10 190-00607-02 Rev CDetailed OperationTornadoesThere is no conclusive radar target return charac-teristics which will identify a tornado, however, torna-does may be present if the following characteristics areobserved:• A narrow, finger-like portion, as shown on theprevious page, extends and, in a short time, curlsinto a hook and closes on itself.• A “hook” which may be in the general shape ofthe numeral 6, especially if bright and projectingfrom the southwest quadrant (northeast quadrantin the southern hemisphere) of a major thunder-storm moving eastward.• V- shaped notches• Doughnut shapes.These shapes do not always indicate tornadoes,nor are tornado returns limited to these characteris-tics. Confirmed radar observations of tornadoes mostoften have not shown shapes different from those of anormal thunderstorm display.HailHail results from updrafts carrying water highenough to freeze. Therefore, the higher the top of athunderstorm, the greater the probability that it con-tains hail. The height can be determined by verticallyscanning the target return.Hail usually has a film of water on its surfacemaking it’s reflective characteristics similar to a verylarge water droplet. Because of this water film, andbecause hail stones usually are larger than water drop-lets, thunderstorms with large amounts of wet hailreturn stronger signals than those with rain. Some hailshafts are extremely narrow (100 yards or less) andmake poor radar targets. In the upper regions of thecell, where ice particles are “dry” (no liquid coating),target returns are less intense.Hail shafts are associated with the same radar targetreturn characteristics as tornados. U-shaped cloudedges 3 to 7 miles across can also indicate hail. Thesetarget returns appear quite suddenly along any edgeof the cell outline. They also change in intensity andshape in a matter of seconds, making vigilant monitor-ing essential.Radar
