We're hearing all about the strengthening El Nino these days and the potential impacts for this fall and winter...
As a refresher, here are a couple of El Nino definitions:
From NOAA:
El Niño is characterized by unusually warm ocean temperatures in the Equatorial Pacific, as opposed to La Nina, which characterized by unusually cold ocean temperatures in the Equatorial Pacific. El Niño is an oscillation of the ocean-atmosphere system in the tropical Pacific having important consequences for weather around the globe.
And a more simplified description:
Back to business... The national media are using some awfully strong terms to describe the potential "consequences" from this particular El Nino phase: "Godzilla", "King Kong", "Unprecedented", "Extreme", "Strongest Ever", "Destructive", "Catastrophic" and the list goes on and on.
First of all, let me assure you that while significant weather events are certainly possible over the coming months, it is simply too early to know whether or not those impacts will be more or less significant than past winter and fall seasons. Seasonal forecasting is very difficult, and even with advanced technology, there is very little skill at this point.
That said, El Nino has been and will continue to be a significant driver in our weather. Here is a text book illustration of what to expect during a typical El Nino Winter season:
As mentioned above, this is a "text book" illustration. Unfortunately, you will hear many seasonal forecasts based on this alone. For us here in Mississippi, this means we should expect a cool and wet winter with above average rainfall and persistent cool (but not cold) temperatures. However, this is broad brushing a seasonal forecast based on a single driver of the pattern, assuming other drivers will remain neutral. There are many other players on the field that when combined with El Nino can yield drastically different results than the above graphic. For example, strong negative phases of the Arctic Oscillation (increasing pressure in the Arctic), and the North Atlantic Oscillation (decreasing pressure in the North Atlantic) cause the polar jet to buckle, spilling frigid air as far south as Mississippi. Why is this important? Because combined with a persistent flow of Pacific moisture caused by El Nino, a wide range of weather is possible across the Deep South and Mississippi, including the potential for severe weather ahead of cold fronts and significant winter weather events as deep pacific moisture flows into an arctic air mass. This is exactly what happened on Christmas 2010; during a moderate El Nino cycle, snow fell over North Mississippi and Alabama, delivering an extremely rare white Christmas.
Bottom line, I urge you to keep a healthy skepticism over the hype that will no doubt intensify over the coming weeks. As always, all of us here at WLBT will keep you posted with the latest local weather information without the unnecessary hype.
Be sure to join us this evening and tonight on WLBT! You can also find me on social media: Facebook and Twitter
Michael Haynes
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