El Nino has continued to be the big talk among meteorologists for most of this year, and just when El Nino seems to be making an appearance, it backs off just enough to keep us below the El Nino classification. To keep things simple, El Nino is simply the warming of waters across the central and eastern Pacific. More specifically, sea surface temperatures have to be at least 0.5 °C (0.9 °F) above average over the east-central tropical Pacific Ocean for a given period of time for an El Nino to be considered in effect. This can have profound effects on the weather around the globe, particularly during the winter months.
What one must realize is that when the El Nino or La Nina events stay weak, there are other variables that can strongly drive the pattern that shapes what the winter will be like. In other words, you can’t just average out all of the weak to weakly moderate El Nino winters and expect to get an accurate forecast for this upcoming winter. One must take into account the placement of warmer waters across the equatorial Pacific and the strength of this event along with other variables that I have discussed in previous articles.
We can take the cold winter of 2013-14 as an example. Water temperatures stayed slightly below average across the central and eastern Pacific this past winter, but the northeastern Pacific warm pool influenced temperatures much more significantly than most meteorologists and forecasters anticipated. My point is that it’s important not to get too hung up this winter on whether or not we’re technically in an El Nino, especially since it’ll likely remain on the weaker side. When I put out my early winter forecast in July, I accounted for a weak to weakly moderate El Nino Modoki, and I still hold to those predictions. In other words, my forecast hasn’t changed much since my original forecast was put out in July.
Waters across the central and eastern Pacific have consistently remained above average since late spring with the exception of the central Pacific (Nino 3.4 region) very briefly experiencing below average water temps. The atmosphere has had a difficult time responding to these warmer waters this year and hasn’t really induced further warming. It’s still been a struggle even as we get closer to October, but most models still are holding onto the prediction that we will be going into a weak El Nino by this winter. It could even strengthen throughout this winter.
I will continue to monitor everything closely through the month of October and will be putting out my final 2014-15 winter forecast in late October or early November. I’ll have a specific release date in a couple of weeks. Please follow Firsthand Weather on Facebook to get daily updates on the latest information regarding El Nino and this upcoming winter.
Matthew Holliday (Curriculum Vitae - Resume) is a graduate of the University of Oklahoma, where he completed a B.S. in Meteorology and a B.S. in Geographic Information Science. He completed his master's degree in meteorology and climatology at Mississippi State University and is currently pursing a Ph.D. in Earth and Atmospheric Sciences.