Tornadoes are classified by the Wind Speed, Path Width and Path Length. Although the the path width and path length are not widely used today, you may find them in some articles and literature on tornadoes. The National Weather Service scales tornadoes by intensity on a scale of - to 5 on the Fujita-Pearson scale which include:

CLASS(SCALE)	FUJITA WIND SPEED	PEARSON PATH LENGTH	PEARSON PATH WIDTH
-	0 to 40 mph	less than 0.3 miles	Less than 6 yards
0	40 to 72 mph	0.3 to 0.9 miles	6 to 17 yards
1	73 to 112 mph	1.0 to 3.1 miles	18 to 55 yards
2	113 to 157 mph	3.2 to 9.9 miles	56 to 175
3	158 to 206 mph	10 to 31 miles	176 to 566 yards
4	207 to 260 mph	32 to 99 miles	0.3 to 0.9 miles
5	261 to 318 mph	100 to 315 miles	1.0 to 3.1 miles

The Fujita Scale is the original scale used to classify tornadoes was developed by T. Theodore Fujita. The Pearson scales were developed researcher Allen Pearson The Pearson Scales were added to the Fujita Scale and adopted for use by the National Weather Service's National Severe Storms Forecast Center in 1973. Today Forecasters use the Fujita Scale shown below. F-0 Light damage: winds up to 72 mph F-1 Moderate damage: winds 73 to 112 mph F-2 Considerable damage: winds 113 to 157 mph F-3 Severe damage: winds 158 to 206 mph F-4 Devastating damage: winds 207 to 260 mph F-5 Incredible damage: winds above 261 mph Using the scales above can you figure the scale of a tornado that had winds of 190 mph, destroyed a small subdivision, had a path length of 20 miles and a path width of 350 yards? If you chose a scale F-3 an the Fujita scale and on the Fujita-Pearson scale chose F,P,P 4,4,4, you were correct. REMEMBER - Mobile homes are extremely vulnerable. A mobile home can often overturn very easily even if precautions were taken to tie down the unit. When a tornado warning is issued, take shelter in a building with a strong foundation. Some tornado danger signs to look out for are: Dark, often greenish skies. Wall cloud. Large Hail. A loud roar, similar to a freight train. CAUTION Some Tornadoes appear as a visible funnel extending only partially to the ground. Look for signs of debris below the visible funnel. Some tornadoes are clearly visible, while others are obscured by rain or nearby low-hanging clouds. Before a tornado hits, the wind may die down and the air may become very still. An approaching cloud of debris can mark the location of a tornado even if a funnel is not visible. Tornadoes gennerally occur near the trailing edge of a thunderstorm. It is not uncommon to see clear, sunlit skies behind a tornado.