Weather Whys: What's El Niño and how does it impact our winter weather?

 

MILWAUKEE (CBS 58) -- By now you've heard rumblings that El Niño will be ongoing throughout the winter, but what does that mean for us in Wisconsin? El Niño, La Niña, and neutral conditions all have to do with sea surface temperatures along the equator in the Pacific Ocean. While large scale winds blow west to east in the here in the mid latitudes, the trade winds along the equator typically blow east to west. This pushes warm surface waters to Asia, but some years those winds are weak and the warmer ocean waters hang out near South America instead. When this happens, El Niño develops and has a direct impact on jet stream patterns globally.

El Niño winters are typically warmer and drier than normal across the northern US and wetter than normal across the southern US due to the positioning of the Pacific and Polar jet streams. The Climate Prediction Center's winter outlook reflects to strong El Niño with warmer than normal temps expected in our area and wetter the normal conditions across the south. This is the outlook for the winter months of December, January, and February.

After three straight La Niña winters (when the sea surface temperatures are below normal), El Niño conditions established themselves over the summer and have already strengthened into a strong El Niño. The last time we had a strong El Niño during the winter was the winter of 2015-2016. That winter our average temperatures was three degrees above normal and we were 15" below normal for snowfall. While El Niño typically brings us warmer and drier weather in the winter, this doesn't mean we won't have snow or any arctic outbreaks this winter, but they may be fewer and farther between.