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Pacific Storm and Surf Forecast
Updated: September 17, 2009 9:53 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 = 2.2 - 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   

Small Gulf Swell Hits CA
More Moderate Activity Scheduled for the Gulf of Alaska


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 Thursday (9/17) North and Central California had chest high locally generating short period northwest windswell and pretty hacked up even early. Southern California was getting some of this windswell mixed with some background generic North Pacific swell with waves thigh high and textured, almost wait high down south. Hawaii's North Shore was getting sideband swell from the gale that was in the Gulf earlier this week with waves head high or a little more and reasonably clean conditions. The East Shore report was unavailable. The South Shore had some lingering background southern hemi swell originating off Northern New Zealand with waves thigh high or so on rare sets and clean. 

The forecast for North and Central CA is for new swell (really windswell) from the Gulf of Alaska to arrive late Thursday (5 ft @ 12-13 secs  - 6 ft faces), then slowly dropping down some on Friday and slowly fading Saturday turning to pure local windswell by Sunday, but rideable just the same. Southern California is to see new swell from the Gulf building in late Thursday  pushing to the waist high range on Friday then heading down on Saturday but holding at thigh high into Sunday. The North Shore of Hawaii is to see more north angled swell from that gale in the Gulf but dropping fast on Friday at waist high and then effectively gone by the weekend. Maybe a little more Gulf windswell is expected in on Sunday at waist to chest high. The East Shore to see some of that Gulf swell on Friday with local windswell too at waist high filling in and holding through the weekend.  The South Shore is to be effectively flat on Friday and stay there with no change forecast.

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 a little down into Southern CA for late in the workweek. Hawaii too is already seeing some sideband energy from this one, but that is to be short lived.  But overall size and period are to remain modest. Another weaker system Pushed through the Western Gulf on Thurs (9/17) with 16 ft seas tracking 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 a quick moving gale is scheduled for the Gulf on Sat/Sun (9/20) arching to the north and producing 25 ft seas aimed at mainly the US West Coast. Maybe a little swell early next week. And Typhoon Choi-Wan remains tracking slowly north in the far Western Pacific. Latest data suggest is to to get picked up by the jetstream and slingshot east early next week, but energy levels in the jet are not to be strong enough to really super charge the remnants when the hit the dateline. Still, some decent swell looks possible. 


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

North Pacific

On Thursday (9/17) the North Pacific jetstream was flowing almost flat off Japan, ridging slightly over the dateline then dipping slightly south through the Gulf of Alaska providing some support for gale development there. Winds were up to 140 kts in pockets. Not too bad. Over the next 72 hrs the Gulf trough is to fade and push inland over British Columbia while a new trough is schedule to dig out in the Western Gulf Saturday with 160 kts winds flowing into it's western flank (a good thing) holding decently in to Monday (9/21). Good support for gale development. Beyond 72 hours the remnants of the Gulf trough are to hold fixed exactly in the Central Gulf but with winds slowly diminishing, down to 110 kts by Wednesday (9/23) and  holding there into late in the work week.  Decent support for modest gale development, but nothing more. 

At the surface on Thursday (9/15) a weak 988 mb low continued circulating in the Northern Gulf with limited 20-25 kt northwest winds pushing towards California.  A new gale low was starting to build just west of the dateline.  And Typhoon Choi-Wan was south of Japan. For now, the system near the dateline was of most interest. Over the next 72 hours this gale is to continue east tracking flat on the 42N latitude with 30-35 kt southwest winds forecast in it's southwest quadrant over a smaller area, and of no immediate concern. But by Saturday AM (9/19) is is to become assimilated in that semi-permanent low in the Gulf and start blooming, with 45 kt northwest winds forecast at 45N 163W aimed south towards Hawaii down the 350 degree path and a bit south of the 296 degree path to North CA. Seas on the increase from 18 ft. This system is to build more in the evening with a larger area of 45 kt winds firmly positioned in the gale south quadrant  at 47N 158W aimed due east or right up the 300 degree path to Central CA also targeting the Pacific Northwest. Seas forecast to 25 ft at 46N 158W mostly pushing towards the US West Coast. By Sunday AM (9/20) most fetch is to be pointing towards Alaska with residual fetch of 40 kts at 49N 155W aimed down the 307 degree path to Central CA. 28 ft seas are forecast pushing towards the Pacific Northwest from 49N 153W.  If all this occurs, some form of decent but short lived swell could result mainly for Central CA northward, with most energy hitting the Pacific Northwest.  But it's still a bit premature to know exactly what will happen.  

