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Pacific Storm and Surf Forecast
Updated: September 22, 2009 8:40 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 = 2.7 - California & 2.9 - 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 9/21 thru Sun 9/27
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   

Extratropical Storm Choi-Wan on Dateline
Quieter Pattern to Follow


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 (9/22) North and Central California had chest high Gulf windswell and fogged-in early. Southern California was getting hardly any of this northwest swell up north and just a touch of  southern hemi background swell with waves thigh.  But down south southern hemi swell was producing waves in the shoulder high range on the sets but with a bit of northwest wind chop on it. Hawaii's North Shore was getting more northwest windswell from the Western Gulf with waves head high and a little more on the better sets. The East Shore report was unavailable. The South Shore had some thigh high sets. 

The forecast for North and Central CA is for more northwest windswell from the Gulf of Alaska continuing into Wednesday then fading Thursday. Another pulse of more local and northerly Gulf swell is Friday but buried under local northwest windswell. Southern California is to see minimal southern hemi swell fading out on Wednesday with perhaps limited small northwest swell moving in late and fading out on Thursday. Perhaps another pulse of Gulf windswell is expected in on Friday, but small is the operative word. The North Shore of Hawaii is to see fading windswell from the Western Gulf of Alaska Wednesday and Thursday as new swell from across the dateline builds in late. The East Shore to see local windswell to thigh high on Wednesday then fading out, returning on Friday before slowly fading through the coming weekend. The South Shore is to be effectively flat for the foreseeable future.

The remnants of Typhoon Choi-Wan redeveloped off the coast of Kamchatka on Monday turning to the east and reach the dateline on Tuesday.  Top winds in this system were up to 50 kts generating seas to 36 ft,  but this was a long ways from the US West Coast and fetch was aimed a bit east of the great circle path to Hawaii. Still some decent utility class swell is expected in late week for the Islands and for the weekend for the mainland. Beyond no systems of interest are on the charts, but that will likely change.  The Active Phase of the MJO is  itching to make headway into the North Pacific, and when that occurs, an upswing in storm activity is likely to result. 


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

North Pacific

On Tuesday (9/22) the North Pacific jetstream had a respectable flow tracking east on the 43N latitude at 110-120 kts with pockets to 130 kts.  A bit pinched off trough was in the Eastern Gulf of Alaska, then ridging hard north into Northern Canada  750 nmiles west of the US coastline. No real support for gale development was indicated up at this level. Over the next 72 hrs the overall flow is to weaken, with a mild ridge building in the West and a stronger one in the East off California. A steep weak trough is forecast diving south in between the two Fri/Sat (9/26).  Maybe some limited support for low pressure development could occur here, but it just isn't modeled to look that impressive. Beyond 72 hours that trough is to wash out quickly with a flat flow returning to the 45N latitude and winds at 120 kts, maybe forming a weak trough on the dateline Tues (9/29) pushing east. Weak support for gale development then.  This is all pretty typical of the Inactive Phase of the MJO. 

At the surface on Tuesday (9/22) the remnants of extratropical storm Choi-Wan were on the dateline and fading but still producing a decent fetch of 35-40 kt west winds (see details below).  Otherwise weak high pressure at 1016 mbs was drifting off the California coast setting up a relatively calm winds pattern for the state. Trades were weak over the Hawaiian Islands too. A small low pressure system at 1004 mbs was trying to organize 800 nmiles west of the Oregon.  Over the next 72 hours the remnants of the dateline storm are to track northeast and fade in the Northern Gulf of Alaska, with all the effective swell producing capacity of this system pretty much gone by Tuesday evening. The little low off the Pacific Northwest is to try and organize with 35 kt northwest winds forecast building on Tuesday PM (9/22) aimed well at Central CA up into Oregon.  But this system is to be lifting north fast pushing into Central Canada by mid-Wednesday.  Limited support for windswell development at best targeting Central CA up into the Pacific Northwest. 

