Weather forecast: La Nina is here, may last through winter

FILE - In this May 18, 2015 file photo, irrigation pipes sit along a dry irrigation canal on a field near Stockton, Calif. Government weather forecasters said Thursday, Nov. 10, 2016, that  La Nina has arrived and may last through the winter. La Nina usually means wetter winters in the northern U.S. and drier conditions in the southern parts including drought-stricken California. (AP Photo/Rich Pedroncelli, File)
FILE - In this May 18, 2015 file photo, irrigation pipes sit along a dry irrigation canal on a field near Stockton, Calif. Government weather forecasters said Thursday, Nov. 10, 2016, that La Nina has arrived and may last through the winter. La Nina usually means wetter winters in the northern U.S. and drier conditions in the southern parts including drought-stricken California. (AP Photo/Rich Pedroncelli, File)

LOS ANGELES (AP) — Government weather forecasters say La Nina is here.

La Nina, the flip side of El Nino, is 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.

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.