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Pacific Storm and Surf Forecast
Updated: August 11, 2009 8:08 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 & 2.5 - 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 8/10 thru Sun 8/16
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   

South Pacific To Stir
North Pacific Not Quite Ready Yet


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 Tuesday (8/11) North and Central California had locally generated northwest short period windswell in the chest high range with northwest winds on it early making it pretty heavily textured. Southern California had some knee high northwest locally generated windswell up north and up to about the same sized background southern hemi swell of undetermined source arriving down south and reasonably clean.  Hawaii's North Shore was flat. The East Shore had 1 ft overhead east windswell from Felicia with onshore winds. The South Shore had some wrap around tradewind swell at waist to maybe chest high on the sets with brisk trades in control. 

The forecast for North and Central CA is for more waist high local north windswell for Wednesday building some into Friday pushing head high or so, then backing off some over the weekend and more early next week. Southern California is to see very limited north locally generated windswell only at exposed north facing breaks, coming up a little Thurs/Friday to the waist high range, then settling down through the weekend. No southern hemi swell of interest is forecast. The North Shore of Hawaii is to be flat for the next 7 days. The East Shore is to see fading short period east windswell in the chest high range Wednesday from Felicia, then fading out entirely. The South Shore is not expected to have any decent southern hemi swell for the next 7 days.  

Looking out over the long term the models continue to suggest a gale forming just off the northern edge of the Ross Ice Shelf on Wed/Thurs tracking east with up to 38 ft seas just barely ice free, but pushing mostly towards Chile than north towards the US. Still some sideband swell might result. Beyond this system is forecast to  reform Sat/Sun (8/16) producing up to 46 ft seas in the Southeast Pacific, but again most fetch is to be aimed to the east with only limited energy pushing north towards the US Mainland. Chile and Peru looks like good targets though. No activity is forecast for the North Pacific, though the tropics are to remain productive. 


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

North Pacific

At the surface today modest high pressure at 1024 mbs was positioned 1000 nmiles northwest of Hawaii ridging east to Central California, but not really starting to generate north winds of much interest there yet. The remnants of Felicia were north of the Big Islands, but there was almost no upper convection associated with it anymore, having been sheared off the day before.But the pressure gradient between it and high pressure northwest of the Islands was enhancing trades at 20+ kts with the surface circulation generating more easterly windswell pushing into exposed east facing shores. Otherwise a string of weak low pressure systems were tracking from off Japan to the dateline, with no fetch of interest occurring. Neutral (light north winds were occurring over the West Pacific equator extending to almost the dateline (175E) symptomatic of the active Phase of the MJO. Over the next 72 hours high pressure is to push east and build some off the California coast, producing the familiar pressure gradient over Central CA mid-Thursday (8/13) and northwest winds there at 20-25 kts easing up to the north towards Cape Mendocino on Friday.  Larger short period northwest windswell to be the result. Trades over the Hawaiian Islands to fade Wednesday and remain less than normal.  Otherwise no decent activity is forecast in the Northwest Pacific.


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


California Nearshore Forecast
On Tuesday (8/11) weak high pressure at 1022 mbs was trying to nose into Central CA but two areas of weak low pressure were stacked up off the North CA coast, holding it at bay and reducing the odds for the usual pressure gradient and north winds building along the coast. those lows are to dissipate late Wednesday with a weak local gradient forecast to return Thursday into Friday with northwest winds forecast at 20-25 kts from the Channel Islands northward to Cape Mendocino and windswell and chop on the rise.  The gradient to start getting pronounced by Saturday AM with winds to 30 kts forecast off Cape Mendo then while the fetch pulls away from the coast, improving local conditions from Pt Arena southward. This pattern is to hold into Sunday with decent windswell forecast and improving conditions. The gradient is to collapse on Monday (8/17)  with windswell on the way down and local winds remaining weak from Cape Mendo southward through Tuesday. 


