Pop out of my helicopter and, lo and behold, the Tornado is sitting right there ripe for the taking. So in a night time rainstorm I fly my other helicopter to the police station (from my furthest helipad as I didn't really think about it) and after a few attempts land successfully on the police station. Run downstairs and outside of the station and then run back to the helipad where the tornado may have spawned. This works better if you fly another helicopter to the roof and land it near the helipad (but not on as the Tornado needs somewhere to spawn). The Tornado Attack Helicopter will sometimes spawn on the Helipad on the Police Station. This is when things started to deteriorate. I found a method that reportedly worked most of the time.

It is possible to earn the Tornado legitimately by completing the final mission of the Ultor epilogue.

It's the helicopter provided for the Heli-Assault activity. The Tornado is an attack helicopter complete with high powered Gatling gun and a laser guided missile launcher. It definitely sucked some of the fun out of Saints Row 2 for me.