Tornado Safety Page 1
There are few words in the English language that bring about as much fear as the word tornado. Of all Nature's moods, this is perhaps the most violent. Though not as large-scale as a hurricane, or as long-lived as a Nor'easter, this particular severe weather event has occurred in every state in the US including Alaska and Hawaii. It has occurred at virtually every time of the day, sometimes coming at night, sometimes in the morning, most often in the afternoon or early evening.
Tornadoes are storm-related events requiring a relatively rare combination of atmospheric conditions to form. Even so, there are approximately 1,000 of them each year in the United States.
Not all tornadoes are of equal intensity. Because tornadoes cannot be easily measured directly we have to analyze the damage to determine the strength of the winds. Dr. Fujita created the original Fujita scale to categorize tornadoes according to the damage they did. Later, he and Dr. Pearson factored in tornado path width and length, and the Fujita-Pearson scale became the standard gauge of tornado intensity until 2007 when the Enhanced Fujita scale was implemented to take into account variables that had not been considered before such as quality of construction of a damaged home.
- EF0 - Wind speeds of between 65-85 mph. Branches broken, shingles lifted, possible chimney damage.
- EF1 - Wind speed of between 86-110 mph. Mobile homes pushed off foundations, cars pushed off roads.
- EF2 - Wind speeds of between 111-135 mph. Trees uprooted, roofs torn off houses, mobile homes demolished, trees uprooted.
- EF3 - Wind speeds of between 136-165 mph. Roofs and wall demolished, cars thrown and trains overturned.
- EF4 - Wind speeds of between 166-200 mph. Houses leveled and cars thrown considerable distance.
- EF5 - Wind speeds over 200 mph. Homes wiped completely off their foundations, trees debarked.
74% of all tornadoes are of F0 or F1 intensity. 25% are of F2 or F3 intensity. The remaining 1% are of F4 or F5 intensity. Yet this strongest 1% of tornadoes accounts for 67% of tornado deaths.
Over the years, our methods of forecasting the storms that spawn these violently rotating columns of air have made major headway. Despite people's invariable statements that the storm "just popped up out of nowhere?, in most instances forecasters are aware of the initial setup of the conditions that breed the storms capable of developing tornadoes days ahead of the event.
MESO members visiting the National Severe Storms Laboratory (NSSL) in Norman, OK.
Why, then, are there still deaths and injuries from tornadoes? People simply are either not aware that they are at risk, or disregard tornado or severe thunderstorms watches for their areas. Tornadoes are relatively rare, and the average life cycle of one is only 8 minutes. Conditions may be favorable for tornadic development over a few states for several hours, but an actual tornado only impacts a portion of a county... or even a town.