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Pacific Storm and Surf Forecast
Updated: July 20, 2010 8:03 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 7/19 thru Sun 7/25
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 #6S Hits California
Models Hint at More to Come After a Short Break


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 (7/20) North and Central California was getting larger locally generated north windswell with waves head high to 1 ft overhead but raw and pretty well blown out even early. Some southern hemi swell was lurking underneath at head high or a little more later. Southern California was getting fragments of the windswell at waist high or a little more and reasonably clean up north early with limited southern hemi swell #6S trying to sneak in through the Channel Islands. Down south Swell #6S was in control with waves up to 1 ft overhead at better breaks and clean early getting textured later. Hawaii's North Shore was 1-2 ft and and clean early but crashing right on dry sand. The East Shore was getting waist high tradewind generated east windswell and lightly chopped. The South Shore was still getting limited southern hemi swell with waves thigh to waist high on the sets and clean early with light trades in effect.

The forecast for North and Central CA is for more local windswell on Wednesday with at 6.0 ft and southern hemi swell up to 6 ft. The fade begins on Thursday with windswell dropping from 4.5 ft and southern hemi swell down to 4.5 ft. Friday windswell is to chest high with southern hemi swell dropping out all together and then windswell down to waist high Saturday with maybe some limited southern hemi swell underneath at waist high or so, with both fading on Sunday. Southern California is to see more southern hemi swell Wednesday at 1.5 ft overhead and windswell at knee high. Thursday windswell holds at knee high and southern hemi swell fades from head high. Friday and beyond no rideable windswell is expected with southern hemi swell rebuilding to waist high later thanks to a new pulse arriving from a southerly angle pushing waist high.cgius on Saturday, then dropping to less than waist high on Sunday.  The North Shore of Oahu is to see no rideable surf through the week on into the weekend and no change forecast anytime soon.  The East Shore to see perhaps a small push of east tradewind generated windswell on Wednesday at thigh to waist high and holding Thursday solidifying at waist high.cgius Friday and holding through the weekend. The South Shore is to see maybe thigh high residual southern hemi swell and fading early Wednesday before it goes flat. Low odds of maybe thigh high background energy on Sunday. 

Up north a quiet summertime weather pattern is forecast offering no potential for swell production over the next 7 days.  Down south the models have changed their tune now suggesting a gale is to lift gently east-northeast Thursday (7/22) generating up to 36 ft seas just southeast of New Zealand, then fading out. Maybe limited sideband swell for Hawaii and shadowed background swell for California if all goes as.cgianned a week or more beyond. 


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

North Pacific

On Tuesday (7/20) the North Pacific jetstream continued tracking generally over the 45N latitude in the west with winds 110 kts, then fading as it passed over the dateline and getting very weak offering nothing in terms of support for low pressure development of oceans surface. Over the next 72 hours more of the same is forecast with a trough holding just west of the dateline but getting weaker, with all it's energy flowing up into a developing ridge in the east most likely supporting the development of high pressure there. Beyond 72 hours the jet is to become focused on a building ridge over the Western Gulf of Alaska with the jet itself flowing almost over the Aleutians and not offering anything that would be considered supportive of low pressure development.  

At the surface on Tuesday (7/20) high pressure was locked centered 1400 nmiles west-northwest of Cape Mendocino California at 1036 mbs ridging some into the coast there generating a modest sized area of 25+ kt north winds positioned just off the coast and producing moderate north angled windswell that was reaching down into exposed breaks of Central CA. The high was also generating limited 15 kt east trades pushing over eastern shores of the Hawaiian Islands and maybe producing up to waist high easterly windswell there. Over the next 72 hours much of the same is forecast with a steady area of north winds holding over Cape Mendocino perhaps building to near 30 kts on Thursday (7/22) but shunted up north more and aimed more west than south, meaning a little less windswell likely tracking down into Central CA. Trades also continuing over the Hawaiian Islands at 15 kts, likely continuing to produce modest easterly windswell there.  


