The much maligned term “Polar Vortex” that was used quite often this winter within the weather blogosphere is about to be replaced….maybe. By what? El Niño. Yep. The Great El Niño could be making a comeback. Remember the Saturday Night Live sketch with Chris Farley about this phenomenon? It was a classic and just another example of how weather mixing with pop culture can be fun but sometimes quite wrong.
El Niño is not a single event like a storm or a hurricane. Instead, it is just a name that us humans have assigned to a change in the tropical Pacific that results in sea surface temperatures being warmer than the long-term average. Once a certain threshold has been met, we call it El Niño. Make no mistake, it will get a lot of play in the media, especially where Global Warming is concerned. The reason? The oceans act like giant cooling or heating agents. When the Pacific, the largest water basin on the planet, is warmer than it should be, then we typically see global temperatures spike – as if someone turned up the thermostat for the earth. My bet is that the pro-global warming crowd will be salivating at the potential El Niño event as it will help to boost their notion that man is screwing things up in a big way. I have no dog in that fight as it does not matter to me. What I mean is, so what? If man is making Earth warmer, who is going to go first to completely stop living in modern times? Anyone? That’s what I thought. My take is: adapt and mitigate. If not, we perish. No debate there, just ask the dinosaurs.
Back to the topic at hand.
The reason El Niño is important, other than acting like a massive thermostat for the planet, is that it seems to wreak havoc on the Atlantic hurricane season. The simple reason seems to point to higher than normal wind shear and sinking air across the tropical Atlantic due to the presence of the warmer than normal water in the tropical Pacific. In other words, El Niño would be perceived as a positive for those who would rather not deal with hurricanes; except for times when something like Andrew comes along. You can add to that list: Audrey, Camille, Alicia and even all of the landfalls of 2004. Those were all El Niño years. The point is, generally speaking, El Niño has a negative impact on Atlantic hurricane activity but this is not a guarantee. Kind of like how the 2013 hurricane season turned out. You just never know even in the face of what seems like a near certainty.
The reason behind the talk of an impending El Niño is due to several things that we can see going on across the tropical Pacific right now and within the past few weeks.
Pressure differences in the west Pacific have resulted in stronger winds blowing from the west. This causes a change in the way the ocean behaves and helps to generate what is called an oceanic Kelvin wave. I call it a Monkey Wrench in the ocean state. Normally, the trade winds in the Northern Hemisphere blow from east to west and thus the west Pacific is almost always warmer than the east Pacific. When the pressure pattern is altered, for reasons yet unknown, then the wind reverses course and that warm water is pushed eastward. This happens more so at the subsurface believe it or not in what is called downwelling. Warm water is literally pushed downward and then begins a very slow trek eastward where it upwells in to the eastern Pacific. The result: the birth of El Niño. It’s much more complicated but that’s the general idea. No one knows precisely what triggers these events to begin the chain reaction but it appears, at least for now, that forces are being set in to motion that could have huge global impacts as we move through 2014.
As for predictions, computer models are very unreliable for predicting long term weather patterns. They just cannot resolve the complex atmosphere coupled with the ocean several months in advance. In fact, the ECMWF, considered to be the very best global model in the world, called for an El Niño event last summer. It did not happen. So we shall see. While there is mounting evidence to support an El Niño event taking shape this year, it’s not clear at all how strong the El Niño would be. Obviously, the warmer the anomalies (departures from normal or average) then the more dramatic the impacts would likely be. We just don’t know yet.
As for how this potential El Niño will affect the 2014 Atlantic hurricane season – well, let’s just make sure we remember Andrew in 1992 as a case study in “it only takes one”. Sure, the overall numbers may be way down compared to the past 15 years or so. All it takes is for one, and it doesn’t even have to be a hurricane, to spoil the summer fun.
Stay tuned. El Niño is about to show Polar Vortex the door…maybe. I’ll have an update on this in mid-April.
M. Sudduth 9:15 AM ET FEb 25