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Pacific Storm and Surf Forecast
Updated: August 21, 2012 7:05 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 = 1.5 - California & 1.0 - 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 8/20 thru Sun 8/26
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   

Quiet On All Fronts for Now
Small Southern Hemi Gale Forecast Longterm

Swell Classification Guidelines

Significant: Winter - Swell 8 ft @ 14 secs or greater (11+ ft faces) for 8+ hours (greater than double overhead).
- 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/Utility Class: Winter - Swell and period combination generating faces at head high to 1.5 times overhead (4-7 ft).
- 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.
- up to waist high swell. Also called 'Background' swell.

Current Conditions
On Tuesday
(8/21) North and Central CA had local windswell producing waves in the waist high range and warbled but clean early. Down south in Santa Cruz surf was thigh high on the sets and clean at protected breaks. Southern California up north had a few thigh high windswell sets and getting ruffled. Down south southern hemi swell was maybe thigh high on the rare sets and heavily textured by eddy winds. Hawaii's North Shore was flat and clean with trades in effect. The South Shore was getting the usual thigh to maybe waist high background swell and clean with modest trades in effect. The East Shore report was not available.   

See QuikCASTs for the 5 day surf overview or read below for the detailed view

Meteorological Overview
Up north high pressure was easing east, centered in the Western Gulf of Alaska producing a minor pressure gradient along the California coast resulting in minimal to small local northerly windswell production. Trades were generally light over the Hawaiian Islands, only in the 10-15 kt range offering no real local windswell production. Beyond high pressure is to moving stronger to the east on Thurs-Fri (8/14) with north winds rebuilding to 25-30 kts along the North CA coast resulting in improving local windswell, then fading over the weekend as a cutoff low falls down the Pacific Northwest Coast into early next week. Trades return at 15 kts over and east of Hawaii by Thursday (8/23) holding into Saturday providing some limited hope for small east windswell. No other swell producing weather systems are forecast. 

Down south no swell producing fetch has occurred for the entire South Pacific and none expected until maybe Thursday (8/23).  Then just a small gale is forecast developing in the deep Central South Pacific tracking mainly due east with seas building to 34 ft late Friday.  Maybe some small southern hemi swell to result for California down into Central and South America. But even 6 hours ago this system was not even on the charts, so confidence is very low in it even forming. 


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

North Pacific

Surface  -  On Tuesday (8/21) the North Pacific high pressure system was getting slightly better organized, with pressure at 1028 mbs centered over the Western Gulf of Alaska.  It was ridging slightly east forming a weak pressure gradient along the North and Central CA coast generating winds at 15-20 kts and minimal weak short period east windswell there. The southern quadrant of the high was also producing easterly trades over the Hawaiian Islands and open waters east of there at 10-15 kts, but not really enough to produce meaningful east windswell for the Islands. Weak low pressure was east of the kuril Islands at 1004 mbs generating only 20 kts winds and no seas of interest.  

Over the next 72 hours the Kuril Islands low pressure system is to fade as it impacts Northeast Pacific high pressure system, still in it's summer configuration. The high itself is to is to be ridging eastward tightening the pressure gradient along the California coast with north winds building to 25-30 kts on Thurs-Fri (8/24) likely increasing the size and period of local windswell pushing down the Central CA coast. Nothing remarkable, just rideable. As the high eases east trades to build slightly east of the Hawaiian Islands to 15 kts on Thursday (8/23) holding through Saturday, incrementally increasing the odds for maybe some rideable windswell along east facing shores, but nothing more. In the extreme West Pacific tropical weather is to build (see Tropics below).  


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


On Tuesday (8/21):
Typhoon Tembin was 200 nmiles east-southeast of Taiwan with winds 100 kts tracking north-northwest. A steady turn to the northeast and west is expected in the next 24 hours putting Tembin moving onshore over Central Taiwan at 06Z Thurs (8/23) with winds 90 kts, tracking over Taiwan and then eventually into mainland China on the 24th winds winds down to 55kts. No swell is suggested for our forecast area.

Typhoon Bolaven was 850 nmiles east of the Northern Philippines with sustained winds 70 kts tracking west-northwest. It is expected to hold this heading while slowly building, pushing 105 kts by Saturday (8/25) positioned 200 nmiles east of the northern tip of Taiwan. A steady turn to the north-northwest is forecast with Bolaven moving just off the west coast of Korea on Tuesday (8/28). No swell is expected for our forecast area.  


