Update at 10:10am: Hurricane watch extended north to Tampa on Florida's west coast.
Tropical Storm Isaac is clearing Haiti at the present time and is now moving toward the United States. The area of south Florida in red is now under a hurricane warning.
If the center of Isaac only goes across the Keys (as opposed to moving across the Peninsula of Florida), I expect the storm to intensify to category 2 or 3 when it makes landfall on the northern Gulf coast.
There is also the likelihood of flooding rains in the Southeast with this storm.