40/70 Benchmark

Right...its about where the forcing sets up. This is why 2018-2019 el nino acted more like a la nina. While this won't be a modoki, we could get similar weather patterns at times...probably later in the seaaon.

No way it goes modoki IMO.

100%.

Sure, but 1983, 1998 and 2016 didn't get below 2.0 until March and April. That is too late...the latter got interesting because it got further west. I'll roll the dice with a weaker version of 2015-2016....though still likely warm.

Hello El Nino My Old Friend: El Nino Watch In Effect After Protracted La Nina El Nino Comes in Many Shapes and Flavors Finally, on the heels of three consecutive la nina events, an el nino watch has been issued for the first time in half a decade as of May 11. While there are no certainties with respect to anything pertaining to the atmosphere, the Climate Prediction Center (CPC) is more than 90% certain that el nino conditions will in fact develop and persist throughout the ensuing 2023-2024 boreal winter season. This level of confidence appears justified at this early juncture. Here is an illustration of the latest guidance from May: Statistical guidance is often very helpful in revealing the most climatologically favored outcome at longer lead times, however, caution is advised when said guidance is in great conflict with dynamical guidance. The latter of which is designed to incorporate what is actually going on in the atmosphere. In this instance, given that the current MAM ONI value is 0.1 and there are several examples of a large enough recovery between now and next fall to achieve to a powerful peak of el nino, the current dynamical mean of a 1.67 peak ONI during the OND tri monthly period seems like a reasonable first approximation. And thus the statistical guidance can be summarily dismissed until further notice. This is in accordance with latest CPC estimation, which places the odds of a strong ONI peak of equal to or greater than 1.5 at 55%, which is exceptionally strong for such a long lead time. Although it is far too early to offer any definitive forecasting insight with respect to how the developing el nino will mold the coming winter season, there are some general inferences that can be made about how it could potentially impact the weather patterns. Sorting El Nino by Intensity A weak el nino is defined by CPC as a tri-monthly ONI peak of equal to or greater than .5 up through .9. Moderate is equal or greater to 1.0 up through 1.4. Strong, which is where guidance currently favors the developing events to peak, is anything equal or greater to 1.5 through 1.9. And an intense event, which remains a distinct possibility, is anything equal to or exceeding 2.0. There are only three el nino events since 1950 that the CPC definition of an intense el nino. They are the 1972-1973 (2.1 peak) event, the 1997-1998 (2.4) peak event and the el nino of 2015-2016 (2.6 peak). While the Eastern Mass Weather el nino intensity designations heavily incorporate ONI, there are other considerations, such as MEI and time of peak. Thus while the 1972-1973 event meets the CPC standard of an intense event per ONI, the MEI value during the winter was hardly considered strong, thus it is debatable how well coupled it remained with the atmosphere throughout the winter season. It is with this in mind that this particular season is considered as a "strong" event, rather than intense. Likewise, the 1987-1988 peaked as a strong 1.7 ONI value during the summer, but had weakened considerably by winter, this it is considered to be moderate, despite peaking as a strong ONI designation. Here are the intense el nino composites, which are comprised of the 1982-1983, 1997-1997 and 2015-2016 seasons. The meteorological differences between the composites will be discussed in great this fall, and over course in the winter outlook. Intense El Nino Intense El Nino SST Anomaly Composite: Intense El Nino H5 Composite: Intense El Nino Forcing Via Velocity Potential: Intense El Nino Temperature Anomaly Composite: Intense El Nino Precipitation Composite: Very strong positive precipitation anomaly (near coast and se) and negative precipitation anomaly (Ohio River Valley) couplet due to presence of very powerful subtropical jet (STJ) Strong El Nino Strong El Nino SST Anomaly Composite: Strong El Nino H5 Composite: Strong El Nino Forcing Via Velocity Potential: Strong El Nino Temperature Anomaly Composite: Strong El Nino Precipitation Composite: Moderate El Nino Moderate El Nino SST Anomaly Composite: Moderate El Nino H5 Composite: Moderate El Nino Forcing Via Velocity Potential: Moderate El Nino Temperature Anomaly Composite: Moderate El Nino Precipitation Composite: Weak El Nino Weak El Nino SST Anomaly Composite: Weak El Nino H5 Composite: Weak El Nino Forcing Via Velocity Potential: Weak El Nino Temperature Anomaly Composite: Weak El Nino Precipitation Composite: Drier due to a less pronounced STJ. It is important to note that the weaker el nino events, which are also colder across the forecast area and feature more high latitude blocking, have the forcing more diffuse and focused further to the west. While the more intense events that feature milder winters for the forecast area and a notable dearth of high latitude blocking, are focused further to the east. Hence it is the stronger events that end up being more evenly distributed that present the greatest forecasting quandaries and it appears as though that may be precisely what is on tap this season. El Nino Distinguished by Orientation Generally speaking, stronger el nino events rate lower on the El Nino Modoki Index (EMI), and weaker events higher. Thus stronger events are generally biased to the east and stronger to the west. Currently, the developing el nino event it strongly biased to the east. This is reflected by the negative EMI reading at this time. However, there is a definitive consensus amongst the various Japanese Meteorological Association (JMA) ensemble members that the event will translate eastward throughout the summer, fall and into the winter. This is often the case with many el nino events, but the degree to which it occurs is dictated by many nuanced relationships between tropical wind and pressure patterns. This implies that a truly challenging seasonal forecasting effort may lie ahead. There is plenty of time to dissect this further over the next several months as el nino continues to evolve, but for now, lets simply present the various composites. East-Based El Nino Given that the most intense el nino events are generally heavily eastern biased, there exists a negative correlation between the ONI and EMI. This is reflected well in the eastern-based SST composite. East Based El Nino SST Anomaly Composite: Note the similarities to the intense, and to a lesser, extent, the strong composites. East-Based El Nino H5 Composite: East-Based El Nino Forcing Via Velocity Potential: East-Based El Nino Temperature Anomaly Composite: East-Based El Nino Precipitation Anomaly Composite: Wetter in general near the east coast due to the active STJ, but the positive precipitation anaomalies and adjacent negative precipitation anomalies are not as extreme as the intense composite. Basin-Wide El Nino Half (12) of the 24 el nino events since 1950 have been designated as basin-wide events. Basin-Wide El Nino SST Anomaly Composite: Similar to moderate composite. Basin-Wide El Nino H5 Composite: Element of high latitude blocking, as in moderate composite. Basin-Wide El Nino Forcing Via Velocity Potential: Forcing placement on par with moderate composite, but stronger and more focused. Basin-Wide El Nino Temperature Anomaly Composite: Cooler like moderate. Basin-Wide El Nino Precipitation Anomaly Composite: Modoki (West-Based) El Nino Modoki el nino is often, not always, synonymous with weaker events. Modoki El Nino SST Anomaly Composite: Same placement as weak composite, but slightly greater anomaly. Modoki El Nino H5 Composite: Great deal of high latitude blocking, as in weaker events. Modoki El Nino Forcing Via Velocity Potential: Same placement as weaker events just east of the dateline, but stronger and more focused. Modoki El Nino Temperature Anomaly Composite: Interestingly enough, although the composite is comprised of stronger el nino events than the "weak" composite, the negative temperature anomalies are actually greater. This makes sense because the forcing is in the same place, just stronger and less diffuse relative to the weak composite. Modoki El Nino Precipitation Anomaly Composite: Drier than the east based composite, but not as dry as the weak composite. Please stay tuned throughout the summer and autumn as these differences are further dissected within the context of the fledgling el nino in order to provide greater insight into the coming winter weather pattern.

