Blogs

This month’s ENSO Diagnostic Discussion starts off with “the chance of El Niño has decreased to about 65% during the Northern Hemisphere fall and early winter.” The last few months, chances were estimated to be around 80% for El Niño to have formed by the fall/early winter. So, we’ve gone from an estimated 1-in-5 chance that we won’t have an El Niño to a nearly 1-in-3 chance.  However, 65% is still almost twice the climatological likelihood – that is, the long-term average of how often we experience El Niño conditions – so forecasters are still predicting El Niño will develop. So, why the decrease in the odds of El Niño? Last month, we discussed how the atmosphere has yet to respo…   Read article

Reading back over the many excellent (if I do say so myself) posts here at the ENSO blog, there have been several re-occurring themes—the biggest of which is that ENSO is not just an ocean phenomena but an ocean-atmospheric interaction. ENSO is no one-man act. If the ocean is Abbott, then the atmosphere is Costello; the ocean…Laverne, the atmosphere…Shirley; the ocean…Kanye, the atmosphere…Kim. And just like there would be no “Kimye” without Kanye West and Kim Kardashian, there is no ENSO event without both an atmospheric and oceanic response. We have previously touched on both aspects of this with a post on the importance of a sea surface temperature (SST) gradient in the equatorial trop…   Read article

In the July 10 update and ENSO discussion, we said the atmospheric part of ENSO doesn’t seem to be responding to the ocean.  El Niño requires that both be in sync and coupled with each other.  Why is the atmosphere acting aloof to the rather warm ocean?  This development may be especially surprising to folks given the rumors and speculation of a very strong El Niño that followed March’s oceanic Kelvin wave. In June, the Bureau of Meteorology in Australia made an interesting observation that might shed light on the lack of coupling between the ocean and atmosphere (1).  They pointed out that an anomalous sea surface temperature (SST) gradient was not in place across the…   Read article

While the focus of this blog is ENSO, there are other important climate patterns that impact the United States during the Northern Hemisphere winter season.  We often focus on the winter season because that is the time of year many climate patterns are most prominent, and in the case of ENSO, this is the season when impacts are most predictable (1). In this post, we will define some of these other patterns and then in a subsequent post in August, we will discuss how much these patterns contribute to U.S. winter climate predictability relative to ENSO.  Long-term Trends A major non-ENSO climate influence, which is particularly important for seasonal temperature, is long-term t…   Read article

Forecasters at the Climate Prediction Center haven’t declared El Niño conditions, even though the Niño3.4 index is currently around 0.5°C above normal, and has been for the past two months. What’s the hold up? In short, we’re waiting for the atmosphere to respond to the warmer sea-surface temperatures, and give us the “SO” part of ENSO. SO what? The Southern Oscillation, that’s what. The Southern Oscillation is a seesaw in surface pressure between a large area surrounding Indonesia and another in the central-to-eastern tropical Pacific; it’s the atmospheric half of El Niño. Since ENSO is a coupled system, meaning the atmosphere and ocean influence each other, both need to meet the criteri…   Read article