California Nearshore Forecast
On Tuesday (8/21) a modest north wind flow was in control of North and Central CA waters with high pressure fading and di.cgiaced to the west with a new high pressure core building in the Western Gulf of Alaska. A building patch of 15 kts north winds was over all North and central CA water but shallow and not well formed. By Wednesday a more typical pattern is to emerge with north winds pushing 20-25 kts up near Cape Mendocino and an eddy flow building up into Central CA to Bodgea Bay. This pattern is to become better established and peak Friday when winds off Cape Mendo reach 30 kts with the eddy flow holding over Central CA. An eddy flow to remain over Southern CA through the period. The Cape Mendo gradient is to start fading Saturday from 25 kts and be gone by Sunday as weak low pressure drops south from Canada  reaching a point off the Oregon coast Monday (8/27). As soon as the low pushes inland there late Tuesday high pressure to again start trying to ease east with north winds rebuilding over Central CA at 20 kts di.cgiaced south just above Pt Conception. 


South Pacific

Jet stream -  We're thinking of starting to switch jetstream monitoring to the North Pacific. But for now we'll continue Southern Pacific monitoring. 

On Tuesday (8/21) a .cgiit jetstream pattern remained locked over much of the South Pacific with the southern branch di.cgiaced well to the south running flat east starting down at 63S. Winds were below 100 kts over it's length. No support for gale development was indicated. Over the next 72 hours a trough is forecast developing in the Southeast Pacific by Thurs (8/23) with winds to 120 kts pushing almost due north, then moderating with winds down to 110 kts Friday and easing to the east, on the edge of the CA swell window. Some decent odds for gale development under this trough if all goes as.cgianned. Beyond 72 hours additional wind energy at 130 kts is to push from the West Pacific eastward moving into the remnants of the trough Saturday (8/25) but quickly moderating.  Perhaps some additional support for gale development possible. A weak ridge to follow pushing well over the Ross Ice Shelf early next week return the Pacific to a tranquil state.  

Surface  -  At the surface in the South Pacific on Tuesday (8/21) high pressure at 1036 mbs was over the Southeast Pacific ridging hard south and reaching down to 63S and in effect preventing any gale development in that region.  West of there no swell producing fetch of any kind was present over ice free waters with no winds greater than 30 kts occurring. 

Over the next 72 hours a small gale is forecast developing in the deep Central Pacific over Antarctic Ice with a small area of 40-45 kt southwest winds trying to become exposed over ice free waters north of there Thursday AM (8/230 with seas building to 30 ft over a tiny area at 60S 153W.  That fetch to lift north in the evening with winds down to barely 40 kts and seas 28 ft at 52S 145W targeting California up the 194 degree path and east of the Tahiti swell shadow. Winds to rebuild to barely 45 kts Friday AM again still lifting and aimed north-northeast with seas 30 ft at 56S 139W (189 degs CA).  This wind to barely hold into the evening with seas building to 34 ft at 51S 130W (186 degs CA).  Additional 40-45 kts more westerly fetch to build Saturday AM (9/25) with 32 ft seas at 56S 123W (182 degs CA) and continuing into the evening. 30 ft seas are to be tracking east from 53S 120W and starting to move out of the CA swell window. Theoretically 50 kts fetch is to develop Sunday AM (8/26) aimed due north with a small area of 32 ft seas building at 58S 132W (186 degs CA) tracking fast northeast with maybe 32 ft seas in the evening at 54S 123W (182 degrees CA). A quick fade after that. This all seems interesting per the models, but the previous run of the models depicted no sign of this system, so this is all likely just a random fluctuation in the model projection and nothing to bet on. 


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 hours weak surface low pressure is to develop off the Northern Canadian coast falling south on Saturday (8/25) tracking down to a point just off Oregon on Monday producing no fetch and serving only to break up high pressure off the US West Coast. In fact, the entire high is to be in retreat.  But by Wednesday (8/29) there's some signs high pressure and usual north winds regime is to start rebuilding. No swell producing fetch, but the start of another cycle perhaps.   

Easterly trades over Hawaii to hold at 15 kts but covering far less area east of the Islands starting Sunday (8/26) into early next week suggesting only small easterly short period windswell at best for that timeframe and likely much less.

No signs of Fall on the models yet.  

Note: The Madden Julian Oscillation is a periodic weather cycle that tracks east along the equator circumnavigating the globe. It is characterized in it's Inactive Phase by enhanced trade winds and dry weather over the part of the equatorial Pacific it is in control of, and in it's Active Phase by slack if not an outright reversal of trade winds and enhanced precipitation. The oscillation occurs in roughly 20-30 day cycles (Inactive for 20-30 days, then Active for 20-30 days) over any single location on the.cgianet. During the Active Phase in the Pacific the MJO tends to support the formation of stronger and longer lasting gales resulting in enhanced potential for the formation of swell producing storms. During the Inactive Phase the jet stream tends to .cgiit resulting in high pressure and less potential for swell producing storm development. The paragraphs below analyze the state of the MJO in the Pacific and provide forecasts for MJO activity (which directly relate to the potential for swell production).

