Irene, Season's First Hurricane, Takes Aim at Florida and Points North

Thrashing Puerto Rico and aiming for Florida, Hurricane Irene strengthened on Monday.

On a track to strike or brush by Florida as early as Thursday night, Irene is forecast to grow to a Category 2 storm, with winds topping 100 mph. It is the first named storm to emerge as a full-blown hurricane this season.

The National Weather Service said that if Irene stays to the west side of the current cone of probability, it will be less severe, weakened slightly by the mountains of Cuba. If it veers to the right side of the cone, Irene will strengthen over open water.

And even if Irene doesn't make landfall in Florida -- some long-range computer models show it striking Georgia or the Carolinas -- forecasters say the state will feel the effect of hurricane-force winds.