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Pacific Storm and Surf Forecast
Updated: September 18, 2012 6:53 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 = 2.0 - California & 3.3 - 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 9/17 thru Sun 9/23
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   

Models Suggest NPac to Stir
A Little Activity Forecast Down South Too

Swell Classification Guidelines

Significant: Winter - Swell 8 ft @ 14 secs or greater (11+ ft faces) for 8+ hours (greater than double overhead).
- 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/Utility Class: Winter - Swell and period combination generating faces at head high to 1.5 times overhead (4-7 ft).
- 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.
- up to waist high swell. Also called 'Background' swell.

Current Conditions
On Tuesday
(9/18) North and Central CA had minimal local windswell up north with waves maybe waist high at top spots and pretty textured with winds from the northwest. Down south in Santa Cruz surf was effectively flat with rare southern hemi sets at knee to thigh high and reasonably clean. Southern California up north had minimal north windswell at knee to thigh high and getting chopped from northwest wind. Down south southern hemi background swell was occasionally producing some waist high sets and fairly clean. Hawaii's North Shore was flat and clean with trades in effect. The South Shore had some minimal southern hemi background swell producing a few knee to thigh high sets and clean with trades in effect. The East Shore had no real east windswell producing waves only knee high and heavily textured.    

See QuikCASTs for the 5 day surf overview or read below for the detailed view.

Meteorological Overview
Up north high pressure was not really a factor with no real north windswell along the California coast and no tradewind swell of interest in Hawaii. Instead modest weak low pressure was trying to get a foothold in the Western Gulf of Alaska, but not quite there yet. But by Thursday reinforcing low pressure is to move over the dateline with a gale forming and driving east into the Gulf with winds in the 40-45 kts range intermittently and seas supposedly to 26-28 ft targeting sideband energy towards Hawaii and better at Central CA northward. But this is still just a projection with no wind  yet blowing on the oceans surface.  And another smaller system is forecast forming in the Gulf on Mon (9/24). Maybe Fall is finally starting.  Down south on Monday (9/17) a modesty gale developed under New Zealand with seas to 34 ft aimed a little bit to the northeast offering limited  potential for small southern hemi swell long term. And another similar system is modeled in the same area but pushing better to the northeast on Thurs-Fri (9/21) with seas at 34-35 ft. So possible energy from a variety of sources is in the cards. Certainly better than where we've been or where we are right now. 

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

North Pacific

Jetstream - On Tuesday (9/15) the jet was still di.cgiaced to the north running west to east generally just south of the Aleutians at 50N with a building trough on the dateline dipping south to 40N with winds feeding into it at 170 kts offering some support for low pressure development there. This is the best so far this season. Big ridges were on either side of the trough, resulting in the jets overall northward di.cgiacement and only supporting high pressure down in lower levels of the atmosphere. Over the next 72 hours the ridge in the west is to fade some allowing the jet to fall southward and continue feeding the broad trough centered near the dateline and slowly pushing east. 150 kts winds are to be falling into the trough Wed-Thurs (9/20) offering improved odds for gale formation. Beyond 72 hours the trough is to loose continuity and track east in the Northern Gulf of Alaska and effectively gone by late Saturday (9/22). Theoretically another pulse of wind energy is to move into the area on Mon (9/24) feeding development of a new trough there with winds 150 kts pushing into it and hold nicely through mid-week. Good support for gale formation if the models are to be believed. And the jet tracking over Siberia a week out is to be down around 42N, a good southerly position. 

Surface  -  On Tuesday (9/18) high pressure at 1024 mbs was over the Northeast Pacific ridging north into Northern Canada and positioned a bit west of the US West Coast offering no pressure gradient or north fetch over the US West Coast.  The high was also centered too far north of Hawaii suppressing the usual easterly trades there, with winds only 10 kts and no real east windswell occurring along east facing shores of the Islands. Weak but broad low pressure was over the Western Gulf of Alaska generating northwest wind at 20 kts, but not producing any seas of interest. 

Over the next 72 hours high pressure off the US West Coast is to slowly ease east forming a weak gradient along the Central CA coast starting late Wed (9/19) centered near Morro Bay and slowly lifting north with winds 20 kts, pushing up to Cape Mendocino by late Friday.  Limited odds for small short period north windswell for mostly Southern Central CA.  There's no indication of a swell producing trades for Hawaii. 


