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Pacific Storm and Surf Forecast
Updated: December 20, 2009 1:18 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 = 3.3 - California & 4.5 - 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 12/21 thru Sun 12/27
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   

Storm Pattern Picking Up
MJO Provides A Late Surge in the Active Phase


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 Sunday (12/20) North and Central California was getting clean relatively leftover local swell from a gale that was off the coast late last week at head high. Southern California was getting the same energy with waves thigh to maybe waist high up north pushing near head high on the sets down south. Hawaii's North Shore was getting more sideband north proto-swell with waves head high to 2 ft overhead at top spots and a bit warbled early. The East Shore has getting the same swell at the same size. The South Shore was asleep for the winter.

The forecast for North and Central CA is for a new very west relatively local swell to arrive for Monday AM at 4 ft overhead, with a new swell from the northern dateline region to arrive Tuesday at about the same size but inconsistent then fading some through Wednesday. A new dateline swell is expected on Thursday getting some size (4 ft overhead) later in the day continuing through Christmas at 2-3 ft overhead, then fading out the day after. Southern California to see new local very west swell on Monday at shoulder to head high fading Tuesday with new longer period swell building underneath and coming from the northern dateline region. That swell to peak on Wednesday at chest high with north local swell intermixed fading on Thursday. New inconsistent dateline swell is expected for Christmas Day at head high then fading through the day beyond. The North Shore of Hawaii is to see more northeast angled sideband windswell on Monday in the head high range while a more northwesterly dateline swell arrives at 1-2 ft overhead, fading some Tuesday with more sideband northwesterly swell layers on top making waves still 1 ft overhead. Larger longer period swell from the dateline is expected right behind at sunset and building overnight to 13 ft (Hawaiian) then be fading by sunrise Wednesday (12/23) but still retaining most of it's size early from 310 degrees.  That swell to continue fading from double overhead on Thursday. Possible large swell is expected in for Christmas if the models are correct. The East Shore is to have no easterly windswell. The South Shore is in hibernation for the winter.

Longterm the Madden Julian Oscillation (MJO) has resurged even more in the Active Phase, helping to fuel the winter storm pattern. A gale is forecast pushing to the dateline Sun/Mon (12/21) with up to 35 ft seas targeting the area mid-way between Hawaii and the US mainland with some weaker follow-on energy, followed by a stronger storm forecast to push from the Kurils to the dateline through late Tues (12/22) with up to 42 ft seas then consolidating better with up to 45 ft seas Wed/Thurs passing well north of Hawaii and targeting the US West Coast. This remains just a projection, but it has been on the charts for days now.  Weak but still decent energy to follow behind too. Looks like a good run of longer period modest sized surf is to be expected for the US West Coast with a significant class swell possibly for at least the Islands. 


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

North Pacific

On Sunday (12/20) the North Pacific jetstream has flowing hard off Southern Japan to the dateline to 200 kts, barely .cgiitting with most energy dipping into a persistent trough that was pushing over Hawaii before lifting and pushing into Central CA just below Monterey Bay. Limited support for gale development was occurring in the trough north of Hawaii lifting up into Oregon. Over the next 72 hrs this pattern is to hold but with 190 kts kt winds starting to fall down into that that trough and inching eastward with winds pushing up to 210 kts on Tuesday (12/22). Good support for storm development approaching the dateline. Beyond 72 hours winds to hold decently pushing flat over the dateline at 180 kts Wednesday with the .cgiit point inching east, and a new trough setting up in the Gulf, but winds dropping to 140 kts on late Thursday (12/24). Good support for gale if not storm development. This trough on the leading edge of the core jet energy is to continue trying to inch east with up to 160 kts winds on Friday then getting almost pinched off but reaching to within 300 nmiles of the CA coast on Sunday (12/27) while a continued decent and consolidated flow of 130-140 kts winds are to be pushing flat over the greater Pacific. A co.cgie of small semi-troughs are to try and organize, but no obvious storm supporters projected.

