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Winter outlook may mean milder temperatures as El Nino forms

ENSO/El Niño state. Sea surface is warm in central and eastern Pacific. Less cold water is pulled up along west coast of South America. Hot air rises in central Pacific, travels east and west before cooling and descending. Graphic by Fred the Oyster - Own work; derived from NOAA/PMEL/TAO diagrams

While recent flurries and colder than normal temperatures seem to be giving winter an early bite, it may relinquish its hold.

In an updated status Thursday, Nov. 8, the National Weather Service Climate Prediction Center rated the chances of official El Nino formation at 80 percent this winter.

Although above-average sea surface temperatures were maintained through October across the equatorial Pacific Ocean, a situation considered neutral by the Climate Prediction Center, the forecast center remains confident a weak El Nino will still form in the coming weeks.

El Nino generally results in milder winter temperatures.

As its recent outlook for January through March of 2019, the Climate Prediction Center estimated most of Minnesota has a 33 percent chance of above normal temperatures. The center notes, in general, the warmest year of any decade will be an El Nino year. The center's winter outlook calls for warmer-than-normal conditions across much of the northern and western United States.

There is an equal chance for above or below average snowfall for the state.

What causes El Nino and its colder counterpart La Nina?

"The winds near the surface in the tropical Pacific usually blow from east to west. For reasons scientists don't yet fully understand, these relatively steady winds sometimes weaken or strengthen for weeks or months in a row," the Climate Prediction Center reports on its website.

"Weak winds allow warm surface waters to build up in the eastern Pacific. Sometimes, but not always, the atmosphere responds to this warming with increased rising air motion and above-average rainfall in the eastern Pacific. This coordinated change in both ocean temperatures and the atmosphere begins an El Nino event. As the event develops, the warmed waters cause the winds to weaken even further, which can cause the waters to warm even more."

Where did the names come from?

"Centuries before it was a focus of scientific study, South American fishermen noticed warmer-than-normal coastal Pacific Ocean waters and dramatic decreases in fish catch occurring periodically around Christmas time," the prediction center noted. "They nicknamed the phenomenon 'El Nino' (Spanish for little boy) in connection with the celebration of the Christian holiday marking the birth of Jesus.

"In the 1980s, when the opposite phase of El Nino was discovered (i.e., cooler-than-normal ocean temperatures), scientists called it 'La Nina' (Spanish for little girl)."

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