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Pacific Storm and Surf Forecast
Updated: Thursday, August 20, 2015 11:01 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 8/17 thru Sun 8/23

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   

Typhoon Atsani Forecast Remains Solid
Solid Storm Forecast South of New Zealand

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.


On Thursday, August 20, 2015 :

  • Buoy 165 (Barbers Point): Seas were 2.9 ft @ 15.4 secs with swell 1.5 ft @ 14.7 secs from 187 degrees.
  • Buoy 46025 (Catalina RDG): Seas were 3.3 ft @ 7.0 secs with swell 1.6 ft @ 12.4 secs. Wind east 6-10 kts early. At Santa Barbara swell was 0.7 ft @ 11.3 secs from 176 degrees. At Santa Monica swell was 1.4 ft @ 12.0 secs from 205 degrees. Southward from Orange County to San Diego swell was 1.5 ft @ 14.7 secs from 187 degrees.
  • Buoy 46012 (Half Moon Bay): Seas were 5.2 ft @ 9.0 secs with swell 2.9 ft @ 12.4 secs. Wind southwest 2-62 kts. Water temp 62.2 degs.
    Note: The hi-res Pt Reyes Buoy has been defunded.  Funding comes from the CA Parks Dept.  We're working to obtain info to e.cgiore ways to reactive this buoy.  

Current Conditions
On Thursday (8/20) in North and Central CA at best breaks local north windswell was producing surf in the thigh to maybe waist high range and textured from southerly winds except at protected breaks. Down in Santa Cruz surf was thigh high on the sets and inconsistent and weak but clean. In Southern California up north no real swell was hitting with waves maybe thigh high and clean. Down south waves were waist high on the sets and clean and a bit lined up. Hawaii's North Shore was flat and clean. The South Shore was near flat with sets thigh high and clean. The East Shore was getting no real tradewind generated east windswell with waves knee high and almost clean. 

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

Meteorological Overview
For the North Pacific no large scale non-tropical swell producing weather systems were occurring. Two typhoons continued tracking on a westerly course in the far West Pacific with the first in the pair just offshore the Northern Philippines and the second forecast to recurve north and then northeast over the weekend offering swell generation potential early next week. This one certainly bears watching. And yet another one is forecast to develop southeast of Hawaii on Fri (8/21) running an intercept course with the Islands longterm. Regarding windswell, relative to California high pressure is projected to start ridging into the North Coast Fri-Sat (8/22) possibly setting up small windswell at the usual focus points down into Central CA. For Hawaii, east windswell is forecast to start building Fri (8/21) in advance of an incoming tropical system near the Islands and might feed the gradient and kick up trades if not something a little stronger and holding well into next week. Monitor this situation closely. For the southern hemisphere an improving pattern is forecast with background swell in the water tracking northeast from a small gale that developed south of New Zealand on Wed (8/19) producing 28-30 ft seas. A cutoff low south of Tahiti is generating 26 ft seas aimed north and expected to hold into late Friday (8/21). And better yet, a solid storm is forecast tracking under New Zealand a week out producing 44 ft seas aimed east-northeast. Something to monitor. And all this on top of a developing El Nino base state. Things are looking better than they've been in years. It's about time.    


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

North Pacific

Surface Analysis
On Thursday (8/20) no swell producing fetch that wasn't tropical was occurring over the greater North Pacific (see Tropical Update section below for tropical details). High pressure at 1032 mbs was in the Gulf of Alaska just a little too far west to be ridging into the North CA Coast, but that is to change shortly. As a result no windswell production was occurring for California. For Hawaii the same high pressure system was positioned too far north to generate trades, with no windswell resulting.     

Over the next 72 hours relative to California the Gulf high pressure system is to start ridging southeast on Fri-Sat (8/22) with the usual pressure gradient growing modest in coverage over North CA generating 25 kt north winds over and off Cape Mendocino with windswell peaking during that window down into Central CA, but in rapid decline by Saturday afternoon and gone by Sunday. Relative to Hawaii trades driven by the same high pressure system integrating with a newly developing tropical system southeast of the Big Island is to start producing fetch locally by Fri (8/21) at 15 kts and possibly more over the weekend as the tropical low moves south of the Islands then takes a motherly track. Longer term this picture become more interesting (see Tropical Update below).  


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


Tropical Update (as of 12Z Thurs 8/20)
Typhoon Goni: This system was 150 nmiles east-northeast of the northern tip of the north most island of the Philippines with winds 115 kts and building. Goni is expected to start making at turn to the northwest today while building, with winds to 125 kts (144 mph) late this evening and then turning fully north to north-northeast. The official track has Goni moving to a point just short of making landfall over Southern Japan Sun PM (8/24) with winds 75 kts. At this time the models suggest no recurvature enough to put Goni free and clear into exposed waters of the North Pacific. Instead a track up the center of Japan is forecast eventually moving into the China Sea.