At the surface on Sunday (12/20) a weak gale was circulating just off Northern CA and Oregon with 20-25 kts southwest winds pushing towards the coast and 35 kt north winds pushing down it's backside aimed somewhat towards Hawaii but a long ways away. This has been the source of Hawaii's northerly windswell (when the gale was closer to the Islands) and is the source of swell pushing towards California for late Sun/Mon (12/21) (See California Gale below). Otherwise a large pool of low pressure was over the dateline extending from almost the Kuril Islands east towards the Central Gulf of Alaska. Imbedded within that was a fetch of 40-45 kt northwest winds that has generated an area of 29 ft seas pushing from Japan towards the dateline. On Sunday AM (12/20) that fetch had produced 35 ft seas at 37N 172E on the 308 degree path to Hawaii and pushing pretty well south of the 289 degree path to NCal.

Over the next 72 hours and by Sunday evening the dateline gale is to be falling apart with 35 kt west winds in the general area of 36N 170-175W producing seas of 32 ft at 35N 180W targeting Hawaii (310 degrees) better than NCal (285 degrees), favoring the Islands by a good margin.  This system to rapidly deteriorate after that. Possible swell pushing into Hawaii starting at 6 PM Tues (12/22) peaking near 1 AM Wed with swell to 8.6 ft @ 16 secs  (14 ft Hawaiian) from 308-312 degrees.    

On Monday (12/21) a new gale is to start building off Northern Japan with pressure 984 mbs and a tiny area of 45 kt west-northwest setting up  and growing in areal coverage through the day, covering a solid area by evening at 42N 160E aimed best at Hawaii down the 312 degree path. 25 ft seas building. On Tuesday AM (12/22) a reasonably consolidated fetch of 45 kts west winds is forecast at 41N 163E with a secondary fetch racing ahead of it. 33 ft seas are to be building at 41N 165E.  In the evening 45 kts winds to hold and sinking southeast at 39N 172E with a new fetch of 45 kts winds developing around the core of the low pressure center at 44N 179E. 40 ft seas forecast from the old fetch at 39N 172E pushing directly towards Hawaii down the 312 degree path and 25 degree south of the 294 degree path to NCal.  Wednesday AM (12/23) the core fetch is to start taking prominence with 45+ kt northwest winds at 43N 175E and starting to assimilate the more southerly fetch (40 kts west winds). 40 ft seas forecast under both areas at 37N 180W (314 deg HI), and 43N 174W (295 NCal). Finally in the evening the two fetches are to consolidate with a solid fetch of 45-50 kts forecast at 42N 168W aimed a bit east of the 338 degree path to Hawaii and 30 degree south of the 291 degree path to NCal. 43 ft seas are forecast at 40N 168W. The fetch is to be fading fast on Thursday AM (12/24) with 45 kt mostly west winds forecast at 40N 160W generating seas of 45 ft over a tiny area at 41N 161W pushing 20 degrees south of the 287 degree path to NCal with nothing aimed at Hawaii. In the evening 35 kt fetch is to be fading at 38N 155W with seas from previous fetch fading from 40 ft at 40N 154W (286 NCal).

Assuming all this develops exactly as modeled some degree of significant class swell seems likely for Hawaii with possible smaller long period energy pushing towards the US West Coast. But as of right now only the first breaths of winds are starting to take root off Japan. Certainly something to monitor though.


California Gale
A gale that was northeast of Hawaii on Friday (12/18) lifted northeast pushing up towards Oregon and Washington on Sunday (12/20) but not before generating  35-40 kts west winds late Friday (12/18) and 28 ft seas at 33N 147 on the 261 degree great circle path to NCal, with residual 35 kts fetch and 25 ft seas at 34N 142W on Saturday AM (12/19) aimed up the 263 degree great circle path to NCal. Residual 20 ft seas were modeled at 37N 139W Sat PM.

Some degree of 15 sec period swell is expected to arrive in NCal on Sunday evening (12/20) just after sunset and starting to peak near 1 AM Monday with pure swell 7.8 ft @ 14 secs  (10 ft faces) and holding in the 13 secs range near sunrise.

North Dateline Storm
On Friday (12/18) a
storm was at the intersection of the dateline and the Aleutians generating a decent sized area of 55 kt west winds at 49N 178E aimed right down the 304 degree path to NCal producing seas of 42 ft at the same location. This system was at it's peak and then moved into the Bering Sea within 12 hours with all fetch fading out.

