Surf Forecasts and Marine Weather - No Hype - Just the Facts!
Southern Hemi Recharging! - Video Forecast HERE (5/26/24)
Buoys | Buoy Forecast | Bulletins | Models: Wave - Weather - Surf - Altimetry - Snow | Pacific Forecast | QuikCAST | El Nino | Tutorials | Great Circles | Video


Stormsurf Mobile App

Create Your Own Surf Forecast
Swell Calculator
Swell Decay Tables
Sea Height Tables
Swell Category Table
Convert from GMT:
 to timezone:

Pacific Storm and Surf Forecast
Updated: August 20, 2009 7:09 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 = 1.9 - 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   

S. Hemi Swell Moves Towards CA
Gulf of Alaska to Stir


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 Thursday (8/20) North and Central California had minimal locally generated northwest windswell with waves waist high and a little textured early. Southern California was basically dead flat with northwest texture on it. Hawaii's North Shore was flat. The East Shore had shoulder high east windswell hitting exposed breaks with onshore winds and chopped. The South Shore had some waist high surf with maybe a few bigger sets, sideband energy coming from the southern hemi, and clean.    

The forecast for North and Central CA is for bare minimal locally generated north windswell holding in the waist high range on Friday then starting to rebuild a little Saturday to 5 ft @ 8 secs (chest high range) and maybe a little north swell intermixed on Sunday to head high or so.  Also small southern hemi swell from a storm that was off the Ross Ice Shelf last week is expected to arrive in time for the Saturday at 2.0 ft @ 18 secs (3.5 ft faces) Pushing 2.5 ft @ 16 secs (4 ft faces) on Sunday (8/23). Southern California is to remain effectively flat until late Friday when the southern hemi swell starts showing to 2 ft @ 18 secs (3.5-4.0 ft faces) holding Saturday at 2.5 ft @ 16-17 secs (4 ft faces) and Sunday (2.5 ft @ 15 secs - 3.5-4.0 ft faces).  The North Shore of Hawaii is to remain flat for the next 7 days. The East Shore is to start seeing a little more easterly local tradewind windswell on Friday at 1 ft overhead and slowly fading through the weekend to chest high on Sunday. The South Shore is expecting to see more sideband southern hemi swell Friday at 2 ft @ 15 secs (3.0-3.5 ft faces) originating from a storm that was off the Ross Ice Shelf,  but pretty well gone by Saturday though a weak secondary pulse might barely show on Sunday (8/23).   

Looking out over the long term down south the gale that was off the Ross Ice Shelf reformed in the far Southeast Pacific Sun/Mon (8/17) producing 32 ft seas, with energy pushing a bit more to the north. Decent utility class swell is expected in US Mainland Mon-Wed (8/26). Up north the models suggest a series of weak gales might try and develop in the Eastern Gulf of Alaska, with the first already developing and another late on Sunday with perhaps a third later next week. Central CA northward into the Pacific Northwest might actually start seeing hints of Fall in their swell forecasts if this pattern develops.     


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

North Pacific

At the surface today high pressure at 1028 mbs was positioned in the Western Gulf of Alaska ridging southeast almost reaching Cape Mendocino, but not and focused more on the Hawaiian Islands. This was resulting in easterly trades there at 15-20 kts and producing some limited windswell for east facing shores.  Of more interest was a gale starting to form in the far Northeastern Gulf of Alaska at 1000 mbs forming a pressure gradient with high pressure to it's west generating confirmed northwest winds at 35 kt at 52N 145W aimed at Washington but likely setting energy up down into Central CA down the 319 degree path. Over the next 72 hours this gale is to fade a little with 30 kt winds on Thursday evening (8/20) at 52N 142W and seas up to 19 ft at 52N 143W and 20 ft Friday AM at 50N 140W while pushing into British Columbia with 25 kts winds later Friday.  possible small 12-13 secs period swell pushing down into the Pacific Northwest on Saturday and limping into Central CA on Sunday at 5 ft @ 12-13 secs (6 ft faces with luck). Otherwise that same high pressure system in the Western Gulf is to push southeast ridging into Cape Mendocino on Saturday generating 25 kt northerly winds there and building some short period windswell for Central CA over the weekend. It is also to foster continued trades over the Hawaiian Islands Friday at 20+ kts and building windswell then starting to fade some Saturday and almost dropping out entirely on Sunday (8/23)   resulting in decreased windswell along east facing shores there.


