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Pacific Storm and Surf Forecast
Updated: September 13, 2009 8:00 PM
Buoys: Northern CA - Southern CA - Hawaii - Gulf of Alaska - Pacific Northwest
Buoy Forecast:
Northern CA - Southern CA - Hawaii - Gulf of Alaska - Pacific Northwest
Pacific Links:  Atmospheric Models - Buoy Data - Current Weather - Wave Models
Forecast Archives: Enter Here
A chronology of recent Mavericks Underground forecasts. Once you enter, just click on the HTML file forecast you want to review (e.g. 073199.html equals July 31, 1999). To view the maps that correspond to that forecast date, select the html file labeled 073199 maps.html
Swell Potential Rating = 2.2 - California & 2.0 - Hawaii
Using the 'Winter' 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 9/14 thru Sun 9/20
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   

Weaker Gale Pattern Expected for the Gulf
West Pacific Tropics Stir - Typhoon Choi-Wan


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 Sunday (9/13) North and Central California had 3-4 ft overhead swell coming from a mix of the dateline and the Gulf of Alaska, down some from the peak which occurred late Saturday morning with waves double overhead.cgius. South winds moved in early and put a damper on what was a good session. Southern California was getting this same swell with waves head high to 1 ft overhead up north with a little wind on it late morning. Down south sets were head high or so with westerly winds getting on it mid-day. At least there's surf. Hawaii's North Shore was still getting decent swell from that same dateline storm with set waves 1-2 ft overhead and pretty clean. The East Shore report was unavailable. The South Shore had background southern hemi swell originating off northern New Zealand with waves shoulder to head high and clean. 

The forecast for North and Central CA is for the current northwest swell to slowly fade into Monday, though still quite rideable at 2-3 ft overhead on the sets, then really dropping out on Tuesday almost gone on Wednesday. Southern California is to see more of this dateline swell on Monday with set waves shoulder high fading to waist high Tuesday AM and then effectively gone by Wednesday. The North Shore of Hawaii is to be seeing the last of the dateline swell on Monday with sets in the head high range and dropping through the day, with nothing left on Tuesday. The East Shore to see some thigh high energy left from this same system at exposed breaks on Monday, then fading to flat. The South Shore is to have more waist to chest high southern hemi background swell on Monday dropping to the thigh high range on Tuesday then going flat. r

Over the long haul the next system of interest is developing in the Western Gulf of Alaska, a weak gale dropping out of the Bering Sea expected to produce seas to 20 ft Monday into early Tuesday aimed best at Central Ca with energy likely to radiate up into the PAcific Northwest and perhaps down into Southern Ca for late in the workweek. HAwaii might even get a touch of sideband energy from this one too, but for all, size and period are to be very modest. Another similar system is schedule for the Western Gulf on Thurs/Fri (9/18) again with maybe 20 ft seas but pushing more to the east, likely bypassing the Islands entirely. And beyond there's suggestions of solid tropical activity south of Japan, currently named Choi-Wan with 60 kts winds and schedule to intensify. If this were to get picked up by the jet, more solid swell could result. But that's only a guess and nothing indicates that will necessarily happen yet. Still, it provides something to monitor. Welcome to the 2009-2010 Fall Season.


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

North Pacific

On Sunday (9/13) the North Pacific jetstream had a bit of a ridge on the dateline but was starting to fall into a trough in the Gulf of Alaska with 160 kts winds flowing into it and the leading edge of that trough was falling into a small trough just off Central CA with rain starting to fall in the SF Bay Area. Pretty early in the year for such a pattern. The Gulf trough was likely starting to support gale development too. Over the next 72 hrs the Gulf trough is to build into early Monday when 180 kt northwest winds are to be feeding it, continuing to support gale development potential the slowly but steadily fading while pinching off in the Eastern Gulf late Tuesday and pushing into British Columbia 24 hours later. At that time the full width of the jet is to be running over the 45N latitude, pretty far south for the time of year. Beyond 72 hours another trough is forecast building in the Western Gulf on Thurs (9/17) with 130 kt winds pushing under it likely helping to support low pressure development there, then digging out even deeper by Sunday (9/20) with 150 kt winds forecast and building to 180 kts late. All said, the pattern is looking pretty good, and that is even without the help of an Active MJO phase.  

At the surface on Sunday (9/13) a gale low was falling out of the Bering Sea into the Western Gulf of Alaska with a small area of 35 kt northwest winds at 50N 168W aimed midway between Hawaii and Central CA providing some potential for swell generation. Another weak low was just off Kamchatka pushing northeast up into the Bering Sea. A tropical Storm was 1200 nmiles south-southeast of Central Japan. Over the next 72 hours the Gulf low is to continue dropping southeast with 30 kt northwest winds holding into mid-Monday with 20 ft seas forecast at 43N 158W pushing 25 degrees south of the 296 degree path to Central CA and 1650 nmiles out, and 1300 nmiles north of Hawaii. Assuming this occurs swell of 4.5 ft @ 13 secs (5.5 ft faces) could arrive in Central CA on Thurs (9/17) at 8 PM from 297 degrees and Hawaii on Wed (9/16) at 11 PM with swell 5 ft @ 13 secs (6.5 ft faces) from 355 degrees. Some secondary fetch is forecast in the Central Gulf associated with this system late Tuesday generating more 18 ft seas at 43N 150W pushing mostly east, likely adding a little more to this back end of this swell when it hits Central CA but too far east of the Islands to have any impact.