Extratropical Storm Choi-Wan
On Sunday PM (9/20) the extratropical remains of what previously was super Typhoon Choi-Wan were reorganizing just east of the Kuril Islands with west winds confirmed at 50 kts positioned at 44N 160E aimed right up the 302 degree path to Central CA and 20 degree east of the 313 degree path to Hawaii. Seas were on the increase. 

On Monday AM (9/21) this storm pushed east with confirmed west winds of 50 kts at 44N 165E aimed right down the 301 degree path to Central CA and 25 degrees east of the 314 degree path to Hawaii. Seas were on the increase from 30 ft at 45N 160W. In the evening 40 kt west winds were confirmed aimed due east at 41S 173E pushing up the 297 degree path to Central CA and 30 degree east of the 317 degree path to Hawaii. Seas were modeled at 36 ft at 45N 166E.

On Tuesday AM (9/22) 35-40 kt west winds were confirmed at 40N 180W aimed right up the 293 degree path to Central CA and 45 degrees east of the 319 degree path to Hawaii.  Seas were modeled at 35 ft at 43N 175E pushing well towards the US West Coast.  In the evening residual 30-35 kt west fetch is forecast at 41N 175W generating 30 ft seas at 43N 180E. 

By Wednesday AM (9/23) winds are to be below 30 kts with residual seas from previous fetch at 27 ft at 42N 173W and fading out.

Note: No Jason-1 satellite data is available to confirm seas heights.  Satellite went into Safe-Hold mode on 9/15 and is not expected to become operational again until early next week. 

This is not an exceptional system, with only 50 kts winds and mid-30 ft seas aimed mostly to the east.  That is about right on-track for this point in an El Nino year.  But compared to the last 3 years, it is a wonderful sight. The net result is some degree of utility class swell with period in the 17 secs range is expected to push into the Hawaii Islands late week and into California for the weekend.  Nothing over the top, just solid fun-sized longer period swell. 

Hawaii: Expect swell arrival starting Thurs (9/24) at 2 PM with swell period 20 sec and size tiny but slowly building.  Swell to start peaking early Friday AM (9/25) as period turns to 17 secs (2 AM).  Swell 5.5-6.0 ft @ 17 secs (9-10 ft faces).  Swell to still be most solid at sunrise with period in the 15-16 secs range through the day, finally dropping down to 14 secs at sunset.  13 sec residuals expected on Saturday (9/26).  Swell Direction: 316-323 degrees     

Central CA:  Expect swell arrival starting Friday (9/25) at 8 PM with period 20 secs and size tiny if even noticeable.  Size building overnight with 18 sec energy arriving mid-morning Saturday (9/26).  Swell to start peaking mid-afternoon at swell 6.0-6.8 ft @ 17 secs (10-12 ft faces).  Size slowly settling down overnight with swell 6.0-6.5 ft @ 15 secs Sunday AM (9.0-10.0 ft faces) and period slowly dropping to 14 secs later in the afternoon. Swell Direction: 296-302 degrees      

Southern CA:  Expect swell arrival starting Saturday (9/26) at 4 AM with period 20 secs and size tiny if even noticeable.  Size building through the morning with 18 sec energy arriving mid-afternoon.  Swell to start peaking near 10 PM with swell 2.9-3.3 ft @ 17 secs (4.9-5.6 ft faces).  Size slowly settling down overnight with swell still 2.8-3.2 ft @ 16 secs Sunday AM (4.5-5.0 ft faces) and period slowly dropping to 15 secs later in the afternoon. Swell Direction: 300-306 degrees     


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


California Nearshore Forecast
On Tuesday (9/22) weak high pressure at 1018 mbs was sitting off the Southern CA coast and not doing much, with a light wind pattern nearshore. No change is forecast until late Wednesday when it is to get reinforcements from the Central Pacific riding into Oregon, setting up a modest area of northwest winds at 15-20 kts over Central CA waters, but pretty quickly consolidating over Cape Mendocino Thursday AM (9/24) at 25 kts with lesser winds draped over outer waters of SF and Monterey Bay. Local bump expected nearshore. That fetch off the Cape is to build to 30 kts late Thursday and holding, though the wind vector is to be a little more in the offshore direction relatively to Central CA on Friday into Saturday.  Still, a decent amount of windswell is expected to be radiating south from this local fetch. This fetch is to finally fad on late Sunday (9/27) as the high finally pushes onshore over British Columbia. Calm winds to follow until late Tuesday (9/29) when another high is forecast moving into the Pacific Northwest. 