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


California Nearshore Forecast
On Thursday (8/20) neutral pressure was in control off the immediate California coast with low pressure building in the Northern Gulf of Alaska, but not for long. High pressure is to surge east again on Friday setting up the usual pressure gradient off Cape Mendo late Friday with north winds building to 25 kts there, but not reaching south of Pt Arena.  This pattern to hold into Saturday with light winds south of the gradient. The whole mess is to start fading on Sunday as more low pressure builds in the Gulf pushes towards the Pacific Northwest. And yet a third system is forecast in the Northern Gulf mid to late next week.  The net result is no winds of real interest (15 kts or greater) are forecast over Central and Southern CA for the next week.  certainly looks like a fall pattern is starting to set up. 


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

On Thursday (8/20) the remnants of  Guillermo were anemic and and dissipating fast north of Hawaii. No swell potential is left.

Typhoon Vamco was positioned 550 nmiles west of Wake Island on Thursday (8/20) continuing to track due north with sustained winds up to 105 kts and forecast to build to near 115 kts by the evening and holding into Friday evening. After that a slow fade is forecast but Vamco is still to be at typhoon force on Tuesday (8/25) while making a turn to the northeast off the Kuril Islands.  This is good news.  It is expected to eventually get picked up by the jetstream and head northeast towards the Gulf of Alaska next week, helping to fuel yet another in a series of gales forecast there. No immediate swell production is forecast, but this is worth monitoring.  


South Pacific

On Thursday (8/20) a fully .cgiit jetstream pattern was in effect, with the northern branch still flowing more or less flat west to east on the 30S latitude while the southern branch pushed weakly south and mostly over the Ross Ice Shelf with winds 80 kts or less and offering no odds for gale development in ice free waters.  Over the next 72 hrs a major ridge is to build  pushing hard to the south over the Southwest Pacific totally shutting down any odds for gale formation there.  But a bit of trough is to result in the far Southeast Pacific with 130 kt south winds flowing up it's westward flank on Sunday (8/23) perhaps offering a glimmer of hope for gale production at the oceans surface. But that is just a quickly to get undercut by the ridge in the West, locking everything back down again.  Beyond 72 hours that ridge in the Southwest Pacific is to hold and push east, totally shutting down any potential for gale development over the South Pacific.  No chance for gale development is indicated. 

At the surface on Thursday (8/20) high pressure at 1028 mbs was well southeast of New Zealand ridging over the Ross Ice Shelf and completely blocking the south Pacific storm corridor in the center of the South Pacific. No low pressure of interest was occurring. Over the next 72 hours reinforcing high pressure at 1032 mbs is build east of New Zealand continuing the lock down eliminating any odds for gale development. 


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.

In Hawaii swell is to be 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.     

Second Pulse - From the Southeast Pacific

On Saturday (8/15) the remnants of the New Zealand Storm (see details above) were 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. This system reorganized better in the Southeast Pacific lifting a bit north on Sunday AM (8/16) with central pressure 948 mbs (over Antarctic Ice) with a fetch of 40-45 kt southwest winds building at 50S 140W generating 30 ft seas at 54S 147W aimed 40 degrees east of the 192 degree route into California.  That fetch continued 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 32 ft sea at 48S 138W.  Some form of 16-17 sec swell is expected to push north towards CA, though Central and South America to get the best of it.

A secondary decent push of 40 kt south winds occurred Monday AM (8/17) at 53S 140W aimed almost straight to the north generating more 32 ft seas at 54S 130W holding into the evening with more 32 ft seas at 52S 132W, then fading after that. A better pulse of small swell is to result tracking up into the California and Central America swell windows.    

Southern CA:  Expect swell arrival on Mon (8/24) at 2.3 ft @ 17-18 secs (4 ft faces with top spot to 5 ft) holding at 2.3 ft @ 16 secs (4 ft faces) on Tues. Additional swell to move in on Tuesday from the second pulse at 3 ft @ 17 secs (5 ft faces with top spots to 6 ft). Swell to continue Wednesday at 3 ft @ 15 secs (4.5-5.0 ft faces) then fading into late Thursday (8/27)     Swell Direction: 193 degrees.

Northern CA:  Expect swell arrival on Mon (8/24) at 2.3 ft @ 17-18 secs (4 ft faces with top spot to 5 ft) holding at 2.6 ft @ 16 secs (4 ft faces) on Tues. Additional energy from the second pulse to arrive late Tuesday pushing up to 3 ft @ 16 secs on Wednesday (5 ft faces with top spots to 6 ft), then settling down into Thursday and early Fri (8/28). Swell Direction: 190 degrees.


