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Pacific Storm and Surf Forecast
Updated: August 20, 2013 7:16 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 = 1.0 - 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 8/12 thru Sun 8/18
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   

Tiny Southern Hemi Swell Possible Longterm
Weak Windswell Until Then

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
(8/20) North and Central CA had surf that was chest high and getting pretty ruffled by southerly wind at exposed breaks. Clear skies. Down in Santa Cruz surf was flat with light winds and clean. Southern California up north was flat and getting textured with northerly wind. Down south waves were knee high and almost chopped with northerly winds in control mid-day. Hawaii's North Shore was flat and clean. The South Shore was getting knee high.cgius tradewind generated wrap-around windswell and clean with trades in effect. The East Shore was getting tradewind produced east windswell at knee high and and lightly chopped from trades.

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

Meteorological Overview
In the North Pacific on Tuesday (8/20) weak high pressure was in control of the entire North Pacific with no large scale swell production occurring. A tropical system was in the West Pacific but not producing fetch aimed east at this time. It might be something to monitor long term though.  

Relative to California the local pressure gradient was fading over the north end of the state with north winds barely 25 kts early and expected to dissipate  by Wednesday AM (8/21) with even the current small local north windswell dropping out for North and Central CA.  There's weak odds for a return of windswell by the weekend.   

Relative to the Hawaii easterly tradewinds were nonexistent offering no odds for easterly windswell development.  No return of easterly trades above the 15 kt threshold forecast this week. 

Over the past 7 days no swell producing weather system of interest have occurred in the South Pacific. And looking forward no storms of solid interest are forecast. That said a gale developed in the deep Central Pacific starting Monday producing 25 ft seas aimed up at Tahiti, Hawaii and the US West Coast while slowly easing east into late Tues (8/20) then building to 32 ft over tiny area aimed only at the US West Coast down into Chile before fading Wed AM.  This is not a remarkable gale by normal standards, but should be good for a pulse of 14-15 sec period swell for our forecast area if all develops as expected. Nothing else to follow. 

Details below...

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

North Pacific

Surface Analysis  -  On Tuesday (8/20) the North Pacific high pressure system was at 1024 mbs centered over the northern dateline ridging lightly into the North California coast forming a pressure gradient with north winds still blowing at 25 kts there producing limited north windswell down into Central CA. The high was too far north and not producing easterly trades above the critical 15 kt threshold east of the Hawaiian Islands resulting in no rideable easterly windswell. No large scale low pressure systems of interest were occurring. 

Over the next 72 hours the high is to retrograde west with the gradient over North California dissipating by later Wednesday (8/21) and not returning for the next 72 hours. 

Relative to Hawaii the pressure pattern is to remain weak with the high too far north to have any affect towards producing trades of interest. trades to remain below the critical 15 kt threshold. Windswell to remain below rideable levels.  

Otherwise no other swell producing fetch of interest is forecast.


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


On Tuesday (8/20) the following tropical systems were being monitored:

Tropical Storm Trami: This system was upgraded from Tropical Depression 12  late Friday (8/16).  Trami is currently 140 nmiles west of Taipei Taiwan with winds 60 kts and tracking west at 12 kts with winds 60 kts and seas to 26 ft.  Trami is to build to minimal typhoon strength this evening (winds 65 kts) then track over Northern Taiwan, overnight entering the China seas on Wed AM (8/21) with winds 55 kts. Trami to push east and be inland over China Wednesday evening. No swell production relative to our forecast area expected. 

Tropical Storm Pewa was just east of the dateline tracking northwest with winds 50 kts, forecast holding this track while building with winds to 65 kts (typhoon strength) Wed AM (8/21). Pewa to hold this track while building to 100 kts Sun AM (8/26) positioned 450 nmiles north of Wake Island then making a turn to the west. The GFS model has Pewa taking a more southwesterly course beyond and holding strength possibly interacting with the North Pacific jetstream beyond.  But for the next 7 days Pewa is to remain a fish storm, tracking though open waters and making no indication of recurving north or northeast towards our forecast area. Still, it's worth monitoring.

The GFS model depicts some form of tropical system developing just south of Cabo San Lucas Baja Mexico on Thurs (8/232) tracking north along the western Baja coast into the weekend.  Will believe it when it happens.

