a small fetch of 45-50 kt south winds at 40S 147W aimed well north towards Tahiti and Hawaii with decent fetch towards the US West Coast too. Seas to build to 35 ft at 37S 145W Tuesday AM (5/25). Possible swell to result if this occurs.  

Swell #5S (California)
On Thursday AM (5/13)
the models indicated 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. The ASCAT satellite provided a less rosy picture with a small core of 40-45 kt winds embedded in a large area of 35 kt southwest winds.  The models looked to be on the high side. 

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. The ASCAT satellite confirmed 45-50 kt south-southwest winds well south at 60S 155W, and brand new fetch south of the main fetch, a bit stronger than the models indicated. 36 ft seas were modeled at 50S 147W.  The Jason-1 satellite passed over the southwest quadrant of this system at 18Z and reported average seas at 34.2 ft with a peak to 38.4 ft while the model suggested 31 ft.  The model was undercalling it both in terms of winds and seas. In the evening stronger 45-50 kt south-southwest winds were modeled building 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 136W.  No ASCAT data was available. The Jason-1 satellite passed over the far eastern edge of the fetch and reported a 15 reading sea average of 26.4 ft with one peak reading to 36.1 ft while the model suggested 28 ft for that area. The model was about 2 ft on the high side. Fetch held solid in the evening at 52S 130W with 43 ft seas at 52S 132W. No ASCAT data was available for this day.

40-45 kt southwest winds were fading on Sunday AM (5/16) with 40 ft seas fading at 46S 127W. The ASCAT satellite suggested only 35 kt winds. The Jason-1 satellite passed over the southwestern edge of the fetch and confirmed average seas at 29.6 ft with a peak to 33.1 ft while the model suggested seas of 34 ft in the same area. The model was way over calling it, at least out on the periphery where the satellite passed over. Residual 37 ft seas were modeled Sunday evening at 43S 119W and moving out of the CA swell window, though much fetch is still forecast pushing towards Chile.  

On Monday (5/17) 36 ft seas were modeled at 42S 108W well outside the CA swell window.  The Jason-1 satellite passed over the far western edge of the fetch and reported seas at 25.1 ft with a peak reading of 32.2 ft while the model suggested seas of 29 ft in the same area. The model again was over hyping the seas.

At this point it looks like a decent gale occurred in the Southeast Pacific.  Notice we said 'gale' and not 'storm' since winds for the most part did not reach storm status (50 kts) other than one 12 hr window on Fri AM (when both the ASCAT satellite reported 50 kt wind and the Jason-1 satellite reported solid seas). But in general the GFS wind model (which drives the Wavewatch wave model) seems to have over represented wind speeds, which in turn resulted in higher sea heights in the wave models. That said, both the ASCAT and Jason-1 data was spotty at best with no good solid passes over the core of the storm.  So maybe there was more going on in the core of the storm than was imaged, but we kinda suspect that is more a case of wishful thinking. Regardless, we suspect some degree of decent significant class swell should push up into California from this gale from a rather southerly angle.  But most size is expected east of there, down into Central America.  

Southern CA:  The core of the second pulse is expected in on Sunday (5/23) as period drops towards 17 secs from noon to 5 PM with pure swell peaking at 3.7-4.3 ft @ 17-18 secs  (6.0-7.7 ft faces with top spots having sets to 9.5 ft). Swell heading down on Monday with swell 4 ft @ 15-16 secs (6.0-6.5 ft) and dropping to 3 ft @ 14 secs on Tuesday (4.0-4.5 ft faces). Swell Direction: 198 degrees first pulse, 187-190 degrees on the second larger pulse    

Northern CA:  The main swell is to still be building through the day Sunday (5/23) with period at 18 secs finally peaking as period drops to 17 secs from 5-11 PM with pure swell peaking at 3.7-4.3 ft @ 17-18 secs  (6.0-7.7 ft faces with top spots having sets to 9.5 ft). Swell heading down on Monday with swell 3.8 ft @ 16 secs (6.0-6.5 ft with top spots to 7.5 ft), then dropping to 3 ft @ 14-15 secs on Tuesday (4.5 ft faces). Swell Direction: 195 degrees first pulse, 184-187 degrees on the second larger pulse   


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 gale off British Columbia is to regenerate some Tuesday (5/25) with 35 kt northwest winds and maybe 20 ft seas, then sinking southeast while fading fast Wednesday and dissipating off Northern CA Thursday. More limited northwest windswell could result. Also a broad low pressure system is to develop of the dateline Tues/Wed (5/26) with maybe up to 30 kts northwest winds and 15 ft seas, possibly offering windswell for Hawaii.