Possible Dateline Gale
Starting Wednesday AM (9/19) a small gale is forecast developing off Kamchatka falling southeast and moving south of the intersection of the Aleutians and the dateline by Thursday AM (9/20) with winds building 45 kts over a small area and seas to 26 ft at 47N 180W.  The gale is to falter some in the evening with winds 40 kts and seas 26 ft at 42N 175W (331 degs HI, 293 degs NCal) aimed at Hawaii and the US West Coast. The gale is to ease east Friday AM (9/21) with fetch increasing in areal coverage and solid at 40 kts targeting the same location with seas holding at 26 ft at 43N 165W bypassing Hawaii and aimed at the 292 deg path to NCal(297 degs SCal). Fetch to become slightly better organized in the evening with seas building to 30 ft at 45N 161W (297 degs NCal). The gale is to be lifting northeast on Saturday with winds fading from 35 kts and seas dropping fast from 26 ft at 46N 155W. If one is to believe the model, possible decent swell could result. But this system is still a ways from even forming. Certainly something to monitor though.


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


As of Tuesday AM (9/18) Tropical Storm Lane was positioned midway between Hawaii and mainland Mexico tracking northwest with winds 60 kts and seas 24 ft. It peaked Monday evening with winds 70 kts at 18 N 127.3W and seas 28 ft. For the most part it was a fish storm though some small energy could possibly radiate east Towards Hawaii with luck.


California Nearshore Forecast
On Tuesday (9/18) high pressure was shunted away from the coast with a weak upper level low circulating off Cape Mendocino. A generally weak wind pattern was in.cgiay. On Wednesday (9/19)  north winds are to build to 20 kts as high pressure starts ridging over Pt Conception and trying to build/move northward but not making it till late Thursday with north winds 15-20 kts over all of North and Central CA. This pattern to hold through Friday then finally Saturday the core of the fetch is to move to North CA with winds speed 20-25 kts with a weak eddy flow become established over Central CA. Winds to hold at 25 kts into Sunday AM producing small windswell for Central CA , then faltering to 20 kts and decreasing in areal coverage, holding north of Pt Reyes through Monday, then falling over Central CA Tues-Wed (9/26). A weak eddy flow to continue non-stop for Southern CA. 


South Pacific

Surface  -  On Tuesday (9/18) fetch under New Zealand was producing seas of interest (see New Zealand Gale below). Over the next 72 hours a new gale is forecast forming southeast of New Zealand on the edge of the Ross Ice Shelf Thursday AM (9/20) with winds 40-45 kts over a broad area and seas building from 34 ft at 60S 179W (207 degs CA and shadowed by Tahiti and 192 degs HI). The fetch is to hold in the evening while drifting east with seas still 34 ft up at 56S 175W. Fetch is to start fading from 40 kts Fri AM (9/21) with seas still 34 ft at 52S 167W (205 degs CA and in the heart of the Tahiti swell shadow and 182 degs HI).  Fetch is to be gone in the evening with seas from previous fetch fading from 30 ft at 48N 160W.  In all some degree of decent swell is possible for HI and CA if one is to believe the models.          


Small Southeast Pacific Gale
Another gale organized in the far Southeast Pacific producing a small area of 45 kt south winds Monday AM (9/10).  Fetch faded to 40 kts in the evening but still aimed northward with seas building to 28 ft at 55S 119W. Fetch regenerated Tuesday AM (9/11) to 40 kts over a broader area with seas to 30 ft over an infinitesimal area at 49S 118W,  then faded while moving out of even the Southern CA swell window. 

Tiny southern hemi swell arrived in Southern CA arriving on Tuesday (9/18) with pure swell 1.3 ft @ 18 secs (2.0-2.5 ft) coming from 180 degrees and is forecast to build to 2.0 ft @ 15-16 secs (3 ft) on Wednesday (9/19), then fading fast from there. 

