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Pacific Storm and Surf Forecast
Updated: May 4, 2010 8:31 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 = 1.0 - 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 5/3 thru Sun 5/9
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   

Windswell Continues for California
Small Southern Hemi Swell Too


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 (5/4) North and Central California was getting more local northwest windswell with waves head high and a tad cleaner than days previous, but not anything that is really rideable. Southern California was getting wrap around local windswell with surf maybe thigh high on the sets up north and hacked by wind,  cleaner down south, but still no more than waist high on the sets. Hawaii's North Shore was getting dateline swell with waves chest high and a few head high sets and clean. The East Shore was getting shoulder to head high east windswell and chopped. The South Shore was getting some thigh high sets with onshore winds late AM. 

The forecast for North and Central CA is for windswell to come up a little on Wednesday to head high or some more with southern hemi swell at shoulder high, then windswell down to chest to shoulder high on Thursday with southern hemi swell still shoulder high. By Friday windswell is to drop out with southern hemi swell fading from shoulder high. Waist high windswell expected on Saturday and dissipating. More windswell on Monday and beyond. Southern California is to see very limited northwest windswell at exposed breaks to thigh high Wednesday with southern hemi swell arriving then to near chest high late. Knee high windswell on Thursday with souther high southern hemi swell fading to chest high on Friday and waist high Saturday. Maybe new thigh high southern hemi swell on Monday again. The North Shore of Oahu is to see northerly windswell on Wednesday at thigh high, then nothing to follow. The East Shore to see east tradewind generated windswell at head high Wednesday fading to chest high Thursday and up a little Friday, back to near chest high through the weekend.  The South Shore is to see limited southern hemi southeast swell Wednesday peaking at chest high fading to waist high Thursday and then out. 

High pressure remains in control of the Northeast Pacific with local junky windswell and poor conditions forecast for the foreseeable future. No swell producing weather systems of any kind are forecast for the North Pacific. Down south a small gale wrapped up well to the north on Wed (4/28) producing 30 ft seas for 18 hours which should result in limited swell pushing north into Hawaii later Tuesday and the US West Coast on Wednesday. There's some suggestion of a new gale in the far Eastern South Pacific developing on Fri with up to 40 ft seas, but again the focus is to be South America with little direct energy tracking north. 


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

North Pacific

On Tuesday (5/4) the North Pacific jet was mostly consolidated running well to the south on the 40N latitude with a cutoff low over the Eastern Aleutians. No clear signs of troughs capable of supporting gale development were indicated. Over the next 72 hrs that cutoff low is to lift northwest and hold over the north Bering Sea while the main flow continue running flat along the 42N latitude.  Perhaps a trough might start developing over the dateline late in the period. Beyond 72 hours a small trough is to build just off the California coast pushing inland on Sun (5/9) while the dateline trough builds some though winds speeds are to be unremarkable, with a big ridge in between the two. Maybe a weak gale might results at the oceans surface on the dateline pushing slowly east.  The trough is to then lift up into the Gulf of Alaska into mid next week. In all a better configuration than weeks previous, but still generally weak. 

At the surface on Tuesday (5/4) high pressure at 1032 mbs was filling the Gulf of Alaska ridging southeast into Central CA continuing the pressure gradient along the coast there and generating north winds at 20-25 kts, resulting in modest short period windswell. The high pressure systems was also generating modest trades pushing up to the Hawaiian Islands at 20 kts, but not quite reaching there. Weak low pressure was over the dateline and another was pushing off the Kuril Islands, but both were exceedingly weak. Over the next 72 hours generalized high pressure is to hold over the Eastern Pacific continuing the gradient along California (and north winds and windswell) and trades over Hawaii (and east windswell) and build some in coverage, while weak low pressure holds in the West.  No swell producing weather systems are forecast through.


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


California Nearshore Forecast
On Tuesday (5/4) high pressure at 1036 mbs continued ridging into the Central CA coast setting up a pressure gradient and moderate north winds at 25 kts along the entire California coast with near shore chop in effect. The gradient is to hold Wednesday in the 25 kts range, then fade some Thursday and Friday with northwest winds down to 15 kts on into Saturday AM. Weak low pressure is to be off the coast Sunday reducing winds even more, then high pressure builds in behind on Sunday evening with north winds back to 25+ and holding Mon-Wed (5/12). In short, no real end to north winds, chop, upwelling and windswell.


South Pacific

On Tuesday (5/4) no swell producing fetch of interest was occurring in the South Pacific. 

South Pacific Gale
On Wed (4/28) a small spurious gale developed in the upper latitudes of the South Pacific with 40 kts winds aimed well north resulting in about 18 hours of 31 ft seas at 36S 141W. This is pushing swell towards Hawaii (from the southeast) and California.

Hawaii: Swell to hold at 2 ft @ 14 secs on Wed (thigh to waist high) then dropping out. Swell Direction: 170 degrees

Southern CA: Expect swell arrival on Wed (5/5) with swell to 2 ft @ 16 secs (3 ft faces) continuing on Thurs at 2.8 ft @ 15 secs (4.0-4.5 ft faces), then fading from 2.8 ft @ 14-15 secs on Thurs (4.5 ft faces). Swell Direction: 195 degrees


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 hrs high pressure is to hold between California and Hawaii, but low pressure in the West is to push east some and build, producing 35-40 kt north winds on the dateline on Sun/Mon (5/10), perhaps resulting in limited swell for Hawaii long term.  This low is to push high pressure closer to California, with the gradient tightening up along the coast there Mon/Tues (5/11) as low pressure drops south from Canada at the same time. Just more wind.