Weak 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.
Additional energy from the Bering Sea dropped southeast and became assimilated with the remnants of the Gulf of Alaska gale generating fragments of 25 kt westerly fetch and some 16 ft seas Wed/Thurs (9/17), likely setting up more follow-on generic 10 sec period windswell for the below locations over the weekend.  

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.


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


California Nearshore Forecast
On Thursday (9/17) high pressure that's been hanging in the Central Pacific is trying to push into Central CA, resulting in northwest winds at 15-20 kts over the entire North and Central CA coast, generating minimal northwest local windswell there and chop. This high and associated fetch is to migrate north and becoming more focused on Cape Mendo early Friday with Central CA winds settling back down below 10 kts. More high pressure out in the Pacific is to try and force it's way east on Saturday, suceeding in generating more north winds isolated to North CA and producing 30 kt winds over Cape Mendo Sunday and Monday producing windswell , but steering clear of the Central and South CA coast. A light wind pattern is forecast beyond into the end of next week (9/24). 


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

Typhoon Choi-Wan as located 700 nmiles south Tokyo Japan on Thursday 99/17) tracking north-northwest with sustained winds 115 kts, down from the whopping 140 kts (160 mph) of Tuesday and 145 kts of Wednesday. A slow turn to the north-northeast is expected on Friday (9/18) with winds still 105 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 on Saturday with a turn more to the northeast, putting Choi-Wan a bit off Northern Japan mid-day with 85 kts winds and turning extratropical. 35 ft seas from previous fetch is forecast at 30N 143E.  A full turn to the east is forecast after that with Choi-Wan approaching the dateline Monday AM (9/21) with winds down to 40 kts. This official forecast is much different than the picture the GFS model paints, with Choi-Wan getting sheared and falling apart before ever reaching the dateline. It remains way too early to tell exactly what will happen, but swell development for Northeast Pacific remains a possibility.  Will monitor.



South Pacific

At the surface on Thursday (9/17) the remnants of a gale that was southwest of New Zealand was fading as it.cgiowed into the Ross Ice Shelf over the Central Pacific. This system previously built 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.  Only Tahiti might get some limited sideband energy. Over the next 72 hours no swell producing fetch is forecast.


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 are to be on Typhoon Choi-Wan off Japan.  It is to do nicely through the weekend. But the latest run of the GFS model has it getting sheared apart as it stalls off the North Japan early Monday (9/21), with a fragment of it's energy stripped and racing towards the Gulf of Alaska but weakening all the while.  No swell to result if one is to believe the models. But it's way too early to believe this is the final outcome, and likely a different scenario will develop in the next run or two of the model.  This is still something to monitor. 

MJO/ENSO Update (reference): As of Thursday (9/17) 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 18.54. The 30 day average was up to 0.94 (effectively neutral) and the 90 average was up to 2.08.  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 Eastern equatorial Pacific, with a faint signal still present over the dateline to south of Hawaii. 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 remained present in the Indian Ocean but only modest in strength.  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. 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.  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. 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 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 we need more warm water over the long haul.  

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 from the west up to the dateline (no change). 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 another solid 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 perhaps a gale might try to organize just southeast of New Zealand on Wed (9/24) generating 29 ft seas aimed well to the north for 18 hours.  Will believe it when it happens. Otherwise nothing 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

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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