California Nearshore Forecast
On Tuesday (8/20) high pressure at 1022 mbs was ridging into the Washington and British Columbia coasts setting up a steady local northerly wind flow off North CA at 25 kts with a eddy flow pushing south winds up the Central and North CA coasts into Pt Arena if not north of there. On Wednesday the gradient is to start fading though still 25 kt north winds early, then dropping to 20 kts over North CA with a weaker eddy flow nearshore for Central CA. Thursday the gradient is to fade completely with a light wind flow over the entire state. Friday a local north wind pattern is to develop at 15 kts by afternoon nearshore for the southern half of the North Coast and all of Central CA holding Saturday into Sunday with north winds to 20 kts for Pt Conception. Basically a southward di.cgiaced version of the normal coastal gradient. This gradient to dissipate some Monday then return on Tuesday.  Southern CA to remain under a light wind flow for the duration.


South Pacific

Jetstream  -  On Tuesday (8/20) the jet was well .cgiit over the Southwest Pacific with the southern branch tracking over the Ross Ice Shelf in the west and effectively landlocked offering no support for gale development in the upper levels of the atmosphere. The southern branch tracked north and merged over the Southeast Pacific forming a trough there. But winds were only 90 kts or less over the entire length of the influential southern branch offering little if any support for gale development. Over the next 72 hours the same pattern is to hold but with 120-130 kts winds building quickly late Tuesday into Wednesday feeding into the trough and perhaps adding a little support for the formation of gale development under the trough, then fading out on Thursday. The trough is to still be present Friday, but with no winds of interest feeding it with support for gale development gone. Back to the west the southern branch is to continue ridging well south into the Ross Ice Shelf if not mainland Antarctica. Beyond 72 hours the ridge in the west is to build east with the jet becoming totally .cgiit over the width of the South Pacific offering no support for gale development.        

Surface  - On Tuesday (8/20) a weak gale was tracking through the South Pacific with limited fetch aimed well to the north (See Better Gale 3) below.  Otherwise no fetch of interest was occurring.  Over the next 72 hours no fetch of interest is forecast. 


Weak Gale 1
A gale developed in the far Southeast Pacific on Tues AM (8/13) producing 40 kt south to southwest west winds aimed barely at Southern CA and better at Chile with 28 ft seas over a tiny area at 58S 120W then quickly raced east by evening with seas to 29 ft at 54S 113W totally east of even the Southern CA swell window. Maybe a dribble of swell to radiate north towards CA. By Wednesday (8/14) this system developed more with seas exceeding 30 ft but all energy targeted Chile and well east of the California swell window. 

Southern CA: Minimal swell arriving late Wed (8/21) building to 1.3 ft @ 18 secs (2.0-2.5 ft) building to 1.6 ft @ 16 secs (2.5 ft) on Thurs (8/22). Swell fading from 1.5 ft @ 14 secs (2 ft) on Fri (8/23). Swell Direction: 175-180 degrees

Weak Gale 2
Weak low pressure circulating in the far Southeast Pacific on Thursday (8/15) starting to generate 30 kt south winds on the eastern edge of the Southern CA swell window and held through Friday building to near 30 kts. Seas built to 26 ft over a tiny area Friday at 18Z (8/16) at 53S 124W aimed north.  

Maybe swell of 1 ft @ 16 secs (1.5 ft0 to reach Southern CA on Sat (8/24) with luck pushing 1.3 ft @ 15-16 secs (1.5-2.0 ft) on Sun (8/25). Swell Direction: 175-180 degrees

Better (but still weak) Gale 3
On Sunday (8/18) a weak gale developed in the Central Pacific but abutted against solid high pressure at 1028 mbs under New Zealand setting up a nice pressure gradient producing 40 kt south winds just north of the Ross Ice Shelf with the whole fetch lifting slowly due north. Seas built to 23 ft at 55S 160W in the evening. On Monday AM (8/19) winds faded to 35 kts over the same area of the ocean with seas 25 ft at 53S 155W pushing die north, with more of the same in the evening with seas 25 ft at 49S 150W. Tuesday AM (8/20) winds were still 35 kts from the south with seas holding at 25 ft at 48S 144W. Fetch is to build to 45 kts in the evening over a small area with seas building to 28 ft at 53S 133W. The gale to fade Wed AM (8/21) with winds dropping from 40 kts out of the south over a small area and seas 30 ft at 51S 131W. The gale to be gone by the evening. 

