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Pacific Storm and Surf Forecast
Updated: Tuesday, September 19, 2017 4:24 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
2.5 - California & 1.0 - Hawaii
Using the 'Winter' Scale
(See Swell Category Table link at bottom of page)

Probability for presence of largest swells in near-shore waters of NCal, SCal or Hawaii.    

Issued for Week of Monday 9/18 thru Sun 9/24

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   

Gulf Swell Hitting CA
Otherwise Windswell Best Hope


On Tuesday, September 19, 2017 :

  • Buoy 146 (Lanai): This buoy is down and there is no backup site and no date if or when it will return to service. Buoy 233/51211 (Pearl Harbor) is available but has a new frequency layout. We'll have to code a new program to read it's output (date TBD).
  • Buoy 46025 (Catalina RDG): Seas were 2.4 ft @ 11.4 secs with south swell 1.1 ft @ 10.8 secs from 207 degrees. Wind at the buoy was east at 4 kts. Water temperature 66.6 degs. At Ventura (Buoy 111) swell was 1.9 ft @ 6.2 secs from 277 degrees. At Santa Monica (028) swell was 2.3 ft @ 6.0 secs from 271 degrees. At Camp Pendleton (043) swell was 0.7 ft @ 13.4 secs from 215 degrees. Southward at Pt Loma (191) swell was 0.8 ft @ 17.2 secs from 233 degrees.
  • Buoy 46012 (Half Moon Bay)/029 (Pt Reyes): Seas were 4.6 ft @ 6.2 secs with local windswell 3.5 @ 6.3 secs from 305 degrees. Wind at the buoy was northwest 16-20 kts. Water temp 60.6 degs.

    46006, 46059, Hi-Res Buoy Dashboards (bottom of the page)
Swell Classification Guidelines

Significant: Winter - Swell 8 ft @ 14 secs or greater (11+ ft faces) for 8+ hours (greater than double overhead).
- 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/Utility Class: Winter - Swell and period combination generating faces at head high to 1.5 times overhead (4-7 ft).
- 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.
- up to waist high swell. Also called 'Background' swell.

Surf Heights for Hawaii should be consider 'Hawaiian Scale' if period exceeds 14 secs.


Current Conditions
On Tuesday (9/19) in North and Central CA local north windswell was was hitting exposed breaks producing surf at waist high and blown out with whitecaps in control early. Protected breaks were thigh to waist high and clean but lumpy from northwest wind just off the coast. At Santa Cruz surf was flat to knee high and clean. In Southern California up north waves were flat to thigh high and clean. In North Orange Co northwest windswell was producing waves occasionally to waist high on the peak and clean and weak. In South Orange Co waves were flat to waist high and some northwest lump was running through it. In San Diego surf was thigh to waist high and clean. Hawaii's North Shore was flat and clean early. The South Shore had waist to chest high sets and clean. The East Shore was getting east windswell at waist to chest high and chopped from easterly trades.

See QuikCASTs for the 5 day surf overview or read below for the detailed view.

Meteorological Overview
On Tuesday (9/19) no swell of interest was hitting the coast in our forecast area. But larger northwest swell from the Gulf of Alaska was pushing towards the California coast and already hitting the Pacific Northwest. Locally produced east windswell was hitting the Hawaiian Islands produced by trades but is expected to slowly be fading. For North and Central CA local north windswell is expected to start building later this week into the weekend. Beyond there's no clear sign of gale development forecast for the North Pacific. And the South Pacific appears to be asleep. On the equator La Nina is setting up stronger than expected.

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

North Pacific

On Tuesday AM (9/19) the jetstream was split with most energy in the southern branch pushing east off North Japan and forming a pinched trough on the dateline, then ridging hard north with the 2 branches merging over the Eastern Aleutians turning east with winds building to 150 kts falling southeast through the Northern Gulf of Alaska eventually pushing inland over Oregon. There was no clear support for gale development indicated. Over the next 72 hours
the same general pattern is to hold into Thurs (9/21) with the jet tracking east off Japan with winds 120-130 kts pushing to the far Western Gulf of Alaska then ridging hard north over the Alaskan Coast before pushing south down the coast of British Columbia and just off the Pacific Northwest before moving inland over Southern CA. The ridge in the east is to start moderating on Fri (9/22) with the jet generally running east on the 40N latitude line. Beyond 72 hours no real change in the jet is forecast with it undulating generally on the 40N latitude line with winds 120-130 kts in pockets but no clearly defined troughs indicated offering no real support for gale development.

