I just did some online research on Charley and actually this does prove my point that Cat 4 / Cat 5 level winds are not sustained very far inland.

First from the NHC documentation of Charley they specify that the high Cat 4 winds were only within a 6 nautical mile radius of the eye at landfall.

Secondly from an online map and writeup documenting the damage from Charley, it was shown to be a Cat 4 for only the first 5 miles inland; by the time it had crossed the peninsula and the Myakka River, and was approaching Port Charlotte, its windfield was already down to a Cat 3. However Port Charlotte and Punta Gorda were right on the bay and within the narrow radius of the highest winds at the time, so they suffered Cat 3 level damage.

To quote from one of the online documents, "The RMS reconnaissance team surveying the landfall area confirmed the highest levels of damage from just south of Fort Myers northward to Port Charlotte. Offshore barrier islands ... took the brunt of the storm’s wind and surge." This refers to a 30-mile strip of coastal areas which took the onshore winds east or south of the eye, and does not mention any inland areas. It also indicates that windfields weakened even after only passing barrier islands, before hitting the mainland.

This is totally consistent with the windfields of Camille and Andrew, which also diminished rapidly from Cat 5 strength after very few miles inland.

So I still feel I make a good case and that it is fair to say that Cat 4 / Cat 5 level damage, which is generally complete devastation due not only to high winds, but also in no small part to storm surge and the force of wind-driven waves, is generally limited to a very small diameter area that does not extend very many miles inland.

So, to tie this to Katrina, if it does reach Cat 4 or Cat 5 intensity, the area of almost total devastation that would occur from that level of damage, if it did hit a populated shoreline, would most likely be a very small area that does not extend for very many miles inland, as was the case with Camille, Andrew, and Charley.

The point I was trying to make in the original post, was to answer the specific question of how far inland someone would have to worry about that frightening level of damage. The answer is, not very far inland, so don't worry about, as Hugh put it, the coast of Arkansas. In other words, let's minimize the panic factor.

However damage at a lower threshold can and does occur and varies with each storm.

If the original question was simply to ask, how far inland is there damage if you start with a Cat 5, then I totally misunderstood the question.

With Camille, there was huge damage in W VA from rains and flooding, long after the windfield was gone.

Edit - went back and looked, and actually I think I did misunderstand what they were asking.

So probably nobody cares just how long a Cat 4 stays a Cat 4.

Hey you can delete this post if you like!