Foreword

 

Sec 1 System

 

Sec 2 PFD

 

Sec 3 MFD

Sec 4

Hazard Avoidance

Sec 5

Additional Features

Sec 6

Annun. & Alerts

 

Sec 7 Symbols

 

Sec 8 Glossary

 

Appendix A

 

Appendix B Index

4.10.5.3Tornadoes

There is no conclusive radar target return characteristics which will identify a tornado, however, tornadoes may be present if the following characteristics are observed:

A narrow, finger-like portion, as shown on the previous page, extends and, in a short time, curls into a hook and closes on itself.

A “hook” which may be in the general shape of the numeral “6,” especially if bright and projecting from the southwest quadrant (northeast quadrant in the southern hemisphere) of a major thunderstorm.

V- shaped notches.

Doughnut shapes.

These shapes do not always indicate tornadoes, nor are tornado returns limited to these characteristics. Confirmed radar observations of tornadoes most often have not shown shapes different from those of a normal thunderstorm display.

4.10.5.4Hail

Hail results from updrafts carrying water high enough to freeze. Therefore, the higher the top of a thunderstorm, the greater the probability that it contains hail. Vertically scanning the target return can give the radar top of a thunderstorm that contains hail. Radar top is the top of a storm cell as detected by radar. It is not the actual top, or true top of the storm. The actual top of a storm cell is seen with the eyes in clear air and may be much higher than the radar top. The actual top does not indicate the top of the hazardous area.

Hail can fall below the minimum reflectivity threshold for radar detection. It can have a film of water on its surface, making its reflective characteristics similar to a very large water droplet. Because of this film of water, and because hail stones usually are larger than water droplets, thunderstorms with large amounts of wet hail return stronger signals than those with rain. Some hail shafts are extremely narrow (100 yards or less) and make poor radar targets. In the upper regions of a cell where ice particles are “dry” (no liquid coating), target returns are less intense.

Hail shafts are associated with the same radar target return characteristics as tornados. U-shaped cloud edges 3 to 7 miles across can also indicate hail. These target returns appear quite suddenly along any edge of the cell outline.

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Garmin G600 Pilot’s Guide

190-00601-02 Rev. E

Page 250
Image 250
Garmin G600 manual Tornadoes, Shaped notches Doughnut shapes, Hail