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Pacific Storm and Surf Forecast
Updated: July 12, 2010 9:31 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 = 2.5 - California & 1.5 - 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 7/12 thru Sun 7/18
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 N. Pacific Swell Pushing Into California
Long Lasting Southern Hemi Gale Tracking Northeast


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 Monday (7/12) North and Central California had no surf of interest with waves thigh high or less.  Southern California was getting weak southern hemi background swell at maybe 2 ft on the faces but in general no swell of interest was occurring with waves knee high up north with northwest wind on it a little and textured conditions. Down south there was no real swell either with occasional thigh high weak lappers crumbling into the beach. There was a fair amount of texture on the oceans surface too. Hawaii's North Shore was getting freakish northwest windswell coming from the dateline with waves chest high with maybe a rare head high section or two and clean, though weak. The East Shore was getting waist high tradewind generated east windswell and lightly chopped. The South Shore was getting minimal background southern hemi swell  with waves waist high or so and clean with light trades in effect.

The forecast for North and Central CA is for new swell from the dateline arriving on Tuesday (7/13) at head high to maybe 1 ft overhead with a bit of period mixed with new building local north short period windswell at shoulder high.  That dateline swell is to be fading from chest high on Wednesday with more local north short period windswell on top of that.  Thursday local windswell is to be all that's left providing weak chest high surf with maybe a little southern hemi background swell underneath at thigh high late and continuing at thigh high on Friday with waist high.cgius local windswell on top.  Southern California is to see no northerly swell exceeding 2 ft on the faces through the workweek.  That said, there's a remote chance for some of the northwest swell to be present late on Tuesday/early Wed at the most exposed breaks. Otherwise barely noticeable weak southern hemi background swell to continue at knee high Wed and fading Thursday, then be reinforced by more of the same on Friday. The North Shore of Oahu is to fall back into flatness by Tuesday with no change forecast anytime soon.  The East Shore to see east tradewind generated windswell at maybe waist high Tuesday, then fading out to nothing with no change forecast till the weekend. The South Shore is to see a bit of an increase in Southern Hemi swell on Tuesday with surf a more solid waist high building to chest high on Wednesday then down to waist to chest high early Thursday and waist high Friday.

Up north a broad area of low pressure built on the dateline into the Western Gulf on Fri-Sat (7/10) generating 40 kt west winds and 26 ft seas pushing towards the Pacific Northwest that swell is to high the California region on Tuesday.  Down south a gale pushed under New Zealand on Sat (7/10) lifting northeast with 32-36 ft seas over a small area but shadowed relative to California, then it is forecast to regenerate and tracking further northeast into the middle of this week with up to 40 ft seas. Possible small swell to result initially for Hawaii by this weekend (7/17) and then better size for the US West Coast the week beyond.  After that no other swell producing weather systems are forecast. 


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

North Pacific

On Monday (7/12) the North Pacific jetstream was tracking generally flat west over the 45N latitude with a very weak and diffuse trough centered over the dateline but so weak as to offer no odds to support surface level low pressure development. And equally weak ridge was over the far eastern Gulf of Alaska. Over the next 72 hours the trough on the dateline is to ease east and disintegrate while reinforcing energy develops on the dateline, effectively holding the same pattern in.cgiay. Beyond 72 hours the jet is to continue flowing generally flat west to east on the 45N latitude with no wind energy of interest developing.  A weak trough is to be centered just west of the dateline with a weak ridge over the Central Gulf of Alaska. No significant change in the weather at the oceans surface is expected. 

At the surface on Monday (7/12) the usual area of high pressure was centered 900 nmiles west-northwest of Cape Mendocino California at 1032 mbs barely ridging into the coast there generating a small area of 20-25 kt north winds just off the coast and producing minimal short period north angled weak windswell down into exposed breaks of Central CA. The high was too far north to be having much impact on trades over the Hawaiian Islands, with a light easterly flow there below 15 kts. Over the next 72 hours much the same pattern is to hold if not a.cgiify some with winds building to near 30 kts over  tiny area over Cape Mendocino Tues/Wed  resulting in a slight increase in localized north windswell pushing down into Central CA.  no change in trades forecast for the Hawaiian Islands with easterly windswell remaining below interest levels.  

Dateline Gale
A gale deepened over the eastern dateline region on Thursday evening (7/8) with pressure dropping down to 968 mbs with a decent sized fetch of 40 kt west and northwest winds building at 46N 173W and holding there, up to 45 kts Friday AM at 47N 171W then fading from 40 kts in the evening at 47N 166W.   This fetch is to be aimed mostly towards the Pacific Northwest down into Northern CA. Seas were modeled jumping to 25 ft Fri AM at 47N 171W, then 26 ft in the evening at 48N 166W and fading from 26 ft Saturday AM at 48N 161W. Swell from this system has already hit the Hawaiian Islands and some degree of decent 14-15 sec period swell is expected pushing into Central CA and points north of there by Tuesday (7/13). This system was 2100 nmiles away from the US West Coast and whatever swell does arrive will experience much decay on the long journey east.  Still, for July it would be a rare treat indeed. For Central CA, expect swell reaching 4.5 ft @ 14-15 secs mid-day Tues (6.5 ft faces) from 300 degrees. 


