An advisory was issued at 5 a.m. on Wednesday morning in the midst of tropical storm Isaac, a weather system that is expected to reach hurricane strength.

Tropical storm Isaac is expected to cross the Leeward Islands today and form a hurricane on a path toward Florida, where the Republican Party holds its convention next week.

While it's too early in the week to estimate where exactly the hurricane is headed, several computer models bring the storm into the Gulf of Mexico, while others move it farther east over Florida, according to CNN.

If Isaac were to land in Flordia, the hurricane would pose a significant threat to the roughly 50,000 people headed to Tampa for the Republican National Convention, which starts on Monday.

The advisory, issued by the National Hurricane Center in Miami, warned that Isaac had sustained 45 mph winds and was moving west at 18 mph. At 8 a.m. ET, the center was about 210 miles east of Guadeloupe, 70 less miles than where it was at 5 a.m.

A hurricane watch is in effect for Puerto Rico, the U.S. Virgin Islands and the Dominican Republic, which means hurricane conditions are possible within 48 hours.

"Strengthening is forecast during the next 48 hours ... and Isaac could become a hurricane by Thursday," the hurricane center said.

The U.S. National Hurricane Center's tracking map shows the system crossing Haiti as a hurricane on Aug. 25 and striking Cuba before arriving at the edge of Florida Keys early Aug. 27, the opening day of the convention.

"The worst case scenario from a Tampa standpoint would be if Isaac were to swing over the Gulf of Mexico, strengthen, then curve northeastward toward or just north of the city on the Florida west coast," Alex Sosnowski, expert senior meteorologist for AccuWeather Inc. in State College, Pennsylvania, wrote on the company website.

If in any case Isaac does pose a significant threat, Puerto Rico Gov. Luis Fortuno said the U.S. commonwealth has as many as 433 shelters ready to be activated by local mayors as the storm approaches, according to CNN.

Fortuno added that rain from the system is expected to reach Puerto Rico Wednesday afternoon.