If all goes as forecast some degree of rideable 15 sec period swell to result for Tahiti, Hawaii, and the US West Coast (SCal on Thurs 8/29).


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 and relative to California high pressure is forecast moving slightly east Saturday AM (8/24) reinvigorating the local pressure gradient for Central CA with north winds building to 15 kts then reaching up to Northern CA on Sunday AM, good for barely ridable short period tiny north windswell for  Central CA, then dissipating some Monday (8/26) only to return 24 hours late. 

Relative to Hawaii trades to remain below 15 kts until Sun (8/25) when a supposed tropical low tracks south of the Islands enhancing trades to almost 15 kts, with maybe just enough areal coverage to produce bare rideable windswell and holding into Monday. Trades fading after that as the tropical low passes well west of the Islands.  And even this assumes the tropical low forms, a low probability venture at this date. 

In all, no clear signs of Fall yet. In 'good' years, those influenced by mild El Nino conditions or better, about 8/15 is when one could expect to see arrival of some early North Pacific swell along the Hawaiian and Us West Coasts originating from tropical cyclones approaching Japan then recurving northeast and becoming extratropical. Unfortunately, there is no indication of such a pattern setting up.

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 (8/20) the daily Southern Oscillation Index (SOI) was up to 0.79. The 30 day average was down to 2.59 with the 90 day average down some at 6.56. The nearterm trend based on the SOI was towards a weak Active Phase of the MJO while overall the pattern was still in weak La Nina territory and not indicative of El Nino and illustrative of a dominance of the Inactive Phase of the MJO.  

Current equatorial surface wind analysis indicated neutral wind anomalies over the Maritime Continent turning barely westerly over the dateline then fading back to neutral south of Hawaii. Neutral anomalies extended from there into the coast of Central America. Of note - there has been a distinct lack of true nor prolonged westerly anomalies for months. A week from now (8/28) modest easterly anomalies are forecast developing over the Maritime Continent  fading to neutral over the dateline region and a bit beyond a point south of Hawaii. West anomalies are forecast building from there almost into Central America. In all this suggests a slight Active Phase of the MJO is in.cgiay pushing east.    

The longer range models (dynamic and statistical) run on 8/19 are in general agreement. Both models suggests a weak Inactive Phase is starting to take hold over the far West Pacific. This pattern is to continue per both models over the next 15 days with the dynamic model a bit more aggressive than the statistic model (typical). The peak is expected 12-15 days out per both. The ultra long range upper level model favors formation of some flavor of modest Inactive Phase of the MJO from 8/25 through 9/19, then falling back towards a neutral pattern if not light Active pattern for the remainder of September.  

The more warm water in the equatorial East Pacific means more storm production in the North Pacific during winter months (roughly speaking). Cold water in that area has a dampening effect. Regardless of what the atmospheric models and surface winds suggest, actual water temperatures are a ground-truth indicator of what is occurring in the ocean. As of now (8/19) a very weak La Nina-like pattern continues in the East Pacific on the equator. The small pocket of cooler water we've been monitoring off the immediate coast of Peru is starting to fade as of this update, with the outflow from it tracking to the Galapagos Islands, then fading west of there, breaking up with pockets of cooler water radiating west almost to a point south of Hawaii. Imagery from 8/5-8/15 to present suggested the cool pool had been re-generating, but the 8/19 image suggested a warming trend in.cgiay, likely the result of a weak Active Phase starting to take root. Historically this is no different from what has been occurring all summer with the cool pool fluctuating and sporadically spitting occasional larger pockets of cool water westward along the equator and keeping a lid on any legitimate warm water from developing. The sympathetic anomalous cool pool off West Africa appears to be gaining loosing some ground recently as the Active Phase gets a toe in the door. It had previously built almost to the coast of South America then retrograded in late June. The African cool pool is a direct reflection of what has been occurred in the Pacific, an unexpected burst of cool water gurgling up off both the South America and West Africa coasts simultaneously - suggestive of a global teleconnection. Further north a.cgiume of slightly cooler than normal water that has been radiating southeast off California for 2 years closed off mid-May, returned in June when the cold pool emerged off Peru and Africa, then fully closed off in July.  8/12 into 8/18 it appeared to be rebuilding off the California coast with a small but well defined track radiating off California almost reaching a point south of Hawaii. But a considerable pocket of warmer than normal water is also building west of California tracking east and show now signs of abating, so it's anyone guess whether the local pool will get mowed over by the eastward moving warm pool. Once thing is for sure, water temps are up in Central CA, the first time in a few years. Looking at the big picture, cooler waters over the equatorial East Pacific are under control, but still present, with no sign of a legitimate warm pattern developing. In short, we're still under some weak influence of La Nina or at least a neutral pattern biased cold.  

