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The Three Phases Of ENSO

Sep 26, 13 The Three Phases Of ENSO

In today’s dose of natural science, we will look at the three phases of El-Nino Southern Oscillation (ENSO), as there are now classifications for each period. The names of these periods are El-Nino, La-Nina and La-Nada. So, what does each period mean?

Let’s start with El-Nino. Some basics to understand about El-Nino is that it’s a Pacific Ocean originating feature; however, it can have global impacts on the weather. El-Nino can occur in three different areas of the Pacific, as well. If we have an eastern-based El-Nino, that means the waters along the coast of Peru are warming up; this will have its own set of implications on weather patterns. However, a central-based El-Nino would have an array of weather events. Finally, a western-based El-Nino would also lead to a set of specific events. So, is there any way to determine which EL-Nino we would be getting in advance? It’s kind of hard; however, in the short term, yes, we would monitor the sea surface temps of each of the three regions. Through my research I have come up with one solution to long-term predicting of El-Nino and that is as follows: “Western-based El-Nino’s are more likely when we are heading into a Solar Max, while an Eastern-based El-Nino is more likely when we are heading into a Solar Min.”

The next stop takes us on to La-Nina, the cooling of the Pacific waters. Like its big brother El-Nino, La-Nina brings its share of forecasting headaches to the weather world. La-Nina acts in an opposite manner than does El-Nino. A few important things about La-Nina are that the tropical pacific waters actually cool down and that, like El-Nino, La-Nina also has phases, including the western-based, central-based and eastern-based. Each of the phases also brings different impacts to the world. A few prime examples of La-Nina events are the significant severe weather outbreaks that occur over the United States, along with increased amounts of hurricanes over the Atlantic. This is all due to more favorable wind patterns in the upper levels during a La-Nina cycle.

Last stop takes us to La-Nada (aka Neutral Phase). This occurs when the Pacific waters show neither signs of El-Nino nor La-Nina, but a more neutral condition of temperatures and sea level pressure. Right now, this winter, we are more than likely going to go through a La-Nada winter, with conditions being very fluid. This means that weather patterns are going to be more likely to drift from one extreme event to another. We can also take note that with a potential colder winter in store for parts of North America. This could mean stronger winter storms for the Plains and the east coast as well.

Another saying that I have and use when I prepare my long range forecasting is this: “ENSO is the starting point of any long range weather forecast,” meaning that if you know what phase we are going to be in, you have one half of the long range planning battle.

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