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Pacific Storm and Surf Forecast
Updated: Tuesday, August 18, 2015 8:17 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 to Turn Northeast
Small Gale Develops in Southwest Pacific

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 Tuesday, August 18, 2015 :

  • Buoy 165 (Barbers Point): Seas were 2.9 ft @ 12.5 secs with swell 1.8 ft @ 12.1 secs from 203 degrees.
  • Buoy 46025 (Catalina RDG): Seas were 3.6 ft @ 12.0 secs with swell 2.9 ft @ 12.5 secs. Wind south 2-6 kts early. At Santa Barbara swell was 1.1 ft @ 12.8 secs from 159 degrees. At Santa Monica swell was 1.7 ft @ 12.7 secs from 181 degrees. Southward from Orange County to San Diego swell was 2.8 ft @ 11.6 secs from 179 degrees.
  • Buoy 46012 (Half Moon Bay): Seas were 4.6 ft @ 10.0 secs with swell 2.1 ft @ 12.7 secs. Wind south 7-12 kts. Water temp 62.6 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 Tuesday (8/18) in North and Central CA at best breaks local north windswell was producing surf in the waist high range and clean and pretty gutless with south winds adding some cross bump on it. Down in Santa Cruz surf was knee to maybe thigh high on the sets and inconsistent and weak but clean. In Southern California up north southern angled weak swell was producing surf at waist high.cgius and clean and looking pretty good. Down south waves were waist high on the sets and clean and better than it's been lately. Top spots were chest high. Hawaii's North Shore was getting TS Molave swell with waves head high and clean on the bigger sets. The South Shore was near flat with sets thigh high and clean. The East Shore was getting tradewind generated east windswell with waves thigh high and chopped from east trades. 

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 though small swell from the remnants of Tropical Storm Molave were hitting the North Shore of Oahu. Two typhoons continued tracking on a westerly course in the far West Pacific with the second in the pair forecast to recurve northeast longterm. Certainly bears watching. Regarding windswell, relative to California high pressure was retrograding away from the north coast, but forecast to push east again Fri-Sat (8/22) possibly setting up small windswell at the usual focus points down into Central CA. For Hawaii, east windswell is minimal and forecast to stay that way until Fri (8/21) when a developing tropical system near the Islands might feed the gradient and kick up trades if not something a little stronger and holding into early next week. Monitor this situation. For the southern hemisphere a .cgiit upper level flow continues to suppress storm production over the bulk of the South Pacific with no swell in the waters and none forecast. But a small gale is  developing south of Tasmania and forecast to track well south of New Zealand on Wed (8/19) producing up to 30 ft seas, but quickly fading thereafter. Perhaps some background swell to result. Otherwise the El Nino base state continues developing.   


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

North Pacific

Surface Analysis
On Tuesday (8/18) 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 1036 mbs was in the Gulf of Alaska ridging into North British Columbia with the normal pressure gradient over North California rapidly collapsing with winds there barely 20 kts.  Windswell production was all but gone. For Hawaii the same high pressure system was positioned too far north to generating trades reaching the 15 kt mark, with no real windswell resulting. Small swell from what was Tropical Storm Molave that faded before reaching the dateline on Thurs-Fri (8/14) was hitting the North Shore at 2 ft @ 13 secs.    

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 25-30 kt north winds over and off Cape Mendocino with windswell peaking during that window down into Central CA, but in rapid decline by Saturday evening. Relative to Hawaii trades driven by the same high pressure system were mainly well north of the Islands offering no swell producing fetch locally into Fri (8/21). But a new tropical systems might result in some windswell for the weekend and beyond (see tropical update below).  


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


Tropical Update (as of 12Z Tues 8/18)
TS Molave - Small swell that miraculously arrived in the Islands on Tues (8/18) despite the odds is to be all but gone on Wednesday.  

Typhoon Goni: This system was 600 nmiles east of the northern tip of the north most island of the Philippines with winds 100 kts and building while tracking flat west, expected to continue on this track with just a slight drift to the northwest with winds to 115 kts on Thurs-Fri (8/21) positioned 90 nmiles north of the Phillipines. A hard turn to the north is forecast on Friday putting the core 60-70 nmiles off North Taiwan on Sun (8/23) with winds 90 kts. Central  Southern Japan or 500 nmiles east-southeast of Taiwan. The GFS model has Goni tracking north-northwest from there poised to push into the Southern tip of Japan on Tues (8/25). No recurvature to the northeast and into the open Pacific is forecast.