The Active Phase of the MJO is fading, which will likely reduce the odds of tropical storm formation over the coming days for the next 3 weeks: 

As of the 21Z update Tues (8/11) Felicia was downgraded to a tropical depression with sustained winds of 30 kts positioned just northeast of the Big Island of Hawaii.  All watches and warning have been discontinued.  Satellite imagery indicated almost no cloud cover was associated with this system.  Windswell associated with it's interaction with high pressure to the north is documented in the North Pacific surf forecast.  Continued dissipation is forecast for the next 24 hours.

Tropical Storm Etau was local a bit southwest of Tokyo Japan heading east towards the dateline at 24 kts with sustained winds 35 kts and fading. It is expected to dissipate by late Wednesday (8/12).  No swell generation potential forecast.    

Tropical Storm Maka was positioned 900 nmiles southwest of Kauai with sustained winds 35 kts and tracking to the northwest.  This track is to continue with it cross over the dateline on Thurs AM 98/13) with winds 55 kts and pushing on to the northwest with winds 75 kts on Sunday AM. No swell potential for US locations.   



South Pacific

On Tuesday (8/11) the northern branch of the Southern Hemisphere jetstream remained dominant pushing straight east-southeast from the 25S degree latitude line into Southern Chile. A strong ridge that has dominated the southern branch was moderating, still flowing effectively east under New Zealand on the 65S latitude and ice-locked over the Ross Ice Shelf. No support for gale development indicated. Over the next 72 hrs a solid patch of 140 kts winds it to push east under New Zealand lifting the southern branch a bit to the north and generating a small trough ahead of it through Thursday.  Possible gale development to result. Beyond 72 hours that trough is to push east and get reinforced with a larger trough resulting int he Southeastern Pacific by Sunday (8/16) with a continuous stream of 130 kt winds feeding up into it. Yet more support for gale development there. But at the same time behind it a new ridge is to be building hard to the south, shutting down any potential in the Southwest Pacific.  

At the surface on Tuesday (8/11) high pressure at 1036 mbs remained locked just east of New Zealand ridging hard to the southeast reaching tot he northern edge of the Ross Ice Shelf, blocking the South Pacific storm corridor there. No swell producing fetch was located in the US swell window. Over the next 72 hours a vigorous storm is forecast building fast Wednesday AM (8/12) over the Ross Ice Shelf with 50 kt west-southwest winds forecast at 60S 175W aimed 20 degrees east of the 205 degree great circle path to CA and in the heart of the Tahitian swell shadow 45 degrees east of the 188 degree path to Hawaii. 30 ft seas building at 60S 180W just barely ice free. In the evening 50 kts winds to move rapidly northeast to 55S 158W aimed 10 degrees east of the 200 degree path to CA and 60 degree east of the 180 degree path to Hawaii. 38 ft seas are forecast at 57S 165W and building, moving a little more clear of the Ross Ice Shelf. Winds to be fading fast Thursday AM (8/13) from 40 kts, not adding any energy to the seas generated the day before. 36 ft seas from previous fetch are forecast at 54S 150W and fading fast. Assuming all this.cgiays out as forecast, some bare minimal background sideband energy could travel north towards the Islands with larger but shadowed energy pushing up towards the US mainland, focused more on Central and South America. Will monitor.        


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




Marine weather and forecast conditions 3-10 days into the future

North Pacific

Beyond 72 hours high pressure is to hold in the extreme East Pacific off the Pacific Northwest Fri-Sun (8/16) generating more northwest winds off Cape Mendocino at 25-30 kts late Sat  providing decent odds for northwest windswell development for exposed breaks in Central CA and select spots into Southern CA for the weekend. Trades are to redevelop on Sunday for Hawaii too fuel more by another batch of tropical energy pushing east towards the Big Island. But the high pressure system itself is to fade early next week with north winds fading off the US West Coast and windswell heading down. 

No clear signs of any swell producing low pressure weather systems are forecast migrating off Japan. 


