Miami ? Federal hurricane forecasters boosted their outlook Tuesday, predicting this season could spawn as many as 21 tropical storms and 11 hurricanes, with seven of them ballooning into intense storms.

That’s a fairly sharp increase over the National Oceanic and Atmospheric Administration’s May prediction, released two weeks before the June 1 start of the six-month season. That outlook called for 12 to 15 tropical storms and seven to nine hurricanes, with three to five of them becoming major ones.

The revised forecast reflects the growing confidence of a team of NOAA scientists that favorable atmospheric and oceanic conditions will keep the already record-breaking season on track to become among the busiest ever.

“If we’re wrong and it’s not as active, I think everybody would be pretty happy about it,” said NOAA meteorologist Chris Landsea. “But that’s not likely. It looks like we’ll have a very busy August, September and October.”

If he and rest of the NOAA team are correct, the 2005 season, which already has produced an unprecedented seven named storms, will mark the ninth above-average season in 11 years, supporting their conclusion that the Atlantic basin is in the midst of another decades-long cycle of more – and more intense – hurricanes.

NOAA’s revised outlook specifically calls for 18 to 21 tropical storms, with nine to 11 of them blossoming into hurricanes, and five to seven of those growing into major hurricanes.

For now, 1993 claims the title for most tropical storms, with 21, while 1969 holds the record for most hurricanes, with 11. And 1950 produced the most intense storms ever – eight in a single season.