The following is a brief summary of selected key reasons/reasoning that support the case that a Super El Nino (with a Nino3.4 of between +2.0 and +3.0) is likely to peak sometime between November 2014 & February 2015:
Short-term considerations (as of April 5 2014):• The following link confirms that for the week ending April 5, the weekly Nino3.4 is now above the threshold value of +0.5 for a provisional weak El Nino, and that ensemble models project this index value will continue to increase at least until though summer (austral winter), see the first attached image of the POAMA monthly mean Nino34 forecast issued on April 3 2014. This is important because the development of an El Nino condition (even if provisional/weak) supports the development of positive feedback mechanisms, and the feedback mechanisms are starting about two to three weeks earlier in 2014 than in 1997:
http://www.kylemacritchie.com/real-time-maps/ensosst-3-4/• The SOI influence is currently providing positive feedback by suppressing the Equatorial Pacific trade winds, even though it is still fluctuating and has a value of -10.5 on April 5 2014 (Sydney Time), see the second attached image.
• Currently, the Western Equatorial Pacific is exhibiting above average convective conditions that are supporting the current (and near-term) development of tropical/depressions/storms/cyclones that are contributing to WWBs in the Western Equatorial Pacific.
• Dr Michael Ventrice states in the following link: "An exceptionally strong atmospheric convectively coupled Kelvin wave (CCKW) is currently propagating across the equatorial Indian Ocean. … The forecast calls for this Indian Ocean CCKW to push across the Date Line during mid-April. This would be a time when we might see another period of westerly winds develop across the equatorial Central Pacific--favorable atmospheric conditions for a full-basin El Niño to emerge. The anticipated westerly wind burst in mid-April may be composed of individual tropical cyclones, or extra-tropical waves intruding the tropics.
In addition to the CCKW itself, there are higher than average probabilities of another developing Madden Julian Oscillation (MJO) to emerge over the West Pacific following the passage of this strong CCKW, in mid-to-late April. …. Once the CCKW passes across Africa to over the Indian Ocean, we often observe a developing MJO event over the Indian Ocean that then propagates eastward across the Pacific region thereafter. There are increased chances of a similar scenario to play out over the next few weeks."" Also, see the attached third image of the CCKW in the Indian Ocean as of April 2nd (updated daily). Also, note that a MJO event near the data line is even more effective at generating conditions that support WWBs below MJOs travel more slowly than CCKWs. Also, note that a similar condition in 1997 lead to strong WWBs that rapidly strengthened that developing El Nino.
http://www.wunderground.com/blog/JeffMasters/article.html?entrynum=2658• Professor Roundy of the Albany University, NY, has estimated that if El Nino conditions are established (note that even though the Nino3.4 index is above +0.5, a full El Nino condition has not yet been established as the Walker Cell has not flipped states yet; however, there are preliminary indications that it could flip before the end of April), then there will be about an 80% chance of a strong El Nino this year.
• A coastal-trapped Kelvin wave, CTW, has been observed off the coast of Peru; which means that the typical cold water input from the Humboldt Current into the Eastern Equatorial Pacific, is currently below normal.
• The current Equatorial Kelvin Wave, EKW, is the largest/strongest ever observed during the modern era and it has reached South America and is in the process of surfacing.
• The cloud cover near the equatorial date line is fluctuating about a relatively high level, which increases the chances that the Walker Cell could flip to an El Nino condition sooner, rather than later.
• Both the Nino 3 + 4 indices are relatively high for this time of year.
• The Equatorial Pacific thermocline is well into the process of changing to an El Nino condition.
Long-term considerations:• Both the PDO, and the IPO, indices are positive and are trending to more positive values.
• Super Typhoons are more likely to occur (resulting in more numerous events) during a strong El Nino event because in El Nino years the storm tracks occur closer to the equator and farther eastward (than during neutral or La Nina conditions), and thus the storms have more opportunity to reach higher intensities as they travel longer distances over the warm tropical ocean, while curving northward towards high targets with high economic value in Japan, Korea and Northern China.
