Preflight: Storm Warning Every kind of aviation hazard is packed into a thunderstorm. Reduced visibility, low cloud, severe icing, turbulence, hail, heavy precipitation, lightning, wind shear, and even the possibility of a tornado, or a waterspout are possible. Almost any thunderstorm can spell disaster for the wrong combination of aircraft and pilot. A pilot in a light airplane must avoid thunderstorms at all costs. Surviving a wild thunderstorm can make for a great story, but it's an experience you want to avoid for the sake of safety. Here are the basics to live by: If thunderstorms are forecast, plan an alternate route before becoming airborne Be prepared to divert before the thunderstorms become unavoidable Remember that vivid and frequent lightning indicates a severe thunderstorm Consider any localized convective cell over approximately 15,000 feet high as a thunderstorm, whether or not there is thunder Don't land or take off in the face of an approaching thunderstorm. A sudden gust front or low-level turbulence could cause loss of control Don't try to fly under a thunderstorm, even if you can see through to the other side Don't trust appearance as a reliable indicator of turbulence inside a thunderstorm To fly safe in Thunderstorm season, the rule is keep clear!