The El Niño weather event developing in the tropical Pacific Ocean is likely to strengthen this fall and last through the Northern Hemisphere winter, the U.S. National Oceanic and Atmospheric Administration (NOAA) said Thursday.

"A majority of the model forecasts ... suggest El Nino will reach at least moderate strength during the northern hemisphere fall," the NOAA’s Climate Prediction Center (CPC) said in its monthly El Niño/La Niña update.

Many model forecasts suggest a strong El Niño will develop, the agency said, but added that "current observations and trends indicate that El Niño will most likely peak at moderate strength."

A weak El Niño continued during August, as sea surface temperatures (SST) remained above average across the equatorial Pacific Ocean, the CPC said.

Expected El Niño impacts during September-November 2009 include greater precipitation over the west-central tropical Pacific Ocean and the continuation of drier-than-average conditions over Indonesia, the CPC said.

El Nino’s impacts on U.S. temperatures and precipitation are typically weak during the Northern Hemisphere summer and early fall, generally strengthening during the late fall and winter, the CPC noted. Typically, El Niño is associated with mild winter conditions across the central and northeastern U.S.

El Niño can also help to suppress Atlantic hurricane activity by increasing the vertical wind shear over the Caribbean Sea and tropical Atlantic Ocean, which disrupts storm formation in the Atlantic basin.

In early August, NOAA reduced its 2009 storm forecast to seven to 11 storms, with three to six expected to become hurricanes, citing El Niño as a prime reason for the reduction in the number of storms seen developing in 2009. In May, NOAA had predicted 2009 would bring nine to 14 storms, with four to seven becoming hurricanes.

Editor’s note: Richard Brock, Corn & Soybean Digest's marketing editor, is president of Brock Associates, a farm market advisory firm, and publisher of The Brock Report.