I read the news report of Emily hitting Mexico resort really hard. Many tourists were compelled to seek shelters in dingy hotels basements where toilets don't work. All grocery store shelves are empty. The weather was hot, humid. There was no food, clean water. What would you do in this situation? How to prepare for disaster vacation in caribbean or Mexico?

Me? I'd head to the nearest consulate. Boil water, even if I had to scrounge a vessel. Boil everything I ate for ten minutes.

That kind of thing is where the PSK comes into it's own. You can hide it in a small first aid kit. If anyone asks about the Micra or Classic on your key chain, well, so long as you put it in your checked baggage, not many people are going to actually see it. If they look at the fire making supplies and the duct tape, just grin sheepishly and tell them you were a Boy Scout.

The sheepish grin is the best concealment I know..

Come back home... or, if you're not there yet, change direction & go some place else.

No, seriously, short of having a full blown BOB in your vehicle, and by full blown, I mean shelter more substantial than a tube tent or poncho liner, more complete menu than jerkey & peanut M&Ms, and a medical kit that would make Markus Welby jealous... I'd say you're gonna be at the mercy of the locals... stay low profile and inoffensive until you can unass the A.O. and get back to home base.

Troy

A good travel agent is going to tell you if it is hurricane season where you are going. Watch the weather before you go, get travel insurance.
Hurricanes usually give a fair bit of warning, leave early and go home if bad weather is approaching.
Your mileage may vary with other types of natural disasters, or civil unrest. The recent tsunamis come to mind, that was an almost entirely unpredictable event.
I second heading for the nearest consulate in that case, be it your native country, or another country that is friendly with yours.
I guess what I am trying to say, is preparedness goes a long way. You can do better by avoiding these situations than by trying to suffer through them.