My wife and I (and a big fuzzy cat) live in SE Wisconsin, close to Lake Michigan. We are not in "tornadoes alley" but we still get hit occasionally. I've seen "water spouts" moving along the Michigan shore about a 1/4 mile out. They are scary and also beautiful at the same time. Last summer we had a small tornado pass within a couple of hundred yards of our house as it carved a five mile path of destruction. It was traveling like a sewing machine needle as it would pull up for a bit and later extend to the ground again, sometimes skipping over buildings left totally intact then pulling the neighbor's roof off.
Wisconsin weather includes blizzards and the occasional ice storm so we have put up with the potential loss of power at any time of year for almost 40 years. A couple of years back I bought a 17Kw alternator driven by a duel fuel engine (natural gas or propane). It is wired in through an automatic transfer switch so that if the utility power drops out for 30 seconds the gen-set cranks up and switches over without human intervention. It is big enough to carry all of our 120 vac loads and the 220 vac well pump. I drop the electric stove, clothes dryer, water heater, & air conditioning to keep the size of the alternator affordable. By the time everything was installed and wired in the total cost was a shade over $5,000, which I consider a good deal for the peace of mind it gives.
I added uninterruptable power supplies to feed all the computers and entertainment gear to smooth out the 30 second "bump" when switching over to "local power".
Our worst outage was four days in a winter ice storm. The basement filled with water to the top step of the basement stairs. A chest freezer was floating around like a rowboat and everything inside it had to be pitched. When we got pumped out the furnace looked to be in bad shape. The insulation soaked up and held enough water to cause rusting of the sheet metal housing and it wound up looking like an old Ford! I'd guess the total damages we suffered over the 40 years we lived here were more then the costs of on site power. In 20-20 hindsight, if we had started out w/ our own gen-set when we first moved in the $5000 would have been much less ($2000???) and there would have been little or no damage to pay out.
Regards,
GtG
GtG