Today is the third day of our Severe Weather Awareness Week for the Mid-South. We are going to focus on the topic of tornadoes. Most of the information provided is by the National Weather Service and for more information you can visit http://www.srh.noaa.gov/jan/. Also, I took information from another blog called MemphisWeather.Net Blog. The blogger had great information on safety and I wanted to include that. For more information, search http://blog.memphisweather.net/
Tornado
A tornado is a violently rotating column of air that extends from the base of a storm cloud to the ground. Some conditions that are conducive for tornado formation include warm, moist, unstable air, strong atmospheric winds that increase in speed and change direction with height, and a forcing mechanism to lift the air. When a combination of these factors comes together just right, tornadoes form. The most common time of year for tornado formation in Mississippi is during the spring months of March, April, and May, with a secondary tornado season in November. Additionally, the afternoon and evening hours are the times of day at which most tornadoes occur, as they are the times at which the maximum heating takes place. However, tornadoes can occur at any time of day, and at any point during the year, given the right environment. Many tornadoes occur at night in Mississippi.
Nighttime Tornadoes Pose Greater Danger
The NWS would like to draw attention to nighttime tornadoes. These tornadoes pose a greater danger than those that occur during the daylight because once most people go to bed, they are no longer connected to the watches or warnings issued by the NWS. Also at night, visibility is reduced and observing a tornado is more difficult. This is elevated during the winter months because it is not the traditional tornado season. Research by Gagan et al. 2010 compared tornado statistics from the Great Plains in the classic “Tornado Alley” to tornadoes in the Deep South or “Dixie Alley.” Researchers found that Dixie Alley had far greater amounts of Killer Strong/Violent Tornadoes between 9pm-9am timeframe. Dixie Alley had nearly twice the number of strong/violent tornadoes from Midnight-Noon timeframe than Tornado Alley from 1950-2007.
Having an properly programmed All Hazards NOAA Weather Radio with S.A.M.E. County Coding technology will alarm individuals anytime of day when a severe thunderstorm warning or tornado warning is issued for their county. This device has been credited for saving numerous lives during nocturnal tornado events.
Enhanced Fujita Scale (EF Scale)
EF Rating Wind Speeds Potential Damage Threats
EF 0 (weak) 65-85 mph Light damage, shallow rooted trees pushed over, some damage to gutters or siding.
EF 1 (weak) 86-110 mph Moderate damage, mobile homes overturned, roof surfaces peeled off.
EF 2 (strong) 111-135 mph Considerable damage, large trees uprooted or snapped, mobile homes destroyed.
EF 3 (strong) 136-165 mph Severe damage, trains overturned, well built homes lose roofs and walls.
EF 4 (violent) 166-200 mph Devastating damage, well built homes leveled, cars thrown.
EF 5 (extreme) Over 200 mph Incredible damage, well built homes disintegrated, automobile-sized objects thrown
>300ft.
Your safety depends on being constantly alert to the possibility of tornadoes from the thunderstorms that approach you. Plan in advance where you will go and what you will do if a tornado threatens you.
Warnings and Watches
A tornado watch means that a tornado development is possible. Stay tuned to a weather radio or television station for weather statements or warnings.
A tornado warning usually issued for one or two counties a a time means that a tornado has sighted or indicated by weather radar. If you are in the path or you know somethere in that path, you need to seek shelter immediately preferably in a sturdy building and below ground if all possible.
Safety Rules
-In homes or small building go to the basement, storm shelter, or to an interior room such as a closet or bathroom. While there be sure to get under something sturdy such as a heavy table or bed. If you are in a bathroom, be sure to take a bed mattress over you while your in the tub to protect yourself.
-In mobile homes and vehicles, please abandon them and go to a storm shelter or sturdy structure. If there is now structure nearby, lie flat in a ditch ravin, gully, culvert, or low spot with your arms and hands shielding your head. Please do not stay in your mobile home. You will be much safer lying in a ditch rather than in your mobile home. Many deaths have occurred due to residing in mobile homes during tornadoes. Mobile home can easily be picked up by a tornado.
-In large buildings such as schools, factories, hospitals, nursing homes, and shopping centers go to the predesignated shelter shelter area. Interior hallways on the lowest floor are usually best. Stay away from rooms that are large in area because they have weakly supported roofs.
AT ALL TIMES... STAY AWAY FROM WINDOWS.
Below are four videos of some great tornado coverage. Be sure to pause the music in the background in order to hear the audio clearly(Scroll to the bottom of the page to stop the music). The first two videos are by a very good friend of mine and was my teacher/instructor for senior meteorology classes. Greg Nordstrom is an avid storm chaser and I've learn much from him. He has alot of information on his page as well as great chase videos not only consisting of tornadoes but hurricanes. You can visit his youtube videos at http://www.youtube.com/ldctstormchaser Some language may be involved, but Greg has some of the best videos of tornadoes I've ever seen and I'm sure you all will concur after watching.
The other two videos are coverages by James Spann in AL and a good friend and advisor of mine in Dave Freeman.
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