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


California Nearshore Forecast
On Sunday (9/13) south winds moved into Central CA in association with a small Fall low pressure system that developed just off Cape Mendocino late Saturday (9/12). Light rain is even modeled pushing into the San Francisco Bay area late Sunday. By Monday (9/14) that low is to dissipate with high pressure trying to get a nose into the area, but another gale is forecast for the Gulf of Alaska with a front pushing up close to the Pacific Northwest,  again suppressing significant winds along the CA coast and holding into Wed (9/16). Limited northwest winds of 15 kts are forecast near Pt Conception in the afternoons (Tues/Wed) down over the Channel Islands but that's it. High pressure is to try again to get a foothold over Central CA Thurs (9/17) as the Gulf gale fades, with northwest winds at 15-20 kts forecast near the entire North and Central CA coast, migrating up and becoming more focused on Cape Mendo on Friday with Central CA settling back down below 10 kts. That high is to slowly ridge and push into the Pacific Northwest through next weekend with a light wind flow forecast from Pt Arena southward.


The Inactive Phase of the MJO is in control of the Eastern Pacific expected to continue influencing the area through 9/22 and likely hampering odds for tropical storm formation in the East Pacific.  But a more favorable pattern is to follow starting in the West: 

Typhoon Choi-Wan as located 1300 nmiles south-southeast of Central Japan tracking west-northwest with sustained winds 65 kts, barely minimal typhoon status. With the Active Phase of the MJO starting to build towards the West Pacific from the Indian Ocean, it could have a positive influence, but is likely not going to reach that area in time. Regardless, Choi-Wan is expected to slowly intensify, reaching 115 kt on Thurs (9/17) positioned 600 nmiles south of Japan and turning north. The GFS model has it turning north-northeast by the weekend while intensifying more, missing Japan entirely and almost looking to make a turn to the northeast. It's way too early to tell what will happen, but a turn to the northeast would be most favorable to support swell development for Northeast Pacific locations over the long term. Will monitor.


South Pacific

At the surface on Sunday (9/13) a massive storm was in control of the far Southeast Pacific generating 50-55 kt west winds just barely clear of the northern edge of the Ross Ice Shelf and aimed totally east towards the southern tip of Chile. Virtually no fetch was aimed north of and 90 degree heading as confirmed by the QuikSCAT satellite. 40 ft seas were modeled at 59S 115W and not even in the SCal swell window. No hope for swell from this one anywhere north of Peru (and even just sideband energy expected there).

Over the next 72 hours a small storm is forecast building under New Zealand on Tues (9/15) with 50 kt west winds over a small area at 55S 170E aimed due east, fading to 40-45 kts on Wed (9/16) then fading more while pushing east. 38 ft seas are forecast Wed Am (9/16) at 55S 177E holding into the evening at 55S 175W, then fading fast Thursday AM. No swell is expected to radiate north towards Hawaii or the US West Coast, and even Tahiti might get only limited sideband energy.


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 yet another low is to push south out of the Bering Sea generating more 30 kt northwest fetch late Wed (9/16) into late Thurs heading mostly due east resulting in a limited area of 20 ft seas Thursday afternoon at 46N 162 W heading almost due east. Maybe yet more 12 sec period swell pushing towards the Pacific Northwest down into Central and South CA. No real size, just something to ride. In all this is a step back from where we were a week or so ago, but accurately reflects the effects of the Inactive Phase of the MJO currently gripping the East Pacific. But with the Active Phase slated to start taking hold of the far West Pacific, and a tropical storm already in.cgiay over there, there's possibilities that another pulse of extratropical low pressure fed storm energy could develop on the dateline about 10 days out. That's is purely a guess, but something one looks for during El Nino enhanced years in the early Fall, especially during the start of and Active Phase of the MJO. So all the pieces are looking to maybe be in the right.cgiace.

MJO/ENSO Update (reference): As of Sunday (9/13) the Madden Julian Oscillation (MJO) remained in the Inactive Phase, but slowly fading. The ENSO (El Nino Southern Oscillation) index had pushed barely into positive territory. The Daily SOI index was at 5.71. The 30 day average was up to 0.30 and the 90 average was up to 1.16.  The SOI index was on the rise, typical of the Inactive Phase of the MJO.