Swell from it is expected to up into the Pacific Northwest and reaching Central CA starting early Tuesday (12/22) at 5 AM with period 18 secs peaking mid-day with swell possibly to 5.5 ft @ 17 secs (9 ft faces).  Swell Direction: 305-305 degrees. Minimal sideband swell possibly to push to Hawaii too.  


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


California Nearshore Forecast
On Sunday (12/20) a broad but generally weak low pressure system was lifting northeast off the coast, with a weak front from it pushing south from Cape Mendocino expected to brush the northern SF Bay area in the late evening reaching perhaps Monterey Bay by late Monday (12/20). Light precipitation for those areas possible, then clearing into Tuesday AM (12/21) with high pressure building in on Monday (12/21) and north winds to 20 kts pushing south to Pt Conception. North winds holding at 20 kts Tuesday evening into Southern CA and holding, then starting to break up on Wednesday with a Santa Ana flow in effect down south but not turning offshore in Central CA until Thursday AM (12/24). Calm to light offshores to follow through Saturday (12/26). A weak low pressure system is to form off the SCal coast then and start drifting east, possibly enhancing east winds for Central CA on Sunday (12/27).

The MJO has moved back into a fairly solid active state.

No tropical systems of interest were being monitored. 


South Pacific

At the surface no swell producing fetch was occurring and none is forecast for the next 72 hours.


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 yet another small storm is forecast forming over the dateline early Friday (12/25) with 45 kts west fetch, but only over a tiny area pushing east for 24 hours. Maybe 35 ft seas to result. A broader system is to start spinning up well north of Japan on Sat/Sun (12/27) with 45 kts west fetch and more 30-34 ft seas forecast. And yet another better system is forecast approaching the dateline from off Northern Japan on Sun/Mon with winds building to 50 kts and seas likely in excess of 30 ft. But all this is a long ways off and much can change between now and then. Still, the trend looks favorable.

The re-ignition of the MJO (Active Phase) is likely to have a favorable impact. 


MJO/ENSO Update (reference): As of Sunday (12/20) the Madden Julian Oscillation (MJO) had moved back into the Active Phase, and strongly so with the SOI well into negative territory. The ENSO (El Nino Southern Oscillation) index was negative with the Daily SOI at -29.43. The 30 day average was down to -10.06 while the 90 average was down to -9.76. This continues looking good.  

Wind anomalies at the 850 mb level (approx 5000 ft up) as defined by models indicating westerly anomalies were in control from eastern Indonesia ramping up nicely over the dateline and pushing east into Central America, providing a nice canvas for storms to develop upon. This area is about peaked out and is expected to slowly fade on the dateline through 12/24, then with remnants drifting east into the east equatorial Pacific into Jan 3. Support for storm formation expected in this region though these timeframes. A stronger version of the Inactive Phase is forming in the Indian Ocean and expected to seep east to New Guinea through Jan 3, then fading while pushing over the dateline Jan 8. This is likely to starting suppressing storm formation at that time.   

Sea Surface Temp anomaly data (12/17) indicated that warmer than normal waters were consolidated on the equator from Ecuador and Columbia west to the dateline and even west of there, and starting to rebuild some along the Baja coast, but not much.  A new strong Kelvin Wave (see below) was erupting along the coast and some evidence of it can be seen with a most solid warm anomaly signature present over and just west of the Galapagos Islands. It is expected that water temps will continue to increase yet more over the coming weeks as this Kelvin Wave (see below) continues impacting the coast there. This is classic El Nino.  Overall the warm water signature remains non-exceptional from a historical El Nino perspective, but clearly in the moderate category and building slowly but steadily.  

Below the surface on the equator things continue to look most favorable. A steady flow of warmer than normal subsurface water continues tracking from the West Pacific (150 m below the surface) under the dateline and breaking the surface near Central America as it has for months now.  As of 12/20 the Kelvin Wave we've been tracking with a core of 5-6 deg C warmer than normal sub-surface water was impacting the Galapagos Islands and Ecuador coast. This is fueling an increase in the warm water surface pool as it continues impacting the coast there.  This pool is expected to continue building and eventually tracking back west on the equator driven by trades. This Kelvin Wave first appeared under the dateline on 9/17 and tracked steadily east through 12/1 and was the result of a prolonged persistent westerly surface wind flow that had been in.cgiace west of the dateline from 9/8 and continued into 11/5.  Of additional interest was the development of a new pocket of warm water on the dateline 3 deg C above normal which started forming on 12/10.  As of 12/20 it had built to 4 deg C above normal and was continuing to slowly grow in areal coverage as it eased east, currently at about 163W. This is a new small reinforcing Kelvin Wave. 