Typhoon Atsani: This is the system all eyes should be focused on. Currently it is positioned 700 nmiles southeast of tokyo Japan with winds peaking at 135 kts (155 mph) tracking northwest.Seas projected at 40 ft but the model suggest 56 ft. Regardless, all that swell energy is targeting Japan. By Friday evening (8/21) a turn to the north is forecast then turning north-northeast Sat PM (8/22). At that time winds are to be 125 kts (144 mph) with swell generation potential starting to take aim on the greater North Pacific. By Sun AM (8/23) Atsani is to start turning northeast positioned 350 nmiles southeast of Tokyo with winds about 100 kts (115 mph) and seas 54 ft at 31.5N 147E. Per the GFS model this system is to continue on a northeast heading in the evening with winds at least 80 kts and seas 57 ft at 33N 149E. Monday evening (8/24) more of the same is forecast with seas 66 ft at 36N 158E. By Tues AM (8/25) a straight east heading is forecast with seas 59 ft at 38.5N 163E. A slow fade is forecast thereafter with Atsani starting to stall while lifting north Wed AM (8/26) while approaching the dateline with 53 kt winds and 35 ft seas at 40N 169E. Winds to be fading in the evening from 48 kts with seas 31 ft at 41N 165E. If all goes as forecast some swell is possible to result for Hawaii and the US West Coast. But that's still a long ways from being a reality. Something to monitor none the less.

Possible Hawaiian Tropical System: Purely by the models a tropical depression is to form 350 nmiles south-southeast of the Big Island of Hawaii on Fri AM (8/12) on a northwest track. It's to be a tropical storm status 350 nmiles south of Oahu on Sat AM (8/22) then lifting more northerly Sun AM (8/23) and south of Kauai. A turn to the north and northwest is forecast Monday then stalling while drifting east-northeast Tues (8/25) pushing directly over the Western most Islands then drifting just north of Kauai mid-week. Raw local windswell/stormsurf is possible. Of course none of this is believable at this early date. Something to monitor though.

California Nearshore Forecast
On Thursday (8/20) high pressure at 1032 mbs was in the Gulf of Alaska ridging east but having limited impact into the Pacific Northwest (10-15 kt north winds) and 20 kt north winds over Cape Mendocino, with light winds in control of all of the CA coast. A gradient and north winds to build Fri-Sat (8/22) as the high pushes east with north winds 25 kts with a weak eddy flow nearshore south of Pt Reyes on Saturday.  But the gradient, north winds and windswell to start fading later Saturday into Sun (8/23) as the high retrogrades with north winds down to 15 kts early mainly off Oregon. Low pressure is to actually be in the extreme north Gulf of Alaska. A light pressure and wind pattern to follow into Tues (8/25) when a new strong high at 1032 mbs builds in the Western Gulf starting to ridge into North CA with north winds 15 kts along the Central Coast and up to 20 kts in the North. By Wed PM (8/260 north winds at 20 kts to cover the entire Central and North Coasts, then becoming more focused over the North Coast Thursday at 20 kts.  


South Pacific

On Thursday AM (8/20) the southern branch of the jetstream had the fading remnants of a trough positioned well south of New Zealand but it's apex was down at 65S and over Antarctic Ice and falling southeast. East of there the southern branch continued ridging hard south pushing into Antarctica over the Central Pacific then slowly rising but never escaping Antarctic Ice even south of the southern tip of South America. The northern branch of the jet was tracking east as it has all summer from a point north of Northern New Zealand on the 27S latitude line with winds building to 160 kt winds in one pocket south of Tahiti forming a bit of a trough supporting formation of cutoff low pressure at the surface there. But other than that there there was no support for gale formation by the jet in lower levels of the atmosphere. Over the next 72 hours more of the same is forecast. A new ridge is to be building in the southern branch south of New Zealand pushing the jet southeast and down 70S with no support for gale development indicated. Beyond 72 hours wind energy is to slowly start fading in the southern branch. And by Tues (8/25) a trough is to start building south of New Zealand with 150 kt winds pushing northeast but quickly collapsing on Wed (8/26). But a broader and less defined but larger trough to follow in the same area on Thurs (8/27) with winds 130-140 kts lifting up to 55S offering continued support for gale development mainly south of New Zealand. Perhaps an improving pattern to result.

Surface Analysis  
On Thursday AM (8/20) a broad cutoff low was developing south of Tahiti generating fetch pushing north (see Cutoff Low below). Remnant 30-35 kts southwest fetch from a previous gale was south of New Zealand (see New Zealand Gale below). otherwise no fetch of interest was occurring. Over the next 72 hours a .cgiit upper jetstream flow is to continue dominating the pattern with no swell producing fetch expected to result.

Cutoff Low
A cutoff low developed south of Tahiti on Wed PM (8/19) generating a small fetch of 45 kt south winds and a sliver of 26 ft seas at 43S 140W aimed at Hawaii and the US West Coast. The low mellowed some Thurs AM (8/20) with 40 kt south winds pushing better to the north generating barely 26 ft seas at 42S 141W. 40 kt southwest winds to hold into the evening with seas 27 ft at 38S 138W. 40 kt southwest winds to hold into Fri AM (8/21) generating 28 ft seas at 37S 133W aimed mainly at Chile with sideband swell pushing north. This system to be fading after that. Possible 15 sec period south angled swell to result for California with a tiny pulse possible for Hawaii.

