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Pacific Storm and Surf Forecast
Updated: September 15, 2009 9:03 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   

Weak Gale Passes Through the Gulf
Super Typhoon Choi-Wan At 140 kts/160 mph & Building


New Swell Classification Guidelines (Winter)

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

On Tuesday (9/15) North and Central California had head high residual Gulf windswell encased in fog but with light winds and glassy conditions. Southern California was getting this same windswell from the Gulf with waves waist high and textured early afternoon, pushing shoulder high down south and almost chopped. Hawaii's North Shore was still getting a little residual  swell from the dateline with set waves shoulder high or so and clean. The East Shore report was unavailable. The South Shore had some lingering background southern hemi swell originating off northern New Zealand with waves waist high or so and clean. 

The forecast for North and Central CA is for the current northwest Gulf swell to fade out with new Gulf windswell arriving a little bit late Wednesday, biggest on Thursday (5 ft @ 12-13 secs  - 6 ft faces), then down some on Friday and slowly fading Saturday turning to pure local windswell by Sunday, but rideable just the same. Nowhere close to last weekend though. Southern California is to drop into the unrideable range Wednesday, then coming late Thursday as new swell from the Gulf starts to build-in pushing up to waist to maybe chest high on Friday then heading down on Saturday but holding at thigh high into Sunday. The North Shore of Hawaii is to be effectively flat on Wednesday but new small north angled swell from that gale in the Gulf on Mon is expected in on Thursday at head high to 1 ft overhead dropping fast on Friday and then not much expected for the weekend. The East Shore to see some of that Gulf swell on Thursday and Friday with local windswell too at waist high filling in by the weekend.  The South Shore is to go flat by Wednesday with no change forecast beyond.

As mentioned earlier, a weak gale developed in the Western Gulf of Alaska producing 19-20 ft seas Monday into early Tuesday aimed best at Central CA with energy radiating up into the Pacific Northwest and perhaps down into Southern CA for late in the workweek. Hawaii too is to see some sideband energy from this one too.  But overall size and period are to modest. Another weaker system is scheduled for the Western Gulf on Thurs/Fri (9/18) with maybe 16 ft seas  pushing more towards the east, bypassing the Islands but generating 10 sec period swell for the US mainland to fill in behind the above swell. Beyond we're still watching super typhoon Choi-Wan in the far Western Pacific. We've been hoping it would get picked up by the jetstream and slingshot east by the weekend, and that appears to be the case, but not exactly as strong as hoped for. Still it's something to monitor. Otherwise a laconic pattern is in.cgiay, at least for now while the Inactive Phase of the MJO holds control of the North Pacific. 


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

North Pacific

On Tuesday (9/15) the North Pacific jetstream was flowing flat off Kamchatka over the dateline then falling into a pretty steep trough in the Gulf of Alaska with 140 kts winds flowing down into it with the leading edge of that trough pushing into the Pacific Northwest. The Gulf trough was supporting gale development there, but not as strong as one would expect. Over the next 72 hrs the Gulf trough is to fade with a flat jet tracking over the 45N latitude late Wednesday and holding, with limited pockets of 140 kt west winds embedded in the flow, but nothing really supportive of gale development. Beyond 72 hours another steep trough is forecast building over the Western Gulf on Sat/Sun (9/20) with 160 kt winds pushing down into it likely helping to support low pressure development there, but maybe a bit too steep to make it be meaningful. That trough is to dig out a bit more width by Tuesday (9/22) possibly helping to support gale development there, but that is really just a early guess by the models.

At the surface on Tuesday (9/15) a weak 994 mbs gale low was circulating in the Central Gulf and fading with limited 20-25 kt northwest winds pushing towards California with a secondary gale low up in the Bering Sea over the dateline tracking southeast. High pressure at 1034 mbs was over the dateline.  no real swell producing fetch was apparent, though the Gulf low is likely generating limited 10 sec period windswell pushing all towards the US mainland.  Over the next 72 hours  the Bering Sea gale is to drop southeast and become assimilated with the Gulf of Alaska low generating fragments of 25 kt westerly fetch and some 16 ft seas Wed/Thurs (9/17), but nothing of real interest.  Typhoon Choi-Wan is to be building and churning north towards Japan. 

