Countdown to Katrina

NASA   Rainfall inside Katrina, as imaged by NASA's Tropical Rainfall Measuring Mission: wettest regions (red) experience over 2 inches of rain per hour

Friday 26 August, 2005, T-3 days

The National Hurricane Center is showing the storm heading straight toward the Gulf coast west of New Orleans. Because a hurricane rotates anticlockwise, with its most dangerous winds on the eastern side, this is the very worst case scenario.

Before its levees were built, the Mississippi River conveyed tons of silt and soil to the coast each year. Every spring, when the river flooded, the wetlands were strengthened and replenished. These wetlands protected New Orleans against hurricane storm surges, soaking up the violent waters like a sponge, while stands of cypress trees acted as a windbreak. But when the levees were built, they kept the river from flooding. The wetlands became starved of new soil and started disappearing at an alarming rate.

Saturday 27 August, T-2 days.

At Louisiana State University, Ivor van Heerden and his team take what the information they have about Katrina and put it into the same computer model they developed for the disaster exercise called Hurricane Pam in 2004.

Van Heerden makes the news public, sending email after email to officials in charge. "We knew on Saturday night that this was going to be the big one," he later recalls, "that it was going to sink New Orleans - and so we tried to get the word out as much as possible."

NASA Beautiful but deadly: Hurricane Katrina approaches New Orleans (top left)

Surveys conducted around the time of the Hurricane Pam exercise indicated that not everyone would be willing or able to evacuate. In the heart of New Orleans, Africa Brumfield, with her house 12 feet below sea level, decides to remain as well. 'Some of our family members decided that they would leave but my parents decided to stay and I wasn't going to leave them and got to safety, so I decided to stay with them'

Sunday 28 August, T-1 day.