I will say this for the north east, a large reason we see very few natural disasters that require evacuations or spur looting and rioting is because most of the "natural disasters" include below freezing temperatures and a crap ton of snow. People aren't worried about stealing a 42" TV when there's snow up to your waist and you have no heat
. Not to mention its hard to run in 12" of snow. As for the evacuation part, well Sandy's are few and far in between, and we haven't had a LA Riot style event in NY in recent history(recent for me is like the past 14 years so). I've never been to L.A, Miami or New Orleans but I'd say a large factor in NYC's lack of riot/evacuation scenarios' is due to the incredibly high population density of the area, almost 10 times that of the Los Angeles Metro Area(or roughly 3.5 Times that of LA proper) and around 17 times that of New Orleans Proper (New Orleans Metro area has a stupid low Pop density so I didn't bother including that, NY Metro area is just under 3 times larger than LA Metro area with almost twice the number of people mostly concentrated in NYC, so NYC showed a better example of evacuation percentages.) NYC also has very few egress routes, so evacuation would be near impossible( I could be very wrong, I am only taking into account the population and limited personal transportation, as well as limited number of ways out of the boroughs, If someone has a better data set hit me up).
In short....you can't evacuate NYC, looting is less likely due to the percentage of "natural disasters" to occur in winter time when everyone is cold anyway. Keeping an extra gun in your car is silly a Northern Metro area, stay home and ride it out, your not going anywhere fast.
EDIT: Keeping "heavier firepower" in ANY metro area is silly, yea sure if you live in a rural area and make a habit of breaking down in the middle of the woods for days on end and need to hunt you might want to consider keeping a rifle in your car, or a sat phone and get AAA. If you think you are going to run into a situation where you are going up against an armed gunman with rifles and MK19's your should probably have an armored car and Level IV chest rig in addition to that rifle, other wise, a spare pistol a lock box is a good idea if you occasionally forget your carry piece or decide against carrying that day, or w/e....I'm always pro back up plan, but having a rifle in your car without the rest of the things that go along with being prepared for a high stakes shootout is just silly. Now if you can't carry a pistol, and a locked rifle or shotgun with ammo stored separately may be the best your going to get legally...then I'd advocate doing that.