Tornadoes: Louisiana Severe Weather Awareness Day 3
POSTED: Wednesday, February 19, 2014 - 12:00pm
UPDATED: Wednesday, February 19, 2014 - 12:01pm
BATON ROUGE, La. (NBC33) — Louisiana's "Severe Weather Awareness Week" is this week, February 17-21. The National Weather Service in New Orleans will choose a topic to focus on and prepare you for any upcoming severe weather that heads toward south Louisiana.
Today's topic is "Tornadoes."
Tornadoes are the most frequent severe weather threat that forms in south Louisiana, next to straight line winds and hail. They are defined as a violently rotating column of air that extends from the base of a thunderstorm to the ground.
A funnel cloud is similar in definition. However, a funnel cloud is a violently rotating column of air that extends from the base of a thunderstorm and DOES NOT touch the ground.
Funnel clouds and tornadoes, even water spouts, can occur any time of the year, but are most common during the spring months of March, April, and May in south Louisiana. They can occur at any time of the day or night. Although, past tornado data shows a peak during the afternoon and evening, from noon to 8:00 p.m.
If a tornado forms, the National Weather Service recommends seeking shelter in a small, interior room or hallway on the lowest floor of a substantial building such as a brick home, school, or office building. If you are caught outside or in a mobile home, get to a sturdy building as quickly as possible. If you are in a car, exit the car and seek shelter.
Meteorologists classify tornadoes as weak, strong or violent based on the Enhanced Fujita Scale. The scale ranges from EF0 to EF5.
Weak tornadoes incorporate 88 percent of all tornadoes and are responsible for less than 5 percent of tornado deaths. Winds range from 65 to 110 mph and last, generally, from one to ten minutes.
Strong tornadoes account for 11 percent of all tornadoes and cause 30 percent of tornado related deaths. Winds gust from 111 to 165 mph and may last longer than 20 minutes.
Violent tornadoes are rare. They are less than one percent of all tornadoes. Although, 70 percent of all tornado deaths are related to these scarce events. Winds spin greater than 166 mph and exceed one hour on the ground.
The National Weather Service in New Orleans says, "Last year was fairly quiet with regard to severe weather in Louisiana, as well as in southeast Louisiana. A total of 28 tornadoes were recorded in Louisiana last year, which is below the long term annual average of 37. Of these tornadoes, only one was rated strong, EF2 on the Enhanced Fujita Scale, which occurred in West Carroll Parish on Jan 29th. Tornado damage throughout the state was primarily limited to minor or moderate property damage. No tornado related fatalities were recorded in the state last year. In southeast Louisiana and coastal Mississippi, a total of 10 tornadoes touched down during 2013. This was well below the total of 22 recorded in the previous year of 2012. Of those 10 tornadoes, 9 tornadoes occurred in southeast Louisiana and were all rated as weak, either EF0 or EF1 on the Enhanced Fujita Scale. The weak tornadoes caused mainly minor property damage. However, two minor injuries occurred when a tornado touched down in Metairie on the afternoon of April 24 and overturned a large truck causing minor injuries to the occupants. One of the tornadoes in southeast Louisiana was the result of a waterspout moving onshore Grand Isle during the afternoon of June 19th causing minor property damage."
Tornado Myths and Truths (NWS):
- Myth Areas near lakes, rivers, and mountains are safe from tornadoes.
- Truth No place is safe from tornadoes. A tornado near Yellowstone National Park left a path of destruction up and down a 10,000 foot mountain.
- Myth The low pressure with a tornado causes buildings to “explode” as the tornado passes overhead.
- Truth Violent winds and debris slamming into buildings cause most structural damage.
- Myth Windows should be opened before a tornado approaches to equalize pressure and minimize damage.
- Truth Leave the windows alone. The most important action is to immediately go to a safe shelter.
- Myth If you are driving and a tornado is sighted, you should turn and drive at right angles to the storm.
- Truth The best thing to do is to seek the best available shelter. Many people are injured or killed when remaining in their vehicles.
- Myth People caught in the open should seek shelter under highway overpasses.
- Truth Take shelter in a sturdy reinforced building if at all possible. Overpasses, ditches, and culverts may provide limited protection from a tornado, but your risk will be greatly reduced by moving inside a strong building.
Check the latest forecast at www.nbc33tv.com/weather.
Click here to see yesterday's topic "Severe Thunderstorms."
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