Strong El Nino Forecasted for Upcoming Winter
COLUMBIA - A strong, and potentially record-breaking El Niño was forecasted to begin summer 2015, and could impact the North American climate for the 2015/2016 winter, with potential impacts lasting into the spring of 2016, including a less snowy winter in Missouri.
El Niño is a warming of the eastern equatorial Pacific Ocean above its normal sea surface temperature. To be classified as an El Niño, the surface temperatures must remain 0.5 degrees Celsius above normal for up to a 5-month period. El Niño opposes a La Niña period, where the eastern Pacific Ocean temperatures are cooler than normal.
El Niño is part of a large is a Pacific Ocean-atmospheric phenomenon called ENSO, or El Niño Southern Oscillation. This occurs every three to seven years, and can affect weather globally.
El Niño got its name from Spanish settlers in central America for "the boy", given that this occurred around Christmas, when warmer waters near the coast increased fishing production.
The warmer water temperatures create an ocean-atmospheric response, weakening easterly trade winds, strengthening the sub-tropical jet stream, which is responsible for supplying moisture into the U.S. and shifting the cold, polar jet stream further north.
Impacts for North America, historically, produce cooler and wetter conditions in the southern U.S., while they produce warmer and drier conditions in the northern U.S. and Canada.
For Missouri, typical El Niño effects are warmer than normal temperatures, and above normal precipitation, with less snow accumulation, mainly due to a more frequent southern storm track.
Notable El Niño periods which have greatly impacted Missouri have been during the middle 1980's, the spring of 1993, and the winter and spring of 1998, all of which resulted in above average rainfall.