When the tornado warning has been issued, how do they determine the time frame?

Question

for example; tornado warning has been issued by 9am...how do they calculate the warning by such time?

Answer 1

It's all predictions.  The meteorologists have to first look at the speed of the storm and the direction in which it is moving.  How they do this is all by radar.  They usually have these rather large radars in the middle of a field (they track storms from pretty much any where) and they "scan" the weather conditions through the air with modern technology.  Usually when a tornado forms it creates a "hook" shape on the storm (from a radar's view), but some times if the tornado has formed somewhere in the middle of the storm (which is harder to see on a radar), the meteorologists have to look at the wind velocities.  So where I am getting with this (lol), it is really all predictions from man and radar, and a tornado can move at different speeds depending on where it has formed in the storm.  Some times a tornado moves the opposite direction inside of a storm so they also have to watch that as well.  But anyways, the radar is like a computer genius so yea.  Prediction and radar.. hope this helps!!!

p.s.  where i live we're expecting some very serious storms today.  =(

Answer 2

I think it's because of the storm that could produce a tornado.  They were saying yesterday the band of storms going through the northern va/dc/maryland area were showing signs of heavy rotatation, and so they predicted the tornado based on that, and when the storm was expected to pass through any given area.  For example, I live in Fairfax County and our warning was lifted at 8:15, which was right when the storm passed.

P.S.  More thunderstorms predicted today.  Oh goody!

Answer 3

They calculate it by the speed of the storm and the distance it has until the storm is out of your area. So if it's traveling at 50mph and the  warning is issued when it's 10 miles until it's out of your county and it's 9:17am, the warning will be issued until 9:30am. You do the distance divided by speed, multiply it by 60 and add it to the minute that the warning was issued.