Surface Analysis
On Tuesday (9/19) no groundswell was hitting either Hawaii or California. But larger swell was pushing southeast towards California and already hitting the Pacific Northwest Coast (see Gulf Gale below). Also a gale formed over the dateline but will result in no swell for Hawaii or elsewhere.

Over the next 72 hours no swell production other than what is stated above is forecast.

For windswell relative to California: On Tuesday (9/19) high pressure at 1030 mbs starting to ridge into North CA setting up a pressure gradient and 20+ kt north winds over all of Central CA up to Pt Reyes making raw local windswell mainly for the southern portion of Central CA while low pressure from the Gulf was moving inland over the Pacific Northwest down to Pt Arena producing a lighter onshore wind flow. The gradient is to weaken Wednesday with no windswell expected then start rebuilding Thurs (9/21) as high pressure again eases east and the low is out of the picture. North winds are forecast at 20-25 kts for all of Central and North CA excluding Cape Mendocino. Windswell on the upswing. The gradient is to weaken some on Fri with north winds 20 kts over all of north and Central CA still making for raw .

For windswell relative to Hawaii: Trades were blowing from the east at 15 kts solid starting 900 nmiles east of the Islands generated by high pressure at 1039 mbs 1200 nmiles north-northeast of Hawaii and sweeping over the state resulting in rideable east windswell at exposed east facing breaks. That fetch is to start getting patchy and fading Wed-Thurs (9/21) with winds 15 kts from the east in pockets. Odds for rideable windswell development are to be fading. After that no rideable windswell is expected.


Gulf Gale
Low pressure tracked east fast from North Japan on Tues (9/12) pushing over the Eastern Aleutians Fri PM (9/15) then started to build while lifting north into the far East Bering Sea with a very shallow fetch of 30 kt northwest winds trying to get traction in the extreme Northwestern Gulf of Alaska. On Sat AM (9/16) winds were 35 kts in the Bering Sea but landlocked. But a shallow fetch of 35-40 kt northwest winds were reaching south of the Aleutians into the Northwestern Gulf with seas trying to build from 22 ft at 53N 162W. By evening fetch was starting to grow from the Eastern Aleutians southeastward at 40 kts with seas building to 26 ft up at 54N 157W (312 degs NCal). On Sun AM (9/17) fetch was tracking east through the Northern Gulf at 35 kts from the west and seas 26 ft at 53N 151W (NCal 314 degrees). Fetch was easing southeast at 30-35 kts in the evening with seas 25 ft at 52N 144W (319 degrees NCal). Fetch faded Mon AM (9/18) from 30 kts falling southeast off Vancouver Island and seas fading from 23 ft at 49N 137W and shadowed relative to Central CA.(320 degrees and becoming shadowed). Maybe some swell to result. Something to monitor.

North CA: Expect swell arrival on Tues (9/19) at 5 PM with period 14 secs and size building quickly. Swell peaking at 7 PM at 9 ft @ 14 secs (12.5 ft) but shadowed with less size reaching the shore, though the buoys will state the unshadowed size. Unshadowed swell down to 7.1 ft @ 13 secs (9.5 ft - less size reaching shore) by sunrise Wed (9/20) and slowly fading from there. Swell Direction: 312-319 degrees


Dateline Gale
Also a gale low developed on the dateline Sun (9/17) producing north winds of 35-40 kts then falling south some through the day with seas 23 ft in the evening at 45N 170E. Fetch faded Monday from 30 kts and seas 21 ft at 43N 170E aimed due south and not aimed at our forecast area. Seas faded in the evening from 20 ft at 43N 173E. This system was gone on Tues (9/19). No swell to result.


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


Tropical Update
No tropical systems of interest were occurring and none were forecast.

