On Thursday, June 11, NOAA's Climate Prediction Center (CPC) announced sea-surface temperatures in the tropical Pacific Ocean have risen enough over a long-enough period of time to classify conditions as being in an El Nino. Current forecasts have this El Nino event becoming the strongest on record.

Ocean temperatures have been above normal for a long time, dating back to April. But the CPC does not declare an El Nino (or its reverse, a La Nina) until certain criteria have been met for a long enough period. In the case of this El Nino, it is a three-month average of sea-surface anomalies of greater than 0.5 degrees Celsius. Sea-surface temperatures in the tropical Pacific Ocean are currently sitting at 1.3 degrees C above normal for the week, indicating we are already well into El Nino territory regardless of the current announcement by the CPC. And, we have been in an El Nino for at least the last month. Evidence of the El Nino's control on the global weather pattern is the recent run of heavy rainfall that has been rather widespread across the U.S., leading to massive drought reductions across much of the Plains and Southeast.

This recent run of warming in the Pacific comes from extremely warm subsurface temperatures, with some areas more than 5.0 C above normal 50 to 100 meters below the ocean surface that have started to make it up to the surface. That, combined with abnormal westerly winds have increased sea-surface temperatures across the central and eastern tropical Pacific Ocean in a rapidly growing trend that is not forecast to slow down anytime soon. In fact, model forecasts are calling for a historic El Nino event that may become the strongest on record. The highest relative Oceanic Nino Index on record comes from the 1982-83 Super El Nino with a reading of 2.5 C above normal. The American CFS climate model, which has been among the most accurate over the last several years, has readings approaching or exceeding 3.0 C above normal in the October to December timeframe. With a slow fall of ocean temperatures in early 2027, El Nino will be the primary climate driver for almost an entire year.

El Nino produces multiple world-wide impacts. Some of the most significant impacts are noted here: https://www.dtnpf.com/…. In the summer for the U.S., El Nino generally produces favorable weather, with reduced heat and frequent rainfall events. It can lead to drought in places that are frequently missed but can also lead to flooding for areas that receive too much. In the winter, much of the country is warmer and the southern tier of the country ends up with higher precipitation, favoring California through the Carolinas.

It is worth noting that our record of sea-surface temperatures is relatively short, with official records dating back to 1950. Other El Ninos may have been as strong or stronger as the one that is starting to build, but the records do not go back far enough. One particularly catastrophic event occurred in 1877-1878, leading to massive droughts, famines, and flooding around the world. However, without any instruments either on land or in the ocean to measure, it is impossible to know how strong the event was.

To find the latest announcement from the CPC, visit https://www.cpc.ncep.noaa.gov/….

To stay up to date with weather conditions and your local forecast for free from DTN, head over to https://www.dtnpf.com/….

John Baranick can be reached at john.baranick@dtn.com

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