El Niño update: May 21, 2015
As the wet weather continues, particularly to our south, questions arise as to the cause and whether it will continue. El Niño is often listed as one of the factors involved. An El Niño is declared when Pacific waters along the equator are at least 0.5 degrees C warmer than average for five, 3-month periods. Normally, this pattern develops in the fall and continues through the winter. Some events have lasted for multiple years. Depending on its strength, the impacts can be felt around the world. Southern California often sees excessive winter rains while the Pacific Northwest frequently sees drought conditions develop during an El Niño event. The further from the coast, however, the less direct and the less consistent the impacts.
In Kansas, an El Niño generally means normal to wetter-than-normal summers, and a milder-than-normal winter, with a greater likelihood of wetter conditions in the southern tier of counties
The current El Niño is still ranked as a weak event. However, the sea-surface temperature anomalies are at some of the highest levels seen at this time of the year. There are three previous El Niño events that followed a similar pattern of a rapid spring onset: 1957, 1968-69, and 1986-87. Only 1957 falls in both the top 15 wettest Mays and in the top 15 wettest years.
Mary Knapp, Weather Data Library