Severe Weather Information

Basic Overview of Tornados

Scattered debris piled up following a destructive and deadly F5 tornado that struck Joplin, Mo. on May 22, 2011.

The bad news is, there is an annual average of 1,000 tornadoes in the United States, and more instances of severe weather than any other country.

The good news is, the accuracy of tornado warnings has increased greatly, and lead-time for tornado warnings has doubled to 10 minutes since the mid-1980s. This is due mostly to improved radar and satellites. In fact, over three billion man-hours are spent under tornado watches in the United States each year, with a tornado occurring in more than half the watch areas issued. This is in spite of the fact that while a tornado watch may be given for today, or possibly tomorrow; there is no such thing as a long-range severe storm or tornado forecast.

According to the dictionary, a tornado is, "a rotating column of air usually accompanied by a funnel-shaped downward extension of a cumulonimbus cloud and having a vortex several hundred yards in diameter whirling destructively at speeds of up to 500 miles (800 kilometers) per hour."

What the dictionary doesnt tell us is that each year, tornadoes and hurricanes are responsible for millions of dollars in property damage, injury and loss of lives. Tornadoes can strike virtually anywhere in the United States with little or no warning, while in a matter of days, a hurricane can strike the Gulf or Atlantic states, devastating hundreds of miles of coastline, and wreaking havoc hundreds of more miles inland.

The Fujita Tornado Scale and Level of Damage

F0 Category Tornado 40-72 mph
Light Damage: Some damage to chimneys; pushes over shallow-rooted trees; damages signboards; some windows broken; hurricane wind speed begins at 73 mph.

F1 Category Tornado 73-112 mph
Moderate Tornado. Peels surfaces off roofs; mobile homes pushed off foundations or overturned; outbuildings demolished; moving autos pushed off the roads; trees snapped or broken.

F2 Category Tornado 113-157 mph
Considerable damage: Roofs torn off frame houses; mobile homes demolished; frame houses with weak foundations lifted and moved; boxcars pushed over; large trees snapped or uprooted; light-object missiles generated.

F3 Category Tornado 158-206 mph
Severe Tornado. Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forests uprooted; heavy cars lifted off the ground and thrown.

F4 Category Tornado 207-260 mph
Devastating damage: Well constructed homes leveled; structures with weak foundations blown off some distance; cars thrown and disintegrated; large missiles generated; trees in forest uprooted and carried some distance away.

F5 Category Tornado 261-318 mph
Incredible damage: Strong frame houses lifted off foundations and carried considerable distance to disintegrate; automobile-sized missiles fly through the air in excess of 300 ft (100 m); trees debarked; incredible phenomena will occur.

Basic Overview of Hurricanes

According to the dictionary, a hurricane is, "a severe tropical cyclone originating in the equatorial regions of the Atlantic Ocean or Caribbean Sea, traveling north, northwest, or northeast from its point of origin, and usually involving heavy rains."

What the dictionary doesnt tell us is that each year, tornadoes and hurricanes are responsible for millions of dollars in property damage, injury and loss of lives. Tornadoes can strike virtually anywhere in the United States with little or no warning, while in a matter of days, a hurricane can strike the Gulf or Atlantic states, devastating hundreds of miles of coastline, and wreaking havoc hundreds of more miles inland.

Few hurricanes have wind speeds reaching the devastating, concentrated punch of the most powerful (300 mph-plus wind speed) tornadoes, but they bring with them their own set of problems. These include high winds sustained over a much longer period of time and spreading a much wider range of destruction than tornadoes, as well as accompanying storm surges 18 feet and more above normal, severe electrical storms, torrential rain, and massive flooding. This ferocity has earned hurricanes the title, "Natures Greatest Storms."

In addition, the hurricane-susceptible Gulf and Atlantic states are exposed to a potential "double-whammy," since the severe weather from hurricane conditions often spawns multiple tornadoes within the weather system.

While mankind will probably never be able to beat the extreme weather and climate events thrown at us by nature, we do have ways to protect ourselves. One of the most effective means of shelter from such storms comes in the form of "saferooms."

The Saffir-Simpson Hurricane Scale

Category One Hurricane 74-95 mph

Storm surge generally 4-5 ft above normal; no real damage to building structures; damage primarily to unanchored mobile homes, shrubbery, and trees; some coastal road flooding and minor pier damage.

Category Two Hurricane 96-110 mph

Storm surge generally 6-8 feet above normal; some roofing material, door, and window damage of buildings; considerable damage to mobile homes, poorly constructed signs, and piers; coastal and low-lying escape routes flood 2-4 hours before arrival of the hurricane center.

Category Three Hurricane 111-130 mph

Storm surge generally 9-12 ft above normal; low-lying escape routes are cut by rising water 3-5 hours before arrival of the hurricane center; terrain continuously lower than 5 ft above mean sea level may be flooded inland 8 miles or more.

Category Four Hurricane 131-155 mph

Storm surge generally 13-18 ft above normal; more extensive curtainwall failures with some complete roof structure failures on small residences; extensive damage to doors and windows; terrain lower than 10 ft above sea level may be flooded requiring massive evacuation of residential areas as far inland as 6 miles.

Category Five Hurricane winds greater than 155 mph

Storm surge generally greater than 18 ft above normal; complete roof failure on many residences and industrial buildings; all shrubs, trees, and signs blown down; major damage to lower floors of all structures located less than 15 ft above sea level and within 500 yards of the shoreline; massive evacuation of residential areas on low ground within 5-10 miles of the shoreline may be required.