Earlier this month, the Climate Prediction Center issued the January outlook. Warmer than average temperatures are in the forecast for the eastern and southern sections of the nation, with below normal temperatures in the Northwest. Drier than average weather is expected across the southern third of the nation. Odds favor above average precipitation in the Great Lakes and Northwest. La Nina was the driving factor in the forecast for the upcoming month and the Climate Prediction Center expects conditions to last for several months.  La Nina occurs when the waters of the Pacific Ocean show a general trend of cooling, the opposite of an El Nino. During La Nina periods, the Jet Stream is not usually active in the Southern U.S. This usually leads to less storms systems and below average precipitation. Cooler than normal weather typically occurs across the northern tier of the country and occasionally wetter periods as well.