Tropical storm a-brewing, headed for Haiti, Cuba ... Tampa?

It's still a tropical depression, but forecasters expect it to become a hurricane by early Thursday. Some models show it dousing Tampa, Fla. – and the Republican National Convention – next week.

The tropical depression out in the Atlantic isn't even a full-fledged hurricane yet, but its early development is attracting more than the usual attention because one possible path would bring it right over central Florida in time for next week's Republican National Convention in Tampa. 

Hurricane forecasting that far in advance is very inexact, certainly, and a lot will happen weatherwise between now and next Monday, when the convention gets under way. Here's how the picture looks now.

Forecasters expect a tropical depression approaching the Caribbean to become a tropical storm during the next 12 hours. Tropical-storm warnings have been issued for the Lesser Antilles.

The storm would become tropical storm Isaac once its maximum sustained winds reach between 39 and 73 miles per hour. Forecasters at the National Hurricane Center in Miami expect the storm to become a hurricane by Thursday morning.

The depression currently is located some 561 miles east of Martinique. By the weekend, the current track forecast could bring Port-au-Prince in Haiti within the storm's tropical-storm force winds, with the hurricane grazing Cuba's southeastern coast by Sunday morning.

The National Hurricane Center has ordered a reconnaissance mission later Tuesday from the US Air Force 53rd Weather Reconnaissance Squadron to take the measure of pre-Isaac tropical depression 9.

So far this year, every tropical depression that has formed has become either a tropical storm or a hurricane. Indeed, the 2012 Atlantic hurricane season, which runs from June 1 to Nov. 30 each year, got off to an unusually early start with two tropical storms in May – Alberto and Beryl.

Some depressions have been late bloomers. Tropical depression 8 emerged from a stormy patch in the Atlantic on Aug. 15 to become tropical storm Gordon the next day, and then hurricane Gordon. The next name on the list, Helene, was ultimately given to a system that emerged Aug. 9 as a depression, only to almost peter out two days later. On Aug. 17 the ragged leftovers had reorganized and strengthened to become tropical storm Helene – although a name like tropical storm Phoenix might have been more appropriate.

The Atlantic hurricane season's peak period runs from mid-August through October. Assuming the current tropical depression evolves as forecast, this season will retain its street rep as a season running well ahead of normal. During an average season, the ninth named storm doesn't appear until about Oct. 4, says National Hurricane Center spokesman Dennis Feltgen. And a season's third hurricane usually appears in early September.

Some long-term forecast models put the storm in the vicinity of Tampa sometime between Tuesday and Friday of next week. 

Even three days out, a hurricane-track forecast carries large uncertainties. Still, it might be prudent for Republican convention-goers to pack some foul-weather gear.