As winter approaches, south Louisiana residents will once again have to unpack the heavy sweaters and umbrellas as the National Oceanic and Atmospheric Administration’s winter outlook is showing a cooler and wetter winter than normal ahead.

However, NOAA is not expecting another bitter cold winter as was caused last year by a series of polar vortex systems, which dragged frigid air out of the Arctic and swept down the country as far as south Louisiana.

“A repeat of last winter is not particularly likely,” said Mike Halpert, acting director of NOAA’s Climate Prediction Center in College Park, Maryland.

That doesn’t mean there won’t be cold air and snow in the nation, which is normal for much of the country during winter, Halpert said. It just won’t persist as much as it did last year, when extreme weather seemed to be stuck in place.

In Louisiana, the likelihood of an El Niño weather condition forming in the Pacific Ocean in the next couple months should help moderate temperatures. The El Niño — which requires ocean water temperatures higher than normal — should impact wind patterns over the United States, including the Gulf Coast.

“They fully anticipate an El Niño to form later this winter,” said Barry Keim, state climatologist.

During El Niño years, there is usually more storm production off the coast of Texas, which then track northeast across Louisiana, bringing more rain and cooler temperatures, he said.

“That doesn’t mean we’re not going to have warm days,” he said. We do, after all, live in Louisiana.

Keim said that while nothing is certain, forecasters don’t anticipate the severe ice events like last winter, which brought freezing rain and sleet to Louisiana, shutting down schools, government offices and highways. Those four bone-chilling icing events last winter were very unusual, Keim said.

He said long-range forecasts like the winter outlook released Thursday need to be taken with a pound of salt.

Elsewhere in the country, Halpert said, the high pressure ridge off the Pacific coast that last year kept rain out of California during its crucial winter rainy season is unlikely to return in force.

NOAA didn’t predict the extremes in last year’s winter forecast.

For December through February, NOAA forecasts warmer-than-normal winter temperatures for most of the West, northern tier and northern New England, with cooler weather in the Southeast and average temperatures elsewhere.

The agency predicts wetter-than-normal conditions stretching from Southern California to Florida and up to northern New Hampshire, with dry patches in the Pacific Northwest and Great Lakes. Average precipitation is forecast elsewhere.

Other private weather forecasters are predicting a slightly cooler winter than NOAA.

Judah Cohen, director of seasonal forecast at Atmospheric and Environmental Research in Lexington, Massachusetts, has pioneered winter forecasts that link colder eastern U.S. weather to years when there is more snow on the ground in Siberia in October. The month has started out unusually snowy in Siberia.

Halpert said Cohen’s method is intriguing, but NOAA needs more years to show that it works as a forecast tool.

Ryan Maue, of the private WeatherBell Analytics of New York, predicts that “a vast majority of the nation will experience significant periods of below-normal temperatures this winter, with the coldest temperatures (relative to normal) occurring in the Ohio Valley and up through the Eastern Plains.”

AP science writer Seth Borenstein contributed to this report.

ä ON THE INTERNET:

NOAA winter outlook: http://www.noaanews.noaa.gov/stories2014/20141016_winteroutlook.html