ENSO Blog

The peak of our current El Niño is expected to occur in the next month or so… but what does that mean? We measure El Niño events by how much warmer the surface waters in a specific region of the equatorial Pacific are, compared to their long-term average. The difference from average is known as the “anomaly,” and we use the average anomaly in the Niño3.4 region as our primary index for El Niño. When the index in this region is at its highest, we have our peak El Niño.   However, El Niño-related impacts have been occurring around the globe for months already, and will continue for several months after the warmest temperatures occur in the tropical Pacific Ocean. For example, du…   Read article

Four years of drought in California. Back-to-back cold and snowy winters over the Midwest and Northeast, while balmy in the West. What’s next, thunder, hail, or maybe locusts and frogs? Or will this winter bring more “normal” winter weather? Actually thunder and hail isn’t too far-fetched this winter, at least in the Southeast, but more about that later. The jury’s still out on the locusts and frogs. So what can we expect this winter? Since this post is appearing on the ENSO blog, readers are well aware that El Niño developed last spring and is currently among the strongest events on record back to 1950. In addition, previous posts have discussed how El Niño can impact the weather and…   Read article

As we approach peak pumpkin spice latte season, we’re also closing in on the peak of the 2015-2016 El Niño, expected by forecasters to occur in the late fall or early winter. This El Niño continues to rank among the strongest in our records, which start in 1950. The July-September 3-month average sea surface temperature (the ONI) was 1.5°C above normal, third in line behind July-September 1987 (1.6°C) and 1997 (1.7°C). The atmospheric response to the warmer-than-average sea surface temperatures is keeping pace, too: the Equatorial Southern Oscillation Index (EQSOI) is -2.2. This is second to 1997’s -2.6, and well ahead of the next two El Niños on the list (1972 and 1982, tied at -1.4). …   Read article

This is a guest post by Dr Andrew Watkins, Leader of the Climate Prediction Services team at the Bureau of Meteorology (BoM) in Australia.  As well as releasing Australia's seasonal outlooks every month, the team write the BoM ENSO updates and communicate ENSO impacts for Australia.  You can follow the Bureau of Meteorology on Twitter @BoM_AU.  Australia and the US share many things. They are roughly the same size, they both sit on the Pacific Rim, and their people love sports, music, and movies, plus the odd donut. But to a climatologist, there are a number of fundamental differences. For a start, America is in the land-heavy Northern Hemis…   Read article

The CPC/IRI ENSO forecast says there’s an approximately 95% chance that El Niño will continue through Northern Hemisphere winter 2015-16, gradually weakening through spring 2016. It’s question & answer time! How strong is this El Nino now?  The only real way to answer this is to throw a bunch of numbers at you. Essentially, it’s “pretty strong.” The three-month, June-August average of sea surface temperatures in the Niño3.4 region (the Oceanic Niño Index) is 1.22°C above normal, via the ERSSTv4 data set. This is the third-highest June-August value since records start in 1950, behind 1987 (1.36°C) and 1997 (1.42°C). The August average is 1.49°C, second behind August 19…   Read article