MJO/ENSO Update (reference): As of Tuesday (8/11) the Madden Julian Oscillation (MJO) was in a moderate Active Phase. This was the first Active Phase since 6/23 when the last of three consecutive Active pulses took control starting April 20th. The ENSO (El Nino Southern Oscillation) index remained just a tad south of neutral. The Daily SOI index was at -8.07 and has been negative (or nearly so) for the past 21 days (since 7/21). This is about all one could expect from a typical Active Phase. The 30 day average was down to -2.82 and the 90 day average was steady at -1.3, likely ready to head down.  The SOI index was regaining some of the ground it lost when the MJO went Inactive in early July.  Wind anomalies at the surface and the 850 mb level (approx 1000 ft up) indicated that weak westerly wind anomalies, the signal of a weak Active Phase, had dissipated and a weak small area of easterly anomalies had developed over the Philippines. This suggest the Active Phase is dead. The models expect the easterly anomalies to wither some through 8/15 never making it to the dateline and then dissipate totally with a neutral configuration holding through 8/30.  If this is all that appears of the Inactive Phase it would be a miracle, but we're not betting on it. Previously we had been thinking that all the momentum associated with consecutive instances of the Active Phase of the MJO in the Spring and early Summer of 2009 had dissipated, and with it the mechanism that had been pushing warm water from the West to the East Pacific (more below). But Sea Surface Temp anomaly data (8/3) indicates that a solid area of warmer than normal water extends over the equator from the dateline east and building into Central/South America with temps to 2.0 deg C above normal. This is suggestive of a moderate El Nino.  These warmer waters are pushing north up the coast of Baja Mexico, but have retreated from Southern CA. Much cooler than normal waters (-2.5 deg C) are mirrored streaming off Africa and building while pushing east, now reaching South America. This is highly suggestive of a burst of perhaps southeasterly winds building across the equatorial South Atlantic. Looking back in the records, exactly the same flow developed during the big El Nino of 1997. So this is not unfamiliar territory (there is a reverse teleconnection between the Pacific and the Atlantic from a surf perspective i.e. what's good for the Pacific hampers the Atlantic, and visa versa). This is likely to completely suppress Atlantic hurricane actively due solely to the frigid water temps. We also closely examined this warm pool of surface waters off Central America in the Pacific and found that it had not lost any ground in June and July during the Inactive Phase, and is doing a good job of holding it's own. So even the relative lack of a strong MJO signal (active phase) during that period has not appeared to hamper the evolution of El Nino. This is what one would expect of a moderate or better El Nino (more on this below). Below the surface on the equator a steady flow of slightly warmer than normal subsurface water was tracking from the West Pacific (150 m below the surface to be exact) under the dateline and breaking the surface near Central America with warmer water just below the surface there at 2 deg C and starting to dissipate. It's time for another Kelvin Wave to move into the area to refresh the flow of warm water there. Previous episodes of the Active Phase had primed the warm water pump and were feeding the warm regime into the equatorial Eastern Pacific.  Previous Westerly Wind Bursts (WWB) associated with the Active Phase of the MJO had generated Kelvin Waves resulting in the movement of warm subsurface water to the east, starting to break the surface near Central America in mid-July. Another Westerly Wind Burst appeared to be developing on 7/6, but faded by 7/12. No Kelvin Wave resulted. So all looked good at a glance, but the lack of any clear symptoms of the Active Phase of the MJO has been pe.cgiexing us.  But interestingly, another bout of westerly winds appeared on 7/21 extending from New Guinea almost to the dateline and became more pronounced on 7/25 into 8/1.  Fully blowing westerly winds were in-charge associated with an area of low pressure there on 7/30 almost reaching to the dateline (not just anomalies).  This was a sign of a much anticipated Westerly Wind Burst. It dissipated on 8/3 but 150 meters down under the equator, warmer water was evidenced building and drifting east, (1 deg C above normal - another Kelvin Wave). As of 8/11 It is at 170W (east of the dateline) and tracking east while building in intensity with water temps 2 deg C above normal. So the warm water pump is still on and reinforcements are on the way.this is critical to the formation of a legitimate El Nino.  The belief at this time is this developing El Nino will not loose it's legs and falter like last year, but will survive in some fashion with effects continuing in the atmosphere until at least the Spring of next year. It is certainly doing much better for much longer than last year. That is not to say this will be a strong El Nino, more likely a weak to moderate one. NOAA is now also forecasting the same outcome. Of note, some data suggests that during the development of moderate to stronger El Nino's and La Nina's, it is normal for the MJO signal to become exceedingly weak. That is certainly the case with this most recent MJO episode. That co.cgied with the solid accumulation of warm water in the equatorial East Pacific is evidence in-favor of continued development. As long as there continues to be WWB's, then warm water will be migrating east, and the warm water pattern will hold if not build, and the atmosphere above it will respond in kind to the change 9towards El Nino). Therefore, in our minds the delineation of whether development will continue versus stall is dependent upon more WWBs. It will be most interesting to monitor the next active phase of the MJO, expected sometime near the 3rd week of Sept, and validate whether water temps hold if not build (i.e.whether another WWB will occur),. A final confirmation would be possible at that time. In the mean time, 21 days of the Inactive Phase, or neutral conditions (if we're lucky) are setting up. Strong El Ninos bring lot's of bad weather to the US West Coast, along with the potential for storm and swell enhancement. A moderate El Nino provides storm and swell enhancement, without necessarily all the weather. So as of right now things remain miles better than anything the Pacific has seen in the past 12 years regarding anomalous sea surface temperatures, besting anything since the big El Nino of 1997. That is very good news.  But the lack of a clear response in the atmosphere as evidenced by a unremarkable SOI remains pe.cgiexing (even though all other indicators suggest an El Nino is well underway), causing us to remain cautious.    