MJO/ENSO Update (reference): As of Saturday (5/22) the Southern Oscillation Index (SOI) was hanging around neutral territory. The daily SOI was at -11.32.  The 30 day average was down to 6.84 with the 90 day average up to 3.02.  Lower readings are expected as the Active Phase of the MJO starts to move over the Pacific.

Wind anomalies at the 850 mb level (approx 5000 ft up) as defined by models suggest light easterly anomalies fading fast over Central America (the end of the Inactive Phase of the MJO) with the Active Phase and westerly anomalies pushing into the Western Pacific. It is to reach the dateline on 5/26, then slowly fade while pushing east towards Central America through 6/5. Maybe some very limited support for gale development from this Active Phase of the MJO when it happens. But odds are low. .    

We believe that El Nino will not hang on for another year, and that rather we'll fall back into some form of a light 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 (5/20) indicated no dramatic change from previous weeks, with warmer than normal waters consolidated on the equator in a pocket of warmer water off Ecuador and the Galapagos Islands, fading west of there then regrouping 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 or whether residual upper level shear from El Nino will chop the tops of developing systems. Suspect shear will be gone by the heart of hurricane season in the Atlantic.

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 (sort of like a cold Kelvin Wave). 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 if not slight cooler than 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 swell producing fetch is 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

Add a STORMSURF Buoy Forecast to your Google Homepage. Click Here: Add to Google
Then open your Google homepage, hit 'edit' button (top right near graph), and select your location


Local Interest

The Mavericks: Everest of the Seas Exhibition has unveiled its latest gallery featuring some of the most heart-stopping images from the epic El Niño-fueled Big Wave Season. This year's lineup includes not only a culmination of images from Award-winning photographers Doug Acton, Frank Quirarte, Seth Migdail, Ed Grant and Art Gimbel but a multimedia slide show and a video recap of the 2010 Mavericks Surf Contest, one of the greatest days in surfing history.

Thanks to an El Nino weather pattern, this has been one of the most dramatic big-wave surf seasons on record, said Doug Acton, Mavericks Veteran Lensmen.

Now Eric Nelson and Curt Myers of Powerlines Productions have come on board to bring the gallery images to life by presenting both water and cliff-angle video of the Mavericks contest, won by South Africa's Chris Bertish in the biggest waves ever ridden in a paddle-surf contest.

The Mavericks crew will transform the Longboard Vineyards tasting room into a virtual caldron of 50-foot drops, glory rides and heinous wipeouts. As you stand under the colorful Tibetan Prayer flags, tasting some of Longboard Vineyards' libations, you'll be hard-pressed not to become immersed in the real-life drama, energy and stoke that surrounds the surfers and photographers every time they head out to the lineup.

Longtime big-wave surfer Mark (Doc) Renneker put it best when he said, “Every time you leave the shore, you head out into the wildnerness.”

“We're coming off one of the most phenomenal big-wave seasons to date," said Quirarte, the longtime Mavericks lifeguard and master lensman. “This season we witnessed so many great rides by so many different surfers from so many different countries. Mavericks is still the No. 1 all-around spot in the world for big-wave surfing.”

Oded Shakked, a longtime surfer who founded Longboard Vineyards, will be on hand at the reception to unveil the latest release in his Mavericks Signature Series, the Ken “Skindog” Collins Syrah.

Veteran waterman Ken “Skindog” Collins (Santa Cruz, CA) is hands down one of the most recognized and respected big wave surfers today. With his recent trip to the podium at the 2010 Mavericks Surf Contest or his epic twenty-foot Puerto Escondido barrel that earned him top honors at the Billabong XXL Global Big Wave Awards. Collins has traveled the world mentoring up and coming crop of big wave chargers -- and has himself pioneered and ridden the biggest waves on the.cgianet.

“I can't think of a better person to honor with our next Mavericks label than Kenny Collins,” said Shakked. “A true icon of the sport.”__

Oded Shakked, along with the featured photographers, videographers, surfboard shapers and wine makers will be on hand at the Longboard Vineyards Tasting room in beautiful Healdsburg California for the Saturday night reception on May 22nd The reception will begin at 5pm and run until roughly 9pm.

“Everest of the Seas” was launched in the summer of 2009, with the idea of bringing together the most memorable photos from Mavericks' best sessions. It drew large crowds and an enthusiastic response in its debut at the Coastal Arts League Gallery in Half Moon Bay, then moved on to successful runs at San Francisco's world-class SFMOMA Museum and Gallery, The Fillmore, The Half Moon Bay Big Wave Surfing Festival and Longboard Vineyards.

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

Free Stormsurf Stickers - Get your free stickers! - More details Here

Read all the latest news and happenings on our News Page here

Surf Height-Swell Height Correlation Table


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