MIAMI, USA (AP) — Forecasters say Tropical Storm Isaac has formed in the Atlantic with a trajectory that could possibly take it toward Florida where the Republican National Convention will be held next week.

Storm warnings have been issued today across a swath of islands in the Caribbean including Martinique, Guadeloupe and St Martin.

It is too soon to say what exact path the storm will take, however, some computer models show it headed toward Cuba and then Florida. That would see the system affecting Jamaica sometime over the weekend.

Other models have it making a sharp northern turn in the next couple days near Puerto Rico and then into the open Atlantic.

The National Hurricane Centre says Isaac has maximum sustained winds near 40 (64 kph) but is expected to strengthen.

The storm is about 500 miles (804 kilometres) east of Guadeloupe and is moving west near 17 mph (28 kph