California Nearshore Forecast
On Tuesday (9/19) high pressure was ridging into the Central CA coast generating north winds at 20-25 kts, but held mostly at bay from Pt Arena northward by low pressure seeping into the Pacific Northwest. Fetch is to fade a little in coverage limited to Pt Conception early at 20 kts then building up into North CA late after noon at 15 kts. By Thurs (9/21) 20+ kt north west winds are to be in control of all of North and Central CA except Cape Mendocino (10 kts) and continuing Friday but now covering the entire state with north winds 15-20 kts. Sat (9/23) the gradient is to lift north over North CA at 20+ kts but light northwest over Central CA. Sunday north winds to build to 25 kts over Cape Mendocino down to Pt Arena but light elsewhere. More of the same on Mon (9/25) but north winds near 30 kts then fading to calm to northwest 5-10 kts mid-day Tues (9/26) over the entire state.

South Pacific

Surface Analysis  
On Tuesday (9/19) no swell from the South Pacific was hitting California or Hawaii.

Over the next 72 hours no swell producing fetch is forecast.


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 a weak pressure pattern is to take over the North Pacific. There's suggestions that two small low pressure systems might start developing either side of the dateline embedded in the jetstream flow down at 37N 180 hours out. Something to monitor but expectations are low.

A local fetch of north winds are to be present over North CA on Sat (9/23) at 20 kts with lighter wind down into Central CA generating some windswell with that fetch building to 25 kts on Sun (9/24) and near 30 kts Monday isolated to Cape Mendocino generating rideable windswell in North and Central CA for the weekend into early next week. But that fetch is to fade by Tues (9/26) and the windswell with it.

For Hawaii trades are to be light below the 15 kt threshold with no rideable east windswell projected.

South Pacific

Beyond 72 hours no swell producing fetch is forecast. A gale previously forecast for the Southeast Pacific has faded from the charts.

More details to follow...


Upwelling Strong West of Galapagos

The Madden Julian Oscillation is a periodic weather cycle that tracks east along the equator circumnavigating the globe. It is characterized in it's Inactive Phase by enhanced trade winds and dry weather over the part of the equator it is in control of, and in it's Active Phase by slackening if not an outright reversing trade winds while enhancing precipitation. The oscillation occurs in roughly 20-30 day cycles (Inactive for 20-30 days, then Active for 20-30 days) over any single location on the planet, though most noticeable in the Pacific. During the Active Phase in the Pacific the MJO tends to support the formation of stronger and longer lasting gales resulting in enhanced potential for the formation of swell producing storms. Prolonged and consecutive Active MJO Phases in the Pacific help support the formation of El Nino. During the Inactive Phase the jet stream tends to split resulting in high pressure and less potential for swell producing storm development. Wind anomalies in the Kelvin Wave Generation Area (KWGA) are key for understanding what Phase the MJO is in over the Pacific. The KWGA is located on the equator from 135E-170W and 5 degs north and south (or on the equator from New Guinea east to the dateline). West wind anomalies in the KWGA suggest the Active Phase of the MJO in the Pacific, and east anomalies suggests the Inactive Phase. In turn the Active Phase strengthens and the Inactive Phase weakens the jetstream, which in turn enhances or dampens storm production respectively in the Pacific.The paragraphs below analyze the state of the MJO in the Pacific and provide forecasts for MJO activity (which directly relate to the potential for swell production).

Overview: La Nina started developing in early 2016, but westward displaced and generally weak. And by March 2017, it was gone with suspicious warming developing along South America and over the Galapagos to a point south of Hawaii. By May the atmosphere returned to a neutral configuration and is holding.

KWGA/Equatorial Surface Wind Analysis & Short-term Forecast:
Analysis (TAO Buoys): As of Mon (9/18) the 5 day average indicated east winds were over the entire equatorial Pacific and strong over the Kelvin Wave Generation Area. Anomalies were modest easterly in pockets over the East Pacific and moderate easterly over all the KWGA. This looks like a classic La Nina setup.
1 Week Forecast (GFS Model): (9/19) Moderate east anomalies were modeled over the core of the KWGA. Moderate east anomalies are to hold through 9/22 then building back to strong status 9/22 holding through the end of the model run on 9/26. This is not the Inactive Phase of the MJO, but is a full pulse of La Nina completely squashing the MJO. This is not a pattern we would wish for.