As of Tuesday (8/21) the daily Southern Oscillation Index (SOI) was surprisingly holding it's own up to -6.43 (after being negative or nearly so for 26 consecutive days, positive for 3 then back to negative for 2 days). The 30 day average was down slightly at -11.42 with the 90 day average at -7.84. With the Inactive Phase of the MJO in control one would expect the SOI to be pushing well into positive territory. Two things are occurring:  Weak low pressure continues to sit south of Tahiti, and (so far) the Inactive Phase of the MJO has not built anywhere near as strong as what was previously modeled.  All this is consistent with a developing El Nino.  
And the presence of two tropical systems in the far West Pacific, during the core of the Inactive Phase, also hints to it's weakness.  

Current equatorial wind analysis indicated a modest area of light east anomalies extending from the dateline to the mid- Maritime Continent (WPac). Moderate east anomalies also extended east from a point south of Hawaii almost to Central America.  This suggests the Inactive Phase was trying to get a foothold, but was more isolated to the Central and East Pacific (a good thing for maintaining the warm water pump).  A week from now (8/29) moderate east anomalies are forecast over the entire Maritime Continent to the dateline with weak to neutral east anomalies in the East Pacific.  This suggests the Inactive Phase might still get it's footing, but we have doubts about that now (more below). All this is based on the GFS model. If all this.cgiays out as forecast, that would not be too bad of an outcome, suggesting a rather anemic Inactive Phase. 

The longer range models (dynamic and statistical) run on 8/20 are in agreement suggesting that the Inactive Phase was in.cgiace over the Maritime Continent reaching the dateline area and pushing east. Both suggest the Inactive Phase has likely peaked, is to hold for maybe 5 more days at most, then is to be in steep decline by 8 day out if not gone. This is more aggressive than what the GFS model suggests. And a weak version of the Active Phase is to be brewing in the Indian Ocean easing into the far West Pacific 2 weeks out (9/4). For now we will continue to be somewhat concerned that this Inactive Phase has the potential to degrade what is already a weak eastward moving warm water transport pattern (feeding the warm pool off Ecuador and Columbia) but current model runs continue to help dampen those concerns.

More warm water in the equatorial East Pacific means more storm production in the North Pacific during winter months (roughly speaking). Warmer than normal water accumulated off Ecuador through 7/2 (part of a continuous pattern that started in Jan 2012) and a pocket of blocking cold water that had been under the equator south of California the bulk of the past Winter (2011-2012) evaporated in April allowing warmer water to slowly but steadily pushing east into the vacuum (Kelvin Wave). This activity was the result of an Active Phase of the MJO (early April) and a continued weak MJO signal beyond, and appeared to be reinforcing itself. A close inspection of the water temperature anomaly charts through 7/2 depict that an unmistakable El Nino-like pattern developed extending from south of Hawaii into Ecuador and extending north to Cabo San Lucas and south well into Chile. Updates through 8/20 indicated some degradation of that pattern with the warmest water temps fading some, but areal coverage actually expanding. 

A weak MJO pattern (both Active and Inactive Phases) is a sign of the weak version of El Nino. Strong Active Phases accompanied by Westerly Wind Bursts (WWB) is a sign of a strong El Nino. Given the data to date, this is looking more like a weak El Nino event at best. As we move into the Fall months (starting late August), the tendency is for whatever pattern has been dominant to only become more that way. In short, the true MJO character will become exposed in Fall, with summer just being a build-up. The expectation is that a near failure of the MJO could occur with trades fading and more slow-but-steady warm water propagation continuing eastward. If this happens the question then becomes: Will it be slow enough and weak enough to turn into a multi-year warm event, or will the atmosphere switch as usual in February 2013 and usher in a new La Nina.  It's way to early to know. 

