By Associated Press

Government weather forecasters say La Nina is here.

La Nina, the flip side of El Nino, is caused by the cooling of the central Pacific Ocean that affects weather patterns worldwide.

Mike Halpert of the National Oceanic and Atmospheric Administration said Thursday he expects La Nina conditions to be weak and short-lived.

La Nina conditions often bring warmer weather, therefore more rain than snow, to the Sierra. Previous La Ninas have brought flooding to the Tahoe-Reno region.

In the United States, La Nina conditions usually means wetter winters in the northern Rockies, Pacific Northwest and Ohio Valley and warmer, drier conditions in the southern parts, including drought-stricken California.

NOAA says there’s a 55 percent chance La Nina will last through winter.