Gulf Gale

On Sunday (9/13) a weak gale 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. The Gulf low continued dropping southeast with 30 kt northwest winds holding into late-Monday and 19-20 ft seas at 42N 155W pushing 25 degrees south of the 296 degree path to Central CA and 1650 nmiles out, and 1300 nmiles north of Hawaii.

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.

Secondary fetch is forecast in the Central Gulf associated with this system late Thursday generating more 16 ft seas at 45N 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 Tuesday (9/15) a neutral pressure pattern was in.cgiay off California with low pressure in the Gulf of Alaska and pushing close to the state suppressing the north wind machine.  That is to hold into early Wednesday, then high pressure that's been holed up from the Central Pacific is to try again to get a foothold over Central CA, with northwest winds at 15-20 kts forecast near the entire North and Central CA coast holding into Thursday.  This high and associated fetch is to migrate north and becoming more focused on Cape Mendo on Friday with Central CA winds settling back down below 10 kts. That high is to slowly ridge and push into British Columbia through the weekend with a light wind flow forecast from Pt Arena southward, though north winds to 30 kts are forecast over Cape Mendo on Sunday likely generating local windswell.  That is to dissipate on Monday 99/21) with a neutral pressure pattern building in and a light winds pattern forecast through mid-next week. 


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: 

Super Typhoon Choi-Wan as located 1150 nmiles south-southeast of Central Japan tracking northwest with sustained winds a whopping 140 kts (160 mph) and forecast to intensify.  Most impressive. Wednesday AM (9/16) winds to peak at 145 kts (167 mph) holding into the evening, then slowly setting down. A slow turn to the north is expected Thurs and then to the north-northeast on Friday (9/18) with winds still 120 kts. 45 ft seas are forecast Saturday at 35N 147E pushing a bit north of the 302 degree path to Central CA, though that is likely just wishful thinking. A steady acceleration in forward speed is forecast with a turn more to the northeast, putting Choi-Wan a bit off Northern Japan on Sunday AM at 42N 152E  with 65 kts winds and turning extratropical. 42 ft seas from previous fetch is forecast at 43N 155E pushing up the 306 degree path to Central CA.  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 Tuesday (9/15) no swell producing fetch was occurring over the South Pacific.  Over the next 72 hours a small gale is forecast building 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 ten sinking southeast and fading. 30 ft seas are forecast Wed Am (9/16) at 58S 177E building into the evening t0 35 ft at 57S 173W, then fading fast Thursday AM from 34 ft at 58S 162W. But all energy is to pushing due east with no swell expected to radiate north towards Hawaii or the US West Coast.  Only Tahiti might get some 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 generalized weak low pressure is to continue circulating in the Gulf of Alaska, then starting to fade early next week. no swell producing fetch is expected. But Typhoon Choi-Wan might make inroads towards the dateline by Tues (9/22), but that is just a guess by the models.  No other swell producing systems are forecast. 

MJO/ENSO Update (reference): As of Tuesday (9/15) 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 4.10 toggling back and forth between barely negative and positive each day. The 30 day average was up to 0.00 (dead neutral) and the 90 average was up just barely to 1.19.  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 were subsiding over the entire Eastern equatorial Pacific, but were still present from west of the dateline almost into Central America. No strong core remained. This was the tail end of this event and is expected to slowly subside loosing coverage through 9/24. The models also indicate that western anomalies associated with a building Active Phase of the MJO were present in the Indian Ocean but not as strong as even 48 hours earlier.  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 9/24, but not expected to hit the dateline at all, just lingering over the Philippines  through 10/4, 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 (9/14) 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 to maybe Southern CA, but not into 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 things are settling down too. 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 for months now.  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. The Kelvin Wave we had 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 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. 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. Otherwise a continuous stream of 1+ degree warmer than normal water extends from 160E under the dateline and into the existing warm pool off Ecuador.  So there's no end in sight.  

Today weak western blowing wind continued on the equator in the far West Pacific up to the nearly the dateline, then gave way to trades as it has all month (and longer). A moderate  westerly anomaly continued in.cgiay. These westerly anomalies started recently 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 (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 no swell producing fetch is forecast.  No swell of interest is 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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Surf Height-Swell Height Correlation Table


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