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Pacific Storm and Surf Forecast
Updated: August 18, 2011 9:41 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 = 2.5 - 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 8/15 thru Sun 8/21
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   

More Small Swell From the South
Models Continue Suggesting Something Better Ahead


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 Thursday (8/18) North and Central California was seeing
thigh high warbled northwest windswell up north with southwest wind 5 kts early adding a slight texture to it. Down south no sideband swell of interest was pushing into Santa Cruz with surf knee high.  Southern California was getting thigh to waist high northwest windswell up north with occasional southern hemi sets to chest high intermixed and heavily textured. Down south southern extreme south angled southern hemi swell was producing waves in the chest to head high range and textured early. Hawaii's North Shore was effectively flat. The South Shore was getting southern hemi background swell with waves at thigh to waist high with a few bigger ones rarely  sneaking in and clean with light trades in effect. The East Shore had waist high  easterly tradewind generated windswell with lightly chopped conditions. 

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

Meteorological Overview
The North Pacific high was regrouping and starting to ridge into the North and Central CA coast on Thursday and by Friday small northwest local windswell is expected to result holding through Saturday.  But the high was only generating easterly trades at 15 kts over Hawaii's Eastern Shores and not providing great areal coverage either with no change forecast through Sunday offering only minimal support for windswell there. Weak low pressure was moving into the Northern Gulf of Alaska expected to maybe produce westerly winds at 20-25 kts there through the weekend possibly resulting in some minimal windswell focused mainly on the Pacific Northwest with sideband energy radiating south into Central CA. Down south a weak weather system formed under New Zealand Monday (8/8) tracking northeast with seas barely 30 ft and producing utility class swell that hit Hawaii earlier this week with some minimal sideband energy for CA on Fri-Sat. Sideband swell from a storm that was off Chile Mon-Tues (8/9) has been hitting CA and is to be all but gone by Friday (8/19). A gale alongside of New Zealand produced only a small pulse of  32 ft seas on Tues AM (8/16) pushing north-northwest, with minimal swell likely for Hawaii on Tues-Wed (8/24).  The models continue teasing concerning a series of two stronger systems tracking under New Zealand next Mon-Thurs (8/25), but nothing is certain yet. We guess a little swell is better than none at all.  


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

North Pacific

At the surface on Thursday (8/18) high pressure at 1028 mbs was building 700 nmiles west of Cape Mendocino CA generating 20 kt north winds there and 15 kt north winds pushing down the Central CA coast.  This was starting to produce minimal northwest windswell, but not much.  This high was also generating normal trades at 15 kts pushing over Hawaii resulting in minimal east windswell. Over the next 72 hours the high is to hold if not expand slightly resulting the same trade winds and windswell over the Hawaiian Islands but building north winds over Northern CA pushing 25 kts on Friday with lesser winds covering the entire North and Central CA coasts and building northerly windswell. At the same time low pressure is to be oozing southeast from the Bering Sea into the Northern Gulf of Alaska resulting in 20-25 kt west winds there late Friday into late Saturday then fading from 20 kts on Sunday. Some weak northwest windswell with period to 10 secs is possible for the Pacific Northwest with far less sideband energy radiating down into Central CA next week. Regardless, with the push of low pressure in the Gulf, it will take the legs out of high pressure off Northern CA, with north fetch off Cape Mendocino all but gone by Sunday and winsdwell fading with it.  


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


On Tuesday (8/16) Tropical Storm Fernanda was 1350 nmiles east-southeast from the Big Island with winds 45 kts and pushing energy up the 109 degree path there. By Thursday AM (8/18) is had slowly intensified to 55 kts positioned 1000 nmiles out with energy pushing up the 110 degree path to the Big Island. It is to be fading by Friday evening with winds down to 45 kts and 850 nmiles out from the Big Island with some energy pushing up the 109 degree path. Possible small swell to result along southeast shores of the Big Island Sat AM (8/20) from 110 degrees. 

Hurricane Greg was roughly 250 nmiles south-southwest of the southern tip of Baja with sustained winds 75 kts and tracking due west at 16 kts.  Minimal strengthening is forecast today, then the system is to slowly fade out as it moves over cooler waters, down to depression status by Sunday (8/21).  The rather rapid forward motion all to the west precludes the propagation of swell to the north pushing towards California. 