New Zealand Gale
On Monday AM (9/17) a gale organized under New Zealand producing a small area of 45 kt west-southwest winds and seas building from 32 ft early at 56S 172E. This system tracked east and held in the evening with winds to near 45 kts and seas peaking at 34 ft at 56S 179E (194 degs HI and 210 degs CA right on the edge of the Tahiti swell shadow. 45 kt winds barely held Tuesday AM (9/18) tracking flat east with and seas fading from 32 ft at 56S 164W. Possible small southern hemi swell could result for both Hawaii starting Tues (9/25) at 1.6 ft @ 17 secs (2.5 ft) and 9 days for California. Will monitor.


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 another gale is forecast developing in the Central Gulf of Alaska on Monday (9/24) with winds 35-40 kts and lifting north tracking into Alaska on Tuesday. Maybe 19 ft seas to result.  Maybe some small 12-13 secs period swell to result for the US West Coast.  

Note: The Madden Julian Oscillation is a periodic weather cycle that tracks east along the equator circumnavigating the globe. It is characterized in it's Inactive Phase by enhanced trade winds and dry weather over the part of the equatorial Pacific it is in control of, and in it's Active Phase by slack if not an outright reversal of trade winds and enhanced precipitation. The oscillation occurs in roughly 20-30 day cycles (Inactive for 20-30 days, then Active for 20-30 days) over any single location on the.cgianet. During the Active Phase in the Pacific the MJO tends to support the formation of stronger and longer lasting gales resulting in enhanced potential for the formation of swell producing storms. During the Inactive Phase the jet stream tends to .cgiit resulting in high pressure and less potential for swell producing storm development. The paragraphs below analyze the state of the MJO in the Pacific and provide forecasts for MJO activity (which directly relate to the potential for swell production).

As of Tuesday (9/18) the daily Southern Oscillation Index (SOI) was at -2.73 (7 days in a row neutral or between -8 and +4). The 30 day average was down slightly to 3.05 with the 90 day average at -3.90. This is neutral territory and not indicative of El Nino.

Current equatorial wind analysis indicated moderate.cgius strength westerly anomalies over the Maritime Continent (WPac) falling to neutral before reaching the dateline and holding at neutral the rest of the way across the equatorial Pacific into Central America.  This suggests that a weak Westerly Wind Burst (WWB) that started Sept 2 in the West Pacific is continuing for 17 days in a row (a good thing for maintaining the warm water pump and possibly setting up a Kelvin Wave) and that the Active Phase of the MJO was in control over the West Pacific. A week from now (9/26) neutral anomalies are forecast to be in control of the Maritime Continent and dateline all the way into the East Pacific suggesting a very weak Active Phase (at best if not it's outright demise). This Active Phase and WWB is what we were hoping for to prevent further degradation of the warm pool. 

The longer range models (dynamic and statistical) run on 9/17 remain in agreement suggesting a weak Active Phase is in.cgiay over the West Pacific with the Inactive Phase moving over Central America bound for the Caribbean and Atlantic Basin. The Active Phase is to slowly decay over the next 5 days per the statistical model and give way to a weak Inactive Phase 2 weeks out, while the dynamic model  has the Active Phase holding on for the next 2 weeks.  Suspect the dynamic model is wrong. This all favors some degree of weak maintenance.cgian for the warm water pool off Ecuador, if not slightly more due to the WWB currently in.cgiay.  

