Severe thunderstorm warning. A severe thunderstorm warning ( SAME code: SVR) is issued by the National Weather Service when trained storm spotters or Doppler weather radar indicate that a thunderstorm is producing or will soon produce dangerously large hail or high winds, capable of causing significant damage.What does tornado warning mean?
The NWS issues a warning if a tornado has already touched down or if radar indicates that a tornado is forming. A tornado warning tells everyone in the affected area to act as though a tornado is coming and to get to safety immediately. A tornado can happen at any time.