California Nearshore Forecast
On Thursday (8/18) high pressure was rebuilding off the Northern CA coast at 1088 mbs located 700 nmiles west of Cape Mendocino and starting to generate north wind at 20 kts there and up to 15 kts down into Central CA waters. These winds to reach 25+ kts Friday evening with increased local north windswell expected and chopped conditions nearshore of all of Central CA. By Saturday (8/20) the high is to try and hold on producing more 20 kt north winds up north early but coming under stress as low pressure starts building east from the Gulf of Alaska and a front approaches Vancouver Island late. By Sunday north winds are to be nearly gone (15 kt off NCal) and windswell is to be on the decline fast with a weak front moving to within 600 nmiles of Cape Mendocino Sunday night and stalling there. This configuration with relatively slack winds off the Central and South CA coasts is to hold through mid-Wednesday before high pressure tries to get a toehold in.  But even that is likely to be short lived.  


South Pacific

On Thursday (8/18) a .cgiit jetstream pattern continued over West and Southeast Pacific with the southern branch running just over the northern edge of Antarctic Ice across the width of the South Pacific. A little bit of a trough was over the Central Pacific with 100 kt winds feeding up into it and marginally supportive of gale formation at the lower levels of the atmosphere. Over the next 72 hours that trough is to persist and build to the west with reinforcing 150 kt winds pushing north under New Zealand late on Saturday (8/20). Beyond 72 hours yet another northward moving pulse is to push under New Zealand Monday (8/22) with winds 140 kts helping to reinforce the trough already present between New Zealand and the Central Pacific. This to provide yet more support for gale development in this area. Beyond the West Pacific trough is to slowly erode with no additional energy forecast pushing north into that area.  

At the surface on Thursday AM (8/18) a modest gale was circulating in the trough over the Southeast Pacific producing a moderate area of south winds at 40-45 kts.  Seas were on the increase.  By evening 40 kt south winds to hold and inching just a little more to the east. 28 ft seas forecast building at 55S 142W.  On Friday AM the fetch is to be all but gone but seas from previous fetch to to reach 32 ft at 53S 138W.  Seas to dissipate quickly thereafter.  If all this comes to pass another small pulse of 17 sec period swell could be radiating north up the 188/190 degree paths to North and South CA respectively. Over the next 72 hours another short lived but better organized gale is to push under New Zealand Sat AM (8/20) with 40 kt southwest winds building to 45 kt in the evening, then fading from 40 kts Sunday AM.  Theoretically some 28 ft seas to result at 52S 171W Sunday AM, but fading before exceeding that height.  Maybe some 15 sec period swell could result for Hawaii, but this system is to mainly serve to rough up the oceans surface acting as a primer for more energy forecast directly behind (See Longterm Forecast below).      

New Zealand Fetch

A new gale organized in an upper level trough positioned under New Zealand late Sunday (8/7). Southwest winds were modeled at 40 kts with seas on the increase, reaching 30 ft on Monday AM (8/8) at 51S 172E. But then winds were down to 35 kts and fading from there. Seas dropped to 28 ft in the evening at 50S 177E moving to 48S 170W Tues AM then dissipating from there.

Background energy for California by Wed noon (8/17) from 210 degrees but shadowed by Tahiti and buried in theoretical Chilean swell. Maybe swell of 1.6 ft @ 16 secs (2.5 ft) on Thursday (8/18) fading from 1.6 ft @ 15 secs on Friday.  


Second New Zealand Gale
On Sunday PM (8/14) 40-45 kt south fetch is to start building just southeast of New Zealand with seas building to 28 ft pushing into New Zealand on Monday. But by Monday AM a new area of 45+ kt south fetch was building off New Zealand resulting in seas to 30 ft seas in the evening at 50S 172W targeting primarily Hawaii. The fetch fading by  Monday night with more 32 ft seas at 45S 175W on Tuesday AM. A quick fade occurred thereafter. Maybe some small swell to push north towards Hawaii arriving late on Mon (8/22) then peaking Tues at 2.3 ft @ 15 secs (3.5 ft).  But little fetch is to be aimed northeast towards the US mainland. 


