Thunderstorms

The three-stage life cycle, the difference between an ordinary and a severe thunderstorm, and the 20-mile rule for staying out of trouble.

14 min read · Weather

After this lesson you can

  • Name the three stages of a thunderstorm's life cycle and what marks the transition between them.
  • State the criteria that make a thunderstorm "severe" under the convective SIGMET definition.
  • Explain why turbulence, hail, and altimeter errors can be encountered well outside the visible storm.
  • Explain the limits of onboard and ATC weather radar and why circumnavigation, not penetration, is the standard response.

A thunderstorm concentrates nearly every en route hazard covered in this module, icing, hail, turbulence, wind shear, into one compact, fast-moving cell. Understanding its life cycle tells you what is happening inside a cell you cannot see into, and understanding its reach, well beyond the visible cloud, is what keeps circumnavigation rules from feeling like an overcautious formality.

The rest of this lesson

  1. 1.Three ingredients, three stages
  2. 2.Types of thunderstorms
  3. 3.Tornadoes
  4. 4.Turbulence, gust fronts, and the effect on your altimeter
  5. 5.The rules of avoidance
  6. 6.What the radar mosaic shows, and does not
  7. 7.The convective SIGMET

These 7 sections, their figures, the checks along the way and the end-of-lesson quiz come with the PPL track. Paid once, yours for good.

See what the PPL track costsEvery module 1 is free to read, no account, no card.

Key terms

Try to recall each definition before turning the card.