Typhoon Atsani: Of far more interest is this system. Currently it is positioned 600 nmiles east-northeast of Guam tracking west-northwest to almost northwest with winds 120 kts. Steady strengthening is forecast with this system peaking on Wed PM into Thurs AM (8/20) with winds to 140 kts (161 mph) 500 nmiles south-southeast of Tokyo Japan. By Sun AM (8/23) Atsani is to start turning towards the north positioned 350 nmiles south-southeast of Tokyo with winds 100 kts. Per the GFS model this system is to turn to the northeast on Monday and continuing that track Tuesday into Wed (8/26). Peak swell production relative to Hawaii and California to occur during that window with peak winds at 32N 155E Tues AM (293 degs HI, 292 degs NCal) and 45N 170E Wed AM (319 degs HI, 302 degs NCal).  The optimal swell generation track is towards the US West Coast.  But Hawaii is to be much closer. It is to theoretically stall there and drift north eventually reaching the Bering Sea on Fri (8/28). This system continues to be an interesting tease. But the models are notoriously inaccurate regarding tropical systems and especially a week or more into the future. Still, this system bears watching.

California Nearshore Forecast
On Tuesday (8/18) high pressure at 1036 mbs was in the Gulf of Alaska ridging into North British Columbia but not North CA, with light winds in control of all of the CA coast. more of the same is forecast on Wednesday. Then on Thursday the high is to start pushing east into North CA forming a gradient and generating north winds at 20-25 kts along the coast of Cape Mendocino with a much lighter flow from Pt Arena southward. The gradient and north winds to build Fri-Sat at 25-30 kts with a weak eddy flow nearshore south of Pt Reyes on Saturday.  But the gradient, north winds and windswell to start fading Sun (8/23) as the high retrogrades with north winds down to 20 kts early mainly off south Oregon. A light pressure and wind pattern to follow into Tues (8/25). 


South Pacific

On Tuesday AM (8/18) the jetstream continued very .cgiit with the southern branch ridging hard south pushing into Antarctica southeast of New Zealand then running east slowly rising but never escaping Antarctic Ice until south of the southern tip of South America. A trough was indicated developing south of Tasmania with 150 kt southwest winds pushing up into it and barely north of Antarctic Ice offering some support for gale development. The northern branch of the jet was tracking east as it has all summer from a point north of Northern New Zealand on the 32S latitude line with winds 160 kt winds in one pocket there reaching almost to a point south of Tahiti but less east of there with the fading bits of a ridge off Chile. A bit of a trough was again organizing south of Tahiti supporting formation of cutoff low pressure at the surface there. Other than the Tasmania trough, 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.  The trough south of the Tasman Sea is to track east and make no northward progress, fading south of New Zealand late Wed (8/19) collapsing to the south. Otherwise the track of the southern branch of the jet is to continue di.cgiaced well south with a ridge building in the far Southeast Pacific pushing the jet into Antarctica proper. Beyond 72 hours no change is forecast until Tues (8/250 when miraculously the southern branch of the jet is to loose energy and start lifting north, with 140 kt winds up at 58S running under the Tasman Sea bound for the Southwest Pacific with almost of hint of a trough starting to form southeast of New Zealand.  Will believe it when it happens, but it's a step in the right direction. 

Surface Analysis  
On Tuesday AM (8/18) high pressure at 1028 mbs was still positioned between the .cgiit jetstream flow southeast of New Zealand ridging south to 60S driving the storm track south over Antarctic Ice. But a gale low wass developing south of Tasmania with 40 kt west winds producing 28 ft seas at 59S 140E (219 degs CA) and tracking east offering some hope near term. No other fetch of interest was occurring.
Over the next 72 hours the Tasmania gale is to track east with 40 kt west-southwest winds Tues PM (8/18) generating almost 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 are to be fading from 35 kts Wed AM (8/19) with 29 ft seas fading at 56.6S 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.  No other fetch of interest 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 high pressure in the Gulf of Alaska is to again retrograde northwest and offering no fuel to support a pressure gradient and generation of north winds over the North or Central Coast until maybe Tues (8/25), and then barely at 20 kts isolated to Cape Mendocino. Relative to Hawaii trades are to not be in.cgiay but tropical weather is to be a greater influence (see Tropical Update above). 

South Pacific

Beyond 72 hours no swell source is indicated until Tues (8/25) when 40-45 kt westerly fetch is to start building south of New Zealand, aided by an improving upper level flow. Perhaps some swell to result long term.

Details to follow...