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 the high pressure system in the Northeast Pacific is to begin retrograding, falling back towards the dateline and opening up the Gulf of Alaska a little on Sunday (8/23). A new gale is to form there off Washington with 35 kt fetch aimed well at California and drifting east with 40 kt northwest winds forecast Monday AM, then starting to fade in the evening as the gale prepares to move onshore over Southern British Columbia.  Sea to possibly reach 25 ft, but that is a highly unstable guess at this early date. Yet another gale is forecast more in the Northern Gulf on Wednesday/Thursday (9/28) fueled by the remnants of tropical systems from the West Pacific sucked to the northeast by the jetstream with a continued fetch of 30-35 kt northwest winds perhaps generating more 20 ft seas.  It's all still really just a guess, but a nice looking guess just the same. 

MJO/ENSO Update (reference): As of Thursday (8/20) the Madden Julian Oscillation (MJO) was moving into the Inactive Phase. The ENSO (El Nino Southern Oscillation) index surprisingly remained in negative territory, but not much. The Daily SOI index was down to -9.59 (2 days in a row) making it effectively a 31 day negative run (since 7/21), typical of the Active Phase. But we expect that to change any day now. The 30 day average was down at -4.69 and the 90 day average was down to 0.89.  The SOI index continues to regain some of the ground it lost when the MJO went Inactive in early July. The SOI is more of a lagging indicator and after looking at the models (below) and the looming upper easterly anomalies, suspect the SOI will lag a little before the change to more positive values are noticed.  

Wind anomalies modeled at the 850 mb level (approx 5000 ft up) indicated that a strong area of easterly anomalies remained over the Philippines with lesser winds reaching to the dateline and east of there while extending back into the Indian Ocean. But those anomalies were somewhat bipolar in that they were straddling the equator, but very weak over the equator itself (from 5S to 5N latitude).  Maybe there is a little opening/hope here. 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). But with the aforementioned gap in it's core, there remains some hope. The models project these easterly anomalies to hold through 8/29, reaching well into the Central and Eastern Pacific before slowly dissipating, but with that big gap over the equator only getting more pronounced with time, suggesting it might not have much impact down at the surface in regards to generating easterly trades, a good thing. The Inactive Phase and these easterly anomalies are to be very weak by 9/3 and effectively gone by 9/8 with a weak version of the Inactive Phase trying to build back in the Indian Ocean behind it. It will be 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. But we are perhaps a little more disposed to be more optimistic than we were even a few days ago. 

Sea Surface Temp anomaly data (8/18) 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 has been tracking from the West Pacific (150 m below the surface) under the dateline and breaking the surface near Central America for months now. Another Kelvin Wave is migrating east from 165W, the result of a Westerly Wind Burst (WWB) in the West Pacific that occurred 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, but will take 2 months from the time it is generated to reach it's target (9/27 or so).  

Of some interest was the appearance of more fully blowing westerly winds in the far West Pacific and developing westerly anomalies reaching to the dateline (starting 8/12). They had pretty much settled down by 8/19, and were reduced to weak anomalies as of 8/20 but do not appear to be going anywhere.  Looking at the models dead slack winds are forecast on the equator from the dateline west through the coming weekend (8/23). This is good and is worthy of note, especially considering the models suggest the Inactive Phase is supposedly in.cgiay. But that gap in it over the equator might help e.cgiain some of this dual-mode configuration we're in at the moment. If this pattern holds for a few more day, perhaps another Kelvin wave could result (not likely), or at least reinforcement for the existing Kelvin Wave already in-transit. Will be interesting to see how this.cgiays out.   

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 far from black and white. 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. And the scales seem to be tipping in favor or more development rather than less. A close monitoring of the next 4 days wind activity (through 8/25) on the equator near the dateline might help to clarify what is really occurring. 

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.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.  

See more details in the new  El Nino update.


South Pacific

Beyond 72 hours no swell producing fetch is forecast with high pressure holding the upper hand over the Central of the South Pacific at 1028 mbs. 

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

Add a STORMSURF Buoy Forecast to your Google Homepage. Click Here: Add to Google
Then open your Google homepage, hit 'edit' button (top right near graph), and select your location


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

Free Stormsurf Stickers - Get your free stickers! - More details Here

Read all the latest news and happenings on our News Page here

Surf Height-Swell Height Correlation Table


Contact | About | Disclaimer | Privacy
Advertise/Content | Links
Visit Mark Sponsler on Facebook Visit Stormsurf on Instagram Visit Stormsurf on YouTube
Copyright © 2024 STORMSURF - All Rights Reserved
This page cannot be duplicated, reused or framed in another window without express written permission.
But links are always welcome.
Buoys | Buoy Forecast | Bulletins | Models: Wave - Weather - Surf - Altimetry - Snow | Pacific Forecast | QuikCAST | El Nino | Tutorials | Great Circles | Calculator