Saffir-Simpson Hurricane scale


Category 1 – Winds 119-153kph
Minor coastal flooding and structural damage

Category 2 – Winds 154-177kph
Damage to roofs, mobile homes and shanty houses. Some trees uprooted. Small boats may break moorings

Category 3 – Winds 178-209kph
Damage to buildings, mobile homes destroyed. Severe flooding near to coast

Category 4 – Winds 210-249kph
Major structural damage, roofs destroyed. Storm surge around 5m requiring widespread evacuation of coastal areas

Category 5 – Winds 249kph or higher
Serious damage to all but strongest buildings. Severe flooding far inland, all trees blown down. Storm surge up to 6m above normal

Eric Blake, a forecaster at a hurricane centre in Miami, said: "We are forecasting it [Felix] to be a Category 3 hurricane in the northwestern Caribbean Sea by the middle of the week."

Residents in Aruba, Bonaire and Curacao have been told to expect storm conditions within 24 hours.

The islands can expect up to 10cm of rain.

There are no indications that Felix will reach the Gulf of Mexico, where a third of US domestic crude oil and 15 per cent of natural gas production is located.

However, according to the national hurricane centre, long-range forecasts are unreliable.

Close monitoring

Energy markets have watched tropical storms and hurricanes since the Atlantic hurricane seasons of 2004 and 2005, when hurricanes Ivan, Katrina and Rita disrupted supplies.

The 2007 hurricane season is approaching its peak. Most storms occur between August 20 and mid-October, reaching a peak around September 10.

In late August, Dean hit Martinique, St Lucia and other islands in the Lesser Antilles chain.

It also hit Jamaica and then struck Mexico's Yucatan Peninsula before weakening over the Mexican mainland.