Irma is more than "just" a category 5. Consider this.
Cat 4 is 131 mph.
Cat 5 is 156 mph.
Right now, Irma has sustained winds of 186 mph, and it's bearing down on Puerto Rico. If there were such a thing as a Cat 6, that's what this would be. While its sustained winds are 186mph, it probably has gusts exceeding 240mph. It'll be blowing buildings over like they're made of tissue paper.
Something I try to remind people is that wind impact increases by the square of the relative change in speed. Double the speed and you have four times the impact. If a 100 mph wind hits with "x" units of force, a 200 mph wind hits with "4x" units. That's because not only are the molecules of air moving twice as fast, but in a given period of time, twice as many of them strike. At 100 mph, you might still be able to lean against it and stay on your feet. At 200mph, you'll be airborne.
Fortunately, Irma will weaken as it gets closer to Cuba.
If it hits Florida, it will likely be a Cat 4. Regardless, it's one hell of a storm.
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