Tropical storm to reach hurricane force

Forecasters in the United States say Tropical Storm Isaac will reach hurricane force as it closes in on the Gulf Coast.

It is expected to make landfall near New Orleans nearly seven years to the day since Hurricane Katrina devastated the region.

The storm now threatens to overshadow the Republican Party's Convention in Florida where Mitt Romney will be confirmed as the party's Presidential nominee.

Barack Obama will be holding a press conference about the storm at 3pm.