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Pacific Storm and Surf Forecast
Updated: May 17, 2009 3:47 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 & 1.0 - 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 5/18 thru Sun 5/24
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   

High Pressure Controls North and South Pacific
One Last Gale for the Tasman Sea


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.

On Sunday (5/17) North and Central California had waist high crumbly northwest local short period windswell at exposed breaks. Southern California was near flat with knee high sets and clean. Hawaii's North Shore was flat. The East Shore was small with thigh high east windswell at best. The South Shore was small with thigh high high background southern hemi swell from the Tasman Sea fading out with clean offshore conditions.

The forecast for North and Central CA suggests that northwest short period local windswell is expected to drop out Monday and Tuesday, then start to rebound for mid-week on into next weekend maybe reaching head high. Southern CA is to see a portion of this same northwest windswell starting Thursday (5/21), but until then nothing of interest is forecast. Oahu's North Shore is asleep for the summer. Some north windswell remains forecast starting Monday (5/18) holding into Wednesday with faces to maybe head high, but period to only be 8-9 secs.  The East Shore is not expected to have any trade induced easterly windswell for the foreseeable future. The South Shore is to see one last tiny pulse of background southwest swell originating from the Tasman Sea starting late Sunday holding into Monday AM (5/18), then disappearing.   

Longterm virtually no swell producing weather system are forecast in the North Pacific. In the South Pacific high pressure to reign supreme for the next 7 days.


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

North Pacific

At the surface weak high pressure at 1028 mbs was centered over the dateline with a second lobe off Japan and neutral pressure pushing into the Gulf of Alaska. No swell producing fetch was indicated. Over the next 72 hours those two high pressure systems are to congeal while pushing east generating a pressure gradient off Cape Mendocino CA by late Tuesday (5/19) setting up north winds to 25 kts there and starting to generate local short period windswell. Also a cut off low is to form under the high and just 700 nmiles north of Hawaii late Sunday through Monday (5/18) producing 25 kt northeast winds which might generate limited windswell for exposed north facing breaks there.  But no other swell producing systems are forecast with summer time rules in effect. 


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


California Nearshore Forecast
On Sunday (5/17) neutral pressure was off coastal California, with high pressure at 1022 mbs pushing into the Pacific Northwest.  Light winds were down the coast with a weak pressure gradient generating 20-25 kt north winds off Cape Mendocino pushing to the southwest. An even weaker flow is forecast Monday. Light winds expected everywhere but Cape Mendo. But a new batch of high pressure is forecast taking over the Gulf of Alaska at 1032 mbs late Tuesday (5/19) with a solid gradient starting to form over Cape Mendocino and 25 kt north winds starting to build there with windswell on the upswing, building to 30 kts late Wednesday holding into late Thursday (5/21).  Local winds from Pt Arena southward to remain decent though, with the north winds staying away from the coast or turning to an eddy flow (southwest) nearshore. By Friday north winds to drop to 25 kts  and down to 20 kts by the weekend and pushing very close if not over the coast with chop moving into Central CA, though SCal will likely be spared.

No tropical activity of interest was occurring.


South Pacific

On Sunday (5/17) the South Pacific jetstream remained highly .cgiit from the west to the east with a solid ridge in the southern branch pushing down over the Ross Ice Shelf from under New Zealand to the Southeast Pacific totally shutting off surface level low pressure production there. A bit of a trough remained in the far Southeastern Pacific but outside the US swell window and of concern for only Southern Chile. A trough was trying to open up south of New Zealand, but not inching into the US swell window just yet. Over the next 72 hrs the same basic .cgiit pattern is to remain in the west offering no help. A pulse of wind energy is to be diving southeast only reinforcing the ridge and suppressing storm development over the Central South Pacific.  The trough under New Zealand is to be gone by late Tuesday (5/19) offering no help. And the trough in the far Southeastern Pacific is to continue pushing east, out of the picture. Beyond 72 hrs no change is forecast with a .cgiit pattern in firm control and the southern branch ridging south over or near the northern edge of the Ross Ice Shelf. No support for gale development is suggested. 

At the surface on Sunday strong high pressure at 1032 mbs remains locked down well south of Tahiti and east of New Zealand, sitting between the two branches of the .cgiit jetstream, forming a blocking bubble and totally eliminating swell production in the South Pacific. Over the next 72 hours virtually no change is forecast with high pressure building to 1036 mbs and continuing to dominate the South Pacific, eliminating any odds for gale development in the greater South Pacific. 

Previously a gale had formed in the far Southeast Pacific off Chile generating 30 kt south winds on and off since late Tues (5/12) with seas to 26 ft by Thurs AM at 56S 122W.  It lifted northeast to 52S 120W by Thurs evening with seas still 26 ft at 53S 120W then faded some before regenerating off Chile Sat/Sun with seas to 36 ft. The best this could do for the US is to produce background 14-15 secs very south angled swell for Southern CA 9 days later, or Sat PM (5/23).  Don't really expected even that will happen.

