Sept. 24, 2010

Spring forecasts are notoriously difficult to predict 6-8 months in advance. However, La Nina winters are typically followed by active severe weather across the central U.S. corridor. La Nina conditions that persist into the summer generally favor significant severe weather outbreaks across central U.S. during May and June.

Across the northern Plains, blizzard activity increases during La Nina periods as warm air from the southern Plains contrasts with Arctic air masses over southern Canada. Like the late fall, significant snowstorms can develop as the spring and winter air masses battle for control of the northern plains. This is what the term bookend winter refers to. Areas of the northern plains can see a significant snow in late fall and late winter with little activity in between as the favored storm track during the winter lies south of the region.

If the La Nina pattern persists into June, drought conditions are likely to affect the Corn Belt. The extent and location of these drought conditions will be directly tied to the position of the upper air ridge that would be expected to form over the southern U.S. If intense drought conditions develop this winter and next spring across the southeastern U.S., the eastern Corn Belt has the highest probability of a growing season drought. If the ridge forms further west, such that drought conditions develop from Louisiana to New Mexico, the western and central Corn Belt would have the highest probability for drought development during the 2011 growing season.

Allen Dutcher
Extension State Climatologist
 

Also see

• La Nina Conditions
• Fall Forecast
• Winter Forecast