New Zealand Gale
A gale low developed south of Tasmania Tues AM (8/18) with 40 kt west winds producing 28 ft seas at 59S 140E (219 degs CA) and tracking east offering some hope near term. The Tasmania gale tracked east with 40 kt west-southwest winds Tues PM (8/18) generating a tiny area of 30 ft seas at 60S 150E (216 degs NCal unshadowed by Tahiti, but becoming shadowed relative to SCal) and totally shadowed by New Zealand relative to HI. Winds were fading from 35 kts Wed AM (8/19) with 29 ft seas fading at 56.5S 162E (shadowed by NZ for HI, 216 NCal and unshadowed, 216 degs SCal and barely unshadowed). This system is to be gone by the evening.  Small swell is possible but it was 7,000 nmiles from CA. Rough data suggests swell arrival with period 17 secs on Sat (8/29) at about 9 PM. Size to be minimal. Swell Direction: 216 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 a new high pressure system is to be moving southeast through the Gulf of Alaska eventually starting to form a pressure gradient over North CA by Thurs (8/27) with north winds 20 kts and with 15 kt north winds pushing down to Pt Conception. This high is to provide a virtual barricade preventing the migration eastward of tropical low pressure in the West Pacific over the dateline. Additionally it's to block the escape route for tropical low pressure theoretically developing over Hawaii. And interesting situation might develop along that boundary long term.

South Pacific

Beyond 72 hours fetch of 35-40 kt west winds is to start building under Tasmania Tues AM (8/25) generating a fleeting area of 32 ft seas at 59S 147E. that is to quickly fade in the evening while moving east, but serving to prime the oceans surface in that area. A new storm is to build behind tracking from the Indian Ocean under Tasmania Wed AM (8/26) with 50 kt southwest winds forecast generating 39 ft seas at 58S 143E. That fetch is to track east with a solid area of 50 kt west winds moving under New Zealand in the evening with 41 ft seas forecast at 59S 162E. Fetch is to be fading from 45-50 kts over a solid area with seas 44 ft at 59S 178E. Assuming all this materializes, which odds are low at this early date, solid swell would result for the Pacific basin.

Details to follow...


Nino1.2 Temps Making No Progress - Interesting Warm Pocket Develop West of Galapagos
Subsurface Reservoir Holding & Strong

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 equatorial Pacific it is in control of, and in it's Active Phase by slack if not an outright reversal of trade winds and enhanced 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.cgianet, 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 help support the formation of El Nino. During the Inactive Phase the jet stream tends to .cgiit resulting in high pressure and less potential for swell producing storm development. 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: A strong El Nino is developing. It began its lifecycle in late 2013 as a primer WWB and Kelvin Wave developed. Then in early 2014 a historically strong push by the Active Phase of the MJO resulted in a large Kelvin Wave, and anomalies continued in the Spring into early Summer transporting more warm water eastward. But the cycle faltered in July due to a protracted bout of the Inactive Phase of the MJO which enabled the upwelling phase of the Kelvin Wave cycle to manifest driving cooler water east, muting warm water buildup along the Ecuador coast. Still the warm water pipe remained open, but surface temperatures near the Galapagos never recovered and any atmospheric momentum was lost. Then in early 2015, another historically strong push from the MJO occurred, effectively a repeat of the early 2014 event, invigorating the warm water transport process and, adding more heat to an already anomalously warm surface pool off Ecuador. That pool has been building steadily in spurts ever since. The paragraphs below describe the current status of various El Nino indicators, followed by a few paragraphs that tie all the pieces together and provide our analysis of what is to come.       (1st paragraph in each section is new/recent data and is typically updated with each new forecast. 2nd paragraph, where present, provides analysis and context and is updated only as required).

