El Niño returns every two to seven years, he says. The opposite phase is La Niña, where a similar area of the Pacific Ocean turns several degrees colder than normal. The transfer of heat and humidity in the upper atmosphere can affect the circulation patterns of the Northern Hemisphere and across North America.

La Niña usually brings warmer winters, drier winters, more sunshine and less storminess to the Southeast. “We have a very strong La Niña this year, and warm air is pushed farther west than usual. Australia is feeling its impact, with torrential rainfall and a category 5 tropical system.

We really didn’t see a warm and dry winter this year, but other parts of the world have.”

El Niño’s are most commonly one-year events while La Niña’s can last three or four years in a row, more recently in 1999 through 2001. This can set up a multi-year drought situation when you’re farming in the Southeast, says Zeirden.

“This appears to be one of the strongest La Niña’s ever. Because of the strength of it, there’s probably a better chance than usual of it lasting multiple years. Chances are we’ll have to deal with it not only this growing season, but into harvest season and into next year.”

To determine how a La Niña affects precipitation patterns over the Southeast, forecasters take weather observations from 60 years of the weather events — about 13 episodes — average them altogether, and compare them to the long-term average, says Zeirden.

“The good news is that the influence of these weather patterns tends to go away in the springtime, in April. When we have a La Niña, when we get into May or June, it kind of reverses itself. So over the Florida Panhandle and southeast Alabama, we can expect more rainfall than normal with this weather event. So this is a bit of good news and some hope for the coming year.”

But the wintertime patterns are much more consistent with the events and much stronger, he adds. “Looking at summertime patterns over the Pacific Ocean, we don’t have as much confidence that they’ll return every time.”

phollis@farmpress.com