Last month, La Niña conditions returned and are expected to gradually strengthen and continue into the Northern Hemisphere through the 2011/2012 winter, according to a National Oceanic and Atmospheric Administration Climate Prediction Center webinar held Thursday.

During the October through December 2011 period, there is evidence that La Niña favors an increased chance of above-average temperatures across the mid-section of the country, according to the weather forecasters.

The nation’s Corn Belt will feel La Niña’s effects through the end of the year. “Moving into this fall, the Corn Belt region weather conditions are typically warm and dry during La Niña,” said Jon Gottshalk, NOAA Climate Prediction Center. “With La Nina we have a 4 in 5 chance of below normal precipitation for November through March.” Gottshalk added that as the winter months proceed there is a tendency for the northern portion of the Corn Belt to return to colder temperatures.

The effects of La Niña also added to the record drought conditions in the Southern Plains. Much of Texas, Oklahoma and parts of New Mexico and Kansas remain mired in extreme to exceptional drought. The agriculture damage in Texas alone is estimated at $5.2 billion. The climatologists say that weather indicators suggest that drought conditions in the area may remain in place.

According to NOAA, U.S. weather disasters in 2011 exceeding $1 billion in damage set a new record at 10.

August precipitation varied considerably across the Midwest as crop stress became much more widespread with the dry conditions of the month, according to NOAA. Due to the weather and following disappointing field surveys in many locations, crop yield estimates were lowered well below the 5-year averages. Yields are also expected to vary considerably from field to field and even within fields.

Drought affected areas in the Midwest expanded from less than 1% on July 26 to more than 18% on Aug. 30. Severe drought area went from 0% to nearly 5% of the Midwest in the same time period.

For details on the weather and climate events of the Midwest, see the weekly summaries in the MRCC Midwest Climate Watch page.