1 September 2005

Hurricane Katrina will probably become the costliest hurricane to have struck the USA and will also prove to be one of the most deadly for many decades. It is hard to imagine, given the pictures of the devastation of the southern states of the USA, but its impact could have been far worse.

Having crossed southern Florida as a category 1 hurricane, Katrina strengthened rapidly and predictions from computer models began to agree that New Orleans and the surrounding area was in the firing line. This enabled timely evacuation warnings to be made. Although some people were unable to evacuate, or chose to stay, many thousands more fled the city, which undoubtedly saved their lives.

Before the hurricane made landfall, forecasters at the National Hurricane Center (NHC) in Miami and local weather offices in the southern USA were working around the clock to warn of the impending disaster. In addition, the 'hurricane hunter' aircraft were being flown in and around the hurricane taking measurements which were fed into the computer models to help improve forecasts. The Met Office routinely provides input to the warning process by sending its forecasts of hurricane tracks to NHC every 12 hours. NHC uses these, along with its other forecast aids, to produce a forecast for the public, emergency planners and the government.

In the case of Hurricane Katrina, Met Office forecasts predicted the location of landfall to an accuracy of 60 km, as early as three days before the hurricane struck the coast. This helped NHC issue timely warnings, which prevented the human cost of the hurricane from being even worse.

However, having occurred at the end of August, Katrina only marks the halfway point in the Atlantic hurricane season which usually runs from June to November.

It was predicted that 2005 would be another active hurricane season, and so far this has proved to be the case. Katrina was the eleventh tropical storm of the season and the fourth of these to become a hurricane. Recent predictions suggest that these totals could rise to 20 tropical storms, of which 10 will reach hurricane status before the end of the season.

Whether any of the remaining hurricanes this season cause further devastation to US coastal communities is unknown at present. Many hurricanes start and end their lives over the Atlantic Ocean without impacting land. Others may strike far less densely populated areas than Katrina and cause modest amounts of damage. However, the population of coastal parts of the USA will be casting a wary eye to the Atlantic Ocean and Caribbean Sea in the next couple of months, in case the next hurricane is headed their way.

More about Met Office tropical cyclone forecast guidance