Kelvin Wave Generation Area wind monitoring model: West and East

Longer Range MJO/WWB Projections:  
OLR Models: As of 9/18 a neutral MJO pattern was in control of the KWGA. The statistical model depicts the Active Phase of the MJO developing in the far West PAcific 5 days out and building some through the next 2 weeks. The dynamic model depicts a dead neutral MJO pattern for the next 2 weeks.
Phase Diagrams 2 week forecast (ECMF and GEFS): (9/19) The ECMF model depicts the Active Phase of the MJO weak and incoherent and is forecast to stay that way, perhaps becoming weakly defined in the West Pacific 7 days out, only to collapse a few days later. The GEFS model depicts the same thing.
40 day Upper Level Model: (9/19) This model depicts the Inactive/Dry Phase was strong over the East Pacific tracking east expected to fade over Central America on 9/27. A weak Active Phase is over the West Pacific tracking east reaching Central America into 10/16. A modest Inactive Phase is to follow in the West Pacific 10/11 easing east over the Central Pacific into the end of the model run on 10/29. This model runs about 2 weeks ahead of what happens at the surface.
CFS Model - 3 month (850 mb wind): (9/19) This model is having technical difficulties. The last run on 9/16 depicted a strong version of the Inactive/Dry Phase of the MJO building over the KWGA with the Active Phase moving east and out of the KWGA with modest east wind anomalies over the far West Pacific. Those anomalies are to fade even as the Inactive Phase tracks east over the West Pacific through 10/5. After that a very weak version of the Active Phase of the MJO is to return starting 10/8 with a neutral wind pattern in play. . After that no clear MJO signal is depicted with a weak wind pattern in play through the end of the model run on 12/14. The low pass filter indicates a very weak La Nina signal is in control of the KWGA and is to hold till 10/2, then building in coverage while drifting east and out of the KWGA by the end of November. There's some sense the pattern is to start shifting east early November entirely east of the dateline. Best guess is a very weak directionless and low energy weather pattern biased towards La Nina redeveloping in Fall of 2017. It will take 5 years for the Pacific to recharge from the 2014-16 El Nino.

CFSv2 3 month forecast for 850 mb winds, MJO, Rossby etc

Subsurface Waters Temps
TAO Array: (9/19) A pattern change set up in August, with warm water retreating to the west and cooler water building in the east. Today in the far West Pacific water temps were depicted at 30 degs centered at 160E. The 28 deg isotherm line continues moving west to 172W. The 24 deg isotherm is stable at 130W today and at 75 meters deep at 140W. Anomaly wise a clear change is present in the East Pacific with warm water gone and turning neutral to weakly negative +0.0 to -1.0 degs at the surface and to -3.0 degs at depth at 140W indicative of La Nina. Warm anomalies are isolated to the West Pacific at +1.0 degrees down to 100 meters deep. The dividing line between cool and warm has moved west to 170W. The hi-res GODAS animation posted 9/15 depicts the same thing, but with more cool water east and less warm water in the west. It looks like the cool water pocket at depth in the East Pacific is poised to erupt to the surface while east winds push all warm surface waters of the equatorial Pacific to the West Pacific. The GODAS image appears to be about 1 week behind the TAO data.
Sea Level Anomalies: (9/15) Negative anomalies are in control at -5 cms from 170W to Ecuador with a large pocket of -10 cm anomalies now present between 105W-160W suggesting a building cool pool at depth. This is not good.

Surface Water Temps: The more warm water in the equatorial East Pacific means more storm production in the North Pacific during winter months (roughly speaking). Cold water in that area has a dampening effect. Regardless of what the atmospheric models and surface winds suggest, actual water temperatures are a ground-truth indicator of what is occurring in the ocean. All data is from blended infrared and microwave sensors.
Satellite Imagery
Hi-res Nino1.2 & 3.4: (9/18) The latest images (1.2 3.4) indicate a clear cold pattern has developed on the equator. Upwelling is strong nearshore along Peru and Ecuador tracking solidly northwest then building in density over the Galapagos and flowing steadily west from there on the equator and well defined out to 160W. There is no breaks in the cool stream over this entire area. This looks very much like a classic La Nina signature. Cooling in the heart of the Nino3.4 region is building.
Hi-res 7 day Trend (9/18): A neutral temperature trend is along Peru then trending cool off Ecuador and then markedly cold from the Galapagos out to 120W and fragmented cool pockets out to 140W. There are no interspersed warmer pockets from the Galapagos westward to 120W. La Nina is pulsing making solid headway.
Hi-res Overview:
(9/18) A clear La Nina cool stream is present starting off Southern Chile pushing north up Peru then turning northwest off Ecuador building strongly while tracking west from the Galapagos to 140W and moderate out to the dateline. This pattern outlines the South Pacific high pressure system well which is assumed to be stronger than normal. There is no sign of warm anomalies in the Nino 1.2 or Nino3.4 regions. Otherwise waters of all oceans of the planet are warmer than normal other than the aforementioned stream. We now assert that climatology needs to be updated to reflect the new reality of warming ocean temperatures over the entire planet.
Nino1.2 Daily CDAS Index Temps: (9/19) Today's temps were falling hard at -1.375, down a full degree in 3 days.
Nino 3.4 Daily CDAS Index Temps: Today (9/19) temps have bottomed out and are rising some for the moment at -0.697. The long arc suggests a clear downward trend.

