La Niña is coming. What is it and how will it affect winter weather here?

With highs in the 70s on Thursday, one couldn’t feel too guilty for stepping out in shorts and flip-flops rather than customary fall garb.

And if National Weather Service’s most recent winter forecast is to be trusted, it looks as if milder temperatures may be here for a while.

Due to a weak La Niña pattern expected to develop this winter over the Pacific Ocean, NWS meteorologists in Wilmington, N.C., are forecasting a mild, drier than average winter for the Carolinas.

“This natural cooling off the coast of South America directly influences our weather by reducing the amount of tropical moisture that streams northward into our wintertime systems,” said NWS-Wilmington in a prepared statement. “This typically created drier than normal conditions across the Carolinas.”

La Niña is also expected to shift the jet stream further north, thus reducing the number of storm systems with the capability of affecting the area. “With fewer clouds and less rain, our winter temperatures run above normal during La Niña,” the weather agency said.

La Niña is a term used to refer to period cooling of ocean surface temperatures in central and east-central Pacific Ocean, affecting rainfall patterns from Indonesia to South America. Though typically known to wreak havoc on the U.S. every three to five years, it can sometimes occur in consecutive years, according to the National Weather Service.

Locally, the most recent La Niña recorded was in 2011-12.

According to data compiled by NWS-Wilmington, the average of the last five “weak” La Niña events registered less than one degree above normal winter temperatures in Conway.

“In a weak La Niña like we are expecting for the winter of 2017-18, temperatures typically average about half a degree above normal,” according to the prepared statement. “During stronger La Niñas, this departure grows to three to four degrees above normal winter temperatures.”

Also expect far less rain, possibly between two to four inches below normal for the season.

“La Niña's most reliable weather impact in the Carolinas is a reduction in winter rainfall,” said NWS-Wilmington. “Depending on the strength of the La Niña, rainfall totals can be reduced by 25 to 50 percent compared to a typical winter. Since this winter's La Niña is anticipated to be weak, rainfall departures are expected to be about 25 percent below normal.”

Annual snowfall amounts are already rather scant for this area. Chances of a winter weather event are even shorter thanks to this year’s La Niña weather pattern.

“Total snowfall amounts have historically averaged about half of normal,” the weather agency said.

Average snowfall for the area is in the avenue of one-inch.

This story was originally published November 2, 2017 at 8:26 PM with the headline "La Niña is coming. What is it and how will it affect winter weather here?."