小蝌蚪APP

Two-Faced El Ni帽o on the Run

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Posted on April 13, 2016

Alice Jackson

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Dr. Keith Blackwell, associate professor of meteorology, said we had fewer of these in 2015 because of El Ni帽o, which also caused both flooding and drought.

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Still taunting Northern friends about your mild Southern winter?

Thank you, El Ni帽o!

Tired of tornados and days of record-breaking rainfall?

Blame El Ni帽o!

No matter your opinion of the two-faced weather phenomenon known as El Ni帽o, it鈥檚 going to be messing with our local, regional and national weather 鈥� and our psyches -- for a bit longer, despite its decline, according to Dr. Keith Blackwell, associate professor of meteorology.

The El Ni帽o phenomenon has been around a long time, usually lasting about a year and occurs on an irregular interval of every two to seven years. El Ni帽o alters some of the strongest and steadiest winds on Earth, such as the mid-latitude Jet Stream and the tropical trade winds, the latter historically considered to have filled the sails of Columbus and other explorers attempting to reach the New World. During El Ni帽o events, early explorers would have found stronger-than-normal trade winds over the Atlantic Ocean, making their trip faster while explorers in the Pacific would have found weak, or non-existent trade winds there, possibly leading to ships becoming stranded at sea and leading to disaster for the crew.

El Nino is a band of warm ocean water that develops in the central and east-central equatorial Pacific and is accompanied by high air pressure in the western Pacific and low air pressure in the eastern Pacific.

鈥淚t enhances the subtropical jet stream over the Gulf of Mexico and in the southern states, so we end up getting very different weather patterns than normal,鈥� said Blackwell, who is also an internationally recognized hurricane expert. 鈥淭he present El Ni帽o has already generated several intense frontal cyclones in the Gulf of Mexico and along the northern Gulf.鈥�

He explained how El Ni帽o normally forms in summer, then peaks around Christmas and, finally, leaves the area by May or June.

鈥淭he timing with this El Ni帽o we鈥檙e experiencing now is a little different because it formed early last March, which was unusually early, and it鈥檚 now nearly tied with the strongest El Ni帽o on record, which was the 1997-1998 event,鈥� Blackwell said. 鈥淥ne of the wettest months in Mobile history occurred then. In January 1998, we had almost 17 inches of rain. Likewise, another very strong El Ni帽o in 1983 produced the wettest February on record in Mobile with nearly 12 inches of rain.鈥�

According to Blackwell, El Ni帽o can sometimes be beneficial:

• Enhancing wind shear 鈥� a change in wind speed and direction, which increases with altitude 鈥� and greatly suppressing hurricane activity in the Caribbean Sea and southern Gulf of Mexico.
• Bringing rain to drought-stricken California.
• Producing milder winters across the southeast, central U.S. and into Canada.

Of course, El Ni帽o has its nasty side as well:

• Producing too much rain in states such as Louisiana with disastrous flooding of towns and interstate highways, and in California where residents have battled mudslides and coastal erosion.
• Bringing severe drought to the islands bordering the Caribbean Sea, such as Puerto Rico and the U.S. Virgin Islands.
• Causing record-breaking hurricanes in the Pacific 鈥� including Hurricane Patricia south of Mexico, the strongest storm ever recorded in the western hemisphere with sustained winds in excess of 200 mph., and Hurricane Winston, the second-strongest landfalling tropical cyclone on record as it struck Fiji with 185 mph. winds.
• We can expect additional storm systems, filled with high winds and rain, until this El Ni帽o ends.

And what of El Ni帽o鈥檚 opposite, La Ni帽a, which can mean increased hurricane activity in the Caribbean Sea and Gulf of Mexico?

鈥淟a Ni帽a events often follow directly after a moderate to strong El Ni帽o and can last one to three years,鈥� Blackwell said. 鈥淭here are indications a La Ni帽a will develop this summer and fall after the present El Ni帽o is gone, but we will have to wait and see if one actually materializes.鈥�

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