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


California Nearshore Forecast
On Monday (7/12) high pressure at 1030 mbs was positioned 900 nmiles west of Cape Mendocino and was ridging lightly into the US West coast over Oregon forming the usual pressure gradient and north winds over the extreme North CA coast at 30 kts.  But no fetch was reaching south of Cape Mendo with a generally light if not eddy flow (south winds) in control.  This general pattern is to hold through the work week with only little variation day to day.  Secondary north fetch at 15 kts is forecast over Point Conception. The gradient is to work it's way south some on Saturday (7/17) with 30 kts north winds still holding up north, and 15 kt north winds sweeping down much of the outer Central CA coast, likely adding a fair amount of warble and bump to nearshore surface conditions and getting more pronounced on Sunday. Then by next week the gradient itself is to dip south with 15-20 kts winds over all Central CA waters, with chop or at least lump in control making a mess of the surf picture.  


South Pacific

On Monday (7/12) the same .cgiit and fragmented jetstream pattern remained in control of the South Pacific. That said, a trough that originated under New Zealand on Sat (7/10) had migrated east while pushing pretty well to the north with it's apex now at 50S 133W but with only 100 kt winds flowing up into it.  Still, it had some momentum potential to support gale development down at the oceans surface. Over the next 72 hours reinforcing wind energy is to be pushing east feeding up into that trough which is to be holding stationary in the same general area, or drifting a bit to the east. 120 kt southwest winds to be pushing up into the trough  late Wednesday (7/14) pushing 140 kts on Thursday.  Good support to feed development of gale energy at the oceans surface. Beyond 72 hours that energy is to push hard to the east pinching the trough off while pushing it to the east and out of the California swell window late Friday (7/16).  At that time and in the days that follow a fully .cgiit jet with a ridging pattern in control of the southern branch of the jet is forecast rending surface level gale development unlikely. 

At the oceans surface a 972 mb gale was continuing to push east across the South Pacific (see South Pacific gale below). Otherwise high pressure at 1040 mbs was just west of the extreme southern tip of South America and a second high at 1028 mbs was adjacent to the east coast of New Zealand, suppressing gale development in those locations. Over the next 72 hours the South Pacific gale is to continue lifting northeast in the Southeast Pacific (see details below). Otherwise no swell producing fetch of interest is forecast. 


South Pacific Gale
Part 1
A broad area of gale force winds developed in association with e 960 mb low southeast of New Zealand Friday night (7/9) with 45 kt west-southwest winds at 61S 172E building to 45-50 kts Sat AM (7/10) from the southwest to south at 58S 171W then holding at 45 ks blowing almost directly from the south in the evening at 59S 162W. Seas were modeled to 34 ft Sat AM at 59S 178W pushing to 36 ft in the evening at 57S 162W, then fading from 30 ft Sunday AM at 53S 159W. This is on the 189-181 degree tracks to Hawaii and the 206-200 degree tracks to California (and shadowed by Tahiti). Possible swell generation potential for Tahiti, with sideband energy for Hawaii and shadowed and somewhat indirect energy for the US West coast.

Hawaii:  Expect swell pushing into the south shore of Oahu starting Saturday (7/17) with period 19 secs and pushing 2 ft @ 18 secs at sunset (3.5 ft faces with sets to 4 ft at top spots). Swell to start peaking as period hits 17 secs at 6 AM Sun (7/18) and holding through the day as period falls to 16 secs.  Pure swell to be 2.6 ft @ 16-17 secs (4.0-5.0 ft faces).  Swell to be dropping from 2.4 ft @ 15 secs (3.5 ft faces) on Monday (7/19). Swell Direction: 182-191 degrees  

South CA:  Expect swell arrival starting early Monday (7/19) with period 20 secs and and size tiny but building reaching 2.6 ft @ 19 secs late (5.0 ft faces).  Swell to start peaking on Tuesday (7/20) at 2 AM with period 17 secs and size up to 3.2 ft @ 17 secs (5.5 ft faces) but inconsistent.  Swell holding into Wednesday AM (7/21) with pure swell 3.0 ft @ 16 secs early (5 ft faces), and slowly settling down.  

North CA:  Expect swell arrival starting early Monday AM (7/19) with period 21 secs and and size tiny but building reaching 2.6 ft @ 20 secs late (5.0 ft faces).  Swell to start peaking on Tuesday (7/20) at 8 AM with period 17 secs and size up to 3.2 ft @ 17 secs (5.5 ft faces) but inconsistent.  Swell holding into Wednesday AM (7/21) with pure swell 3.0 ft @ 16 secs early (5 ft faces), and slowly settling down.     

