The March outlook was issued Thursday from NOAA's Climate Prediction Center. It calls for warmer than average temperatures across most of the nation, from the Four Corners to the East Coast. The Pacific Northwest is expected to see cooler than normal weather. Odds favor drier than normal conditions for the Southwest and Southwest, with the potential for above normal precipitation in the Northwest, Great Lakes, and Ohio Valley. A well established La Nina was the driving factor in the forecast for March and the Climate Prediction Center expects conditions to last into the spring.  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.