Hazards

Tornados

• Tornadoes are nature’s most violent storms. Spawned from powerful thunderstorms, tornadoes can cause fatalities and devastate a neighborhood in seconds. 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. Every state is at some risk from this hazard.
   

• Some tornadoes are clearly visible, while rain or nearby low-hanging clouds obscure others. Occasionally, tornadoes develop so rapidly that little, if any, advance warning is possible.

Fujita Scale

Category	Category Description	Level Of Damage
F-0	Gale Tornado 40 - 72 MPH	Chimneys damaged; branches broken off trees; shallow-rooted trees uprooted; sign boards damaged.
F-1	Moderate Tornado 73 - 112 MPH	Roof surfaces peeled off; mobile homes pushed off foundations or overturned; moving autos pushed off roads.
F-2	Significant Tornado 113 - 157 MPH	Roofs torn off frame houses; mobile homes demolished; box cars pushed over; large trees snapped or uprooted; light-object projectiles generated.
F-3	Severe Tornado 158 - 206 MPH	Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown.
F-4	Devastating Tornado 207 - 260 MPH	Well-constructed houses leveled; structures with weak foundations relocated; cars thrown and large projectiles generated.
F-5	Incredible Tornado 261 - 318 MPH	Strong frame houses lifted off foundations and carried considerable distance to disintegrate; automobile-sized projectiles hurtle through the air in excess of 100 yards; trees debarked; other incredible phenomena expected.

Source: FEMA

Before a Tornado

Before a tornado hits, the wind may die down and the air may become very still. A cloud of debris can mark the location of a tornado even if a funnel is not visible. Tornadoes generally occur near the trailing edge of a thunderstorm. It is not uncommon to see clear, sunlit skies behind a tornado.

The following are facts about tornados:

• They may strike quickly, with little or no warning.

• They may appear nearly transparent until dust and debris are picked up or a cloud forms in the funnel.

• The average tornado moves Southwest to Northeast, but tornadoes have been known to move in any direction.

• The average forward speed of a tornado is 30 MPH, but may vary from stationary to 70 MPH.

• Tornadoes can accompany tropical storms and hurricanes as they move onto land.

• Waterspouts are tornadoes that form over water. Tornadoes are most frequently reported east of the Rocky Mountains during spring and summer months.

• Peak tornado season in the southern states is March through May; in the northern states, it is late spring through early summer.

• Tornadoes are most likely to occur between 3 p.m. and 9 p.m., but can occur at any time.