Warmer or colder than average ocean temperatures can act as a harbinger of what the weather will be like in certain parts of the world. From January to November of last year, sea surface temperatures along the equatorial region of the Pacific warmed drastically, producing what is predicted to be the strongest El Niño on record. El Niño events often cause flooding in California and parts of the midwestern United States. Although winters are typically warmer than usual in the northern half of the United States under El Niño, the southern half experiences cooler than usual winters.
Although North America is currently in the midst of experiencing the impacts of El Niño, researchers at Columbia University wondered if the effects of El Niño could have been predicted in advance. Being able to predict weather events a priori would afford those who manage water reservoir levels in California, for instance, a way to prepare for what is to come.
Here Steinschneider and Lall investigated this question by retrospectively analyzing El Niño forecasts issued in mid-November 2015 and the effect of El Niño on seasonal precipitation and the likelihood of local flooding during the winter months (January to March of 2016).
The authors’ results so far suggest that forecasts of El Niño made 1.5 months ahead of time could have predicted seasonal rainfall changes in regions of the southwest and southeast United States and flood risk throughout the United States. These predictions are already in line with the intense flooding that Texas, Florida, and Southern California experienced. However, the uncertainty of El Niño also makes predicting precipitation and flooding in other areas—such as the Central and Southern Plains, Northern California, the Pacific Northwest, and the Ohio Basin—more difficult. This uncertainty, the authors say, can “substantially hamper planning efforts for water supply allocation in the upcoming months, particularly in regions that depend on winter precipitation to bolster supply.”
After the winter of 2016 has passed, the researchers plan to assess the final accuracy of seasonal forecasts as well as examine what actions resources managers took before and during the winter to account for climatic changes due to El Niño. (Water Resources Research, doi:10.1002/2015WR018470, 2016)
—Wudan Yan, Freelance Writer
Citation: Yan, W. (2016), Could we have predicted what El Niño would bring?, Eos, 97, doi:10.1029/2016EO048007. Published on 22 March 2016.