Part 2
Then a secondary fetch of 45 kt south to southwest winds started building southwest of Tahiti on Sunday AM (7/11) at 60S 170W and building while tracking east. In the evening a solid fetch of 50 kt southwest winds was located at 56S 160W and just east of the core of the Tahiti swell shadowed at 201 degrees and lifting steadily northeast.  Seas were building from 32 ft at 57S 166W.  On Monday AM (7/12) a solid fetch of 45+ kt south-southwest winds was located at 52S 149W aimed almost right up the 195-196 degree path to California, completely unshadowed. 38 ft seas are modeled at 54S 151W pushing up the 196 degree path to CA. In the evening the fetch is forecast to shrink a little but build in intensity with 50 kts south winds at 51S 140W aimed right up the 192 degree path to California.  40 ft seas are forecast at 49S 141W pushing well up the 193 degree path.  On Tuesday AM (7/13) the fetch is to hold with a small area of 50 kts south winds at 48S 131W pushing right up the 187 degree path to California. A tiny area of 44 ft seas are forecast at 45S 134W. By evening the fetch is to be fading fast with 40 ft sea from previous fetch fading at 42S 127W.

There's some decent potential for swell pushing up to the US West Coast with maybe sideband energy into Tahiti. Hawaii is to be pretty far off and great circle route from this fetch though. 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 hrs weak high pressure is to again ease east causing the pressure gradient over Cape Mendocino to tighten up some and re-generating north winds at 30 kts over a tiny area on Friday (7/16) and Saturday then backing off a notch Sunday to the 25 kt range. Small short period north windswell is expected pushing south into Central CA. But after that the gradient is to fade a little with winds down to 20-25 kts, and the core of that fetch is to push over Central CA waters, with windswell there turning raw and jumbled into Tues (7/20).


MJO/ENSO Update (reference): As of Monday (7/12) the Southern Oscillation Index (SOI) remained in positive territory. The daily SOI was at 16.00 and has been positive for 18 days running. The 30 day average was up to 7.07 with the 90 day at 6.97. This is looking like the start of a modest run of the Inactive Phase of the MJO.  

Wind anomalies as of Monday (7/12) at the 850 mb level (approx 5000 ft up) as defined by models suggested light west anomalies holding over most of the equatorial Pacific with light east anomalies limited to the Indian Ocean. This suggests the Active Phase of the MJO was still trying to hold on over the Eastern Pacific and had actually expanded it's coverage, not dying as fast as previous forecast. The Inactive Phase was trying to build in the Indian Ocean, but was not making any headway. Regardless, the Active Phase is to fade quickly through 7/21 while the Inactive Phase builds into the far Western Pacific at the same time, then weakly in control of the entire Pacific by 7/26, fading slowly in to the end of the month (7/31).    

We believe the remnants of El Nino are trying to linger in the upper atmosphere for a while longer. But in reality, they are almost gone. The expectation is that we'll fall back into some form of a light to moderate La Nina Pattern (where the Inactive Phase takes control) for later 2010 into 2011. NOAA seems to support that.cgian too per the latest ENSO update last week. 

Sea Surface Temp anomaly data (7/1) indicates that cooler than normal waters have developed over a moderate strip on the equator from South America drifting west to the dateline and are in fact getting cooler and covering a larger area over time, extending the whole way to almost New Guinea now.  And feeder bands of colder than normal water have developed pushing off the US West Coast and South America reaching to the dateline, only serving to reinforce the existing pattern, suggesting stronger than normal high pressure has built in both hemispheres. Looks like a classic La Nina setup. This is a turn for the worse and only seems to be getting stronger. At the same time a massive buildup of warmer than normal waters continues in the Atlantic almost bleeding into the far Eastern Pacific, of concern to hurricane forecasters there. We'll see if upper level winds support development of hurricane activity or whether residual upper level shear from El Nino will chop the tops of developing systems. Suspect shear will be gone by the heart of hurricane season in the Atlantic.

Below the surface on the equator no Kevin Wave activity was present and if anything colder than normal water was building strong over the dateline and pushing east (sort of like a cold Kelvin Wave). This pocket was -4 degs below normal. Not good. 

Over the entire Equatorial Pacific trades were blowing all the way to the Philippines and beyond, but only in the normal range. But there has begun to be some signs of slight easterly anomalies developing, which is to be expected given all the other data. This is typical for this time of the year but is likely to change towards an increased easterly flow as Fall approaches symptomatic of La Nina.  

El Nino is effectively gone and slowly losing it's grip on the global upper atmospheric weather pattern. Still some lingering impact is to continue through the Summer of 2010, but likely not enhancing the  storm track in the South Pacific any longer. A slow transition to a normal if not cooler than normal conditions (La Nina) is expected through Nov 2010, and the signs continue to point to a La Nina pattern for the long term future. 

See more details in the new  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

Powerlines Productions Greatest Hits - Come see excerpts from Powerlines greatest Mavericks movies at the Red Vic in San Francisco on Wednesday July 7th at 2:00, 7:15 and 9:15 PM. Also a sneak peek at their new movie featuring footage of the epic 2009/2010 El Nino winter will be screened. The producers will be on-hand to take your questions.

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:
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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:

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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

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.

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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