Let me preface what I have to say by noting that I have been chasing tornados since the mid 1970's. I was trained originally by Alan Mueller, who was one of the ones who really started the spotter program. He also worked a lot with Dr. Fugita. I have spent many hours under their tutelage. All that to say I have lived with NWS Skywarn spotting and warning for many years.
We need to go watch how the NWS actually does the process of warning today. The Doppler radar systems we were so eager to put on line have progressed to the point that most of what we see in the NWS center are computer controlled systems that actually "spot" wind patterns that might indicate tornado formation. As has been said, 99% of those observations do not produce a tornado - or even a funnel cloud. The computer alerts the forecaster who issues a tornado warning.
I have watched as three warnings were issued while a trained ham spotter was actually observing the cell in question and could not even report a wall cloud, much less a rotating one. However the warnings went out because "doppler radar indicated a possibility of a tornado." More precisely, what the computer and doppler observed was an intake to a thunderstorm that approcahed the velocity vectors that have been set to indicate a "possibility" of a tornado.
I have observed, in the field, a thunderstorm that I know was incapable of producing a tornado (because of atmospheric conditions) produce a tornado warning based solely on doppler observations.
In the "old days" (pre-doppler) it took a radar-observed hook echo (observed by a trained radar operator) and some kind of human visual confirmation of storm structure before warnings were issued. Only rarely did we miss one. In fact, in nearly 40 years, I can't remember ever missing a tornado. We missed some that produced no tornado. To be sure, seeing a rain-wrapped tornado on a dark night was not easy to spot. But we spent a great deal of time training our spotters and fine tuning the system. And it worked. When we issued a warning, you had better take cover.
Today countless warnings are issued, we again hear the cry of "wolf" and no one pays any attention. Why? I think possibly because EVERY thunderstorm has an intake. Air is drawn up into the storm around a small, intense low pressure area and consequently produces a doppler "footprint" that looks like a tornado. The warning goes out and frequently the storm has dissipated before it ever reaches public ears. (I hope I'm being clear about this life and death issue.)
Gentlemen, the problem IS with the NWS. Only the NWS can issue a tornado warning (by law). TV stations with radars can play all they want. I will say it again. Only the NWS may issue tornado warnings. If anyone is to blame for the terrible tornadic death toll, it IS the NWS. The warning went out, you (and they) say. Fine. But no one paid attention because hundreds of warnings go out each day and only a few kill. In my humble opinion, some changes need to be made to the system, before more people die.