The Inactive Phase of the MJO remains in-control of the Eastern Pacific, expected to continue influencing the area through 9/28 or so and likely hampering odds for tropical storm formation in the East Pacific.  But a more favorable pattern is to follow starting in the West:

No tropical storms of interest are occurring nor forecast to occur for the next 3 days. 


South Pacific

At the surface on Tuesday (9/22) 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 the models suggest a solid gale is to develop starting Friday (9/25) producing a broad fetch of 40-45 kt south winds due south of Tahiti and north of the Ross Ice Shelf. This system is to drift steadily east and hold if not build some, resulting in 35-36 ft seas late Friday into Saturday AM (9/26) at 50S 148W moving to 50S 140W aimed well to the north, or right up the 192-196 degree great circle paths to California (unshadowed by Tahiti) and possibly setting up sideband swell into Hawaii up the 170-173 degree paths (slightly shadowed by Tahiti).  If this occurs a good pulse of southern hemi swell could result. 

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 high pressure is forecast to take over the Gulf of  Alaska by Saturday (9/26) with no sign of low pressure in the East Pacific.  A gale is forecast landlocked over the Kuril Islands drifting northeast, but no fetch of interest is forecast over exposed waters. It is forecast to push into the Bering Sea early next week with 25 kt west winds south of the Aleutians, generating perhaps some windswell, but nothing more.  No other fetch of interest is forecast.  

MJO/ENSO Update (reference): As of Tuesday (9/22) the Madden Julian Oscillation (MJO) remained in the Inactive Phase, but slowly fading. The ENSO (El Nino Southern Oscillation) index had pushed well into positive territory. The Daily SOI index was at 12.66 (8 days in a row positive). The 30 day average was up to 3.57 (effectively neutral) and the 90 average was up to 2.48.  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 remained in control of the Eastern equatorial Pacific, with a faint signal present on the dateline and building while extending east into and over Central America. It had previously looked like this event was reaching a close, but has since reenergized in the East (or at least the models suggest so). This event and is expected to slowly subside loosing coverage through 9/26, but not out, then finally dying by 10/3 or so. The models also indicate that western anomalies associated with a building Active Phase of the MJO remained present in the Indian Ocean, building more compared to previous model runs, We're not sure whether this is a real change, or just the usual fluctuations in the model. Regardless, the Active Phase is starting to exit the Indian Ocean pushing into the Western Pacific, expected to holding north of New Guinea and reaching the dateline by 10/8. The models continue to depict this event as ungraded in strength (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. We are in the 'actually develops' part of that scenario. 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 (9/21) 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 2.0-3.0 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 in 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 off Africa, almost gone now with warm anomalies covering the entire tropical North Atlantic. Perhaps there is some hope for the tropical season there, but is likely a case of  'too-little too-late' to make a difference. 

Below the surface on the equator perhaps things continue to look decent. 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 110W. 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 on 9/17, and has moved east to 170W by 9/22, possible a new mini Kelvin Wave. This might be associated with a persistent weak westerly anomaly flow that had been in.cgiace west of the dateline from 9/8-9/17. 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 today either). 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. 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, which appears to be gaining ground today (9/22), right on track. The models indicate it is pretty strong and to hold for a few weeks. Also water temps need to hold if not build (as is happening now). A final confirmation should be possible in the next week or so. 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 no swell producing fetch 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

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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