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Pacific Storm and Surf Forecast
Updated: September 19, 2009 12:26 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   

Incidental Low Pressure In Gulf
Choi-Wan To Make Headway Towards Dateline


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 (9/19) North and Central California had head high modest period swell coming out of the Gulf of Alaska providing well rideable surf with lightly textured conditions early. Southern California was getting some of this swell swell with waves waist high and occasionally a little more and textured up north, but clean down south. Hawaii's North Shore was really small, effectively flat with no swell in the water, but not for long. The East Shore report was unavailable. The South Shore was flat. 

The forecast for North and Central CA is for a little more of that swell from the Gulf of Alaska to continue slowly fading Sunday from 4 ft @ 10 secs (4 ft faces) with local north windswell a little more dominant. That local windswell to continue intermixing with generic background windswell from the Gulf Monday in the 4 ft @ 10-11 secs range, then fading into Tuesday. Southern California is to see more of that Gulf swell fading on Sunday at 2.0 ft @ 10 secs (2ft faces) maybe returning on Monday afternoon a little larger (2.5 ft faces) before fading out completely. The North Shore of Hawaii is to see a tiny pulse of north angled windswell from follow-on fetch that pushed through the Gulf of Alaska earlier, pushing maybe 3 ft @ 12 secs (chest high sets) late Saturday into early Sunday. And larger (but still not remarkable) sideband swell from a gale that is just now getting organized in the Gulf might arrive late on Monday into early Tuesday at shoulder high. The East Shore to see local windswell to chest high on Sunday fading to waist high.cgius on Monday and waist high Tuesday before dissipating. The South Shore is to be effectively flat on Friday and stay there with no change forecast.

A quick moving gale is scheduled for the Gulf on Sat/Sun (9/20) arching fast to the north producing 40 kt winds and 18 ft seas fleetingly aimed towards Hawaii and a little more at the US West Coast, but mostly towards Northern Canada. Maybe a little taste of swell late Tuesday (9/22) in Central CA. And of more interest is Typhoon Choi-Wan, currently off Japan turning to the northeast and eventually the east. Latest data suggest is to to get picked up by the jetstream and push over the dateline and into the Gulf of Alaska and regenerate to some degree. But the devil is in the details, and with each new run of the models the outlook changes dramatically. So the best bet is to watch this one closely, and see if some particular outcomes stabilizes. But at this time, it is possible some decent swell could result (but far from guaranteed). 


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

North Pacific

On Saturday (9/19) the North Pacific jetstream had a healthy flow generally tracking east on the 43N latitude. A bit of a ridge was off the Kuril Islands dropping into a building trough on the dateline with 180 kt winds flowing down this troughs western flank proving goods support for gale development. A weak ridge was off the the US West Coast. Over the next 72 hrs the dateline trough is to hold while pushing towards the Gulf of Alaska on Sunday while the ridge off the US West Coast builds. The trough is to pinch off on Tuesday (9/22) in the Central Gulf reaching a far south as 38N, becoming ineffective at supporting gale development, while the huge ridge in the east tries to push into and over the Canadian coast. Beyond 72 hours a weak new trough is to try and take root on the dateline Wednesday (8/23) with barely 140 kt winds flowing under it and providing modest support for gale development, and slowly decaying into Saturday (9/26) with winds down to 90 kts then.

At the surface on Saturday (9/19) a weak 988 mb gale low was in the Central Gulf of Alaska generating a tiny fetch of 40-45 kt northwest winds at 45N 162W aimed a bit east of the 350 degree path to Hawaii and and 30 degrees south of the 296 degree path into Central CA. Typhoon Choi-Wan was off Central Japan tracing northeast. Otherwise weak high pressure at 1020 mbs was off Central CA generating light northwest winds at 15 kts over outer waters. Over the next 72 hours the Gulf gale is to lift northeast fast with 40 kt northwest winds at 48N 155W Saturday evening aimed exclusively at Oregon down into Central CA down the 304 degree path (Central CA) with 16 ft seas forecast at 45N 160W. By Sunday AM (9/20) 40 kt fetch is to be pointing towards Alaska and positioned in the northern Gulf of Alaska, effectively out of the picture. 20 ft seas are forecast at 50N 150W all aimed towards North Canada and Alaska. This one is to be of no more use to our forecast area. If all this occurs, some form of background windswell might radiate east towards Central CA, maybe reaching 3.7 ft @ 12 secs (4.0-4.5 ft faces) late Tues (9/22) from 303 degrees fading to 11 secs on Wed.


