If you fly much around the middle of the country, thunderstorms seem woven into the general fabric of flying life. The good thing about your garden-variety thunderstorm is that if you keep your distance, there's no problem, other than possibly having to divert and spend a few more minutes en route. But there are times of year, and this is one, when the nature of the storms seems to change, when there's so much sudden convective activity in the atmosphere that a quick look before you hop in the airplane and head out might not be enough. By the time you get airborne and cleared on course, the picture might have changed substantially. I watched the other day a storm form from nothing and build to a 50,000-foot tornado-spawning monster in the course of a little more than an hour. And believe me, you didn't want to be messing with it even shortly after it began to build.
The way storms build and form in the plains is still little understood, or rather, it's well understood but still impossible to predict with much accuracy. Tornado watches are just fine to give you a general idea that you might be in for severe weather, but the bottom line is, you can safely fly through areas of predicted possible severe weather just so long as there's no actual severe weather there. Understandably, meteorologists err on the conservative side; they'd much rather have predicted severe weather when there was none than predict blue skies while mobile homes blew hither and yon.
When you're flying any kind of airplane, but especially a small one, you're a part of the big system of weather, and that's the way to look at it. While you can scope out the weather before you head out the door of the FBO, that only gets you so far down the road, even if there are no new cells or lines that form in the interim, which is unlikely. It's a little like looking for lions in the grass, seeing none, and then figuring you'll probably be okay. You will be, but only so long as you didn't miss any lions or no new lions wander by.
The GA equivalent of a big bore hunting rifle is satellite weather, and when it comes to satellite weather, Nexrad is the killer app. Unlike onboard radar, which few GA pilots have, XM gives you the big picture, allowing you to strategize instead of reacting to immediate threats. The idea is to zoom out, look at the big picture and then plan your diversions accordingly, sometimes hundreds of miles in advance.
With lines of storms, sometimes this means taking a route on the front side of the weather, if the back side is very active, which you can often tell by seeing how returns change in color over time. Are the little concentrations of convective energy building, staying about the same or diminishing in energy? This kind of eyeball evaluation can tell you a lot--though not everything--about what you're likely to see ahead. If you do go around the front side of a line, you need to give any storms a wide berth, as the outflow from them can ruin your day. Also, keep a close eye on the indicated movement of the cell, which is shown on the XM Nexrad presentation. Storms that are moving fast present greater risk to your flight than ones that are slower moving. They also tend to pack more severe weather.
The same kind of strategic planning is critical when you're approaching your destination, too. Several of most tragic air transport accidents we've suffered over the last few decades have been the result of pilots trying to beat weather to the airport and failing. If you'll be arriving to the airport around the same time as a cell, you might want to think twice and delay until the storm has passed, which typically takes only 10 or 15 minutes, or go somewhere else altogether.
And remember that you’re the boss in all of this. During a particularly active day one time before satellite weather, I was on arrival to Savannah, Georgia, a fuel stop on my way down to Sun 'n Fun. I was flying on an IFR flight plan in trail by 10 miles or so of a flying buddy. I heard him go from Approach to Tower only to pop up with Approach on the missed a few minutes later, reporting heavy rain, bad turbulence and no airport in sight. I was lining up for the same approach and the tower merely continued sequencing me as though this other guy in a light airplane hadn't just had the ride of his life.
I asked for a diversion to Hilton Head, where the weather was fine and the fuel was cheaper. With XM onboard, I never would have headed to Savannah, never mind started the approach.
It's not a case of the technology making what we do safer; it just gives us more information with which to make our decisions. Those decisions are what make us safer or not.