Powerful Hurricane Katrina roared towards the Louisiana coast yesterday with 233 kph winds and a massive storm surge that threatened to swamp the historic city of New Orleans.

At least a million people had fled the area ahead of the powerful storm, which was once a fearsome Category 5 storm with 280 kph winds, but as of 1000 GMT was a Category 4 on the five-step Saffir-Simpson scale.

A tropical storm becomes a Category 1 hurricane when its sustained winds reach at least 119 kph. A Category 2 hurricane has winds of at least 154 kph, followed by Category 3 with at least 178 kph, Category 4 with 210 kph, and Category 5 of winds greater than 249 kph.

New Orleans has not been hit directly by a hurricane since 1965 when Hurricane Betsy blew in, flooding the city. The storm killed about 75 people in the US.

The following are five facts about the Atlantic hurricane season from the National Oceanic and Atmospheric Administration:

¤ Atlantic hurricane season runs from June 1 through November 30, with most activity in August and September.

¤ Average hurricane season has 10 tropical storms. Of those, 6 become hurricanes and two are ranked as major ones with winds of at least 111 mph.

¤ 2005 hurricane season prediction calls for 21 tropical storms. Of those, 11 may become hurricanes and seven may have powerful enough winds to rank as major ones.

¤ 2004 hurricane season had 15 tropical storms. Of those, nine became hurricanes and five were ranked as major ones.

¤ Most active Atlantic hurricane season was in 1933 with 21 tropical storms, followed by 1995 with 19 tropical storms. The most hurricanes in a season occurred in 1969, when there were 12 hurricanes.

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