using your TV to detect tornados

Cecil's Columns/Staff Reports
1

In the straightdope column http://www.straightdope.com/classics/a1_166b.html

Cecil describes how your tv set can be used to to detect tornados.
I was curious if anyone out there as ever done this before.

I’ve never heard of this, but it seems like a cool thing to try out in the next big thunderstorm that moves through.

I’ve learn so much from the straightdope, even if they never answered any of my emails.

2

The procedure described specifically states “turn to channel 13” in order to adjust the brightness. Is there a specific reason why channel 13 is used? Is it, perhaps, because on the old dial channel televisions channel 13 was next to channel 2, so you only had to click over one channel?