Generally speaking a strong tornado is one rated EF2 or higher. These account for about 11% of tornadoes. This number may be higher as ratings are based on damage and it is difficult to judge the strength of a tornado that doesn't hit much.
In the United States, strong tornadoes, counted as those rated F2 or higher, account for about 11% of all tornadoes.
As with all places, most tornadoes in Wisconsin are weak. Wisconsin has had its fair share of strong tornadoes, though not as many as in Tornado Alley. A few tornadoes in the state have been rated F5.
Tornadoes usually strike in the afternoon or evening. Over 80 percent of tornadoes occur between 12:00 p.m. and 12:00 a.m.
Based on data from 1991-2011 (when the number of tornadoes in the U.S. was accurately recorded) F4 and EF4 tornadoes averaged about 0.5% of all tornadoes.
Weak tornadoes (EF0 and EF1) are by far the most common accounting for 89% of all tornadoes. Strong tornadoes (EF2 and EF3) are next, accounting for about 10% of tornadoes. Finally come violent (EF4 and EF5) tornadoes, which account for less than 1% of all tornadoes.
Big tornadoes are usually strong, but not always. A large, poorly organized tornado is not likely to be very strong. Some tornadoes even weaken as they expand.
About 20% of tornadoes are rated as strong (EF2 or stronger).
In all likelihood, yes. Much of Croatia has a climate similar to nearby Italy, which occasionally has strong tornadoes.
About .05% of all tornadoes are rated F5 or EF5. Or, in other terms, about 1 tornado in every 2000.
An area the size of a city is too small for any comprehensive tornado statistics. Miami itself has been hit by tornadoes as strong as F1 while areas not far from the city have had tornadoes up to F3 strength. This means that while strong tornadoes have not struck the city in recent history, it can still happen. As with all areas, most tornadoes in Florida are weak with strong ones occurring less frequently.
Tornadoes are sometimes divided into "weak" tornadoes "strong" and "violent" tornadoes. Weak tornadoes are those rated EF0 and EF1. Most tornadoes are weak. Strong tornadoes are those rated EF2 and EF3. Violent tornadoes are those rated EF4 and EF5. They are the rarest of tornadoes, only about 1% of tornadoes are this strong.
Tornadoes can probably occur in any country as any place that can get thunderstorms can get tornadoes.