Atmospheric Co.cgiing Index's (lagging indicators rather than driving oceanic change): As of Thus (8/20):  
Daily Southern Oscillation Index: Was falling hard at -31.30. We've just completed a roughly 20 day run of values below -10 with 14 days of that below -20 (7/23-8/17).  
30 Day Average: Was falling -20.46, responding to the negative run above ad almost tying the lowest point in years on 7/18/15 at -20.49.
90 Day Average: Was falling slightly at -12.55. It has been at or below -10.0 since early July and bottomed out at it's lowest reading in year on 8/5 at -14.17. 
Trend (looking for negative SOI numbers, indicative of the Active Phase of the MJO or El Nino): The near term trend based on the daily average was indicative of a building El Nino base state. The longer term pattern was indicative of a steadily building El Nino base state.  
SOI Trend - Darwin (looking for high pressure here): High pressure was fading over Southeast Australia at 1020 mbs with lower pressure trying to build over EAus on Thurs (8/20) but getting deflected south by presumably the previous high. Still a weak pressure pattern is forecast over East Aus to hold into Mon (8/24) with weak high pressure then moving into the picture Tues-Thurs (8/27).   
SOI trend - Tahiti (looking for low pressure here): An upper trough was supporting development of large cut off gale south of Tahiti on Thurs (8/20). But that is to move east with weak high pressure forecast Fri-Sat (8/22) with a small low pressure system starting to south of Tahiti Sun-Mon (8/24). Tues and beyond a semi tropical low to s tart building west of and moving directly over Tahiti Tues-Thurs (8/27).  
SOI 1 week Forecast: The net result is to be a modulating SOI but moving lower into next week.     
SOI Analysis: During El Nino, the SOI functions as a measure of how well the ocean and atmosphere are co.cgied. Current numbers suggest good but not great co.cgiing and that trend to continue for the immediate future. That will likely change for the better as the El Nino base state builds as we move into Fall. A consistent 90 day average of -18 is our target, indicative of a strong El Nino.
Southern Hemi Booster Index (SHBI) Analysis (which is theorized to supercharge a developing El Nino): South winds are fading Thurs (8/20) and are not in the forecast until Tues (8/25) and then only weakly so, and fading Wednesday with no return forecast. It is high pressure over Southeast Australia that sets up the southerly surface flow. South and southeast wind anomalies have been building in this region off and on for weeks now (previous run 7/29-8/10, this run 8/13-8/18). The SHBI appears to positively influencing El Nino development, but we have no hard numbers to confirm. 
ESPI (like SOI but based on satellite confirmed cloud cover): (8/20) Today's value is +2.27 falling from +2.42 on (8/18) and had been steady in the +2.5 range since 8/10.  Historically the peak of the '82 El Nino was +2.2 and the '97 event +2.85. This suggests the '15 El Nino is already very well co.cgied with the atmosphere, more so than some of the other indices indicate.       

Equatorial Surface Wind Analysis & Short-term Forecast: As of Thurs (8/20):
7 Day Models: Models are not updating. Owner is working to rehost on a new server. We are e.cgioring options to build similar images too.
Analysis from TAO Buoys: Down at the surface the TOA array (hard sensors reporting with a 24 hr lag) indicated no actual west winds any more in the KWGA. Moderate anomalies extend from 180W to 150W running through the eastern 1/3rd of the KWGA. Normal winds continued east of there. The anomalous west wind pattern continues but has faded in the heart of the KWGA now compared to previous days and are purely a function of the El Nino base state now. These anomalies were steady for the past 29 days (7/19-8/19) and followed directly behind a very strong WWB burst (third of the year) that was associated with a robust Active Phase of the MJO (historically strong) 6/24-7/17 (nearly 2 months of west anomalies or stronger). But now we're in a bit of a weak phase.
1 Week Forecast: West anomalies have faded west of the dateline and are theoretically to turn to weak east anomalies (up at the 850 mb level - 4,500 ft) from a line extending west from the dateline 8/18-8/26 courtesy of an Inactive Rossby Wave moving through the area. The GFS model is not as negative though, depicting southwest winds in that region now (mainly north of New Guinea) fading out by Tues (8/25). And west winds (not just anomalies) are to start rebuilding from 160E and points east of there by Sat (8/22) at 12 kts and drifting northwest into Wed (8/26) with a dead wind pattern following. At this point, no east winds are forecast in the KWGA, and even the odds of east anomalies looks remote.  

A huge WWB occurred in March followed by a second smaller one (9 day duration) in early May with weaker but still solid west anomalies continuing after that through 6/10. Anomalies faded to neutral for 8 days through 6/18 as the Inactive Phase of the MJO interfered with the pattern (the first such event of the year), then weak westerlies started again on 6/18. A significant WWB, the strongest of the year so far, starting on 6/26 peaking near 7/4 but held nicely through 7/17 (22 days), the result of a historically strong Active Phase of the MJO which produced a strong and large Kelvin Wave, the third this year and the strongest by far. Moderate westerly anomalies redeveloped 7/29 when a Rossby Wave started interacting with the building El Nino base state, enhancing the westerly flow, developing a mini-WWB at 175E through 8/5. And westerly anomalies continued through 8/19). That is nearly 2 months of non-stop anomalies if not out and out west winds (6/26-8/19). But for the next week, we will have to deal with lesser westerly anomalies than almost anything seen so far this year. That should not be a game changer assuming it is limited to that small window. And even that might be overstated. West wind anomalies at the surface are the hallmark of the Active Phase of the MJO and El Nino and drive Kelvin Wave production.  