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 the generic low pressure is to remain holed up in the Northern Gulf of Alaska Monday (8/22) onward suppressing development of the Northeast Pacific High but also not strong enough to result in an swell producing fetch of its own. Generic northwest wind at 15 kts are forecast along the Central CA late Thurs (8/25) but of no real interest. Trades to remain suppressed (below 15 kts) over the Hawaiian Islands the whole of next week..    

As of Thursday (8/18) the Southern Oscillation Index (SOI) was still relatively low. The daily SOI was up barely to 4.79. The 30 day average was down slightly to 5.38 with the 90 day average up barely at 5.49. This continues to look like a neutral if not slightly La Nina biased long-term pattern.  

Current wind analysis indicates light easterly anomalies were in control over the Central and Western equatorial Pacific and building to stronger easterly anomalies north of Indonesia.  This suggests that whatever was hanging in in relation to what was essentially a weak version of the Active Phase stationary over the extreme Western Pacific/Eastern Indian Ocean has now faded. The models indicate that easterly anomalies are to persist over the West Pacific through at least 8/26 and likely much longer.  This suggests the Inactive Phase is in control and will likely help to dampen storm development (especially in the Northern Hemisphere) for the next 3 weeks or so. 

Sea Surface Temp anomaly data (8/18) remains essentially unchanged and continues to indicate that cooler waters (-1 C degs) had a grip on the equator covering from a point south of Hawaii to the dateline and holding steady if not increasing their coverage slightly. The larger issue was cooler than normal waters present in feeder bands originating off the US West Coast and Chile sweeping fully to the intersection of the dateline and the equator, serving to continue the existing La Nina pattern.  This is typically what is referred to as a horseshoe pattern.  And those cooler waters off the US West Coast were getting cooler still and expanding some. Warmer than normal waters appeared to not be building anymore over the Galapagos Islands extending west to a point south of Hawaii. And tongues of warmer water are positioned in the both the Northwest and Southwest Hemispheres trying to make inroads to the east but not very effectively. A cold tongue of water previously developing in the tropical Atlantic tracking west from Africa on the equator was fading. For now the big picture still looks like a La Nina.  

Below the surface on the equator things continue to look bad. Colder than normal water that had been locked all winter (2010-2011) southeast of Hawaii under the equator evaporated in late February 2011, but then returned starting in early July. An impenetrable wall of colder than normal water (-3 degs C) developed in mid-July locked at 140W separating warm anomalies in the east and west, blocking any eastward progress of warmer subsurface water. But then on 7/21 it vaporized, with a clear subsurface path present allowing warmer subsurface water to flow eastward. But then as quickly as it redeveloped, it died with the cold pool re-emerging starting on 7/30 and built far stronger by 8/2 with waters -3 deg C below normal, down to -4 degs C below normal on 8/4 and down to -5 degs C below normal on 8/8 and holding strength and position on the equator and south of Hawaii through 8/18 and blocking the warm water flow eastward. It was down at 100 meters and was rising while gaining areal coverage.  This suggests the foretasted 2 year La Nina is growing roots.  

Ocean currents for the equatorial Pacific on 8/11 we flowing anomalously west in the far West Pacific with a small pocket of strong easterly flow at 120W. Previously we found anomalies developed flowing from west to east starting in February and were continuing through June 2011 (a little weaker towards mid-June than earlier in the month). Westerly anomalies continued in July to (thru 7/22)  Easterly anomalies were isolated to a small area on the equator at 120W. We oft look at such symptoms as an El Nino indicator, but that does not seem likely given all the other data.  But that co.cgied with a falling SOI at least it depicts a tendency towards normal conditions.  Will monitor. Historically it is very unlikely if not impossible to have an El Nino form directly behind a La Nina.  More typical is several years of a slow buildup before an actual El Nino event occurs.  This suggest the warm waters currently pooling up off Ecuador will likely dissipate as summer progresses but at the same time, the cooler than normal horseshoe pattern over the North and South Pacific will dissipate too. 

Remnants of what was a moderate.cgius strength La Nina Pattern (where the Inactive Phase takes control) are still evident and momentum from this La Nina event are expected to hold well into the Fall of 2011 (and likely to early 2012) in the upper atmosphere regardless of how quickly La Nina's demise occurs in the ocean. In short, it's going to be tough for surfers on west facing shores in the Eastern Pacific and Eastern Atlantic, though east facing shores of the West Pacific and Atlantic might do well from the Inactive Phase's dominance, especially in summer months.  That is not to say there will be no storms, in fact, there could be short periods of intense activity when the Active Phase gets an opportunity to come to fruition, but that will be the exception rather than the rule, with the Inactive Phase trying to keep a cap on storm activity. Best bet's at this time are for an enhanced tropical season in the Atlantic (2011).

