A late El Nino and increased dryness in the Atlantic led to a slightly below-average hurricane season this year, contradicting the predictions of Colorado State University hurricane forecasters William Gray and Philip Klotzbach, the team said Friday.

Gray and Klotzbach had predicted a well-above-average season in their forecasts issued in December, early April and late May. They said in the previous seven years, their early June forecasts were correct.

“A variety of factors interact with each other to cause year-to-year and month-to-month hurricane variability,” Klotzbach, the forecast lead author, said in a written release.

“It is impossible to understand how all these processes interact with each other to 100 percent certainty. Continued research should help us better understand these complicated atmospheric/oceanic interactions,” he said.

The statement did not address how El Nino, a warming in the Pacific Ocean that can alter the flow of jet stream winds, affected the Atlantic hurricane season. The forecasters did not immediately return a call.

The 2006 Atlantic hurricane season had nine named storms, five hurricanes, two major hurricanes and no Category 4 or 5 hurricanes.

The team said the season started nearly a month earlier than average and had the fewest named storms since 1997, the fewest hurricanes since 2002 and the fewest named storms to make U.S. landfall since 2001.

The CSU team has provided seasonal Atlantic basin hurricane forecasts for 23 years. Its first forecast for the 207 season is scheduled for Dec. 8.

On the Net:

CSU hurricane forecast team: http://typhoon.atmos.colostate.edu/forecasts/