Click for Full Sized Image

CFSV2 Forecast for Nino3.4 SST Anomalies

SST Anomaly Projections
CFSv2 Uncorrected Data (9/19) The forecast has temps falling steadily from -0.5 degs early Sept to -0.8 in early Oct and down from there to -1.5 in Dec. Then the trend is to turn upwards rebounding to -0.5 in April and neutral in June 2018. This suggests a legit La Nina now expected for the Winter of 2017-2018. The CFS SST images (9/11) continues to suggest a modest La Nina cool pattern building on the equator off the Galapagos in Sept and building steadily into Jan/Feb 2018. A full on La Nina is setting up.
IRI Consensus Plume: The mid-Sept Plume updated (9/19) depicts temps forecast to fade -0.4 degs in Sept, and fading to -0.6 degs in Nov, slowly rising from there turning neutral in April 2018. See chart here - link.  The NMME consensus for Sept average indicates temps -0.75 degrees below normal Nov-Jan 2018 then rebounding to normal in April. It sure looks like La Nina is on the way. The CFSv2 is the outlier, colder than all other models. Still, given all the oceanic signals, we a tending to side with it more than the other models.

Atmospheric Coupling (Indicating the presence of El Nino in the atmosphere driven by the ocean):
Southern Oscillation Index (9/19): The daily index was negative at -6.71, one of a cluster of 3 negative readings in an otherwise unbroken positive streak that has been ongoing for months now. The 30 day average was falling at 4.73. The 90 day average was steady at +3.83. This suggests a turn towards La Nina.
ESPI (like SOI but based on satellite confirmed precipitation. Positive is good, negative bad): (9/19) The index was rising some -1.00 (up from -2.20 on 6/28) but still suggesting a turn towards La Nina. A supposed peak of this La Nina was reached on 11/2/16 at -1.94 (last year). But we're deeper than that now. So the index is about as negative as it was at the peak of last years (2016) La Nina. At this time it looks like La Nina is returning for a double dip/2 year La Nina (not unusual). This index is a forerunner of what happens in the ocean by 2-3 months in developing El Nino and La Nina events.

Pacific Decadal Oscillation: The PDO continues positive, though much weaker lately (as expected with La Nina setting in).
Per NOAAs index recent values (Jan-Dec): Jan 2017 = +0.10, Feb = +0.04, March = +0.12, April=+0.52, May=+0.30, June=+0.19, July= -0.50, Aug= -0.68. This continues to look like the warm phase of the PDO discounting the recent La Nina dip. No consistently negative readings have occurred since Feb 2014
The Washington EDU index (Jan-Dec): Jan 2017 = +0.77, Feb = +0.70, Mar = +0.74, April=+1.12, May=+0.88, June=+0.79, July=+0.10. No negative readings have occurred since Dec 2013
The PDO turned from a 16 year negative run (Jan 98-Feb 2014) in early 2014 and has been positive ever since (other than a few months of negative readings in Fall 2016, the result of a turn towards La Nina). Looking at the long term record, it is premature to conclude that we have in-fact turned from the negative phase (La Nina 'like') to the positive phase (El Nino 'like'), but the data strongly suggests that could be a possibility. By the time it is confirmed (4-5 years out), we will be well into it.

See imagery in the ENSO Powertool


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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