UPDATE 1-La Nina to keep US north cold, south dry-NOAA
* La Nina to play major role in US winter weather -NOAA
* Drier and warmer conditions seen in the South - NOAA
* Outlook covers the December through February period
WASHINGTON, Oct 20 (Reuters) - A strengthening La Nina will grip the United States this winter, causing colder and wetter weather to the North and drier and warmer conditions throughout the drought-ravaged South, government forecasters said on Thursday.
The National Oceanic and Atmospheric Administration said it expects La Nina's to become the most dominant factor influencing weather across the country.
The ocean phenomenon that affects global weather will exacerbate warm and dry conditions in Texas, Oklahoma and New Mexico, already hurt by extreme and exceptional drought, and spread similar weather to surrounding states, particularly in the central Gulf Coast state and parts of Florida.
The agency also forecast cooler and wetter conditions to affect the Northern Plains and Great Lakes region.
"We are fairly confident that La Nina isn't going anywhere," said Mike Halpert, deputy director of NOAA's Climate Prediction Center. "The evolving La Nina will shape this winter," he said.
La Nina, which means "little girl" in Spanish, is associated with cooler-than-normal water temperatures in the Equatorial Pacific, unlike its sibling El Nino, which has the opposite effect.
The winter outlook covers the December through February period.