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


California Nearshore Forecast
On Saturday (9/19) high pressure at 1024 mbs was trying to ridge into Central CA, resulting in northwest winds at 15 kts over outer waters mainly off North CA. This scenario is to only build with 30 kt north winds forecast over Cape Mendo on Sunday (9/20) and 15 kt winds pushing south over outer waters of all of Central CA. Moderate period windswell is to result for exposed north facing breaks on Sunday. By Monday the high is to be pushing inland over British Columbia with light winds taking control of North and Central CA, and near calm winds forecast on into Wednesday (9/23). The on Thursday 99/24) weak high pressure is again forecast off the coast with a 15 kt northerly flow forecast for Central CA building to 20-25 kts early Friday and migrating north towards Cape Mendocino. By Saturday 30 kt north winds are again forecast up there generating local windswell while a calm wind pattern takes hold of Central CA continuing through the weekend (9/27).


The Inactive Phase of the MJO remains barely in-control of the Eastern Pacific, expected to continue influencing the area through 9/23 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 350 nmiles southeast Tokyo Japan on Saturday (9/19) tracking northeast with sustained winds 65 kts, way down from the whopping 140 kts (160 mph) of Tuesday (9/15) and 145 kts of Wednesday. A steady acceleration in forward speed is forecast on Sunday with a turn more towards the northeast, putting Choi-Wan a bit off Northern Japan mid-day with 55 kts winds and turning extratropical. 30 ft seas from previous fetch are forecast at 34N 153E.  Choi-Wan is to get pulled apart some on Sunday and early Monday with part of it tracking north and the core trying to hold on the east-northeast track. The result is to be a fragmentation of it's fetch during that period. Finally on late Monday (9/21) this system is to reorganize up near 50N 170W with a fully consolidated fetch of 40 kt winds forecast. See the LongTerm NPac forecast below for more details.


South Pacific

At the surface on Saturday (9/19) no swell producing fetch was indicated and whatever fetch was present was generally aimed to the southeast, away from our forecast area. Over the next 72 hours no swell producing fetch is forecast.

New Zealand Gale
A gale formed under New Zealand on Wed (9/16) with 45 kt west winds over a small area at 58S 175E aimed due east, holding into the evening at 58S 173W then sinking southeast and fading. 30 ft seas were modeled over a tiny area Wed AM (9/16) at 58S 175E building into the evening to 35 ft at 57S 175W, holding into Thursday AM at 35 ft at 58S 164W. But all energy was pushing due east with no decent swell expected to radiate north towards Hawaii or the US West Coast.  There are low odds of swell reaching 1.6 ft @ 16 secs (thigh to waist high faces) hitting Hawaii on Thurs (9/24) from 190 degrees, then fading from there.


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 all eyes remain on Typhoon Choi-Wan currently off Japan. The models suggest it is to track northeast up to a point off the Northern Kuril Islands late Monday, reorganizing there with a broad fetch of 35-40 kt northwest winds near 45N 168E, then tracking east with up to 45 kt winds forecast at 45N 173E on Tuesday AM with 26 ft seas developing. 40-45 kt west and northwesterly fetch is to hold Tuesday PM into Wednesday AM (9/23) as this system crosses the dateline with seas building from 32 ft to 35 ft at 44N 175W, then fading from there. But at this early date any outcomes is only idle speculation. in fact, with each new run of the models the prognosis has changed radically, and we expect that trend to continue for another few days. So this system is unstable (as is any tropical system) and any particular outcomes is highly uncertain. And with the jetstream not expected to be very energetic as this system moves under its influence, we are not predisposed to expect much. Still, this system bears ongoing monitoring.

