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Pacific Storm and Surf Forecast
Updated: April 21, 2009 9:04 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 = 4.0 - California & 2.0 - 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 4/20 thru Sun 4/26
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   

Swell #1S Pushing Toward CA
Quiet Pattern After That Both North and South


New Swell Classification Guidelines (Winter)

Significant: Swell 8 ft @ 14 secs or greater (11+ ft faces) for 8+ hours (greater than double overhead)
Advanced: Swell and period combination capable of generating faces 1.5 times overhead to double overhead (7-10 ft)
Intermediate: Swell and period combination generating faces at head high to 1.5 times overhead (4-7 ft)
Impulse/Windswell: Swell and period combination generating faces up to head high (1-4 ft) or anything with a period less than 11 secs.

We want to congratulate all the winners of the Billabong XXL awards held Friday night (4/17) in Southern CA. A solid contingent of Northern CA folks made it down for the awards including Jeff Clark (presenter Monster Paddle), Grant Washburn and Frank Quirarte. Mike Parsons provided great commentary too. But a big call out to winners who put in time up here in Northern CA, including Derek Dunfee for the Monster Paddle at Mav's on Nov 30th, our friend Twiggy Baker for Biggest Wave of the Year at Tafelberg reef on Aug 9 2008 (outside Dungeons) and Performance of the Year, and the big money to our friend Greg Long for Ride of the Year at Dungeons on July 26. An excellent performance by all and very articulate and thoughtful acceptance speeches by both Greg and Twig. You do the sport of surfing and Billabong proud! A new generation is in-control of the helm.

On Tuesday (4/21) North and Central California had waist high residual northwest windswell with decently clean conditions. Southern California was near flat with minimal northwest windswell wrapping into only the most exposed breaks at thigh high with clean conditions. Hawaii's North Shore was getting limited north-northeast windswell at chest high and reasonably clean. The East Shore had shoulder to head high north-northeast windswell. The South Shore was knee to thigh high and on the increase coming from the southern hemi. 

The forecast for North and Central CA is for next to northing surf-wise until southern hemi swell #1S starts arriving on Thursday, peaking Friday and then on the decrease Saturday into Sunday.  This is to be a pretty decent swell so make the most of it. Southern CA is to be the standout spot in the US for the southern hemi swell, peaking late Thursday into early Friday.   Oahu's North Shore is to continue seeing limited north windswell into early Friday (4/24) then heading down. Much smaller after that. The East Shore is expected to see that same north windswell, turning more northeasterly through the workweek and dropping off over the weekend.  The South Shore is to continue seeing sideband swell from a Storm #1S into  Wednesday (4/22) then dropping off.   

Longterm virtually nothing of interest is forecast in either the North or South Pacific for the next 7 days.  Sure, there rumors of a gale on the dateline over the weekend, but odds of that actually occurring are low. So make the most of the swell you have coming, cause it might be a while till you get another shot at it. 


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

North Pacific

On Tuesday (4/21) the North Pacific jetstream remained a fragmented mess with no troughs of interest occurring and a large .cgiit pattern over the Eastern Pacific. Over the next 72 hours through Friday (4/24) a decent weak trough is to set up off Kamchatka with 145 kt winds feeding into it pushing to the dateline and offering limited support for gale development. Beyond 72 hours that trough is to fade out on the dateline Sunday (4/26) with a singular flow pushing northeast from Japan to the northeast .cgiitting in the western Gulf with residual energy tracking up into North Canada and offering no support for low pressure development.  

At the surface the only system of remote interest was a cutoff low circulating 900 nmiles northeast of Hawaii producing up to 30-35 kt northeast winds and 19 ft seas near 37N 153W aimed well of Oahu as it has since Monday evening. This will result in some 4-5 ft @ 11-12 sec period windswell for northeast shores Wed PM into Thurs (4/23) with 5-6 ft faces at exposed breaks from 10 degrees. Over the next 72 hours high pressure at 1032 mbs is to build in the Gulf of Alaska producing 15-20 kt north winds down the Pacific Northwest coast peaking at 25 kts over Cape Mendocino and producing short period windswell down into Central CA, then fading into Friday. A gale low is to build east of Japan lifting northeast Thursday (4/23) but all fetch is to be aimed north towards the Aleutians offering no swell generation potential.   


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


California Nearshore Forecast
On Tuesday (4/21) a neutral pressure pattern had set up calm winds and warmer than normal temperatures over California. But by Wednesday building high pressure in the Gulf of Alaska  is to start producing 30 kt north winds over Cape Mendocino pushing south to Pt Arena late and building into the San Francisco/Monterey Bay area by evening, likely bringing a much desired drop in temperatures but also producing 20 kt northwest winds nearshore and chop above Pt Conception. By Friday (4/24) the gradient over Cape Mendocino is to die along with any windswell it produces, but a shallow area of nearshore 20 kt north winds are to prevail with the high holding strong in the Gulf ridging southward to the Channel Islands by evening with chop likely everywhere except protected breaks in SCal and holding that way into Saturday and Sunday (4/26). A bit of a break from the wind is forecast Monday and Tuesday (4/28) nearshore, with improving conditions.  