Kelvin Wave Generation Area monitoring model here

Longer Range MJO/WWB Projections: As of 8/20: 
OLR Models: Indicate a dead neutral MJO signal over the West Pacific. The Statistic model suggests a dead MJO pattern is to hold for the next 15 days. The Dynamic model depicts the same. In essence no MJO influence is forecast. This is typical of the pattern when an El Nino base state strengthens.  
Phase Diagrams 2 week forecast (ECMF and GEFS): They suggest the Active Phase of the MJO is weak and collapsed and is to not return.  
40 Day Upper Level Model: It depicts a modest Active MJO pattern fading while tracking east over Central America through 9/4. A weak to models Inactive Phase is starting to develop in the far West Pacific 8/20 tracking east through 9/22.  This makes sense given the CFS forecast for weak east anomalies in the far west KWGA for the next week. It is suspected a little bit of destructive interference to develop regarding surface west anomalies west of the dateline from this weak Inactive Phase and a Inactive Rossby Wave in the area as well. The stronger El Nino base state starts it's influence from the dateline heading east though, with the Inactive MJO having no impact there.       
CFS Model beyond 1 week (850 mb): A weak Inactive Phase of the MJO is forecast 8/20-9/20. Some positive enhancement from Rossby waves might result for a few days around 8/28-9/18, with a major push of the Active Phase of the MJO remaining scheduled starting Sept 24 in the far West Pacific holding till 10/28. No easterly anomalies are forecast for the long term. Westerly anomalies are to rule from 8/30 and beyond well into mid-Nov. The question is, will another Kelvin Wave result?

The general consensus by the models is that we are to hold in a neutral to slightly Inactive MJO pattern for the next 4-5 weeks, but with some positive support from a Rossby Wave, then perhaps giving way to the Active Phase.  In reality, a pure El Nino base state is at.cgiay driving current west anomalies and not expected to change much. Westerly anomalies, regardless of their source, are all that's required to push warm water to the east.

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

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.
Satellite Imagery
On (8/17) first impressions indicating a fading warm water signal covering the entire equatorial Pacific. The pattern is ill defined and poorly organized. If it wasn't for our foreknowledge of what is happening subsurface, we'd say the bottom just fell out of the El Nino machine. Still a huge pool of lukewarm water is covering the entire equatorial Pacific and filling the entire North Pacific Ocean. But compared to previous imagery (7/16), the pattern is looking progressively diffuse and weak. But compared to any other year at this time other than '97, an obvious El Nino signal is apparent. Temperatures in the NINO1.2 region as of the latest image appear to continue to be loosing concentration and temperature. Still no cool waters are present.  Just no markedly warm or concentrated warm waters are depicted. Along the West African Coast, cool water continues there, but loosing it's grip. Very warm water continues off the US West Coast and holding while extending west the whole way to Japan but unrelated to this years El Nino, but possibly attributable to the building warm phase of the PDO. Slightly cool water is over Australia. Slightly warm water continues near Madagascar. 
Hi-res Nino1.2: (8/20) No change is indicated nearshore to Ecuador. But a pocket of very warm water is depicted starting to bloom just east of the Galapagos at 95W and has been building for the past 3 days. And other pockets are starting to appear west of there to 120W. We're thinking that the Big Kelvin Wave is starting to get some exposure on the surface west of the Galapagos. This is not be unexpected, but the bulk of the Kelvin Wave is still anticipated to push past the Galapagos and erupt there. Need more days of data to confirm. Anomalies crashed on 8/15 east of 100W with only limited pockets of +2.5 deg or greater anomalies present, with the rapid decline starting 8/13. And this pocket was thought to be is working it's way west over the Galapagos and tracking west from there, but other data is starting to contradict that observation. The upwelling phase of the Kelvin Wave cycle is here, or at a minimum a heavy backdraft from a huge Kelvin Wave building just east of the Galapagos is occurring. Peak temps occurred between the Galapagos and Ecuador on 7/14, then faded between 7/14-7/30 (and is reflected in the low res imagery too - see above). From 7/31-8/13 temps between Ecuador and the Galapagos stabilized then crashed starting 8/13.
Hi-res NINO 3.4:
 (8/18) Unbroken +2.25 degs anomalies continue advecting west from a previous Kelvin Wave that impacted the Galapagos, but have started to retract in the west from 158W (8/15) to 145W today with another pocket at 155-160W. Previously these anomalies reached to 133W as of 7/16 and then 138W (7/31) pushing to 149W on 8/10 and 158W on 8/15. This is advection west of warm water resulting from eruption of the 1st and 2nd Kelvin Waves earlier this year.
Galapagos Virtual Station:
This station reported temps at +2.1 degs today (8/19), holding in the 2.1-2.3 range since 8/14. Previously a solid reading occurred on 5/23 at +4.59 degs suggesting the first Kelvin Wave generated in Jan-Mar had arrived, then built to +5.45 degs on 6/14. Temps faded from that high peak down to +4.1 degs in late June then rebuilt up to +4.94 on 7/17. Then a fade set in, down to +3.1 degs as of 7/31 and bouncing from +3.1-3.5 through 8/7, then falling dramatically to 2.0 on 8/10. Much more warm water is poised at depth just off Ecuador (see below) and required immediately.  
Other Sources
TAO Data: +1.0 anomalies are in control over most entire equatorial Pacific, the warmest in years, presumably advecting west from the Galapagos covering the entire area west to the dateline. There's some solid evidence that the large surface warm pool is pushing east, at least north of the equator with the +1 degree anomaly periphery at 165W. A previous pool of +1.5 deg anomalies on the dateline has vanished and the extent of +1.0 deg anomalies is shrinking. There is an embedded area of +2.0-2.5 deg anomalies extending from the Galapagos to 143W (holding) with +1.5 deg anomalies reaching to 150W (holding). Overall the warm water signature is holding but not migrating west any. This is likely the peak for a few months.
Nino1.2 Index Temps: (8/20) Temps continue crashing, down to +1.0 degs, presumably the result of the backdraft occurring off Ecuador. Previously temps hovered at +2.1 degrees early June then spiked reaching +3.0 degs on 7/3, faded then spiked again on 7/13 at +3.0 degs and yet again at +3.0 degs on 7/22. Temps fell to +1.9 degrees on 7/27 and have been steadily fading from there.
Nino 3.4 Index Temps: Temps are holding today at +1.95 (8/20), having just beat the previous all time peak (so far) for this year event on 8/10 at 1.8 degrees. This is well into the major El Nino category. But this will be a short lived peak based on what is happening in the Nino 1.2 region unless the 3rd Kelvin Wave erupts partially west of the Galapagos (some evidence suggesting that is happening now). Water temps previously held in the +1.0-1.3 deg range since mid-April, then started building pushing +1.5 degs on 6/30, held then crept up, peaking at +1.75 degs on 7/19 and +1.7 degs on 7/29 and then peaking at +1.8 of 8/10.

