ENSO Blog

Here at the ENSO Blog we’ve explored the effects of El Niño and La Niña on Australia, South America, Africa, India, and the northern Pacific and Atlantic Oceans. Our posts about North American impacts are too many to list—check out the index page to see some of those. We’ve even visited the Arctic! Today, we’ll add the fifth-largest continent, a vast, ice-covered disc at the bottom of the world, surrounded by a roaring ocean. Keep going south until you’re going north Antarctica is about as close to being on another planet as you can get while still on Earth. Its 5.5 million square miles have been covered in ice for 35 million years, the average summer (December–February) temperature at…   Read article

La Niña continued to gain strength in November as we approach the normal peak for these events in the Northern Hemisphere winter—usually November–January. Forecasters estimate at least a 95% chance that La Niña will last through the winter, with a potential transition to ENSO-Neutral during spring 2021 (~50% chance). La Niña sticks out like a sore thumb when taking a gander at a map of sea surface temperature anomalies (the difference from the long-term average) over the Pacific Ocean. The Niño3.4 region of the tropical Pacific (the area we look at for determining ENSO status) was much cooler than the La Niña threshold of -0.5°C, at -1.4°C below average for November according to the ERSST…   Read article

In a year when many traditions have been disrupted, I’m happy to say one remains intact—my annual blog post on NOAA’s Winter Outlook! (1) This year is a bit different from some of my recent winter outlook posts because there’s no need to wait around to see if either El Niño or La Niña will develop in time to impact winter. Instead, the tropical Pacific is already taking center stage, and it doesn’t want to give up the spotlight any time soon. La Niña steals the show La Niña developed during late summer and has strengthened, leaving virtually no doubt that it will persist through the winter. So, what does that mean for temperature and precipitation across the United States over the next…   Read article

La Niña strengthened over October, with both the tropical Pacific Ocean and the atmosphere clearly reflecting La Niña conditions. Forecasters estimate at least a 95% chance La Niña will last through the winter, with a 65% chance of it hanging on through the spring. The October sea surface temperature anomaly (departure from the long-term average) in the Niño 3.4 region of tropical Pacific was -1.3°C according to the ERSSTv5 dataset, substantially cooler than the La Niña threshold of -0.5°C. This is the eighth-strongest negative October value in the ERSSTv5 record, which dates back to 1950. I’ll talk more about feats of strength (vis-à-vis La Niña, that is) later. Let’s count our ch…   Read article

We often get asked how El Niño or La Niña events form and increase in strength. The key is in the ocean-atmosphere coupling across the tropical Pacific Ocean. Without it, ENSO would not exist, and it would be considerably more difficult to predict climate impacts seasons in advance. Various ingredients of the ocean have to be combined with the atmosphere in order for ENSO to blossom and grow. Flour and yeast also would be pretty boring and inert on their own, but when put together, they reinforce each other, the combined product increases in size, and eventually it releases the heavenly scents of fresh baked bread. That’s right, I’m basically saying ENSO is fresh baked bread (…   Read article