Tornadoes are nature's most violent storms, and Central Texas is on the southern edge of Tornado Alley: the most common area for tornado development in the world. Historical records tell us that on average more than 100 tornadoes are reported in Texas every year, with April-June being the most active months. Locally, the Austin metro area averages one tornado per year. Fortunately, Doppler radar allows meteorologists to warn the public of approaching tornadoes. Conditions that could signal an approaching tornado include a dark, greenish sky, large hail, a "wall" cloud, or a loud roar (described like a freight train).
If conditions are favorable for tornadoes, the National Weather Service will issue a TORNADO WATCH, meaning you should pay close attention to the weather. If a tornado is radar indicated or reported on the ground by the public, then a TORNADO WARNING is issued. Warnings are very specific in terms of location and direction. If you’re in the warning area, you need to take action immediately. Head for the basement - if you have one - or go to the center of the room on the lowest floor, away from windows. A bathroom or central closet provides better protection. Use blankets or a mattress to protect yourself from flying debris. If caught outside or in a vehicle, do not try to outrun the tornado in your car. As a last resort, lie flat in a nearby ditch or depression. You can read more about tornado safety here.
Given a scenario where strong or severe storms are occurring, tornadoes have the best chance of forming when winds are blowing in different directions, and at higher speeds, with increasing height in the atmosphere. This creates a rolling column of air along a horizontal axis. Rising air within the updraft of a thunderstorm tilts that column along a vertical axis. In supercell thunderstorms, sometimes there will be an area of rotation two to six miles wide. This is where a tornado may develop. On radar, it looks like a hook.
Tornadoes are ranked on a scale from EF0 to EF5, 5 being the strongest. This is known as the Enhanced Fujita Scale. A tornado’s rank is based off of the destruction left in its path. Experts survey the damage, then determine an estimated wind speed that would have created that damage. Generally, the wider the tornado, the stronger the winds.
Frequency of Weak vs Strong Tornadoes
The majority of tornadoes, about 70 percent, are weak with winds of 110 mph or less. These only account for 3 percent of tornado deaths. On the opposite end of the spectrum, a mere 2 percent of tornadoes are considered violent (EF5) with winds of 200+ mph. These account for 70 percent of tornado deaths. Four of the six F5 tornadoes in Texas history occurred in Central Texas. The most recent was in Jarrell on May 27, 1997 with 27 deaths.
Top 10 tornadoes to strike in Texas since 1900
MAY 11, 1953 -- WACO
The deadliest tornado in Texas history struck shortly after 4 p.m. on May 11, 1953. An F5, the tornado killed 114 persons and injured 597. It destroyed about 600 homes and other buildings, damaging more than 1,000. It was one-third of a mile in width.
MAY 18, 1902 -- GOLIAD
The second deadliest tornado in Texas struck 50 years earlier and also killed 114 persons. There were 250 injuries. It was estimated to be an F4 tornado, destroying hundreds of buildings. It was one-eighth of a mile in diameter.
APRIL 12, 1927 -- ROCKSPRINGS
An F5 tornado nearly one mile wide, the Rocksprings tornado struck in Edwards County. The tornado killed 74 people and injured 205, destroying 235 of the 247 buildings in the town.
APRIL 9, 1947 -- THE TRI-STATE TORNADO
The fourth deadliest tornado in Texas history also moved through western Oklahoma and Kansas. The funnel was reported to be between one and two miles wide. Just before crossing into Oklahoma, it destroyed the town of Glazier (near Pampa) and most of the town of Higgins. It killed 68 Texans, with 40 injured at Glazier and 232 injured at Higgins. The three-state death toll was 181, with 970 injuries.
APRIL 10, 1979 -- WICHITA FALLS
This 1.5-mile-wide killer was an F4, killing 42 people in Wichita Falls. It caused over 1,700 injuries, destroyed over 3,000 homes and left 20,000 homeless.
MAY 6, 1930 -- FROST
The F4 tornado struck the town of Frost in Navarro County, Ennis in Ellis County and several points between these two locations. The death toll from Texas' sixth deadliest tornado was 41 with 200 injuries.
MAY 6, 1930 -- KARNES-DEWITT
Killer tornado No. 7 occurred on the same day as the Frost tornado. The F4 tornado ran through Karnes and Dewitt counties, striking a number of homes and shelters that were not well constructed. The death toll was 36, with 60 injuries.
MAY 30, 1909 -- ZEPHYR
The Zephyr tornado in Brown County struck around midnight, killing 34 and injuring 70. Texas' eighth largest tornado was rated F4.
MAY 22, 1987 -- SARAGOSA
Also an F4, this tornado struck in Reeves County, destroying more than 80 percent of the town of Saragosa. It killed 30 residents and injured 121. At Guadalupe Hall, 22 deaths occurred during a graduation ceremony, as parents and grandparents died shielding children from debris with their own bodies.
MAY 11, 1970 -- LUBBOCK
The 10th deadliest tornado left an eight-mile path of destruction through Lubbock, killing 28 and injuring 500. The storm destroyed more than 1,000 homes and apartment units. It was rated F5 and was one of the key storms used in developing the Fujita scale.
Information provided by the National Weather Service and the book "Significant Tornadoes 1680 - 1991" by Thomas P. Grazulis.