Rafael is strengthening and will likely become a hurricane by Tuesday night as it batters the western Caribbean on the first leg of an uncertain journey toward the US Gulf Coast. Forecasters are warning there’s more uncertainty than usual about where the storm could go once it’s in the Gulf of Mexico midweek.

MIAMI - The lower and middle Florida Keys are now under a tropical storm warning as Tropical Storm Rafael is forecast to grow steadily as it churns past Jamaica's west coast on a path for Cuba, where it's expected to arrive later in the week as a hurricane.

The Climate Prediction Center says the Caribbean next week "will provide a favorable environment for late-season tropical cyclone development."