Hurricane Isaac made landfall last night as a category 1 storm on the vulnerable, low lying Gulf coastline of Louisiana – including New Orleans, 7 years to the day after Hurricane Katrina hit the same area.
Isaac has mean wind speeds of 80mph and higher gusts, with the added risk of triggering tornadoes in the surrounding areas, but flooding is the biggest threat.
Up to 20 inches of rain is expected to fall locally, and this combined with huge, dangerous battering waves and high tide will bring storm surge of anything up to 12ft above normal sea levels, leading to a huge impact from severe and extensive flooding.
Katrina was (the most powerful) category 5 hurricane, before making landfall at a category 3 storm on the 29th August 2005. It was one of the costliest and most intense Atlantic hurricanes on record.
2005 was a remarkable, record breaking year. A record 28 tropical and subtropical storms formed, of which a record 15 became hurricanes. Of these, 7 strengthened into major hurricanes.
On average, two major hurricanes (category 3-5) strike the US every three years. In all categories, about five hurricanes make landfall every three years. On average, a hurricane of category 4 or higher only strikes once every six years.
Hurricane season runs from June to November- with September usually the most active month.