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


South Pacific

Beyond 72 hours the models suggest a far more organized gale is to develop south of New Zealand on Sun PM (8/21) with southwest winds to 45 kts.  That fetch is to push hard to the northeast over night with a large area of 40-45 kt southwest winds forecast Monday AM (8/22) with 32 ft seas blooming at 52S 176W. Secondary 45 kt southwest fetch is to rebuild embedded in the faltering main fetch (with winds still 40 kts) pushing hard to the northeast resulting in a solid area of 36-38 ft seas at 48S 170W right on the edge of the Tahitian swell shadow relative to NCal and SCal (210-212 degrees) but clear up the 188 degree path to Hawaii. 45 kt southwest fetch to hold through the night then be fading from 40 kts Tuesday AM (8/23) resulting in 39 ft seas at 42S 163W, just barely in the western edge of the Tahitian swell shadow relative to NCal/SCal (209-211 degrees respectively) and 185 degs for HI. Fetch is to be gone in the evening with residual seas fading from 34 ft at 36S 156W and in the heart of the Tahitian swell shadow for CA (207-209 degs) and 180 degs HI.  Of note: The rather hard push of this system to the north puts it a mere 1500 nmiles from Tahiti, with solid sized swell with period at 18 secs pushing directly towards those island and arriving near noon on Thurs (8/25) if one is to believe the models.     

Also on Tuesday (8/23) another   strong storm is forecast tracking under New Zealand with a solid area of 55 kt west winds. It actually is to originate under Southern Australia on Monday.  40 ft seas are forecast just off the northern edge of the Ross Ice Shelf at 58S 155E (216/218 degs NCal /SCal) and unshadowed by Tahiti though and incredible long distance away but shadowed by New Zealand relative to Hawaii. 50 kt westerly fetch to hold in the evening resulting in 44 ft seas at 59S 175E pushing flat east or in the heart of the Tahitian swell shadow (208/210 degs) for NCal/SCal and 193 degs for HI and unshadowed by NZ. A rapid fade in fetch is forecast Wed AM (8/24) with barely 45 kt fetch left and seas fading from 38 ft at 57S 175W (205-207 degs) and shadowed by Tahiti for NCal/SCal and 188 degs relative to HI but most fetch passing east of the great circle tracks heading there.  This system to be a very long ways away and not optimally set up, but still pretty powerful certainly capable of producing some swell for all Northern Hemi locations in our forecast area.   

Still, both these system are just projections and not a breath of wind is yet blowing to produce swell.  At least it's something to monitor.    

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

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: 

Mavericks Surf Shop Grand OpeningSunday, December 19 2:00 - 6:00 p.m. rain or shine!  Check out the new home of Jeff Clark's Mavericks Surf Shop, now located at 25 Johnson Pier in Pillar Point Harbor.  The shop features much of Clark's surfing memorabilia, classic boards and photos, as well as an entirely new line of Jeff Clark original Mavericks clothing, accessories and surfboards. The shop has been open in the new location since December 8, and the Grand Opening party is set for this coming Sunday, just in time for Christmas.  The party starts at 2 p.m., with live music, food and drinks. Jeff Clark and many Mavericks surfers will be there to meet the public. Local restaurants Ketch Joanne's and Princeton Seafood will serve up delicious food, while San Francisco Wine Trading Company is providing the beverages.  The shop will be open all weekend, from 9 a.m. to 8 p.m. on Saturday and Sunday.

Stormsurf Maintenance Upgrades: Buoy 46059 and 46012 were r.cgiaced a month or so ago. Totally new buoys were installed. Here on Stormsurf we had to reset the algorithms used to calculate 'pure swell' for them. That was acco.cgiished on 11/13. Pure swell numbers are now correct. Links: 46012, 46059

Also since we moved to the new weather model server last month we discovered that our Longrange Precipitation Models ceased to display frozen precipitation (as they once did). Some of our scripts did not get installed on the new server. That has been fixed (11/13) and now snow is again viewable worldwide. Here the new North America sa.cgie.

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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