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Pacific Storm and Surf Forecast
Updated: August 15, 2009 11:38 AM
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 = 1.9 - 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 8/17 thru Sun 8/23
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   

Small S. Hemi Swell Heading North
Hurricane Swell Headed for the Big Island


New Swell Classification Guidelines (Winter)

Significant: Winter - Swell 8 ft @ 14 secs or greater (11+ ft faces) for 8+ hours (greater than double overhead). Summer - Head high or better.
Advanced: Winter - Swell and period combination capable of generating faces 1.5 times overhead to double overhead (7-10 ft) Summer - Chest to head high.
Intermediate: Winter - Swell and period combination generating faces at head high to 1.5 times overhead (4-7 ft). Summer - Waist to chest high.
Impulse/Windswell: Winter - Swell and period combination generating faces up to head high (1-4 ft) or anything with a period less than 11 secs. Summer - up to waist high swell. Also called 'Background' swell.

On Saturday (8/15) North and Central California had more locally generated northwest short period windswell in the chest high range with heavy northwest texture on it early. Southern California had knee high northwest locally generated windswell with a few thigh high sets and clean even in the early afternoon.  Hawaii's North Shore was flat. The East Shore had knee high northeast windswell at exposed breaks. The South Shore had some weak knee to thigh high background swell of undetermined source. You could stand up on it if you had too.   

The forecast for North and Central CA is for a little more locally generated north windswell to shoulder high on Sunday (8/16) with improving conditions. A slow fade is expected through next week but still rideable with waist high.cgius northwest windswell even into Friday (8/21), with perhaps a little background southern hemi swell for the later part of next weekend. So it stays rideable, but not much more. Southern California to continue seeing only very limited north locally generated windswell at exposed north facing breaks for Sunday into Monday and Tuesday reaching thigh high, then settling down through the remainder of next week. Perhaps a drop of southern hemi swell on Tuesday at thigh high, but gone of Wednesday. Better southern hemi swell expected in on late Friday on through the weekend. The North Shore of Hawaii is to remain flat for the next 7 days. The East Shore is to see no east windswell until next Wednesday tropically enhanced east to northeast windswell is scheduled to arrive from a system forecast pushing northeast of the Islands. How often do tropical storm push north of the Hawaiian Islands chain? Answer - not too often. The South Shore is not expected to have any decent southern hemi swell until late Wednesday into Thursday (8/20), when swell from a storm that was off the Ross Ice Shelf arrives (more below).  

Looking out over the long term a storm formed just off the northern edge of the Ross Ice Shelf on Wed/Thurs tracking east with 50-55 kt winds confirmed and generating confirmed seas of 38 ft just barely ice free, but pushing more towards Central America than north towards the US or Hawaii. Still some rideable sideband swell is expected in to Hawaii by Thurs (8/20) and the mainland by Sat/Sun (8/23).  Beyond this system is forecast to try and reform with a double pulse on Sunday and then again on Tues (8/18) in the Southeast Pacific producing maybe 32 ft seas, the second pulse having a bit more energy aimed to the north. Maybe some limited background swell could result for the US Mainland. Will believe it when it happens. Otherwise no activity is forecast for the North Pacific other than some activity in the tropics focused best on Hawaii. 


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

North Pacific

At the surface today modest high pressure at 1028 mbs was positioned 500 nmiles west of southern Washington ridging northeast towards British Columbia generating a pressure gradient over Cape Mendocino producing north winds there at near 25 kts resulting in limited north windswell for Central CA. This high was also producing northeast winds at 15 kts pushing towards Hawaii but not quite reaching there yet, with trades suppressed in the Islands. Hurricane Guillermo was tracking west-northwest mid-way between Mexico and Hawaii and imbedded in the south side of this high pressure system, theoretically bound for the Islands. Limited weak low pressure was on the dateline having tracked east from off Japan, with a small area of 30 kt southwest winds aimed mostly towards Alaska, No hope here. In all pretty quiet. Over the next 72 hours that high pressure center is now forecast to hold off the Pacific Northwest continuing to produce the usual pressure gradient over Cape Mendocino with 25 kt north winds and limited northwest windswell pushing down into Central CA through at least Tuesday (8/18). Trades to remain suppressed over the Hawaiian Islands as Guillermo tracks well northeast of the Islands, perhaps setting up some small swell for East Shores. There's some signs that high pressure is to start building over the West Pacific likely driven by the building Inactive Phase of the MJO, perhaps shutting down what was almost looking like an early start to Fall pattern. This was not unexpected.


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


California Nearshore Forecast
On Saturday (8/15) high pressure at 1030 mbs was holding off the Pacific Northwest producing the usual pressure gradient and north winds at 25 kt up at Cape mendocino but only 10-15 kts nearshore from Bodega bay southward. The local gradient is forecast to hold Sunday. Monday into early Tuesday (8/18) with northwest winds over the Cape forecast at 25-30 kts, but only 10 kts or so nearshore pt Pt Reyes southward to the Channel Islands. In short, improving conditions likely. The gradient to start really pulling away from the coast on Tuesday and start fading Wednesday with light local winds forecast for the foreseeable future. Clean conditions likely for Central and South CA.


