CERT National News Letter

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Can You be Next?

According to the National Oceanic and Atmospheric Association, the most recent tornado to hit a major city's downtown was on Aug. 12, 2004, in Jacksonville, Fla. Downtown tornadoes have also struck Fort Worth, Texas; Salt Lake City, Little Rock, Ark.; and Nashville, Tenn., in the past decade. If confirmed, the tornado would be the first in recorded history to hit downtown Atlanta, said Smith, the meteorologist. The last tornado to strike inside the city was in 1975, and it hit the governor's mansion north of down town, he said.

What is a Tornado?

Tornadoes form when three very different types of air come together in a particular way. Near the ground lies a layer of warm and humid air, along with strong south winds. Colder air and strong west or southwest winds lie in the upper atmosphere. The warm, humid air near the surface is much less dense than the cold, dry air aloft. This condition, known as instability, is a necessary ingredient for tornado formation.

Instability means that if the warm, moist air can be given an initial push to move upwards, the air will keep on rising, delivering its moisture and energy to the formation of the tornado's parent thunderstorm. The change in wind speed and direction with height (wind shear) is also a necessary ingredient of tornado formation it is linked to the eventual development of rotation from which a tornado may form.

The third ingredient is a layer of hot, dry air between the warm, moist air at low levels and the cool, dry air aloft. This hot layer acts as a cap and allows the warm air underneath to warm further, making the atmosphere even more unstable. Explosive development of the severe thunderstorms that spawn tornadoes begins to occur when a storm system high in the atmosphere moves east and begins to lift the various layers. Through this lifting process the cap is removed, thereby setting the stage for explosive thunderstorm development as strong updrafts develop. As the rising air encounters wind shear, it may cause the updraft to begin rotating.

Tornado Ratings

Forecasters and researchers use a wind damage scale to classify tornadoes. The original Fujita scale was developed by T. Theodore Fujita and was put into use in 1973. The scale was enhanced in 2007, with rankings running from EF (Enhanced Fujita) - 0 through 5. The ratings are based on the amount and type of wind damage

The Fujita Tornado Intensity Scale:

F0 - Gale With winds of less than 73 miles per hour
F1 - Moderate With winds from 73 to 112 mph
F2 - Significant With winds from 113-157 mph
F3 - Severe With winds from 158-206 mph
F4 - Devastating With winds from 207-260 mph
F5 - Incredible With winds from 261-318 mph
F6 - Inconceivable With winds above 318 mph

Enhanced Fujita

EF-0. Light damage Wind 65 to 85 mph.
EF-1. Moderate damage Wind 86 to 110 mph.
EF-2. Considerable damage Wind 111 to 135 mph.
EF-3. Severe damage Wind 136 to 165 mph.
EF-4. Devastating damage Wind 166 to 200 mph.
EF-5. Incredible damage Wind above 200 mph.

It should be noted that the Enhanced F-scale is a set of wind estimates (not measurements) based on damage. It uses three-second estimated gusts estimated at the point of damage

So how does effect me in Florida?

Florida has two Tornado Seasons.

The Summer Season, from June until September has the highest frequencies with usual intensities of F0 or F1 on the Fujita Scale. This includes those tornadoes that form from land falling Tropical Cyclones.

The Deadly Spring Season, from February through April is characterized by more powerful tornadoes because of the presence of the jet stream. When the jet stream digs south into Florida and is accompanied by a strong cold front and a strong squall line of thunderstorms, the jet stream's high level winds of 100 to 200 mph often strengthen a thunderstorm into what meteorologists call a super cell or mesocyclone. These powerful storms can move at speeds of 30 to 50 mph, produce dangerous downburst winds, large hail and the most deadly tornadoes.

Florida tornado climatology shows us that strong to violent tornadoes are just as likely to occur after midnight as they are in the afternoon. This unique feature makes these tornadoes more dangerous, because most people are asleep after midnight and cannot receive weather warnings relayed by commercial radio or television stations.

tornado pressure
Overturn Home  

Maintaining a lean, clean and green* landscape within 30 feet of a structure can make a significant difference in whether it survives a wildfire. The important thing is that action must be taken before wildfire threatens.

  • Lean- small amounts of flammable vegetation
  • Clean- no accumulations of dead vegetation
  • Green- plants are healthy and green; lawn is well irrigated

Reducing fuel within the defensible space means creating a landscape that breaks up the continuity of brush and other vegetation that could bring wildfire in contact with any flammable portion of the structure.

Build or identify a Safe-Room in your Home
Safe Rooms

Every year, tornadoes, hurricanes, and other severe windstorms rip through hundreds of towns and cities across the United States, injuring and killing people and causing millions of dollars in property damage. You can protect your family from injury caused by the high winds and flying debris of a windstorm by constructing or installing a safe room in your home. A safe room is different from the other rooms in your home because it has been specially designed and tested to withstand wind speeds of up to 250 miles per hour and the impact of a 15 pound 2 by 4 flying at a speed of 100 miles per hour. Typically, the safe room should be located in a central, interior, ground-floor area of the home for additional protection as well as accessibility. The basement of a home can also be used as a location for a safe room. A safe room can be incorporated into the construction of a new home, or it can be retrofitted into an existing home. The safe room can function year-round as a usable area, such as a bathroom, closet or utility room. Safe rooms can be constructed out of reinforced concrete, reinforced concrete masonry or combinations of wood frame and steel sheathing or concrete masonry infill. Safe rooms can also be manufactured, assembled and installed on site.

All components of safe rooms, including walls, ceilings, and door assemblies, must be designed and tested to resist the specified wind forces and prevent perforation by windborne debris.

The Federal Emergency Management Agency has ready-to-use plans for homeowners to build a shelter in an existing house or in a new house. Visit or call toll-free (877) 221-SAFE for more information about protecting your home from disaster.

Here are some things to consider when constructing or installing a safe room:
  • Safe rooms must be structurally isolated from the main structure of your home.
  • Safe rooms must be securely anchored to the foundation.
  • Safe rooms installed in or over a crawl space must have a separate foundation.
  • Safe rooms must have adequate ventilation.
1st ever Hurricane Conference dedicated to training CERT members

The conference is being held on Friday night and all day Saturday, May 30th & 31st at the Allstate Campus of Saint Petersburg College located at 3200 34th Street South, St. Petersburg, FL 33711.

The CERT Hurricane Conference includes four general sessions, two exercises, and a multitude of breakout sessions for you to choose from. Thanks to sponsors, they are able to offer over 10 hours of training, snacks for breaks, and lunch on Saturday for only $25 per person. If you are in need of lodging accommodations for the conference, the Holiday Inn Sun Spree Resort - Marina Cove has offered a special rate of $88 per room. Please take an opportunity to visit the following website at for conference courses, lodging information, and registration. I'm assured that you will find this conference invaluable as the bar of CERT training in Florida is raised.


  • Ebbin Spellman
  • CERT Program Coordinator
  • Alachua County Fire Rescue
  • Telephone: (352) 264-6550
  • Fax:(352) 264-6565


Calendar of Events

  • Governor's Hurricane Conference 12-16
  • CERT Hurricane Conference 30 & 31
  • Get Ready Campaign The Oaks Mall 6-14 (CERT member who would like to volunteer 2 hours of their time please contact Ebbin)
(All dates subject to change)