Wind anomalies at the 850 mb level (approx 5000 ft up) as defined by models indicated that strong easterly anomalies were starting to subside over the entire Eastern equatorial Pacific, but were still present from the dateline into Central America. But not real strong core existed. This was the tail end of this event and is expected to slowly subside loosing coverage through 9/22. But of more interest, the models also indicate that western anomalies associated with a building Active Phase of the MJO were taking root over the entire width of the Indian Ocean reaching to Thailand. As the Inactive Phase pushes over Central America, the Active Phase is to be starting to exit the Indian Ocean pushing into the Western Pacific on 9/17, but not expected to hit the dateline at all, just hanging north of New Guinea until 9/27, then dissipating. The models have downgraded the strength of this event (at least as of right now). This is pretty typical of the models, in that they show the system stronger than reality out of the gate, then downgrade it, only to upgrade it again as it matures. Not sure whether this is really a case of the model trying to catch up with reality, or whether this is how these events actually develop. In either case, we expect the Active Phase to be a bit stronger than what is currently modeled.

Sea Surface Temp anomaly data (9/10) indicates only subtle change over the past month, with a solid area of warmer than normal water extending over the equator from the dateline east and building into Central/South America with temps holding at 2.0 deg C above normal in the east. This is suggestive of a moderate El Nino.  But the expanse of the warmer waters has increased some solidifying there grip north up the coast of Baja Mexico and Southern CA, but still retreated from the Central California coast. There is also more coverage over the dateline region pushing east, suggesting the warm pool is in fact building not in intensity but in area. This would likely have a stronger effect on the environment over the long term. Cooler than normal waters (-2.0 deg C) remain mirrored streaming off Africa and pushing east reaching South America. Typical of stronger Classic El Ninos of the past. . 

Below the surface on the equator major changes have evolved. A steady flow of 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. And if anything that pattern has built. 2-3 deg warmer than normal waters are in control from 150W extending the whole way into Central America in one non-stop contiguous stream. Most impressive. The Kelvin Wave we have been tracking earlier in the month near 165W is embedded in that stream now easing into Central America. Arrival was initially forecast at 9/27, and that continues to look to be the case. This Kelvin Wave was the result of a Westerly Wind Burst (WWB) in the West Pacific that occurred on 7/25-8/2. This is exactly the sort of situation we've been looking for and is critical to the formation of a legitimate El Nino. Expect to see water temperature jump up in late Sept and early Oct off Central America, feeding the developing warm water pool there and fueling El Nino. Next up we'll be looking for another WWB and associated Kelvin Wave from the Active Phase of the MJO schedule for later this month.  

Fully blowing westerly winds in the far West Pacific and westerly anomalies reached to the dateline starting 8/12. They had pretty much settled down by 8/19, and were reduced to weak anomalies by 8/20, continuing steady 8/31. But on 9/3 more fully blowing west winds were indicated and were holding into 9/10 extending from the west to 170E with a solid westerly anomaly in.cgiay. This is the result of a tropical system (Dujuan) in the West Pacific, classic El Nino symptoms.  Those west winds have dissipated now that Dujuan is gone though weak westerly anomalies continue almost to the dateline. This is good news and might continue to gently feed the subsurface warm water flow pushing east. At a minimum it suggests reinforcements for the existing Kelvin Wave pattern already in.cgiay (pushing into Central America) and with a little help, might possibly help to form another distinct Kelvin wave (odds low). But warm water at 1+ deg C (but less than 2 degs) extends from 160E to 150W feeding directly into the eastward pushing Kelvin Wave off Central America. So the warm water faucet is still on.    

The belief at this time is this developing El Nino is past the critical juncture, and will survive in some fashion with effects continuing in the atmosphere until at least the Spring of next year. All data suggests this will not be a strong El Nino, more likely a moderate one. NOAA's most recent update today forecasts 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 August, but started to come on a little strong in Sept, but looks to be backsliding again. Regardless, 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 the delineation of whether development will continue versus stall is dependent upon more WWBs. And current data indicates that the warm pool will continue to build.

The next milestone we're looking for is development of the next Active Phase of the MJO, expected sometime near the 3rd week of Sept. The models (as of 9/13) indicate it is forming as expected. Also water temps need to hold if not build (as is happening now). A final confirmation should be possible in late-Sept. In the mean time, the current Inactive Phase currently in-progress faltered as it passed over the West Pacific, a good thing in that it allowed the prime area for Westerly Wind Bursts to remain unscathed, allowing the warm pool to continue to build. 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, a gentle but steady push/momentum in-favor of storm development rather than the manic frenzy of a strong El Nino, but without all the weather associated with a strong event. So in many ways a moderate El Nino is more favorable from a surf perspective. As of right now things remain 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 the only pe.cgiexing indicator. But we're becoming more disposed to think the SOI of more of a lagging indicator, at least for this event.     

See more details in the new  El Nino update.


South Pacific

Beyond 72 hours the models suggest only limited gale energy is forecast pushing under New Zealand reaching the mid-South Pacific all tracking on a due west to east route and offering little if any fetch pushing to the north. Sea all to be 30 ft or less. No swell of interest if forecast radiating north into US territories.

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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