Often times in a line of thunderstorms, there will be gaps at the higher altitudes that will allow for safe passage through the line. Thunderstorms are 3D, 4D
if you add in velocity inside of them, animals. When we see the composite radar image on the weather channel, it is showing a lot of information blended into an easy to view 2D
display. Some of the new images with the doppler additions also display the extra velocity dimension. The radar in a jet only gives a 2D
image, but with controllable settings, the pilot can gain a "3D image" using his memory of all that he is seeing.
The most used setting is the tilt which adjusts the beam width of the dish up and down. This will need to be adjusted as the airplane climbs to altitude. Typically you would takeoff with the tilt pointed up at around 5*. By the time you reach 10,000' you would adjust it down to around 2.5*. By 20,000' it would be around 1*, and by 30,000' -0.5 to -1.0*. As you can see the higher you go the more you point it down as you are climbing in relation to the visible moisture which tends to mostly be below 30,000'. This will change based upon the range of the cell that you are looking at. The super cells that produce tornadoes are quite tall, but this doesn't mean that the rest of the line around them will be that tall. Using the tilt angle you can scan the line and find a low spot. If all of the precipitation is below you, I generally want 5-10,000' of clear zone above an area of heavy precip, it'll be a safe area to pass, given you give enough lateral separation from a super-cell. Generally you want to give at least 20 miles laterally to the super-cell to avoid having it spit hail and other debris at you.
Another feature that I use on the radar is the Gain setting. The Gain is basically a sensitivity setting. You can temporarily turn up or turn down the sensitivity to see what is going on inside of an area of weather. Turning the Gain up while pointing the tilt up will show if there is a high level of moisture moving around at the higher altitudes. It will give a pretty good idea if there will be a bumpy ride through an overhang if something is painting. On the other hand, if you point the tilt down and back off the gain while looking into a cell, you can get a better idea of how heavy the precip is inside of the storm. If you back off the gain by 2 and it still is painting red, don't go there.
The gist of all of this is you can safely maneuver around this nasty weather using the radar, but you don't ever want to just go pushing headlong through it. The gaps will usually be safe for passage, but that doesn't mean it will be smooth in there. There is a lot of air moving around and the airplane must react to all of that. Rest assured the radar will be in use anywhere near that kind of weather.