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


California Nearshore Forecast
On Tuesday (7/20) high pressure at 1036 mbs remained positioned 1400 nmiles northwest of Cape Mendocino and was ridging modestly into the US West coast over Oregon forming the usual pressure gradient and north winds over the North CA coast at up to 30 kts.  Core fetch to 25 kts was reaching as far south as Monterey bay mainly over outer waters. Nearshore a more modest flow was in effect with a eddy flow still holding (southwest winds) as far north as Half Moon Bay.   This general pattern is to hold into early Wednesday, then the gradient is to start fading with winds 25 kts, only to rebuild on Thursday up north with winds back to 30 kts but blowing more out of the northeast and a stronger eddy flow nearshore over all of Central CA and likely down into Southern CA.  This pattern to hold Friday, then the gradient is to really dissolve through the weekend with an eddy flow and an upper low pressure holding just off the Central CA coast. Next week a steady 15-20 kt north winds flow is forecast for the Pacific Northwest down into North CA coast likely generating minimal short period windswell down into Central CA, with light if not eddy winds in control down into Southern CA. 


South Pacific

On Tuesday (7/20) the jetstream was fully .cgiit with fragments of energy traveling between the two .cgiits.  The ill defined southern branch was running due east on the 63S latitude, over the northern edge of the Ross Ice Shelf with no troughs of interest present offering no support for gale formation at the oceans surface. Over the next 72 hours a very mild trough is forecast tracking under New Zealand with it's apex up at maybe 60S and winds to 130 kts, offering just a little window of opportunity to support gale formation. But it is to be tracking fast to the east while flattening out, effectively gone by Friday (7/23). Beyond 72 hours the same old  unsupportive pattern is forecast until Monday (7/26) when a semi real trough is forecast tracking under New Zealand with 140 kt southwest winds pushing well up it's western flank and slowly moderating into over the following 24 hours while moving towards the Central Pacific.   Decent support for gale development possible. 

At the oceans surface no swell producing low pressure or fetch of interest was occurring with high pressure at 1024 mbs in control of the entire Southeast Pacific. But over the next 72 hours on Wednesday (7/21) a 936 mb gale is to form well inland over the Ross Ice Shelf tracking east but with fragments of 40 kt winds extending north over ice free waters, with a secondary fetch developing back west from it, setting up a small area of 45 kt southwest winds Thursday AM (7/22) at 59S 178E.   36 ft seas are forecast at 59S 180W.  In the evening fetch is to fade to the 40-45 kts range but lifting northeast at 53S 162W generating 36 ft seas at 55S 168W. This is to the in the heart of the Tahitian swell show relative to California at 205 degrees.  The fetch is to be dropping to 35 kts on Friday AM at 52S 148W with seas fading to 30 ft at 53S 158W.  Possible swell pushing northeast with sideband potential for Hawaii  but mostly shadowed by Tahiti relative to California. 

South Pacific Gale/Swell #6S
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.

South CA:  Swell holding into Wednesday AM (7/21) with pure swell 3.6 ft @ 16 secs early (6 ft faces), with energy from the second part of the storm taking control (see below).  

North CA:  Swell holding into Wednesday AM (7/21) with pure swell 3.6 ft @ 16 secs early (5.5 ft faces), with energy from the second part of the storm starting to take control (see below).     

Part 2

Then a secondary fetch of confirmed 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 45-50 kt south to southwest winds was located at 54S 161W and just east of the core of the Tahiti swell shadow at 201 degrees and lifting steadily northeast.  Seas were building from 32 ft at 57S 166W.  At 06Z Monday the model indicated 35 ft seas and the Jason-1 satellite passed right over the core of this area confirming something less, with seas 30.4 ft with a peak reading of 33.8 ft.

On Monday AM (7/12) a solid fetch of 45+ kt south-southwest winds was located at 52S 150W 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 shrank a little but built in intensity with 50 kts south winds confirmed at 50S 140W aimed right up the 192 degree path to California.  43 ft seas were modeled at 49S 141W pushing well up the 193 degree path.  The Jason-1 satellite passed right over the core of this fetch and confirmed seas at 38.8 ft (15 reading average) with a peak reading to 41.3 ft, about 3 ft less than modeled.

