La Nina is back. What does it mean for our weather and wildfires?

This GOES-16 GeoColor satellite image taken Thursday, Sept. 10, 2020, and provided by NOAA, shows tropical storms forming in the Atlantic. | Photo by NOAA, Associated Press, St. George News

COLLEGE PARK, Md. — La Nina, which often means a drier and perhaps a more fire-prone Southwest,  has popped up in the Pacific Ocean.

File photo from the Brian Head fire taken on June, 23, 2017 | Photo courtesy of Color Country Fire Interagency, St. George News / Cedar City News

The National Oceanic and Atmospheric Administration announced Thursday that a La Nina, the cooler flip side of the better-known El Nino, has formed in the Pacific Ocean. Meteorologists had been watching it brewing for months.

A natural cooling of certain parts of the equatorial Pacific, La Nina sets in motion a series of changes to the world’s weather that can last months, even years. This one so far is fairly weak and is projected to last through at least February but may not be the two-to-three-year type sometimes seen in the past, NOAA Climate Prediction Center Deputy Director Mike Halpert said.

The changes that happen during La Ninas and El Ninos aren’t sure things, meteorologists say. Different sizes and types trigger varying effects and some years, the usual impacts just don’t show up. It’s more an increased tendency than an environmental edict.

Effects expected in the West

In La Nina, the jet stream that steers daily weather shifts a bit in the winter. That generally means a drier winter in the South and Southwest from coast to coast. It usually means a bit warmer in the South, too. It gets wetter in the Pacific Northwest and the Ohio Valley in the winter and colder in the Northern tier in the winter.

Diagram shows the typical effects caused by the La Nina weather pattern. | Chart courtesy NOAA, St. George News

The drought’s already pretty bad in Utah, west Texas, Arizona and Colorado, Halpert said. This could make things worse. And California has “a tendency to have dry conditions in La Nina years,” Stanford University climate scientist Noah Diffenbaugh said.

“La Nina is not a good sign for the wildfire outlook,” Diffenbaugh said. But he added that it’s mostly a potentially bad sign for next year’s wildfire season because it makes the West’s winter wet season drier, setting the stage for dry conditions when fires start in 2021.

Meteorologists don’t quite know enough about what La Nina does in the fall to say what it means for the current record bad California wildfire season, according to Diffenbaugh. He said that, for the next few months, what matters most is when the fall rains begin and offshore winds, not La Nina.

It is Spanish for “little girl” and El Nino means “little boy,” at times referring to the Christ child. The name comes from the first El Nino being characterized and identified around Christmas by fishermen in South America.

The last La Nina went from fall 2017 to early spring 2018. Before that there was a brief La Nina at the end of 2016, coming on the heels of a super-sized El Nino. This year started with a brief, weak El Nino.

Following the brief La Nina in late 2016, the June 2017 Brian Head Fire consumed 71,000 acres in Iron and Garfield Counties. The fire resulted in the loss of 13 homes, the evacuation of 1,500 people and cost more than $30 million in suppression.

The 2018 La Nina came before the July 2018 West Valley Fire that consumed 11,771 acres of Dixie National Forest.

St. George News Weekend Editor/reporter Chris Reed contributed to this story.

Written by SETH BORENSTEIN, Associated Press.

Copyright 2021 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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