At this time there is only limited atmospheric evidence of a possible El Nino pattern in.cgiay (as of 8/21).  Remnants of La Nina are still affecting the atmosphere and will likely continue for several months into the middle of Fall (mid-Oct). One such indicator is the continued presence of high pressure over the Eastern Pacific. It has been locked in.cgiace for 2 years now and it's momentum is not going to be easily be halted. The high is causing drought conditions over portions of North America and unrelenting north winds pushing down the California coast and stronger than normal trades over Hawaii. The high is evidenced by a large pool of cooler than normal water radiating southeast off California and over Hawaii reaching the equator at the dateline, the result of enhanced upwelling.  But recent imagery suggest the high is shifting west some and north winds along the California coast are becoming less of an issue, with local water temperatures on the rise. this could be attributed to the change in season, or a fading La Nina.  We're in a hybrid atmospheric state but the trend is starting to move more towards the normal category. The longer the MJO remains biased towards a neutral or Active state, and the longer warm water holds if not builds off Central America, the more the atmosphere will respond (especially come Fall) turning towards at least a neutral if not an El Nino-like configuration. The atmosphere is like a big ship, it takes a long time to turn. We remain on the bubble as of this date. Historical Note: It is unusual for El Nino (of any magnitude) to develop directly following 2 years of La Nina.            

As of right now its seems the Active Phases of the MJO are not strong enough to usher in some flavor of real El Nino, but the Inactive Phases are not strong enough to shut off the warm water pump to the East Pacific either.  Regardless, we are effectively past the La Nina hump and the tendency will be for a return to a normal if not slightly El Nino-like enhanced state. All this is way better than where we've been for the past 2 years (under the influence of La Nina).    

See imagery in the ENSO Powertool and more details in the  El Nino update.  


South Pacific

Beyond 72 hours no swell producing weather systems 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

Chasing Mavericks - The Jay Moriarty Movie: Two trailers for the new movie about Jay, Frosty and Mavericks has been posted. Movie opens on 10/26/12. Here's the link: &

Props from the Pros:  Stormsurf was mentioned over the past week in two different media sources.  One was in an interview Kelly Slater did with the New York Times and another was in a promotional piece Ramon Navarro did for the Big Wave World Tour. Many thanks to Curt Myers from Powerline Productions for alerting us and of course thanks to Kelly, Ramon and the Tour for using our service. Here's the links:

Steve Colleta Surfboards - Check out surfboards by local shaper Steve Coletta - A long time Santa Cruz local and master shaper. Progressive shapes for North and Central CA waves

Chasing the Swell has been nominated for a Webby Award. See details of this great piece of video journalism below. Some say this is the "Oscars" of online awards.One of the awards is voter based. If you have a moment,.cgiease cast your ballot by going to:, register, then click on the "Get Voting" tab and then to the "Online Film and Video" > "Sports" category and vote for "Chasing the Swell".

Timmy Reyes - Curt Myers from Powerlines Productions found this little gem with Timmy Reyes providing a brief statement about which sites he uses for swell chasing. Thought we'd pass it on. Enjoy:

Buell Wetsuits - When surfing in Santa Cruz, we've been seeing a new wetsuit in the line-up worn by many top flight surfers. They're getting good traction and are well respected. Take a look:

Stormsurf Mobile App (1/9/11) We are proud to announce the official public release of our smartphone mobile app. It provides access to our most popular and commonly used products, optimized for use on the road, on the beach or anywhere you don't have a desktop or laptop.  With a smart phone and signal, you will have access to our data. And we're not talking just a few teaser products - We're talking full feature wave models, weather models, real-time buoy data, manually built forecasts and hundreds of spot wave and wind forecasts enabling you to construct a surf forecast for any location on the.cgianet, all from your cell phone and all for free.  No subscription required and no hidden fees. And better yet, there's a few new things sprinkled in that are not yet available even on our full-featured web site. From your smart phones browser just navigate to: 

Chasing The Swell: Sachi Cunningham from the LA Times spent the entirety of last winter chasing surfers and swells around the North Pacific with her high def video cam. Her timing couldn't have been any better with the project exactly coinciding with the strongest El Nino in 12 years resulting in the best big wave season in a decade. And being an acco.cgiished surfer herself helped her to bring a poignant and accurate account of the what it's like to ride big waves and the new (and some not so new) personalities that are revitalizing the sport. This is must-see material for any surfer or weather enthusiast. Check it out here:

New Weather Models With the activation of our new server we have now released a new block of weather models including North America jetstream, wind and precipitation, local coastal wind forecasts in 1 hr increments and snow and mountain wind forecasts in both 1 and 3 hours increments. The new animations can be found here (look for those items tagged with the New! icon):

New Weather Model Server Stormsurf has installed another weather model production server. This has enabled us to spread the load across more servers allowing us to post both wave and weather model updates much quicker.  Also we are testing new content (like North America jetstream, winds and precipitation, local wind forecasts in 1 hr increments and snow and mountain wind forecasts in both 1 and 3 hours increments). The model menus will be updated shortly with these new links.   

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

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.

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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