MIAMI (Reuters) - The 2011 Atlantic hurricane season will be above average in activity and there is a more than 70 percent chance of at least one major hurricane hitting the U.S. coastline, Colorado State University forecasters predicted on Wednesday.
The 2011 forecast from the respected CSU team followed an active season last year which saw high levels of storm and hurricane activity but no landfall on the U.S. coastline.
Slightly reducing an early December forecast, the CSU team said the June 1-November 30 season would spawn 16 named storms.
Of these, nine were expected to turn into hurricanes, with five developing into major hurricanes of Category 3 or higher on the five-step Saffir-Simpson intensity scale.
The CSU forecast was generally in line with predictions made for the 2011 season by other private forecasters.
The 2010 season spawned 19 named storms, tying for the third most active season with 1887 and 1995, according to the U.S. National Hurricane Center. Of those storms, 12 became hurricanes, tying the second highest season of 1969. There were five major hurricanes in 2010.
The CSU team predicted a "72 percent chance that at least one major hurricane will make landfall on the U.S. coastline in 2011," adding that the long-term average probability of this was 52 percent.
"Basically the reason that the probability goes up is just because we're speaking about a well-above-average hurricane season," said Philip Klotzbach, who heads the CSU team with forecaster William Gray who is renowned for his research on seasonal hurricane forecasting.
"In general, more active seasons tend to have more landfalls," Klotzbach said.
CSU saw a 47 percent chance of a major hurricane making landfall along the U.S. coast of the Gulf of Mexico, where major oil and gas installations are located. The long-term average for this was 31 percent.
Although there were surprisingly no U.S. landfalls during the busy 2010 season, Klotzbach called that exceptional, saying the odds for going without a U.S. landfall during such an active season were probably only "about 3 percent."
He said the "primary uncertainty" about CSU's latest forecast stemmed from the possible warming of Pacific sea surface temperatures due to the El Nino weather phenomenon, which tends to lower the threat of storm activity in the tropical Atlantic.
"Right now we don't think one (El Nino) is going to develop but there are some signs that it (the Pacific) certainly has warmed quite a bit and there is that potential," Klotzbach said.
"In June, if El Nino really were to look like it's going to develop we'd have to lower our forecast quite a bit." he added.
An average hurricane season brings 11 storms, six hurricanes and two major hurricanes in the Atlantic, Caribbean and Gulf of Mexico. The region is still in a multidecade period of high activity for hurricanes.
Reporting by Pascal Fletcher and Tom Brown; editing by Jim Marshall