(Refreshed regularly - 8/20) If one is to make a direct comparison of the 2015 event to '97 at this time of year based on water temp alone, there is no comparison. '97 imagery leaves this years event in the dust and whatever comparison there was is fading out quickly. The '97 event built non-stop from this point forward. Instead, the 2015 event is currently in deep decline. It is not building any other than leftovers from previous Kelvin Waves advecting east. Warm water at the source has all but dried up. Total coverage of warm waters in the current imagery still remains respectable, but the depth of concentration is gone. A clear and significant downgrade is occurring in the Galapagos area, as evidenced by the apparent drop-off of NINO 1.2 water temps, the hi-res satellite data and the hi-res temp trend imagery for the past 7 days. This is likely the result of a pause in upwelling of warm water in that region, a break between the first and second Kelvin wave eruptions and the third poised just off Ecuador. This is turning into a true Upwelling Phase of the Kelvin Wave cycle. But we suspect it just a backdraft or pull back of warm waters ahead of a massive Kelvin Wave set to erupt in the Ecuador region in the next week. But, the point is, until that eruption occurs, these cooler water will advect west and eventually negatively impact temps in the NINO3.4 area, driving it down too. There appears to be.cgienty of water poised in the subsurface reservoir, and if anything, is building driven by the strength and duration of the most recent WWB (late June) when the resulting Kelvin Wave hits (peak temps in Nino 1.2 expected 10/4). Still given the current pause in warming near the Galapagos, no additional expansion of the warm pool is expected in the short term. Still, this pause is temporary, with much warming, the biggest yet of this event, still in the pipe. Regardless, the eventual effects of this cooling water pattern on the atmosphere will not go unnoticed.  The one possibility is that if the 3rd Kelvin Wave partially erupts west of the Galapagos. There are signs that might be occurring with 4 pockets of building warm anomalies between the Galapagos and 120W.  

Subsurface Waters Temps
TAO Array: (8/20) On the equator and under the dateline (160-180W) temperature anomalies have rebuilt significantly. 29 deg temps are between 160E to 135W (expanding) with a pocket of 30 deg temps building at 155W, 70 meters down. +2.0 degs anomalies are fully bulging from the dateline eastward and +4 deg anomalies taking root from 150W eastward (shrinking slightly), the direct effects of the massive June-July WWB. A large warm reservoir at +5-7 deg above normal is poised to erupt into Ecuador. That reservoir is holding coverage with peak +6 degs anomalies centered at 110W (holding) and +5 deg anomalies extending east from 139W to Ecuador (shrinking slightly). This pocket is a mixture of warm water from a WWB in early May merging with water from the most recent strong WWB in late June-July. The pipe is open with more warm water rushing in and very warm water poised to erupt into the Galapagos.
Sea Surface Height Anomalies (SSHA):  Data from 8/16 depicts 0-+5 cm anomalies over the entire equatorial Pacific starting at 175E with a core at +15 cm from 110-150W (shrinking slightly). No anomalies were from the Galapagos to Ecuador indicative of the Pause mentioned above. This is most impressive. All this is indicative of a wide open pipe with a large Kelvin Wave in flight in the mid-Pacific poised to merge with a subsurface reservoir poised off Ecuador. This is a classic major El Nino setup, not a standard El Nino.
Upper Ocean Heat Content: As of (8/16) this data drives the point home. It indicates +0.5-1.0 deg anomalies are tracking east between 180W and the Galapagos (holding). +1.0-1.5 degs are from 173W eastward. +1.5 deg anomalies are doing the same easing east from 155W. All these sectors are holding. A pocket of +2.0 degs anomalies are at 150W-->106W (holding) with a large pocket of +2.5 deg anomalies between 140W-->118W (shrinking some). A pocket of cooler 0.5-1.0 degs anomalies is holding between the Galapagos and Ecuador (from 91W-80W) and not moving east. This is the backdraft pool that we hoped would be shrinking by now.  