No tropical activity of interest was occurring.


South Pacific

On Tuesday (4/21) the South Pacific jetstream was .cgiit pushing east from Australia, then consolidating south of Tahiti but flowing generally flat east from there into Chile.  No troughs were present offering no odds for surface level gale development. Over the next 72 hours a decent pulse of upper level energy is to build in the southern branch pushing under New Zealand Thursday (4/23) starting to build a trough south of Tahiti by Friday with up to 130 kt wind building northward offering some odds for gale development. But by late Saturday that trough is to be undercut and fading out fast. Beyond 72 hrs a flat zonal flow is forecast to take over and centered generally pretty well to the south near 65S, not offering much chance for low pressure development.

At the surface a 980 closed isobar low formed just south of New Zealand producing 50 kt southwest winds at 60S 165E with seas on the increase.  In the evening though winds are to track northeast quickly and fade to 49 kts at 56S 178E with 31 ft seas forecast at 57S 174E pushing 30 degrees east of the 193 degree great circle path to Hawaii.  By Wednesday AM (4/22) almost all fetch is to be gone with residual 30 ft seas forecast at 54S 177W and fading fast, gone by evening. There's some potential for small 16 sec sideband utility swell to reach up into Hawaii from this one if it does are forecast.  Will monitor. Otherwise over the next 72 hours no swell producing fetch is forecast. 

A storm formed Friday PM (4/17) well south of New Zealand producing a small area of 55 kt south winds at 65S 172E aimed well up the 193 degree path to Hawaii but practically over the Ross Ice Shelf. It was quickly fading Saturday AM (4/18) with 45 kt southwest winds modeled at 65S 175W and seas barely 29 ft over a tiny area at 64S 175W. Winds were gone by evening with 29 ft seas from previous fetch fading at 64S 165W. Doubtful any noticeable swell is to result.  

Storm #1S
A gale started developing under New Zealand pushing east Monday (4/13). by the evening 45-50 kt wind blowing to the northeast were confirmed at 60S 170W with seas building.  The Jason-1 satellite passed over this are and confirmed seas at 30 ft with a single peak reading to 40 ft.

By Tuesday AM pressure dropped to 968 mbs with a decent sized fetch of 50 kt winds confirmed building at 56S 158W starting to get traction on the oceans surface and building in size pushing up the 198 degree path to California and barely unshadowed by Tahiti. 35 ft seas were modeled at 59S 162W. In the evening pressure dropped to 964 mbs with a solid area of 40-45 kt southwest winds at 53S 153W pushing northeast on the 197-198 degree path to California and unshadowed by Tahiti. Seas were modeled up to 42 ft at 56S 155W. The Jason-1 satellite passed over the northeast corner of the fetch an confirmed seas at 37.4 ft where the modeled suggested seas should be 35-36 ft.  The model was right on track if not a foot low.   

By Wednesday AM (4/15) this system was fading with a large fetch of 40-45 kt southwest winds modeled at 53S 145W but the QuikSCAT satellite found only 35-40 kt winds blowing to the north-northeast, pushing right up the 197-199 degree paths to California and unshadowed with seas holding at 39 ft at 52S 147W. In the evening winds were on the way up as the second pulse of this storm got organized.  50 kt winds were confirmed even though models suggested only 35-40 kt at 52S 1451 with 35 ft seas from previous fetch modeled at 50S 140W (191 degrees CA). The Jason-1 satellite passed right over the core of this system at 0Z and reported seas of 33.7 ft with a peak to 40 ft. A second pass over the northwest corned at 06Z confirmed seas at 30.4 ft with a peak to 41 ft where the model indicated 30 ft seas.  So again the model was pretty much right on track. 

Thursday AM (4/16) the gale peaked out 55 kt southwest winds confirmed at 48S 128W aimed 30 degrees east of the 188 degree path to California pushing seas back to 39 ft at 49S 132W. A shrinking area of 45-50 kts southwest winds were fading in the evening at 48S 123W with seas modeled peaking at 43 ft at 48S 123W. 

40 kt winds were modeled continuing into Friday AM with seas fading from 36 ft at 45S 120W and starting to push well east of the CA swell window focusing on Chile and Peru better. 

