with heavy rain bands spinning out 300 miles from the center. 200 people evacuated from guantanamo bay, cuba, where troops are sandbagging buildings. in miami they're feverishly buying provisions. >> every family should be prepared to sustain themselves up to 72 hours. >> reporter: in tampa, all eyes and headlines on the storm. it happens that tampa is the most flood-prone city in the entire country. >> even a category 1 can push up to eight feet of water. >> if you have the right storm at the right angle moving at the right speed, obviously, it has the ability to funnel a lot of the water up into the bay. >> reporter: as many as 800,000 people live in the evacuation zone here and would have to live if a category one storm threatened the area. travel delays are expected. airlines allowing passengers to change tickets without penalty. they're not the only ones changing itineraries. abc news learned that a number of security officials from other parts of the state have canceled their plans to help at the convention to help their own communities get ready.