ENSO Blog

While many of us in the U.S. are reveling in the excitement of college basketball tournaments and trying to win our March Madness pools, it’s also a good time to look back at this past winter’s (December 2024– February 2025) precipitation pattern over North America. Were the seasonal forecast models a winner or a bust this winter? Was La Niña a star or a benchwarmer? Let’s go to the videotape! Pre-Season polling Early last December, I wrote about the predicted winter North American precipitation pattern from a group of state-of-the-art computer forecast models, the North American Multi-Model Ensemble (NMME). At that time, I argued that the forecasted precipitation pattern was…   Read article

La Niña conditions persisted through February, but forecasters expect ENSO-neutral conditions to develop in the next month and persist through the Northern Hemisphere summer. ENSO La Niña is the cool phase of the El Niño/Southern Oscillation, or ENSO, a pattern of changes in the tropical Pacific Ocean and the atmospheric circulation over the tropical Pacific that persists for many months. La Niña’s signature is cooler-than-average surface water in the east-central tropical Pacific, stronger-than-average trade winds, more rain and clouds over Indonesia, and drier conditions over the central Pacific. El Niño is the opposite, with warmer-than-average surface water and weaker atmospheric c…   Read article

In the, roughly, 250 years of the ENSO Blog and our 3.4 million posts, we’ve discussed ad nauseum how complicated El Niño and La Niña are, and how difficult it is to forecast all of the ENSO nuances. Heck, I even wrote a three-part series 75 years ago that evaluated all of our seasonal forecasts (ok, it was 2014-2015 but it still feels that long ago). In a new paper, Azhar Ehsan, friend of the blog and a member of NOAA’s ENSO forecast team, and colleagues analyzed over 20 years’ worth of climate model forecasts of ENSO and found some interesting results. Why is this paper unique? Well, most seasonal forecasting evaluations focus on model hindcasts, which are forecasts run using past obser…   Read article

La Niña conditions continue, but forecasters estimate a 66% chance of a switch to neutral in March–May. This is looking like a weak and short La Niña. Also, while La Niña’s ocean conditions are currently weak, the atmospheric component is fairly strong. Today, I’ll cover current conditions, the forecast, and that mismatch between the ocean and atmosphere across the tropical Pacific Ocean. Live in the moment La Niña and its counterpart El Niño make up the El Niño/Southern Oscillation, or ENSO. La Niña’s characteristic cooler-than-average tropical Pacific surface water changes global atmospheric circulation in known ways, providing an early picture into potential upcoming temperature, ra…   Read article

Right now, with La Niña conditions currently underway, I guarantee at least one of our readers is currently thinking “This alleged ‘La Niña’ is going to bust so hard in my region. It’s supposed to be DRY and it’s been WET so far. What the heck is wrong with you people!? BUST, BUST, BUST…” It’s frustrating! I get it! That’s because I too am human and get weirdly annoyed when the forecast is for something I want to happen, say 5 inches of snow, and then we end up with dry pavement. But, being a scientist, I also realize that weather and climate predictions contain uncertainty. And uncertainty stinks especially when you really want that outcome to materialize. So, today I am going to try to …   Read article