ENSO Blog

I’m definitely starting to sound like a broken record here! La Niña is favored to continue through the summer and into the winter. That said, chances of La Niña through summer have a fairly small edge over chances of a transition to neutral—52% for La Niña vs. 46% for neutral in July–September. There’s about a 59% chance of La Niña by early winter. Dig deep Speaking of broken records, let’s start with the sea surface temperature in the tropical Pacific. The three-month-average sea surface temperature anomaly in the Niño-3.4 region, specifically, according to the ERSSTv5 dataset. (The anomaly is the difference from the long-term average; long-term is currently 1991–2020.) This index…   Read article

With so much focus here and elsewhere on how ENSO (El Niño-Southern Oscillation) impacts the conterminous United States, our friends in the 49th and 50th states might feel a little neglected. As a former resident of Hawai’i, I am happy to throw the spotlight onto a state that is still near and dear to my heart. Here I attempt to channel the Aloha Spirit and explain how ENSO impacts the weather of our most remote state. (Alaska, don’t worry, you’re up next month!). Recipe for rainbows Before I discuss any ENSO impacts, I would like to say a few words on the unique climate of Hawai’i. When I moved there in 2009, I was immediately struck by how much the rainfall can vary over such sho…   Read article

La Niña continued through April, and forecasters estimate a 61% chance of a La Niña three-peat for next fall and early winter. Current El Niño/Southern Oscillation (ENSO, the entire El Niño and La Niña system) conditions, the forecast for the rest of the year, and some potential impacts are all on the dessert menu today. Mix the butter and sugar together We’ll start by measuring out the tropical Pacific ocean-atmosphere system. The first ingredient in any ENSO recipe is the sea surface temperature anomaly in the Niño-3.4 region of the Pacific. An anomaly is the difference from the long-term average; in this case, the average is 1991–2020. When the sea surface temperature anomaly in…   Read article

This is a guest blog by Michael Tippett (professor at Columbia University) and Tim DelSole (professor at George Mason University), adapted from material in their new text book Statistical Methods for Climate Scientists. Predictability is a word that often comes up in discussions here on the ENSO Blog (another is variability). Let’s see if we can understand what climate scientists mean by predictability without having to read an entire book on statistics! As you might guess, climate scientists use the word predictability a little differently than the rest of the world. For instance, you might say that I am predictable because I take the same path each day on my morning walk, with small var…   Read article

La Niña continues in the tropical Pacific, with both the ocean and atmosphere clearly reflecting La Niña conditions. The current forecast favors the continuation of La Niña through the summer (59% chance), with a slightly lower chance into the fall (50-55% chance). A third-year La Niña would be pretty unusual—we’ve only seen two others since 1950. I’ll run the numbers to see how current conditions add up and what’s factoring into the odds for La Niña later this year. Paint by numbers Let’s take stock of current ENSO conditions (ENSO=El Niño/Southern Oscillation, the whole ocean-atmosphere El Niño/La Niña system) in the tropical Pacific. In March, the sea surface temperature in the key …   Read article