• Due to the more southeasterly locations for the locations of genesis of typhoons during strong El Nino conditions; the westerly wind bursts, WWBs, associated with these geneses provide a strong positive feedback to strength the El Nino event.
• The closer that we get to the peak typhoon (tropical cyclone/storm) activity season (July-October), the more likely we are to get positive WWB feedback from tropical storms for strengthening the current fledgling El Nino; which is one of the reasons (together with the projected coming of the MJO in the Pacific) that I am concerned about a major typhoon occurring in April (similar to Super Typhoon Isa) that could kick our current El Nino into a trend leading to the Super category.
• Both the WWV (warm water volume) and the volume of warm water in the Eastern Equatorial Pacific are at historical highs for the satellite era.
• The forecasts indicate the possibility of a positive IOD later this Fall (austral Spring); which could boost a moderate El Nino into a Super category.
Theoretical considerations:
• It has been estimated that strong El Ninos will be (have become) more frequent with increasing global warming, and global warming has continued unabated since the last Super El Nino in 1997-98.
• ENSO is a chaotic cyclic phenomena with strange attractors (that the ensemble models cannot fully represent), and historically Eastern Pacific Super El Ninos roughly occur every 15 to 25 years.
• The following linked reference confirms that most current ENSO projection models treat westerly wind bursts, WWBs, as random (stochastic) forcing events; however, particularly for strong El Nino events this paper indicates that there is a SST-WWB feedback loop where a strong Equatorial Kelvin wave, EKW, creates more WWBs than normal which then strengthens the EKW (as we have seen this year). Furthermore, WWB's are most likely during the period from November through to April; and therefore, April may well experience an increase in the number and severity of tropical storms (and possibly typhoons), that together with the CCKW that is projected to reach the date line by mid-April and the MJO that is projected to reach the Central Equatorial Pacific by late April (or possibly not); these timing considerations could kick the current fledgling El Nino event into high gear:
Geoffrey Gebbie • Eli Tziperman, (2008), "Incorporating a semi-stochastic model of ocean-modulated westerly wind bursts into an ENSO prediction model", Theor Appl Climatol., DOI 10.1007/s00704-008-0069-6
https://www.whoi.edu/fileserver.do?id=100084&pt=2&p=119089• El Nino events are typically more severe than are La Nina events, which is called ENSO Asymmetry, and as the linked reference cites, the current CMIP5 models cannot capture this fact, and thus and ensemble El Nino strength projection must be somewhat underestimating the possible future El Nino strength, most likely because these models cannot properly account for full atmospheric positive reinforcing such as from WWBs:
Tao Zhang and De-Zheng Sun (2014), "ENSO Asymmetry in CMIP5 Models", Journal of Climate, doi:
http://dx.doi.org/10.1175/JCLI-D-13-00454.1http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-13-00454.1Key extract: "The study suggests that the underestimate of ENSO asymmetry in the CMIP5 coupled models is at least in part of atmospheric origin."
• Sherwood et al 2014 state that the influence of convective mixing (down-drafting) dehydrates the cloud cover near the equator both north of 5N and south of 5S, increases with increasing humidity (see also Reply #161), thus as a Super El Nino will clearly increase the humid boundary layer along the Equatorial Pacific; it is probable that a Super El Nino will result in greater solar irradiance near the Equatorial Pacific, both north of 5N and south of 5S; which should result in more atmospheric convection that could contribute to WWBs.
Considerations related to "process-based" El Nino model projections:
• Current process-based El Nino computer model projections, are probably incapable of projecting Nino3.4 ensemble mean values greater than +2.0; and thus are incapable of projecting Super El Ninos (primarily due to ensemble models cannot currently adequately forecast WWBs and other positive atmospheric input, and thus underestimate both the timing and the strength of El Ninos).
• "Official" El Nino projections are typically out-of-date and do not represent the most current information available.
• Process-based projections tend to be "Frequentist" rather than "Bayesianist" thus they typically have trouble projecting "fat-tailed" events (such as Super El Ninos).
• Frequently users of process-based projections prefer to ignore all the caveats and uncertainties (& confidence levels) associated with these projections, and to assume that they are entitled to stationary rather than non-stationary conditions.