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

On Saturday (8/15) Hurricane Guillermo was positioned 1223 nmiles east of the Big Island of Hawaii and holding in intensity, with sustained winds 110 kts and heading west-northwest at 13 kts. This system was near peaked out with a slow decrease in strength forecast at it tracks east and a little more to the north. It is to fall below hurricane strength Monday AM (8/17) with winds down to 60 kts and continuing to decline, down to 30 kts on Wednesday as it prepares to pass 360 nmiles north of the Big Island. That's said, solid groundswell is currently being generated pushing west towards exposed breaks along the East Shore of the island of Hawaii with period 15-16 secs. Swell arrival is expected on Monday at 10 AM or so. Swell size roughly 4 ft @ 16 secs (1-2 ft overhead) coming from 85-90 degrees.


South Pacific

On Saturday (8/15) the same old .cgiit jetstream pattern that has dominated for weeks continued with the northern branch remaining the dominant of the pair, though not as much as before pushing more or less flat over the 30S degree latitude into Central Chile. The southern branch was positioned too far to the south flowing under New Zealand, effectively over the Ross Ice Shelf and shutting down gale development potential there. But it was pushing a bit better to the north as it reached into the Southeast Pacific trying to form almost an upper level low pressure center, though still mostly over Antarctic Ice. Over the next 72 hrs that upper low is to get better developed in the far Southeast Pacific by Monday (8/17) producing 130 kt winds pushing up it's western flank offering much better odds to support gale development down at the surface. The flow is to be aimed almost due north on Tuesday and still in the 130-140 kts range. Good odds for gale development down at the surface here. Beyond 72 hours that trough is to fade by early Thursday (8/20) while at the same time a strong ridge builds over the Southwest Pacific pushing down into Antarctica proper and totally shutting down any potential for gale development there.   

At the surface on Saturday (8/15) high pressure at 1028 mbs was trying to hold on east-northeast of New Zealand, but was not able to hold it's ground due to a large gale tracking through the deep South-Central Pacific. This gale was the remnants of the New Zealand Storm (see details below) and was positioned mostly over the Ross Ice Shelf, though a fragment of it's winds in the 30-35 kt range were still blowing over Ice free waters at 52S 145W resulting in a small area of 30 ft seas off the edge of the Ross Ice Shelf at 58S 150W.All of this was aimed due east towards Chile rather than north towards US interests. Over the next 72 hours this system is forecast to reorganize better in the Southeast Pacific lifting a bit north on Sunday (8/16) with central pressure 948 mbs (over Antarctic Ice) with a fetch of 40-45 kt southwest building at 50S 140W generating 32 ft seas at 50S 142W aimed 40 degrees east of the 192 degree route into California.  That fetch is to continue into Sunday evening aligned about the same way with 35-40 kt southwest winds at 49S 130W aimed 45 degree east of the 190 degree path to NCal (193 SCal) generating more 32 ft sea at 47S 133W.  Some form of 16-17 sec swell might push north if all goes as.cgianned.  Central and South America to get a good pulse too. 

A secondary decent push of 40 kt south winds are forecast Monday AM (8/17) at 53S 140W aimed almost straight to the north generating more 29-30 ft seas at 51S 134W perhaps holding into the evening with more 32 ft seas forecast at 50S 130W, then fading after that. Perhaps a better pulse of small swell is to result tracking up into the California and Central America swell windows.            

New Zealand Storm

A vigorous storm started building fast on Wednesday AM (8/12) over the Ross Ice Shelf with 50 kt west-southwest winds confirmed 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 were modeled building at 60S 180W just barely ice free. In the evening 50-55 kts winds were confirmed moving rapidly northeast to 55S 158W aimed 30-35 degrees east of the 203 degree path to CA and 65 degree east of the 180 degree path to Hawaii. 38 ft seas were modeled at 58S 165W and building, moving a little more clear of the Ross Ice Shelf. The Jason-1 satellite passed over the southeast quadrant and reported seas 36.4 ft with a peak reading on 41 ft were the model suggest seas should have been 32-33 ft. This was much better than what was expected. Winds were fading fast Thursday AM (8/13) from 40 kts, not adding any energy to the seas generated the day before. 38 ft seas from previous fetch were modeled at 56S 156W and fading fast. Thursday PM no fetch of interest was forecast with seas fading from 33 ft at 55S 146W. The Jason01 satellite passed over this area and confirmed seas at 32.4 ft with a peak reading to 37.1 ft where the model suggested 30 ft seas. Again, the models appeared to be on the low side.

Some minimal background sideband energy is expected to travel north towards the Islands with larger but slightly shadowed energy pushing up towards the US mainland.  But the main issue here is that although the Jason-1 satellite reported seas higher than what was modeled, almost all the fetch was aimed well east of any great circle path to either Hawaii or the US mainland, instead focused more on Central and South America.