MJO/ENSO Update (reference): As of  Tuesday (5/4) the Southern Oscillation Index (SOI) was heading up again. The daily SOI was up to 22.08.  The 30 day average down to 11.16 with the 90 day average up to -2.97. A massive upward trend started in early March, Peaked at the end of April, and is loosing little if any ground, symptomatic of the Inactive Phase of the MJO and possibly La Nina. 

Wind anomalies at the 850 mb level (approx 5000 ft up) as defined by models suggest light westerly anomalies over most of the Eastern Pacific, suggesting that the Active Phase of the Madden Julian Oscillation has been occurring and is fading out. If that's the case it has had little effect on storm generation. Of more concern is that in the Indian Ocean almost up to the dateline easterly anomalies are in control, suggesting the Inactive Phase is brewing. It is scheduled to seep east into 5/10 and hold on the dateline pushing over the East Pacific into Central America by 5/13 covering the entire Pacific, then dissipate while pushing over the Eastern equatorial Pacific through 5/23. This signals the end of El Nino and eliminates any support for gale development. The Active Phase is forecast brewing behind it, but only weakly. At this point were believing that El Nino will not hang on for another year, and that rather we'll fall back into a La Nina Pattern (where the Inactive Phase takes control). Of other interest will be whether the Iceland Volcano will spew enough high level fine particle dust and aerosols into the atmosphere to produce a reflective effect, dropping surface temperature and pushing us into a multi-year La Nina.  This is a very real concern.  

Sea Surface Temp anomaly data (4/29) indicated no dramatic change from previous weeks, with warmer than normal waters consolidated on the equator more towards the dateline and less in the vicinity of the Galapagos Islands, but not gone from South America and if anything, holding their ground. Erosion of warmer waters over the Galapagos is expected, symptomatic of the fading of El Nino, but is not occurring yet. A massive buildup of warmer than normal waters is occurring in the Atlantic,.of concern to hurricane forecasters there. We'll see if upper level winds support development of hurricane activity though. Suspect residual upper level shear from El Nino will have an impact well into the summer there.

Below the surface on the equator no Kevin Wave activity was present. 

Over the entire Equatorial Pacific trades were blowing all the way to almost the Philippines, but only in the normal range. This looks like the normal Springtime transition typical for this time of the year. 

El Nino is effectively gone and slowly loosing it's grip on the global atmospheric weather pattern. Still some lingering impact is to continue into the Summer of 2010 enhancing the storm track in the South Pacific some. A slow transition to a normal state is expected through Nov 2010.   

See more details in the new  El Nino update.


South Pacific

Beyond 72 hours the models indicate a gale might wind up in the far Southeast Pacific on Thurs-Fri (5/7) resulting in a fetch of 45-50 kts southwest winds on Thurs PM at 53S 137W aimed 35 degrees east of the 189 degree path to California with 40 ft seas by Fri AM at 52S 131W.  If this occurs some sideband swell could result pushing up into California, though mostly focused on Central America down into South America. Will monitor. 

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

A Luau for the Wave Riders is presented by the HMB Surf Club (an affiliate of the Boys and Girls Cub of the Coastside). All proceeds will benefit the HMB Middle and High School Surf Teams. Date: Saturday the 8th of May 2010 at 6pm Location: Sea Crest Gym at 901 Arnold Way, Half Moon Bay, CA. Cost: $40.00 per person [tickets purchased after May 1st $50], $25.00 per kid (12 and under) For more information or to purchase tickets,.cgiease contact Paula (email: or call: 650-269-3180)

  • 6:00pm - Appetizers
  • 7:30pm - Buffet Dinner
  • 8:30pm - Live Music by, Blame it on the Dog
  • Cash Bar- Beer & Wine
  • Raffle & Silent Auction

Stormsurf Hi-Res Coastal Precipitation Models Upgraded Though a bit late in the season, on 3/20 we i.cgiemented the same basic technology used in our new snow/ski models into the coastal hi-res precipitation models. So now you can not only determined whether rain is forecast for your area, but also snow. And not just light, medium or heavy snow like most sites, but the exact snowfall amount (in inches) for each 3 hr frame of the animation. Here's a sa.cgie, but now this approach is used in all our precipitation models.

Stormsurf Precip Models Upgraded! On 2/20 we upgraded some of the broader precipitation models driven by the hi-def GFS model to include snow fall. The algorithm used is similar to the recently released snow models for the Southwest US in that the areas where snow is expected are identified and the exact amount of snow forecast over a 3 hr window is e.cgiicitly color coded. For East and West Coast US interests the following links provide good exa.cgies:
West Coast:
East Coast:

Stormsurf Weather Models have all been upgraded! Over the New Years break we installed all new and upgraded weather models. Also new are experimental snow models for the Southwest US. Take a look here:

Read about Eric Nelson and Curt Myers, the makers of Ride-On and other Big Wave Surf Movies here:

Ride On! Powerlines new big wave epic is now available on DVD. Get the entire big wave story of the 2008-2009 season here:

Click here to learn more about Casa Noble Tequila! Casa Noble Tequila If you are looking for an exquisite experience in fine tequila tasting, one we highly recommend, try Case Noble. Consistently rated the best tequila when compared to any other. Available at BevMo (in California). Read more here:

Interview With Stormsurf:  The crew at worked with Stormsurf on a feature about why surfers should be able to read wave charts themselves. They are firm believers that a little learning can go a long way to help your surfing.  This is a great article to help convince your friends that they can benefit from being able to read the data themsleves rather than just relying on the forecasts of others.  See the full thing here:  Create Your Own Surf Forecast with Stormsurf

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

Free Stormsurf Stickers - Get your free stickers! - More details Here

Read all the latest news and happenings on our News Page here

Surf Height-Swell Height Correlation Table


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