So very sad. Good points are brought up by all.
Airborne weather radar is an avoidance tool. I learned early on that it isn't for picking your way through cells, it's so you can avoid them completely.
In the heat of battle, it can be used tactically to make decisions relevant to what the weather very close to you is doing right now. If you're fortunate enough to have a stormscope, eve better. A cell that looks harmless and flyable on the radar but that displays electrical activity on the stormscope would be good to avoid. The best policy is to simply avoid them. ten miles for every ten thousand feet of development is a good start.
Airborne WX R/T units uses X-band frequencies that are not viable for distance beyond 120 miles.
This is where having Nexrad is useful. It is a strategic tool to make decisions about what will be happening later in your flight. It should never be used to pick your way through cells or a line. Weather changes too rapidly. I can't tell you how many times I've had to alter a decision about convective activity within ten minutes of my flight path.
Nexrad is a historical picture for planning purposes only. ("I'm going to land before Pocket City." or; "These cells that are ninety minutes in front of me seem to be dissipating, with no training on the upwind side. I'll continue and see if I exit this stratus at least fifty miles before I reach them, so I can verify that visually.")