A strong Kelvin Wave impacted the Ecuador Coast in May-June with a second somewhat weaker one impacting it in June. And now a third is setting up, the strongest of all an getting stronger with each update. A pause in warming near Ecuador is evident in the subsurface data too, suggestive of a break between successive strong Kelvin Waves. And that gap is not getting smaller (i.e. moving east). If anything, it is holding, and appears to be influenced by backdraft from the expanding 3rd Kelvin Wave developing west of it. Unfortunately the Upwelling Phase of the Kelvin Wave cycle is occurring. Still no 'cooler than normal' waters are expected to result, just a pause in the steady incremental increase in surface warming. But that will likely have an affect on the overall heat signature at the surface, reducing it some in the short term (as is currently occurring in Nino1.2). We've calculated Kelvin Wave arrival using satellite data to identify the leading edge of it and using 2 and 3 m/sec travel speeds. The eruption should be poised to occur now. But based on satellite and other data, no eastward movement of the leading end of the Kelvin Wave is occurring. This suggests is is still organizing east of the Galapagos. Regardless, the subsurface configuration suggests there are 2.5 months of warm water in this reservoir (till Nov 1) and some of that water is extremely warm. And with an expected pause now setting up in the KWGA of westerly anomalies, the question becomes, is this third Kelvin Wave the final one, or will another follow? We all hope the answer is more is on the way. but that is entirely dependent upon how strong the El Nino base state really is. Historically this is a great setup if we can just get through the short term 'pause' and then get another WWB behind that.  

North Pacific Jetstream:  As of Thurs (8/20) a weak flow was continuous across the North Pacific roughly centered at 50N with a .cgiit from the Kuril's to the dateline. This is not impressive but suggests some weak influence by El Nino is occurring by virtue of the jet being present at all south of the Aleutians. More of the same is forecast over the coming week with a large ridge over the East Pacific. As of right now, the jet remains unremarkable and does not reflect a strong El Nino influenced pattern.

Pacific Counter Current:  As of 8/17 the current continues solid and building. The current is pushing strongly west to east over the west equatorial Pacific filling the Kelvin Wave Generation Area mainly north of the equator and still solid but fading while pushing west from 160W to 120W before fading out. A pocket of modest east anomalies was over the immediate Galapagos. Anomaly wise - Strong west anomalies were spread mostly north of the equator over the West Pacific to the dateline, with a strong pocket north of the equator from the dateline to 140W, then fading in pockets continuing to 100W. No east anomalies were indicated. This is fairly impressive, suggesting this event is getting legs. Compared to the '97 El Nino at this time, today's image actually is fairly similar, if just a hair less strong. This is a significant improvement.  

SST Anomaly projections (CFSv2 model - PDF Corrected):  For the model run 8/20 for the Nino 3.4 region, peak temperatures remain stable if not upgraded slightly. It suggests water temps are at +1.65 deg C (verified at 1.95 degs today) and are to steadily warm continuing to +2.0 degs by Oct peaking at +2.05 degs by Nov, then dropping off. Even given the current pause occurring In Nino1.2, and considering the size of the new Kelvin Wave forming subsurface, we suspect this projection is on the low side. The mid-July consensus Plume suggests development of a strong El Nino with peak temps (depending on model type) spread between 1.5-2.0 degs above normal. See the chart based version here - link. 

Analysis: In late 2013 into 2014 the Active Phase of the MJO and successive Kelvin Waves warmed waters over the Eastern equatorial Pacific and primed the atmosphere out of a 15 year La Nina biased pattern that had been in.cgiay since the demise of the '97-98 Super El Nino. It is assumed some greater force was dictating the change from a cool regime to warmer pattern, (the PDO). This warming and teleconnection continued building in 2015 with two Kelvin Waves arriving in Ecuador warming surface waters well into El Nino territory and a third, the strongest so far, in flight now. Preceding this Kelvin Wave is a pocket of less warm water. But with a large warm reservoir lodged just west of the Galapagos and the third Kelvin Wave directly behind, warming is expected to resume shortly. At this time we believe the classic El Nino feedback/teleconnection loop is in effect, with the atmosphere and the ocean are well co.cgied.   