Hello El Nino My Old Friend: El Nino Watch in Effect After Protracted La Nina | Eastern Mass Weather

Hello El Nino My Old Friend: El Nino Watch in Effect After Protracted La Nina | Eastern Mass Weather

Agree.

Agree.

Yea, subtle warmth and big precip is 2004-2005...but last season had prohibitive warmth mid winter.

I would bet on above normal in that case, but an earlier peak may be a bit better.

DM SST composite charts for modoki, basin-wide, east based, weak, moderate, strong and intense. I did DM temps 1951-2010 and 1991-2020 DM Precip 1951-2010 and 1991-2020 DM H5 1951-2010 and 1991-2020 I also did VP vs 1991-2020 for each composite group.

Yea, I think a peak ONI between 1.4 and 1.8 is reasonable attm.

Not in the MID atl, anyway because their season is often defined by one event. I would bet below normal snowfall north of NYC with an ONI of 2+....south of there you can't rule out a one storm season, especially if its basin wide, as opposed to east.

@griteaterThinking about it within context of 2015-2016, I think the answer maybe that intensity can be the main factor in extreme cases, but for the most part its orientation. Seems like orientation is less important in very weak and very extreme ENSO events.....the former it is other extratropical factors and the latter its the sheer magnitude of ENSO taking proxy.