Aberdeen, SD
Weather Forecast Office
The 2015-2016 Winter Outlook indicates that our upcoming winter has an increased chance of having above normal temperatures and equal chances of above or below normal precipitation (not necessarily snowfall).
One of the main drivers behind this outlook is the presense of an El Niño, which is expected to become one of the strongest on record (record keeping began in 1950). What is El Niño? Basically it's the warming of the sea surface across the equator in the Pacific Ocean such that above normal water temperatures are observed. An El Niño is considered strong when a section of the equitorial waters reach +1.5 degrees C above normal. Even though these waters are thousands of miles away, strong El Niños can have drastic impacts here in the Northern Plains and worldwide. This was well documented and observed during the last strong episode 17 years ago (1997-98). For more information on how El Niño affects our weather, check out this video: https://www.youtube.com/watch?v=_Tuou_QcgxI and for even more information, visit https://www.esrl.noaa.gov/psd/enso/.
Below is a graph of the 6 strongest El Niño years, along with 2015 so far. The x-axis displays time, depicted by 3 month averages (SON = September October November, OND = October November December, and so on).
A good place to start then, when predicting how the coming winter will turn out, is to look back at the winters from these past strong El Niño years. Below are temperature and snowfall departures from normal over the winter months (December, January, and February). Years are in order of strength.
1997-98