Ecuador Nearshore SST Anomalies Make No Progress - Overall SST Cohesiveness Loosing Definition
Subsurface Reservoir Very Solid But Not Budging

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 Tues (8/18):  
Daily Southern Oscillation Index: Was rising at -7.70. 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 rising from -19.15, responding to the negative run above. It's lowest point in years was on 7/18/15 at -20.49.
90 Day Average: Was falling slightly at -12.24. 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 1024 mbs with lower pressure expected to build over EAus on Thurs (8/20) and moderate some but effectively not relent until at least Wed (8/26).   
SOI trend - Tahiti (looking for low pressure here): An upper trough was supporting development of weak low pressure south of Tahiti on Tues-Thurs (8/20). Weak high pressure is again forecast Fri-Mon (8/24) with a building large low pressure trough starting to develop west of Tahiti on Tues (8/25) building east. 
SOI 1 week Forecast: The net result is to be a rising steady SOI near -5 through Thurs (8/20), then rising into positive territory at least through Tues (8/25).    
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 in control of the Tasman Sea and East Aus offering some support for the SHB. South winds are forecast continuing into Thurs (8/20), then fading for the foreseeable future, till high pressure sets up again over Southeast Australia. It is high pressure there 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): (8/18) Today's value is +2.42 and has been steady in the +2.5 range since 8/10.  We just started following this index. 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 Sat (8/15):
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 165E to 150W running through the eastern 2/3rds of the KWGA. Normal winds continued east of there. This west winds pattern continues impressive but looks to be fading some now compared to previous days and are purely a function of the El Nino base state now.  These anomalies have been steady for the past 28 days (7/19-8/18) 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).
1 Week Forecast: West anomalies are to fade if not turn to weak east anomalies from a line extending west from the dateline 8/18-8/24. The GFS depicts southeast winds in that region (mainly north of New Guinea). But west anomalies (light surface winds) are to start rebuilding weakly from 150E to the east thereafter with weak winds in the entire KWGA by 8/26. West anomalies to continue from the dateline eastward. 

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 continue through today (8/18). That is nearly 2 months of non-stop anomalies if not out and out west winds (6/26-8/15). 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. 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 8/18: 
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 weak Active MJO pattern fading while tracking east over the Central Pacific. A moderate Inactive Phase is to develop in the far West Pacific 8/23 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. The stronger El Nino base 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 Rossby influence is forecast 8/17-8/25, but westerly winds are to persist minimally from the dateline east. The Inactive Phase of the MJO is also forecast 8/18-9/18. 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. 

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, 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. Temperatures in the NINO1.2 region as of the latest image appear to continue to be loosing concentration.  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: (8/18) No change indicated. 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 is working it's way west over the Galapagos and tracking west from there. 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, making it to 158W (8/15) and holding today. But the total thickness of the stream (coverage) is slightly less than days past (i.e. the stream is getting stretched while moving west with no backfill from the Galapagos occurring). Previously they reached to 133W as of 7/16 and then 138W (7/31) pushing to 149W on 8/10. 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 +2.3 degs today (8/18), 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. 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 142W (shrinking some) 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: (8/18) Temps are crashing, down to +1.1 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 up again today at +1.96 (8/18), having just beat the previous all time peak (so far) for this year event on 8/10 at 1.8 degrees.But this will be a short lived peak based on what is happening in the Nino 1.2 region.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.

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 west.  But 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. This is the opposite of what would be expected if one were trying to compare 2015 to '97. 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.   

Subsurface Waters Temps
TAO Array: (8/18) On the equator and under the dateline (160-180W) temperature anomalies have rebuilt significantly. 29 deg temps are between 165E to 138W with a pocket of 30 deg temps pooled up at 155W, 70 meters down. +2.0 degs anomalies are fully bulging from the dateline eastward and +4 deg anomalies taking root from 154W eastward (expanding 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 +7 degs anomalies centered at 110W (holding) and +5 deg anomalies extending east from 142W to Ecuador (holding). 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 8/11 depicts 0-+5 cm anomalies over the entire equatorial Pacific starting at 175E with a expansive core at +15 cm from 110-150W (holding). No anomalies were from the Galapagos to Ecuador. 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 (8/11) 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 171W eastward. +1.5 deg anomalies are doing the same easing east from 155W. All these sectors are sliding east slightly. A pocket of +2.0 degs anomalies are at 151W-->108W (holding) with a large pocket of +2.5 deg anomalies between 146W-->118W (holding). 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.  

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 Tues (8/18) a weak flow was continuous across the North Pacific roughly centered at 55N. A bit of a .cgiit was occurring from the dateline westward. 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. As of right now, the jet remains unremarkable and does not reflect a strong El Nino influenced pattern. .       

Pacific Counter Current:  As of 8/6 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 then lifting a bit north of the equator and still solid 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 on the equator over the West Pacific to the dateline, then lifting a bit north of the equator from the dateline to 130W, then fading but continuing to 100W. Light west to east anomalies were also south of the equator from the dateline to 110W. This is fairly impressive, suggesting this event is getting legs. Compared to the '97 El Nino at this time, today's image actually beats the imagery for '97.  This is the first time this has happened. 

SST Anomaly projections (CFSv2 model - PDF Corrected):  For the model run 8/18 for the Nino 3.4 region, peak temperatures remain stable. It suggests water temps are at +1.6 deg C (verified at 1.9 degs today) and are to steadily warm continuing to +1.95 degs by Oct peaking at +2.0 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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