ENSO Blog

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

La Niña conditions emerged in the tropical Pacific in December. There’s a 59% chance La Niña will persist through February–April, followed by a 60% chance of neutral conditions in March–May. Read on for the recent observations that led us to declare the (long-awaited) onset of La Niña and lots of details for current and potential upcoming conditions. Just the facts, ma’am A quick briefing, if you’re just joining us—La Niña is one phase of the El Niño/Southern Oscillation (ENSO), a pattern of sea surface temperature and atmospheric changes in the tropical Pacific Ocean. La Niña’s signature is cooler-than-average surface water in the east-central Equatorial Pacific, while its counterpart…   Read article

There’s a 59% chance that weak La Niña conditions will develop shortly. This is very similar to last month’s estimate, just applied to November–January. It’s true; if you read last month’s post, you can pretty much carry that information over to this month. However, we have lots of fun sciency details to talk about this month, so stick around! The office holiday party La Niña, the cool phase of the El Niño/Southern Oscillation (ENSO), is a coupled ocean-atmosphere pattern in the tropical Pacific Ocean. To qualify as La Niña conditions, we need to see (1) surface water in the tropical Pacific that is at least 0.5 °C (just shy of 1˚F) cooler than the long-term average (long-term=1991–202…   Read article

Although it’s taking its sweet old time to get going, a weak La Niña, the cool phase of the El Niño/Southern Oscillation (ENSO), is expected to develop this winter. Much like I did last November, I thought it would be a good time to delve into how these expected tropical Pacific conditions might influence the pattern of precipitation over North America this winter. After all, ENSO—the entire El Niño and La Niña system—is the single most predictable influence on year-to-year differences in average winter precipitation across the United States. Without further ado, let’s get to it! Break out the models!  Last November we were anticipating a big El Niño to do…   Read article