In October 1859, the U.S. military arsenal at Harpers Ferry was the target of an assault by an armed band of abolitionists led by John Brown (1800-59).
A tornado appears as a rotating, funnel-shaped cloud that extends from a thunderstorm to the ground with whirling winds that can reach 300 miles per hour. Damage paths can be in excess of one mile wide and 50 miles long. Some tornadoes are clearly visible, while rain or nearby low-hanging clouds obscure others.t is not uncommon to see clear, sunlit skies behind a tornado. 1  Tornadoes cause an average of 70 fatalities and 1,500 injuries in the U.S. each year. 2  The strongest tornadoes have rotating winds of more than 250 mph.
The NOAA states that the current average warning time before a tornado-due to advances in weather technology, such as Doppler radar-is 13 minutes.The residents of Moore, Oklahoma, got 16 minutes lead time, but this may have been due to Oklahoma having more spotters than other areas.he average lead time for a tornado warning in the United States is 14 minutes. However, in recent years lead times have been as long as 39 minutes, while in other â¦ cases there has been no warning.