Over the Equatorial Pacific anomalous surface winds started to move from the west to the east on 11/28 extending the whole way from Indonesia to a point south of Hawaii, with fully blowing west winds confirmed in the far West Pacific. This was a new Westerly Wind Burst and continued very obvious on 11/30 with fully blowing west winds near 165E, and strong. This Westerly Wind Burst (WWB) continued on 12/2 through 12/8 with a most solid area of west winds pushing almost to the dateline. On 12/6 strong west anomalies pushed to 170W and held solid through 12/15, with fully blowing west winds reaching to the dateline and anomalies to 170W. This WWB started fading by 12/17 but was still present pushing to 175E with neutral (normal) winds east of there. Fully blowing West winds were evidenced on Sat (12/19) too reaching to the dateline with westerly anamolies now pushing east to a point well southeast of Hawaii. This configuration is feeding the a newly developing Kelvin Wave under the dateline (see above), and is helping to fuel the development of El Nino.  If anything, subsurface water temps are expected to increase as the WWB continues pushing warm water into the depths on the dateline, feeding the developing Kelvin Wave there. And the Kelvin Wave currently hitting Ecuador was formed from a prolonged bout and mult.cgie pulses of westerly winds and westerly anomalies that occurred from 9/8 through 11/2. At one point towards it's end the anomalies reached the whole way from the West Pacific to almost Ecuador. Embedded in that run were Typhoons Dujuan, Choi-Wan, Parma, Melor and Nepartak. All this helped to deepen the surface warm pool in the tropical Eastern Pacific.   Typhoon Nida and Storm #5 was associated with the most recent WWB. So at this time two Kelvin Waves are in the pipe. Impressive.

El Nino is expected to affect the global atmospheric weather pattern at least through Spring of next year if not into the middle of summer. All data suggests this will not be a strong El Nino, more likely a moderate one. NOAA's last update (11/5) forecasts the same outcome, though hints at some uncertainty.  In short, all the best models aren't exactly sure how this is going to.cgiay out. Regardless a solid accumulation of warm water in the equatorial East Pacific is evidence in-favor of continued development. As long as there continues to be WWB's (as there obviously is), then warm water will be migrating east, and the warm water pattern will hold if not build, and the atmosphere above it will respond in-kind to the change (towards El Nino). At this point there is no evidence to suggest this El Nino will stall or dissipate. The only remaining question is whether it will hold, or grow. And current data indicates that the warm pool will hold if not slowly build. And historically it is already larger and strong than any other in the past 12 years. 

The current El Nino is gaining strength, with a 2 degree water temp anomaly in the tropical East Pacific the likely outcome. Coverage is pretty solid for this event, but the lack of really high water temp anomalies will likely limit it's strength. Strong El Ninos bring lot's of bad weather to the US West Coast, along with the potential for storm and swell enhancement. A moderate El Nino provides storm and swell enhancement, a gentle but steady push/momentum in-favor of storm development rather than the manic frenzy of a strong El Nino, but without all the weather associated with a strong event. So in many ways a moderate El Nino is more favorable from a surf perspective. As of right now things remain better than anything the Pacific has seen in the past 12 years regarding anomalous sea surface temperatures, besting anything since the big El Nino of 1997. That is very good news.  But the lack of anomalous water temps exceeding 3 degrees and an unremarkable SOI suggests a modest El Nino at best. Still, it should be enough to provide storm enhancement, and a better than average winter surf season for the North Pacific, and still likely better than anything in the past 10 years. Better yet, if it's not too strong (as this event appears to be) perhaps it will not degrade into La Nina the year after (which typically happens after stronger El Ninos), but hold in some mild El Nino like state for several years in a row. This would be an even better outcome.   

See more details in the new  El Nino update.


South Pacific

Beyond 72 hours the models suggest no swell producing fetch is to develop.   

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

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

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

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Surf Height-Swell Height Correlation Table


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