Colorado Forecasters Predict Two Hurricanes in October-November

The final months of the 2007 Atlantic hurricane season are expected to experience above-average activity, forecasters at Colorado State University in Ft. Collins, Colo., are predicting.

According to its latest forecast, the two-month period of October-November is expected to experience a total of four named storms. The CSU team had predicted five named storms with their earlier October-November predictions, but they downgraded the forecast slightly to four named storms with two becoming hurricanes with their latest update.

Of the four named storms predicted in October-November, two are expected to become hurricanes and one is expected to become a major hurricane with sustained winds of 111 mph or greater (Category 3-4-5).

As of Oct. 1, a total of 13 named storms, 4 hurricanes and 2 major hurricanes have developed this season.

“August had somewhat above-average activity — about 130 percent of average — while September had about average activity — about 92 percent of average,” said Phil Klotzbach, lead author of the hurricane forecast. “We expect October-November to be very active.”

September witnessed the formation of eight named storms, tying a record for most named storm formations during the month. However, most storms were short-lived and not particularly intense. Sea surface temperature and vertical wind shear values were near their long-period averages, while sea level pressure values remained somewhat below average.

Source: CSU

“Typically, the end of the Atlantic basin hurricane season is governed by rising values of vertical wind shear,” said William Gray, who is in his 24th year of issuing forecasts at Colorado State. “We expect La Nina conditions through this fall. La Nina conditions tend to reduce levels of vertical wind shear in the tropical Atlantic, and therefore, the end of the Atlantic basin hurricane season will likely be extended this year.”

The Colorado State team continuously works to improve forecast methodologies based on a variety of climate-related global and regional predictors. For a detailed description of the forecast factors, visit http://tropical.atmos.colostate.edu.

The team will issue its forecast verification on Nov. 27 followed by an early 2008 season forecast in early December. The full report is available with the news release at http://newsinfo.colostate.edu/.