A disturbance in the Caribbean Sea became Tropical Storm Matthew Thursday and could post a threat to Florida.
Forecasters expect Matthew to approach Belize as a hurricane by Sunday. Then its path is less certain.
"There are a lot of variables involved that make this a complicated forecast," said Michael Lowry, a meteorologist at the National Hurricane Center.
A strong trough plowing down from the United States is expected to draw the system to the north, and the official forecast shows the system turning sharply and tracking along the coast of the Yucatan Peninsula. But by that time, depending on whether and how much time Matthew spends over land, it could have melted into a mess of disorganized storms or turned into a serious hurricane.
Some computer models, Lowry said, suggest the storm might split, with Matthew moving inland but a remnant left behind re-forming into a new system. Lowry said the storm is too far off to get a solid handle on it, but the path should become more clear in coming days. For Florida, he said, it was a concern that many computer models predicted the system moving somewhere across the state.
The beginning of fall is usually when tropical waves stop forming off Africa and begin developing in the Caribbean, where they are more likely to curve toward the Gulf of Mexico.
Matthew should be a reminder to Floridians to "start directing our eyes south," said National Hurricane Center spokesman Dennis Feltgen. "The Cape Verde season is all but over, and now everything shifts west. Some of the worst storms in history are the ones that form during this time."