A tornado is a violently whirling column of air that extends downward from a cumulonimbus cloud and seen as a rapidly rotating, slender funnel shaped cloud that has a wind velocity of up to 300 miles per hours at the central core. It therefore destroys everything along its narrow ground path.
Usually, prior to the development of a tornado, a pre-tornadic thunderstorm develops a circulation, that is, it starts rotating (a meso-cyclone). As this rotation becomes stronger, the chance that a tornado may develop also increases. Although the National Weather Service's Doppler Radar generally can not see the actual tornado, the Radar does detect rotation of the thunderstorm cloud, and thereby gives some indication of the possibility that a tornado may be forming or has formed.
The scale used to measure tornado damage is the Enhanced Fujita scale (named after Theodore Fujita, a famous tornado damage expert). This scale is commonly referred to as the E-F scale. Based on scientific studies of tornado damage, the original Fujita scale was modified and the new "Enhanced Fujita Scale" was officially implemented in 2007.
- EF-0 - Light damage (winds 65 to 85 mph)
- EF-1 - Moderate damage (winds 86 to 110 mph)
- EF-2 - Considerable damage (winds 111 to 135 mph)
- EF-3 - Severe damage (winds 136 to 165 mph)
- EF-4 - Devastating damage (winds 166 to 200 mph)
- EF-5 - Incredible damage (winds over 200 mph)
Maine has on average 2 tornadoes every year. The tornadoes in recent history in Maine have formed during severe summer storms within the southwestern and central sections of the State. Because Maine has a sparse population, there has not been significant amount of property damage or personal injury.
Mitigation: However, evacuation of high risk areas may be required on short notice. Sheltering an mass care efforts may be needed along with debris clean up, search and rescue and emergency fire and medical services. Mobile homes are the most vulnerable to substantial damage.
The National Weather Service provides warning of tornado producing conditions and sends out alerts via radio and television broadcasts. Immediate notification is extremely vital as minimal warning is usually the case with tornadoes. Citizens are urged to go below ground areas at the earliest warning with flashlights and a radio until the danger has passed. Public information on the dangers of tornadoes and the recommended responses should be undertaken at the beginning of each tornado and periodically thereafter.
Tornadoes and Maine
Peak tornado activity in northern New England occurs between June and August, but tornadoes have occurred as early as May and as late as November. Most tornadoes occur between 3 and 9 pm and have an average forward speed of about 30 mph. For the 40 year period between 1950 and 1990, 74 tornadoes occurred in Maine. This is an average of about 2 tornadoes per year. During 2017 seven tornadoes touched down in Maine.
Due to the usual short life-span of tornadoes in northern New England, there is often little, if any, advance warning. Tornadoes in New England generally touch down and then lift off the ground very quickly. Many of the tornadoes that have occurred in the past, have occurred while severe thunderstorm warnings have been in effect. If you hear that a severe thunderstorm warning is in effect for your area, be alert for the possibility of a tornado. A low rotating cloud, large hail, and/or a load roar are all signs that may precede the touchdown of a tornado.
Here are some tornado facts and safety tips
- Flying debris causes most deaths and injuries in tornadoes
- The safest place in your home during a tornado is your basement.
- Stay away from windows.
- Get out of vehicles or mobile homes, they offer little protection. Seek shelter in a substantial building.
- Do NOT seek shelter under a bridge overpass. Bridge overpasses offer little, if any, protection from wind- driven debris.