THUNDERSTORM FORECASTS - Here are what my thunderstorm forecast zones mean:
STRONG is somewhere between general and severe. A storm can produce a weak tornado but be non-severe otherwise.
SEVERE equals numerous severe storms with all hazards, potentially widespread.
SIGNIFICANT is for the worst of the worst, major outbreak or widespread concern...I haven't used a SIG zone yet in the 3 years I've been using this criteria.
TARGET used to narrow down a zone of maximum impact.