On Tuesday AM (7/13) the fetch held with a small area of 50 kts south winds modeled at 48S 131W pushing right up the 187 degree path to California. The ASCAT satellite confirmed winds at something less though, looking to be more at 40 kts. A tiny area of 42 ft seas were modeled at 46S 134W. The Jason-1 satellite passed over the western flank of this area and reported a 15 reading average of 35.0 ft with a peak reading to 40.7 ft where the model reported 38 ft.  The model was right on track. By evening the fetch was fading fast with a tiny fetch of 45 kt south winds at 46S 129W aimed due north and 36 ft sea from previous fetch fading at 42S 129W. The Jason-1 satellite passed right over the core of this fetch and reported a 15 reading average significant sea height of 34.2 ft with one peak reading of 39.7 ft, right on track with the models.  

Overall the second pulse of this gale developed pretty close to expectations, with winds in the 45 kt range and unshadowed by Tahiti relative to California but blowing perhaps a bit better up the great circle paths than was originally anticipated.  And the latter part of the storm followed what the wave models predicted almost exactly.  This indicates that there's decent potential for a modest significant class swell to push up into the US West Coast with maybe sideband energy into Tahiti. Hawaii is to be pretty far off and great circle route from the second pulse of this fetch though.

South CA:  Swell to peak early Wednesday at 1 AM AM (7/21) with pure swell 3.7 ft @ 17 secs early (6.0 ft faces) and holding decently through the morning. Swell to be fading on Thursday from 3.3 ft @ 14-15 secs (5 ft faces early). Not much left on Friday. Swell Direction: 193-198 degrees       

North CA:  Swell to peak on Wednesday at 6 AM (7/21) with pure swell 3.7 ft @ 17 secs early (6.0 ft faces). Swell to be fading on Thursday from 3.3 ft @ 14-15 secs (5 ft faces early). Not much left on Friday. Swell Direction: 190-195 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 at 1036 mbs is to build slightly and continue ridging into the North California coast generating a decent sized area of 25-30 kt north winds into Thursday (7/22) offering decent odds for local windswell production there with the gradient remaining pretty well to the north leaving local conditions not too bad. Trades are to be peaking over Hawaii at near 20 kts on Thursday too offering increased odds for Northeast windswell along exposed shores. Next week the high is to bloom to 1040 mbs filling the entire Central and East Pacific but pulling away fro the California coast increasing the odds for trades and windswell over the Hawaiian Islands. But by the weekend the high is to rapidly fade and retrograde back tot he dateline with north winds fading along Cape Mendocino and trades also fading over the Hawaiian Islands, meaning windswell will likely be falling way back at both locations at that time.


MJO/ENSO Update (reference): As of Tuesday (7/20) the Southern Oscillation Index (SOI) remained in positive territory. The daily SOI was at 18.77 and has been positive for 26 days running. The 30 day average was up to 12.35 with the 90 day average holding at 7.90. This continues looking like the Inactive Phase of the MJO was in control.  

Wind anomalies as of Tuesday (7/20) at the 850 mb level (approx 5000 ft up) as defined by models suggested a fading area of westerly anomalies were holding over the extreme eastern equatorial Pacific. But very strong east anomalies continued were in control from eastern Africa across the Indian Ocean to the dateline and almost to southern South America with the core over the Philippines. The coverage of this area was huge and a very clear signal of a building Inactive Phase of the MJO. The Inactive Phase is to hold through 7/24, then slowly give up a little ground on 7/29, but continuing to hold on well into early August (8/8). This is a very bad sign for later this winter.

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 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 (7/19) 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.  It was downright cold just off Ecuador, a clear signal of strong easterly winds there and solid upwelling. Feeder bands of colder than normal water were 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 -3 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.  Previous we have believed that easterly anomalies usher in La Nina, but this has not been apparent in any data we have seen to date.  But the Pacific current that runs along the equator turned abruptly from flowing to towards South America to flowing towards the west in mid-March, right as the SOI started it's impressive drive into positive territory and the storm machine abruptly shut down. And it has not wavered since.  This suggest trade wind anomalies might be a byproduct of the Pacific equatorial current change and not the other way around.  Something to study in the years ahead.     

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 a broad and fairly well organize gale is forecast tracking under New Zealand on Sunday (7/25) supported by a good jetstream flow aloft, with 45 kt winds tracking up to the southern tip of New Zealand an points just east of there and continuing solidly into Monday, then fading while lifting further northeast on Tuesday. In all if this were to develop, there would be good support for swell formation.  But this is a long ways off and much can and likely will change between now and then. At least it's something to 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

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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Surf Height-Swell Height Correlation Table


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