Wrong, the Tornado in Monson, MA lead to robberies and gun fire, as did Katrina.
http://www.lslproducts.com/NOLA_Katrina.pdf
Only a fool would attempt evacuation unarmed.
People in this thread go well beyond the definition of "armed". I didn't mean to convey that you should be unarmed. Just that you will have more need for copies of your insurance docs than that second thousand rounds of 5.56x45 for that third AR. Not to mention all the end of the world stuff that is nearly useless in the most likely evacuation scenario you are likely to face.
If there is one thing Katrina taught us about firearms is that you NEED handguns. The "authorities" went around confiscating every gun they could find. The ability to hide or conceal a firearm is invaluable. Yes a rifle/shotgun is preferable, but don't forget the Glock/1911/etc.
Also, those that actually EVACUATED during Katrina generally didn't need firearms. Sure they were comforting, but the evacuation was pretty orderly on the slow moving interstates out of NO. They were out before the place imploded. My ex-fatherinlaw a lifelong resident of New Orleans and the Gulf Coast was out of the city the day before Katrina hit and holed up with the family at the little biloxi wildlife refuge for about 2 months. The only thing he needed his guns for was poaching. It was all he could do to pass the day. He worked as a salesman in the construction industry in the NO area and had nothing to do for a couple of weeks. His waterfront home was wiped from its pad.
In the end, the only people who stayed behind in NO were idiots who thought the government would take care of them and well prepared die-hards who were planning to ride it out. These die-hards had guns, ammo, food, generators, fuel, etc. There are stories of them using firearms to defend their property. But they are a small minority compared to most people.
Also, significantly, they did NOT evacuate. So what they had/did does not address the OPs question. I'm going to generalize and say that firearms were MUCH more necessary for those who stayed behind in NO than those who left.