The highest wind speed measured at an altitude of 10 meters in open terrain over a period of time it takes one mile of wind to pass by the anemometer. The speed by which the hurricane advances. In addition to the forward speed, the wind rotates around the hurricane's center at much higher speeds depending on the central pressure . Forward speeds are in the order of 5-30 mph. The scale ranges from F0 to F13 with only F0-F5 used as credible wind speeds for tornadoes.
Wind speeds are very difficult to measure in tornadoes.
Tornadoes are much smaller and unpredictable compared to hurricanes. Wind speeds measured at high altitudes unaffected by local terrain conditions. Hurricane hunters, the planes flown over hurricanes to make measurements of wind speeds and pressures, measure the gradient wind speed. Gradient wind speeds are usually measured over a 10-minute duration. Any any given location, wind speed increases with height in what is known as the boundary layer, up till a certain point, beyond which wind speed does not increase.