Expect swell to arrive in Hawaii on Thurs early AM (8/20) with swell pushing to 2 ft @ 16-17 secs  (3.5-4.0 ft faces) in the afternoon.  Swell fading from 2 ft @ 15 secs (3.0-3.5 ft faces) on Fri (8/21).  Swell Direction: 182-186 degrees

Expect swell arrival in California on late Friday afternoon in SCal with swell 1.5 ft @ 19 secs   (2.5-3.0 ft faces) and building overnight. Swell to peak early Sat (8/22) in SCal and late in NCal at 2.5 ft @ 17 secs  (4.0-4.5 ft faces with top spots to 5.0 ft). Period dropping to 16 secs on Sunday.  Swell Direction: 205 degrees SCal/202 degrees NCal.   


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 new high pressure is to develop on the northern dateline region dropping southeast is to merge with high pressure off the Pacific Northwest on Wednesday (8/19) pulling the whole system a bit to the west and setting up a good sized northeast fetch of 15-20 kt winds targeting the Hawaiian Islands well after Guillermo passes northwest of the Islands, resulting in a healthy dose of trades by Thursday (8/20) and holding into the weekend. The tropical storm machine is to keep on pumping off Mexico, with 2 more systems modeled following the now familiar path west towards Hawaii. It's seems like it's only a matter of time before a strong one moves too close to the Islands for comfort. Otherwise no swell producing fetch of interest is forecast.

MJO/ENSO Update (reference): As of Saturday (8/15) the Madden Julian Oscillation (MJO) was moving into the Inactive Phase. The ENSO (El Nino Southern Oscillation) index remained just bit in negative territory, but not much. The Daily SOI index was up to 3.52 likely ending what was a 25 day negative run (since 7/21), typical of the Active Phase. The 30 day average was holding at -4.20 and the 90 day average was down a little at  -1.65.  The SOI index has regaining some of the ground it lost when the MJO went Inactive in early July, but not that much. 

Wind anomalies modeled at the 850 mb level (approx 1000 ft up) indicated that a strong area of easterly anomalies had developed over the Philippines with lesser winds reaching to the dateline and back into the Indian Ocean to Africa. This was the strongest Inactive Phase we've seen since April 2009 right before the start of a 3 consecutive Active Phase run in May and June. This current Inactive Phase is modeled much larger and stronger than previous forecasts.  The models expect these easterly anomalies to hold solid through 8/24 reaching well into the Central Pacific and slowly dissipating, but still not gone even by 9/3, with weak easterly anomalies still present over the greater part of the Pacific Basin. This is not good news. The models typically undercall it out of the gate, but that certainly is not the case this time. Will be quite interesting to see how much steam this Inactive Phase takes out of the developing El Nino, and whether it undercuts the developing warm pool in the east equatorial Pacific. Meanwhile the current Active Phase is to dissipate, exiting out over Central America on 8/24 while a new Active Phase starts building over the Indian Ocean on 8/29. At this early date the Active Phase is looking to be a weak event. More bad news.

Sea Surface Temp anomaly data (8/10) 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 and are now pushing up over the California coast too. Much cooler than normal waters (-2.5 deg C) are mirrored streaming off Africa and pushing east, now reaching South America. This is probably the height of this Atlantic event. Looking back in the records, exactly the same flow developed during the big El Nino of 1997 and is likely to suppress Atlantic hurricane actively due solely to the frigid water temps. 

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) under the dateline and breaking the surface near Central America with a previous Kelvin Wave now dispersed there. Another Kelvin Wave is migrating east from 165W, the result of a Westerly Wind Burst (WWB) in the West Pacific on 7/25-8/2. It is 2 deg C above normal and building while feeding the warm water pump, providing reinforcements on the way to Ecuador. This is critical to the formation of a legitimate El Nino.  A pool of cooler than normal water that is 120 meters down at 140W does not appear to be blocking the Kelvin waves eastward progress as previous mentioned.

Of some real interest is the appearance of more fully blowing westerly winds in the far West Pacific and developing westerly anomalies reaching to the dateline (starting 8/12) and holding as of 8/14. This almost makes no sense considering what the models are saying regarding the strong Inactive Phase supposedly in.cgiay. Looking to the QuikSCAT satellite it's data also confirms that slack winds and limited west winds (10 kts) were blowing up to the dateline. So apparently 1000 ft up the winds are blowing hard east, but at the surface (the only thing that matters in regard to developing El Nino) winds are west. This is good news, but doubt it will last. If this pattern were to hold, even for 5 more days while the Inactive Phase is building in the West, it would be a significant event. We suspect those winds will subside in a day or so as the Inactive Phase takes root. Either that or the models are grossly incorrect (doubtful).  

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. But the picture is still muddled. 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 was the case in late July into early August, but that pattern appears to be breaking. 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 (towards El Nino). Therefore, in our minds the delineation of whether development will continue versus stall is dependent upon more WWBs. 

t 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.or whether another WWB will occur - as is maybe happening even now on 8/15),. A final confirmation should be possible in Sept. In the mean time, 21 days of the Inactive Phase are setting up with vigor. 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.

An update to the Stormsurf El Nino forecast page is in-work and should be posted in a few days.     


South Pacific

Beyond 72 hours high pressure and a generally.cgiacid weather pattern is to take over the South Pacific.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

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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