Subsurface waters temps on the equator indicate a neutral temperature pattern. Warm water from the West Pacific previously migrated east over top of a cold pool - eliminating it's impact and continues holding.

Projections from the CFSv2 model run 8/20 indicate water temps have been hovering near neutral since January within only a +-0.25 deviation. Recent runs of the model have consistently been suggesting a slow warming trend (up to +0.25 degs C) by Oct 2013 and near +0.6 C by April 2014. But for the immediate future a neutral pattern is expected. So overall the immediate outlook remains nothing stellar, but trending towards something that would be considered right on the threshold of warm, by Spring 2014, assuming one were to believe the model. This is good news. If anything the ocean is in a recharging mode, with cold water dispersing and temperatures gradually on the rise again in fit's-and-starts. Historically, if a warm water buildup indicative of any kind of El Nino pattern were to occur in 2013, it would have started building in Feb-Mar. That is clearly not the case for this year. Expect a neutral pattern for Winter of 2013-2014 with perhaps a slightly warmer pattern for 2014. 

We are in a neutral ENSO pattern with neither a solid El Nino or La Nina imminent. But a weak prevalence of the Inactive Phase of MJO seems to be biasing the weather global pattern. This is a better.cgiace than previous years (2010-2011, 2011-2012 and 2012-2013) under the direct influence of La Nina, but we're still not in a pure neutral pattern either. We're still recovering from the 2009-2010 El Nino. Longer term the expectation is there will be at least one to two years of neutral temperatures ultimately converging in a stronger warmer pattern and possible El Nino 2-3 years out (2015 or 2016). And historically, this is the 'normal' pattern (a few years of false starts post La Nina before a legit El Nino forms).

See imagery in the ENSO Powertool and more details in the  El Nino Update Last Updated 10/6/12 


South Pacific

Beyond 72 hours 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

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Local Interest

Visit! Boardshorts - Looking for a sick pair of boardshorts? Check out the selection at with brands from O'Neill, Quiksilver and Rusty and free shipping on every order. They won't disappoint.

Wall of Skulls - Here's a great video featuring Tahiti's famous wave. There's also a nice little.cgiug for Stormsurf in it too.

Super Natural - Powerlines Productions has released their new big wave surf video chronicling the epic El Nino winter of 2009-2010.cgius many other big wave event through the 2012-2013 winter season. It's a must see event for any big wave rider. It's for sale here:

Nantucket Marine Mammals has documented a short video concerning whale conservation and awareness off the Northeast US Coast. See it here:

Jason-1 Satellite Decommisioned - On June 21 an error occurred on board the Jason-1 satellite and it automatically shut down all critical functions. The satellite has since officially been decommissioned. It's last working transmitter failed on 6/21. All efforts have been made to get a response to no avail. The satellite has been.cgiaced in a parking orbit with it's solar panels turned away from the the sun. It's batteries are to discharge in the next 90 days. No additional data is expected from this satellite. We are working to start capturing data from the Jason-2 satellite, but that will take some time. More information to follow.

'CBS This Morning' with the Mavericks Invitational Surf Contest - See a nice morning TV show piece on the Mavericks Contest held Sun 1/20/13. The show aired Wed 1/23. Interviews with Colin Dwyer, Jeff Clark, Mark Sponsler and Grant Washburn:

Jaws Redbull Contest Forecast E.cgiained By Stormsurf

Cortes Bank Mission (12/21-12/22/2012)

The Making of 'Chasing Mavericks' - See some background footage on how the movie was made: Part1, Part2

The Psychology of Big Wave Surfing with Greg Long - A must see for any aspiring big wave rider:

Greg Long XCel Core Files - Here's a great profile of Greg Long and his contributions toward pushing the state of big wave surfing. Well Done -

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:

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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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