MJO/ENSO Update (reference): As of Saturday (9/19) the Madden Julian Oscillation (MJO) remained in the Inactive Phase, but slowly fading. The ENSO (El Nino Southern Oscillation) index had pushed into positive territory. The Daily SOI index was at 13.55 (4 days in a row well positive). The 30 day average was up to 1.71 (effectively neutral) and the 90 average was up to 2.45.  The SOI index was on the rise, but about peaked out, 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 had redeveloped over the Eastern equatorial Pacific, with a faint signal still present west of the dateline reaching the whole way into and over Central America. It had previously looked like this event was reaching a close, but has since reenergized (or at least the models suggest so). This event and is expected to slowly subside loosing coverage through 9/23, but not out, then finally dying by 10/3. The models also indicate that western anomalies associated with a building Active Phase of the MJO remained present in the Indian Ocean, building a little compared to previous model runs, We're not sure whether this is a real change, or just the usual fluctuations in the model. Regardless, 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 9/23, holding north of New Guinea and reaching the dateline by 10/8. The models have upgraded 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 actually develops. 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, the hindcast data is the only thing that matters,Everything else is just speculation by the computer.

Sea Surface Temp anomaly data (9/17) 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 with perhaps a pocket to 3 deg. This is suggestive of a moderate El Nino.  The expanse of the warmer waters has held up to the north solidifying it's grip up the coast of Mexico and Baja up into Southern CA, and now into the Central California coast. There was no change in the area over dateline pushing east, but not retracting any either, suggesting the warm pool is holding but not building in intensity. Cooler than normal waters (-1.5 deg C) were fading some  off Africa while reaching east to South America. This is typical of stronger Classic El Ninos of the past. . 

Below the surface on the equator perhaps things are looking up. A steady flow of warmer than normal subsurface water continues tracking from the West Pacific (150 m below the surface) under the dateline and breaking the surface near Central America as it has for months now.  A solid pocket of 2-3 deg warmer than normal waters are in control from 140W extending the whole way into Central America in one non-stop contiguous stream. This is the Kelvin Wave we had been tracking earlier in the month. Arrival was initially forecast at 9/27, and that continues to look to be the case, with the core now at 120W. This Kelvin Wave was the result of a Westerly Wind Burst (WWB) in the West Pacific that occurred on 7/25-8/2.  Expect to see surface water temperatures jump up in late Sept and early Oct off Central America, feeding the developing warm water pool there and fueling El Nino as this Kelvin wave impacts the coast. The interesting part is another little core of 2 deg warm water has appeared under the dateline, possible a new mini Kelvin Wave. This might be associated with a persistent weak westerly anomaly flow that has been in.cgiace west of the dateline for weeks now (see details below). Will be interesting to see if this develops into a full blown Kelvin Wave. It is embedded in a continuous stream of 1+ degree warmer than normal water extends from 155E under the dateline and into the existing warm pool off Ecuador.  So all looks good for maintaining the existing warm pool for a while.  But for a legit El Nino to form, we need more warm water over the long haul.  

Today neutral/calm winds were in-effect on the equator in the far West Pacific up to the nearly the dateline, then gave way to easterly trades as it has all month (and longer). For weeks now (since 9/8) a moderate westerly anomaly has been in.cgiay from the west up to the dateline (no change). These westerly anomalies started with typhoon Dujuan and continue with Choi-Wan. This is continuing 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 form another distinct Kelvin wave (see above). But another full blown WWB is required.  The hope is that it will happen in this next incarnation of the Active Phase of the MJO.  

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 a gale might try to organize in the far Southeast Pacific Tues/Wed (9/23) generating 32 ft seas barely in the Southern CA swell window, but with little wind energy aimed north. Most energy to track towards South America, assuming this system even forms.

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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