What is La Niña?
By Katy Galimberti, AccuWeather staff writer
La Niña, the direct opposite of El Niño, occurs when sea surface temperatures in the central Pacific Ocean drop to lower-than-normal levels.
The cooling of this area of water near the equator, which typically unfolds during late fall into early winter, yields impacts around the globe.
In the United States, a La Niña winter means more rain in the Pacific Northwest, brief periods of below-average temperatures in the Northeast and generally dry and mild conditions for the southern tier.
While an El Niño can fuel streams of moisture into California, a typical La Niña winter prevents storms from delivering snow and rain to the region.
"During a moderate to strong La Niña, Southern California can run drier than normal throughout the wet season, leading to more drought conditions," AccuWeather Senior Meteorologist Paul Pastelok said.
La Niña puts more emphasis on the northern jet stream, weakening the southern jet stream. The change yields more frequent storms in the northern U.S.
Western Canada and the Northwest endure the stormiest conditions during a La Niña winter, but the systems generally weaken as they travel over the northern Rockies. If a storm is potent enough, it can reach eastward and deliver snow, but on average the systems lack enough moisture to produce a major storm.
Weak storms may be higher in frequency in the Midwest and Great Lakes, keeping snowfall totals at average to above-normal levels.
Winter in the Northeast is extremely variable during La Niña, ranging from colder and drier to mild and stormier.
With a weakened southern jet stream, mild conditions span from Texas to the Southeast and into the mid-Atlantic.
La Niña keeps hot, humid air concentrated over the south-central U.S., increasing the likelihood of tornadoes and damaging hailstorms.
Meanwhile, La Niña creates prime breeding grounds for tropical systems in the Atlantic Ocean.
When La Niña occurs, less wind shear is found in the developmental regions of the Atlantic, increasing the potential for a higher-than-normal amount of tropical systems.
La Niña does not always immediately develop after an El Niño. However, research shows that strong El Niños are more likely to transition to La Niñas.
"Historically, some hurricane seasons that have followed a transition from El Niño to La Niña have been very active," AccuWeather Hurricane Expert Dan Kottlowski said.
La Niña typically lasts between 10 and 12 months.
Comments that don't add to the conversation may be automatically or manually removed by Facebook or AccuWeather. Profanity, personal attacks, and spam will not be tolerated.
More Weather News
Weather News - February 21, 2019, 12:15:08 AM EST
Millions faced disruptive snow and ice as a monster winter storm blanketed the northeastern and midwestern United States.
Weather News - February 21, 2019, 3:32:11 AM EST
The same storm set to bring feet of snow to parts of Arizona and significant snow to the rest of the Southwest late this week will swing onto the Plains and evolve into a blizzard over part of the north-central United States this weekend.
Weather News - February 21, 2019, 3:33:29 AM EST
A storm will unload feet of snow, create blizzard conditions and shut down travel over the mountains of Arizona, New Mexico and Southern California from Wednesday night to Friday.
LIVE: Accidents unfold amid robust snow, ice storm; Over 2,000 flight cancellations in Midwest and Northeast
Weather News - February 21, 2019, 12:36:16 AM EST
Millions are facing disruptive snow and ice from Philadelphia through Chicago and Minneapolis as a far-reaching winter storm pounds the northeastern and midwestern United States.
Weather News - February 20, 2019, 2:21:35 PM EST
After battering parts of Vanuatu and New Caledonia with heavy rainfall and damaging winds, Tropical Cyclone Oma will now take a turn toward Australia.
Weather News - February 20, 2019, 2:02:06 PM EST
As the Philadelphia Flyers and Pittsburgh Penguins play outdoors Saturday night, rain could move through and impact play.
Weather News - February 20, 2019, 9:39:27 AM EST
An avalanche killed at least one and injured several others on Tuesday at a popular ski resort in Switzerland.