More warm water in the equatorial East Pacific means more storm production in the North Pacific during winter months (roughly speaking). Warmer than normal water accumulated off Ecuador through 7/2 (part of a continuous pattern that started in Jan 2012) fueled by a Kelvin Wave, weaker than normal trades and a MJO pattern dominated by the Active Phase in early April and a continued weak MJO signal beyond. The warm water pattern peaked on 7/2 in an unmistakable El Nino-like configuration. But since then a steady but weak degradation of the warm pool has ensued. The warm pool has also showed signs some signs of shrinking in areal coverage, but has also migrated some to the north (up along Baja) while shrinking in the south along Chile. And the latest update on 9/17 has again depicted a thin track of cooler than normal water snaking it's way west through the heart of the warm pool off Ecuador. We've also been tracking the cool pool that has dominated between California and Hawaii, generated by 2 years of La Nina and stronger than normal high pressure there. There's some signs it is weakening, but it is still quite obvious and a force to be reckoned with atmospherically. There is also a steady build up of very warm water migrating east from Japan towards the US West coast (presumably driven by the north quadrant of the North Pacific High). Something that looked very much like a weak Kelvin Wave propagated east both subsurface (2 deg C anomaly at 118W) and at the surface (1 deg C anomaly), moving east of 120 and off the charts by 9/17. If this is real, it would help to r.cgienish the warm water pool maybe 3-4 weeks out (early Oct), but nowhere near the levels it was in July (our best guess). The overriding concern is there is no indication that the warm water pool is building in temperature or areal coverage as one would expect if El Nino were developing, and.cgienty of evidence that it is in a slow but steady decline or at best just just barely hanging on in maintenance mode. In fact the models are now picking up on the decline in water temps in the Nino 3.4 region, depicting a sharp decline in temps of 0.5 degs there for late September.  Hopefully the Kelvin Wave (mentioned above) pushing east will add a little fuel. And if in fact the WWB that occurred 9/2-9/18 in the far West Pacific is productive, another Kelvin Wave could result with yet more warming expected 90 days out (Dec). But this is looking less like a legitimate El Nino and more like a pulse towards a neutral or slightly warm pattern. Water temps are now modeled only .75 degs above normal in the Jan-Feb 2013 timeframe for the Nino 3.4 region, just barely within El Nino thresholds. So the evidence is not promising, but the models are hopeful for some degree of rebound longterm.       

A weak MJO pattern (both Active and Inactive Phases) is a sign of the weak version of El Nino. Strong Active Phases accompanied by Westerly Wind Bursts (WWB) is a sign of a strong El Nino. Given the data to date, the current event is looking more like a weak El Nino at best. As we move into the Fall months (starting late August), the tendency is for whatever pattern has been dominant to only become a.cgiified. In short, the true MJO character will become exposed in Fall, with summer just being a build-up. The expectation is that a near failure of the MJO could occur with trades fading and more slow-but-steady warm water propagation continuing eastward. If this happens the question then becomes: Will it be slow enough and weak enough to turn into a multi-year warm event, or will the atmosphere switch as usual in February 2013 and usher in a new La Nina.  As of right now, with the very weak MJO pattern in.cgiay, the weak evidence of any WWBs, the declining warm pool, our bets are for this warm event to not reach a real El Nino status. And this would actually be a good thing (see final paragraph).    

At this time there is only limited atmospheric evidence of a possible El Nino pattern in.cgiay.  Remnants of La Nina are still affecting the atmosphere and will likely continue for several months into the middle of Fall (mid-Oct), but steadily degrading. One such indicator is the continued presence of high pressure over the Eastern Pacific. It has been locked in.cgiace for 2 years now and it's momentum is not going to be easily be halted. The high has caused unrelenting north winds pushing down the California coast and stronger than normal trades over Hawaii. The high is evidenced by a large pool of cooler than normal water radiating southeast off California and over Hawaii reaching the equator at the dateline, the result of enhanced upwelling.  Recent imagery suggest the high is shifting west and north some and winds along the California coast are becoming less of an issue.  But there has been no change in local water temperatures off Central and North CA. 

We're in a hybrid atmospheric state but the trend is starting to shift more towards the normal category. The longer the MJO remains biased towards a neutral or Active state, and the longer warm water holds if not builds off Central America, and the more the cool pool fades between CA and HI, the more the atmosphere will respond (especially come Fall) turning towards at least a neutral if not an El Nino-like configuration. The atmosphere is like a big ship, it takes a long time and alot of energy to turn. We remain on the bubble as of this date. Historical Note: It is unusual for El Nino (of any magnitude) to develop directly following 2 years of La Nina.            

As of right now its seems the Active Phases of the MJO are not strong enough to usher in some flavor of real El Nino, but the Inactive Phases are not strong enough to shut off the warm water pump to the East Pacific either.  Regardless, we are effectively past the La Nina hump and the tendency will be for a return to a normal if not slightly El Nino-like enhanced state. This is way better than where we've been for the past 2 years (under the influence of La Nina). The preference is that El Nino does not form this year, because that would only usher in another La Nina the year or two beyond.  Rather, a neutral pattern biased slightly warm would be good, followed by at least another year of slightly warmer temps ultimately converging in a stronger El Nino 2-3 years out. And historically, this is the 'normal' pattern (a few years of false starts before a legit El Nino forms).So it will be interesting to see whether the pattern we are currently in is a tease or the real thing. The preference is for a tease with a slowly building storm pattern occurring over a multi-year period, culminating with a real El Nino 2 or more years beyond.    

