Guest Author - Erik Moeller
A colleague of mine was coming to Texas from California for a conference. We were discussing the California weather and I said that Texas was about the same as California now except for the tornadoes. She said that mentioning tornadoes had spoiled her planned outing to the pool. I wondered why she would be concerned about tornadoes when there are earthquakes in California. She said that earthquakes are over in less than a minute so you don’t have time to be scared. With tornadoes weather forecasters put warnings on TV hours before the storm arrives, sirens blast alerts and she would be scared for hours. I guess it all depends on your point of view.
By almost everyone’s definition tornadoes are the most violent storms in nature. First the technical stuff- what causes a tornado? Tornadoes often occur along a “dry line.” This is a line that separates warm, moist air (often from the Gulf of Mexico) from hot, dry air (coming from the Rockies across the Central Plains). Heating from the sun causes the greatest chance of tornados during the late afternoon hours.
Ever heard of Tornado Alley? If you live from North Texas north through the Dakotas and as far east as Ohio, you know the meaning of the term. There are many ways to determine where the most tornado action occurs. NOAA (National Oceanic and Atmospheric Administration) rates the number of tornados recorded per 1000 sq. mi. area. The areas with the highest ratings are Fort Worth, Texas and the counties to the west of the city and the counties between Oklahoma City and Tulsa in Oklahoma. These areas have recorded more that 15 tornados per 1000 sq. mi.
How is the severity of a tornado determined? Wind speed is the primary determining factor:
F1- 73 to 112 mph. Can blow off roof material and roll mobile homes
F2- 113 to 157 mph. Can remove roofs, destroy mobile homes and uproot large trees
F3- 158 to 206 mph. Can tear off roofs and walls in houses and uproot most trees
F4- 207 to 260 mph. Can level well constructed houses and throw cars around
F5- 261 to 318 mph. Can carry off houses, throw cars more than 100 meters, badly damage re-enforced concrete structures
What to do if you are in a tornado warning area:
1. Listen to weather reports, especially if you have activities planned outdoors
2. Know your area so that you can follow weather bulletins and updates
If the storm is coming:
1. Go to an underground shelter or basement, if one is available
2. Move to an interior room and get under a heavy piece of furniture
3. Stay away from windows
4. Get out of your car
5. Mobile homes provide little protection, find a safer location
If you are in a tornado area, review procedures for dealing with a tornado and practice what you plan to do often.