South Pacific

Beyond 72 hours the same gale that was in the Southwest is to reorganize in the Southeast Pacific on Saturday AM (8/15), covering a larger area and generating 45-50 kt southwest winds at 55S 150W aimed a bit better to the north.  up to 50 kt winds are forecast in the evening at 54S 138W aimed a bit more to the east, fading from 40-45 kt kts Sunday AM (8/160 at 50S 130W. Theoretically up to 46 seas are forecast Sunday AM at 52S 130W pushing best towards Peru but likely pushing some energy north toward Central and Southern CA. But that is a long ways off and the forecast will likely change significantly if it even forms at all. At least it's something to watch as we wait for the Fall season to begin. 

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

The Kelly Slater Project - A fundraiser is scheduled for Aug 29th at the Cocoa Beach Country Club to help raise funds for both the Kelly Slater Project and the Central Florida Animal Reserve. A Casino night is.cgianned including a silent auction and raffle. Sponsors are also needed. Learn more about these projects at :

Rebuild Jeff Clark: Jeff Clark the first pioneer of Mavericks, recently underwent hip resurfacing surgery due to severe pain from deterioration of his hip. Needless to say the procedure is very expensive and his insurance only covers tiny portion of the bill. If you're interested in learning about the procedure or would like to donate to help Jeff out,.cgiease take a look here:

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

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

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

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

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

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

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

Time Zone Converter By popular demand we've built and easy to use time convert that transposes GMT time to whatever time zone you are located. It's ion left hand column on every page on the site near the link to the swell calculator.

Need Chiropractic Help? Visit our friends at Darrow Chiropractic. Not only will Dr. Darrow fix you up, he might give you some big wave surfing tips too! See more here:

Stormsurf Google Gadget - Want Stormsurf content on your Google Homepage? It's si.cgie and free. If you have Google set as your default Internet E.cgiorer Homepage, just click the link below and a buoy forecast will be added to your Google homepage. Defaults to Half Moon Bay CA. If you want to select a different location, just click on the word 'edit', and a list of alternate available locations appears. Pick the one of your choice. Content updates 4 times daily. A great way to see what waves are coming your way! .xml

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Surf Height-Swell Height Correlation Table


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