See imagery in the ENSO Powertool and more details in the  El Nino update.  


South Pacific

Beyond 72 hours no swell producing fetch of interest is forecast. 

Details to follow...


External Reference Material: El Nino Southern Oscillation (ENSO), Madden Julian Oscillation (MJO), Pacific Decadal Oscillation (PDO), Southern Oscillation Index (SOI), Kelvin Wave

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Local Interest

Greg Long XCel Core Files - Here's a great profile of Greg Long and his contributions toward pushing the state of big wave surfing. Well Done -

Chasing Mavericks - The Jay Moriarty Movie: Two trailers for the new movie about Jay, Frosty and Mavericks has been posted. Movie opens on 10/26/12. Here's the link: &

Props from the Pros:  Stormsurf was mentioned over the past week in two different media sources.  One was in an interview Kelly Slater did with the New York Times and another was in a promotional piece Ramon Navarro did for the Big Wave World Tour. Many thanks to Curt Myers from Powerline Productions for alerting us and of course thanks to Kelly, Ramon and the Tour for using our service. Here's the links:

Steve Colleta Surfboards - Check out surfboards by local shaper Steve Coletta - A long time Santa Cruz local and master shaper. Progressive shapes for North and Central CA waves

Chasing the Swell has been nominated for a Webby Award. See details of this great piece of video journalism below. Some say this is the "Oscars" of online awards.One of the awards is voter based. If you have a moment,.cgiease cast your ballot by going to:, register, then click on the "Get Voting" tab and then to the "Online Film and Video" > "Sports" category and vote for "Chasing the Swell".

Timmy Reyes - Curt Myers from Powerlines Productions found this little gem with Timmy Reyes providing a brief statement about which sites he uses for swell chasing. Thought we'd pass it on. Enjoy:

Buell Wetsuits - When surfing in Santa Cruz, we've been seeing a new wetsuit in the line-up worn by many top flight surfers. They're getting good traction and are well respected. Take a look:

Stormsurf Mobile App (1/9/11) We are proud to announce the official public release of our smartphone mobile app. It provides access to our most popular and commonly used products, optimized for use on the road, on the beach or anywhere you don't have a desktop or laptop.  With a smart phone and signal, you will have access to our data. And we're not talking just a few teaser products - We're talking full feature wave models, weather models, real-time buoy data, manually built forecasts and hundreds of spot wave and wind forecasts enabling you to construct a surf forecast for any location on the.cgianet, all from your cell phone and all for free.  No subscription required and no hidden fees. And better yet, there's a few new things sprinkled in that are not yet available even on our full-featured web site. From your smart phones browser just navigate to: 

Chasing The Swell: Sachi Cunningham from the LA Times spent the entirety of last winter chasing surfers and swells around the North Pacific with her high def video cam. Her timing couldn't have been any better with the project exactly coinciding with the strongest El Nino in 12 years resulting in the best big wave season in a decade. And being an acco.cgiished surfer herself helped her to bring a poignant and accurate account of the what it's like to ride big waves and the new (and some not so new) personalities that are revitalizing the sport. This is must-see material for any surfer or weather enthusiast. Check it out here:

New Weather Models With the activation of our new server we have now released a new block of weather models including North America jetstream, wind and precipitation, local coastal wind forecasts in 1 hr increments and snow and mountain wind forecasts in both 1 and 3 hours increments. The new animations can be found here (look for those items tagged with the New! icon):

New Weather Model Server Stormsurf has installed another weather model production server. This has enabled us to spread the load across more servers allowing us to post both wave and weather model updates much quicker.  Also we are testing new content (like North America jetstream, winds and precipitation, local wind forecasts in 1 hr increments and snow and mountain wind forecasts in both 1 and 3 hours increments). The model menus will be updated shortly with these new links.   

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New Wave Model Facts: Click HERE to read more about the new wave models. Important info.

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.

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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