But a glance at the SST Anomaly charts suggest the El Nino pattern is now becoming not as impressive as earlier. Given this pause in warming, the big question then becomes: How strong will this El Nino become? That is purely a function of the strength and duration of westerly anomalies in the Kelvin Wave Generation Area. And the frequency of those events is dictated by the character of the El Nino.  All El Nino events are different.  The pace of the WWBs and Kelvin Waves, their duration, depth and speed all help to define any given ENSO event. The '97 event was fast paced and furious, with no breaks, transitioning from La Nina to the strongest El Nino ever (by some measures) in a quick 7 month window starting 4/23 peaking on 11/26 (+2.69 deg). The '82 El Nino took longer to build starting in May and peaking in late Jan of '83 (+2.8 degs) (data OISSTv2). Other strong events in '72, '86, and '91 had dissimilar profiles. The point being, there is no exact te.cgiate for a strong El Nino other than they tend to form in the Spring and peak during the following Winter. And regarding the exact micro-details of each WWB, the resulting Kelvin Wave speed and arrival time in Ecuador etc, all vary though fall into the general guidelines established above. Given the false start of this El Nino in 2014 (and for that matter the other false start in 2012), this event has taken it's sweet time getting organized. But it's been struggling against an atmospheric bias towards La Nina driven by  the cool phase of the PDO. We believe the atmosphere is trying to transition to the warm phase of the PDO, but is still fighting momentum from the cool phase, hence elongating this El Nino's lifecycle. And regarding the 'warm blob' off the Pacific Northwest, we believe that is more a symptom of the developing warm PDO, and will get punctured by incoming storms once El Nino gets traction and the jetstream energizes in the late Jan/early Feb 2016 timeframe. Winds from storms cause mixing and upwelling, which in turn cool surface waters. Of course that assumes this El Nino event develops into at least Strong if not Super status.

The longer it takes El Nino to develop, the thought is it will take proportionally longer to dissipate.  That is, once El Nino atmospheric momentum takes hold, and if it takes longer to make that transition, it will be more stubborn and take longer to dislodge.  There is no scientific data to support that thesis, it's just an opinion. But if the Active Phase of the MJO does develop in the Sept/Oct timeframe as predicted by the CFS model, and if a significant Kelvin Wave results, it would not arrive in Ecuador till ~Jan 1, 2016, and not disburse till a month later (Feb). That said, the character of this event is not at all like '97, but is starting to show signs of developing slower, like '82. And that would not be a bad thing, in that it could slow the inevitable transition to La Nina until later in the winter of 2016-2107.

Finally the discussion of 'atmospheric co.cgiing' needs to be considered. How much affect is El Nino having on the atmosphere? That is ultimately what impacts the jetstream and fuels winter storm development. The SOI is one such indicator. Changes in surface wind in the equatorial West Pacific another. But it is the total effect of El Nino on a wide variety of indicators, and the weighting of those indicators into a single number that can be used to track this event against others.  This approach provides a clearer picture, where tracking an individual condition in the absence of others leads to a less comprehensive view. NOAA has developed just such an index, the Multivariate ENSO Index. It is used for research purposes, but is useful for our need too. It is conservative, has a pedigree, and has been hindcast tested against previous ENSO events. Per the MEI, the top 5 events since 1950 in order are: '97, '82, '91, '86, and '72 with '97 and '82 classified as 'Super El Nino's' because they reached 3 standard deviations (SD) above normal. '91 and '86 were at about 2.2 and 2.1 respectively with '72 peaking at 1.8 SD's above the norm.   The current ranking (July) for 2015 is 1.97 SD (65).  At this same time in '97 the ranking was 2.85 SD (66) and in '82 it was 1.7 SD (61). So we're slightly above the '82 event but well below '97, or comfortably on track for this time of year to move into Super El Nino territory. And even more interesting, the MEI for July actually went down (0.09 SD) from last month. Suffice it to say were are somewhere between '82 and '97 in term of of atmospheric co.cgiing.       

So where does it go from here? Having a MEI that today is equivalent to two other Super El Nino events is no guarantee that this years event will eventually evolve into a Super El Nino. We still have 1.0 SDs to go. Though looking at the record back to 1950 for other events that have similar values in July, the odds favor that outcome. Still, the argument goes back to monitoring WWB and Kelvin Waves. That ultimately is the best leading indicator of what's to come.  The more west anomalies, the more warm water gets pushed down into the pipe and the rest turns into an assembly line process with a more or less fixed outcome. Said another way, it appears an evolving El Nino base state is in control and building which in turn should dampen any future Inactive Phases of the MJO cycle and/or potential for easterly anomalies. This is required for a major El Nino to develop. So the current concern is focused on the pause in warming in the Nino 1.2 region and it's eventual impact as it advects into the Nino3.4 region. But again, with a very vigorous Kelvin Wave locked and loaded in the pipe poised to erupt near Ecuador in the next few weeks, it seems the nearterm outcome is certain. The future concerning more and stronger WWBs is unknown, but we are betting on the CFSv2 being largely on the right track with the El Nino base state slowly having greater influence over time and being enhanced by the MJO and Rossby Waves at times. And that doesn't count the change of seasons scheduled to start in early Sept, again favoring enhancement of the El Nino base state and the MJO. We just need to get though the next 3 weeks.        

So for now we're tracking towards an El Nino that will end up somewhere between the 82' and '97 event, with very good atmospheric momentum in.cgiay, and that's a good.cgiace to be.  We'll continue monitoring the North Pacific jetstream and will be looking for tropical activity in the West Pacific to recurve northeast moving towards the Gulf of Alaska, and for swell to result from such systems in later August and Sept. To us, those are the sure signs of deep changes in the atmosphere influenced by El Nino. Until then, continue on your training routines and complete.cgians to procure additional boards. And if you own beachfront property in California, pay your insurance premiums.     

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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