ENSO Blog

La Niña’s reign continues in the tropical Pacific, with an approximately 85% chance of lasting through the winter. Forecasters currently think this La Niña will be on the stronger side. Let’s check in with the tropical Pacific The temperature of the ocean surface in the Niño3.4 region was about 0.8°C cooler than the 1986–2015 average, according to the ERSSTv5 dataset. We monitor the Niño3.4 index with a few different temperature datasets—more on that here—but they are all comfortably below the La Niña threshold of -0.5°C. The three-month-average Niño3.4 index, called the Oceanic Niño Index (remember this for later!) was -0.6°C. The Oceanic Niño Index is our primary metric for the El Ni…   Read article

Marybeth Arcodia is an Atmospheric Science Ph.D. Candidate at the University of Miami Rosenstiel School of Marine and Atmospheric Science. She works with Dr. Ben Kirtman (previous ENSO Blog guest writer) studying climate variability and predictability. Along with a few members from her lab group, Marybeth helped create a subseasonal-to-seasonal forecasting blog called Seasoned Chaos, for scientists and non-scientists alike. Her research looks at how particular atmospheric and oceanic conditions in the tropical Indian and Pacific Oceans can affect weather and extreme events in the United States to lead to more confident climate forecasts on two week to two month time scales. She received her …   Read article

La Niña conditions were present in August, and there’s a 75% chance they’ll hang around through the winter. NOAA has issued a La Niña Advisory. Just how did we arrive at this conclusion, and what does a La Niña winter portend? Read on to find out! Checking the boxes Let’s revisit our La Niña decision tree. The answer to the first question, “Is the monthly Niño3.4 sea surface temperature anomaly equal to or less than -0.5°C?” is an easy “yes.” August’s value was -0.6°C according to our most consistent sea surface temperature dataset, the ERSSTv5 (though that is not the only SST dataset we monitor). For a quick refresher, the Niño3.4 sea surface temperature anomaly is the differen…   Read article

This is a guest post by Dr. Sang-Ki Lee, a physical oceanographer at the NOAA Atlantic Oceanographic and Meteorological Laboratory in Miami, Florida. His research focuses on the interactions between the atmosphere and ocean, and how these interactions impact extreme weather and global climate. Do you know that El Niño has a little brother? Yes, El Niño does have a little brother who lives just across the South American continent in the Atlantic Ocean. His name is Atlantic Niño, and he has an uncanny resemblance to his big brother: Like El Niño, Atlantic Niño is characterized by warmer-than-average sea surface temperatures in the eastern equatorial basin and weaker-than-average tra…   Read article

The chance of La Niña developing this fall is up slightly from last month, at around 60%. Our La Niña Watch continues! Becalmed The Oceanic Niño Index—the three-month mean sea surface temperature anomaly (difference from the long-term mean, 1986-2015 in this case) in the Niño3.4 region—was -0.2°C during May–July 2020. The Oceanic Niño Index is our official metric for ENSO (El Niño/Southern Oscillation). -0.2°C is solidly in the “neutral” category of greater than -0.5°C and less than 0.5°C, so we continue in ENSO-neutral conditions for now. The current 60% chance of La Niña is largely based on the dynamical computer models, most of which slightly favor La Niña in the fall and win…   Read article