This storm actually beat what the models called for 5 days ago, a rarity. It produced 108 hours of decent fetch with peaks to near 55 kts, resulting in two 24 hr long spurts of 40 ft seas aimed reasonably well to the north up the 198 and 188 degree paths to California. This is the best we've seen so far this season by a mile and seems entirely likely to produce longer period significant class summer time swell for the US West Coast, the first significant class swell of the 2009 summer season. Side band energy is likely for Hawaii from early in the this storms life (when it was under New Zealand) with healthy size expected into Mexico down to Chile. This system was 4969-6127 nmiles from North CA and 4708-5969 nmiles from SCal. One can expect two distinct swell pulses from this storm relative to California, one from when it was just southeast of New Zealand from a more westerly direction and the second from when it was in the Southeast Pacific, coming from a more southerly direction.  Both to produce energy up to near 20 secs, with peak size in the 17 sec bandwidth.       

North CA: Expect swell pushing into the coast starting early Wed (4/22) with period 20+ secs, with the second pulse arriving Thursday AM again at 20 + sec, peaking late Thursday evening after sunset for the first pulse and 2 PM Friday for the second, then dropping into the 15-16 sec range for Sat (4/25) and 14-15 secs Sunday (4/26).  Peak swell size for the first pulse is expected at 3.5-4.0 ft @ 17 secs (6-7 ft faces with top breaks to peak at 7.5-8.5 ft) from 192-198 degrees with the second pulse perhaps up to 4.0-4.5 ft @ 16-17 secs (6.5-7.5 ft faces with top spots to 8-9 ft) from 180-186 degrees (though that might be a little on the high side).

Southern CA: Expect swell arrival starting well before sunrise early Wed (4/22) with period 20+ secs, with the second pulse arriving Thursday before sunrise again at 20 + sec, peaking late Thursday late afternoon for the first pulse and 6 AM Friday for the second, then dropping into the 15-16 sec range for early Sat (4/25) and 14-15 secs early Sunday (4/26).  Peak swell size for the first pulse is expected at 3.5-4.0 ft @ 17 secs (6-7 ft faces with top breaks to peak at 7.5-8.5+ ft) from 192-198 degrees with the second pulse perhaps up to 4.0-4.5 ft @ 16-17 secs (6.5-7.5 ft faces with top spots to 8-10 ft) from 180-186 degrees (though that might be a little on the high side).


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 the gale off Japan is to track northeast reaching the intersection of the dateline and the Aleutians with 30 kt northwest winds Saturday (4/25) aimed at the US mainland into Sunday, then fading. Theoretically 26 ft seas are forecast at 46N 180W Saturday evening fading from 25 ft Sunday AM at 46N 175W.  If this occurs there limited odds of 14 sec period swell for the US West Coast about 4 days out. Otherwise high pressure is to hold in the Gulf of Alaska into Sunday generating north wind at 20-25 kts and producing some flavor of short period north windswell for the Pacific Northwest down into Central CA. Trades to remain no stronger than 15-20 kts through the week over the Hawaiian Islands reducing the probability for east windswell there.     

MJO/ENSO Update (reference): As of Tuesday (4/21) the Madden Julian Oscillation (MJO) was in the Inactive Phase with the ENSO (El Nino Southern Oscillation) index holding in the positive range. The Daily SOI index down to 6.49, showing signs of weakness from the 14 day positive streak it was on. The 30 day average was up to 8.3 and the 90 day average was up to 8.44. The SOI indicies remained weakly symptomatic of La Nina mainly attributable to the 90 day average. Wind anomalies at the surface and the 850 mb level (approx 1000 ft up) indicated that the Inactive Phase is on it's way out with easterly anomalies only isolated to the Eastern Pacific tracking well into the Atlantic and fading fast while anomalous west winds associated with the Active Phase were holding on the equator north of Australia seeping toward the dateline. This Inactive Phase is to be gone by 4/25 with the new Active Phase building in moderately behind it, pushing to the dateline by 4/25 but weakening as it tracks east filling the Pacific by 4/30 ad then heading east towards the Atlantic by 5/5.  A new flavor of the Inactive Phase is forecast building in the Indian Ocean by 5/5, but is expected to be weak as it moves east.  The residual effects of 3 years of La Nina remain in-control in the atmosphere. Cooler than normal surface water off of Central America appears to be gone with normal water temps back in.cgiay. And below the surface on the equator cool water that had locked down the region is essentially gone, the first time in months. So now we are waiting to see if something will kick us into a warm regime in the equatorial Eastern Pacific, or whether neutral conditions will prevail.  Regardless, it will still take months before the atmosphere begins to simmer down from the La Nina induce pattern currently in effect. Expect 3-4 months from  about now before a neutral pattern takes hold (i.e. no .cgiit in the jetstream over the North Pacific). 


South Pacific

Beyond 72 hours the models have taken a dose of reality, given the strong Inactive phase of the MJO and a flat if not .cgiit jetstream flow in.cgiace aloft.  Virtually no swell producing fetch is modeled.

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

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:

The Kelly Slater Project - A group of dedicated surfers from Cocoa Beach are working to construct a statue of the the home town legend and set it up for all to enjoy near the break where Kelly grew up surfing. Take a look at the statue and read all about it here:

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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