Tasman Sea
On Wednesday (5/6) a push of wind energy originating under Australia with 35 kt south winds fed by an upper trough in that area. Seas built to 25 ft at 47S 158E late. That fetch pushed up to northwest New Zealand on Thursday (5/7) with 30-35 kt south winds there and more 23 ft seas aimed straight at Fiji pushing up to 37S 162E late and to 33S 167E Friday AM. This should be good for 14 sec period swell. Another gale built in the South Tasman Sea on Friday again with 35-40 kt south winds pushing into the center of the Tasman Sea with a secondary south fetch arriving on Saturday AM (5/9) to 45 kts resulting in seas building to 26 ft at 43S 165E, pushing 30 ft Saturday evening at 40S 167E aimed due north at Fiji. Winds were holding Sunday AM at 30 kts from the south with 26 ft seas modeled at 34S 163E dropping from 25 ft in the evening at 32S 165E aimed due north. Winds were fading Monday (5/11) from 30 kts off Northwestern New Zealand with seas at 23 ft at 38S 164E in the morning and gone in the evening. This continues to indicate a nice run of swell for Fiji, with some limited background southern hemi swell potential for Hawaii. Small southern hemi background swell expected to arrive in Hawaii on Thursday (5/14) with swell 1.6 ft @ 16 secs (waist high with chest high sets at top breaks) from 210 degrees. Period slowly dropping to 13 secs by Saturday (5/16) . A second pulse is possible arriving on Sunday (5/10) with swell 1.6 ft @ 15 secs fading to 13 secs on Monday. 

On Saturday (5/16) some more wind energy seeped into the Tasman Sea at 35 kts from the southwest winds expected to push to New Zealand on Sunday. 30 ft seas from previous fetch rounded under Tasmania Sat AM (5/16) at 43S 154E dropping to 26 ft in the evening at 41S 161E. 26 ft seas held to Sunday AM at 40S 155E and are then to fade out. More swell likely for Fiji with perhaps some very limited swell southwest for Hawaii starting Sunday (5/24) at 1.6 ft @ 16 secs (3 ft faces) from 215-220 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 hours high pressure is hold pushing east from the dateline at 1032 mbs pushing east into the Gulf of Alaska Wed (5/20) likely continuing to fuel the standard summertime pressure gradient along the California coast generating north wind at 25-30 kts and short period north windswell through Fri (5/22), then fading into the weekend.  Trades to remain light over the Islands offering no local east windswell potential. There's some hint of a low pressure system forming in the Gulf late next weekend producing 25 kt northwest winds targeting Oregon down to Central CA, but that seems more like wishful thinking.


MJO/ENSO Update (reference): As of Sunday (5/17) the Madden Julian Oscillation (MJO) was well past the peak of the Active Phase with the ENSO (El Nino Southern Oscillation) index heading up. The Daily SOI index dropped momentarily to -9.4 but the previous 3 days had been in the positive range. The 30 day average was down to -3.25 and the 90 day average was down to 2.45 (the lowest since Mar 2007, but still not negative). The SOI indicies remained completely neutral at the moment. Wind anomalies at the surface and the 850 mb level (approx 1000 ft up) indicated that the Active Phase was gone with neutral winds over the entire equatorial Pacific. A dead neutral pattern was in.cgiay. A new version of the Inactive Phase forecast to push into the Pacific Ocean has dissipated. A completely neutral pattern is expected through June 5.  The residual effects of 3 years of La Nina are effectively gone over the ocean, and fading fast in the atmosphere. Cooler than normal surface waters off of Central America are gone with slightly warmer than normal waters temps reported over the entire width of the equatorial Pacific. Below the surface on the equator, cool water that had locked down the region was gone, with a steady flow of normal subsurface water was tracking from the West Pacific over the dateline and then breaking the surface near Central America with warmer water starting to pool up there.It appears that this last episode of the Active Phase will pump limited  warm waters of the West Pacific eastward, feeding a neutral if not slightly warm regime in the equatorial Eastern Pacific.  Months of high pressure off California and stiff north winds there turning trades over Hawaii had resulted in a huge cool tongue of water extending from Central CA the whole way over Hawaii to the dateline which generated massive upwelling. That continues to moderate, through a large pocket of cooler than normal waters remains off California extending to almost Hawaii. We expect 1-2 more months of high pressure before a fully neutral pattern takes hold (warmer waters off California).


South Pacific

Beyond 72 hours the models suggest that high pressure is to continue ruling the South Pacific, though a building pattern of gales are forecast to start setting up pushing over the Ross Ice Shelf traveling west to east. All are to be over ice, meaning no fetch is to contact ice free waters. But at least there is to be some sort of a pattern setting up. Now if the high could only dissolve or lift north allowing the gales to push north off the Ross Ice Shelf. Wishful thinking at this time.

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

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:

Half Moon Bay Surf Club, "A Luau for the Waveriders", May 16th, Seacrest School Half Moon Bay
The Half Moon Bay Surf Club is hosting its annual fundraiser on May 16 at 6:00. The club consists of students from 6th Grade - High School who compete in the Interscholastic Surfing Federation against schools along the central coast. This is the primary fundraiser for 2009 and your smile would add to the rich gathering of friends. The location is Seacrest School, 901 Arnold Way, HMB. Tickets are $40 for adults ($50 after May 9th) and Kids 2-12 are $25. Music entertainment is by Blame It On The Dog. There will be lots of prizes, a silent auction and a raffle. Several surprise guest appearances and a few bonus prizes may find their way in through the doors. Please contact Tracy at 650-712-1242 for tickets. 

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

Surf Height-Swell Height Correlation Table


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