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Severe Storms Awareness Week in Maine

April 23rd through April 27th is Severe Weather Awareness Week in Maine. The NWS Forecast Office in Caribou will issue a Public Information Statement each day during the week featuring a different educational topic. These topics also appear on this page, for your convenience.

The master web site for the whole program is NWS' Severe Weather Awareness page. For example, their color brochure, titled Thunderstorms, Tornadoes, Lightning—Nature's Most Violent Storms, includes the topic "Tornado Safety Information for Schools." There are many more valuable goodies on that page, including info tailored for kids and families. Pleach check it out!

Table of Contents

Severe Weather Terminology

With severe weather season rapidly approaching, it is a good idea to refresh your memory in regard to severe weather terminology. In Maine, severe weather season generally runs from May through August. In northern Maine, mid-June to around August 1 is the most active period for severe local storms.

The term watch, when used in conjunction with tornado or severe thunderstorms, means that tornadoes or severe thunderstorms are possible. Watches are usually in effect for several hours and indicate that atmospheric conditions are favorable for severe storms to develop. When a watch is in effect, you should keep your eye to the sky and make plans for what you need to do if severe weather occurs.

The term warning means that either a severe thunderstorm or tornado is imminent or is already occurring. Warnings are usually in effect for 1 hour or less. If a warning is issued for your area, take action immediately.

A severe thunderstorm is any thunderstorm that produces winds of 58 mph or more and/or hail of 3/4 inch in diameter or more. Severe thunderstorms can produce microbursts, which are damaging straight line winds that affect a relatively small area. Macrobursts are damaging straight line winds that affect a relatively large area. Macrobursts are usually associated with rapidly moving squall lines. Winds in both microbursts and macrobursts can exceed 100 mph.

A tornado is a violently rotating column of air in contact with the ground. The funnel usually descends from the base of a severe thunderstorm. They are usually wedge shaped with the narrowest end at the ground. Tornado witnesses have heard a "roaring" sound similar to a freight train. Tornadoes vary in intensity. Weak tornadoes have winds less than 100 mph while violent tornadoes have winds in excess of 200 mph.

A funnel cloud is a violently rotating column of air that descends from the rain free base of a thunderstorm but does not make contact with the ground. A tornado usually passes through the funnel cloud stage during its development and dissipation. Not all funnel clouds become tornadoes, but you should still take cover if one approaches.

Severe Weather Safety Rules

Severe weather often develops quickly, so it is important that you know severe weather safety rules before the storm hits. Many times, only minutes are available to react when a severe thunderstorm or tornado threatens. Lost seconds can be the difference between life and death.

If a tornado threatens and you live in a mobile home, get out and find a sturdy building. The safest place in buildings is the most interior room on the lowest possible level, such as a bathroom in the basement. If you cannot get to a building, lie flat in a ditch or low spot, covering your head and the back of your neck with your arms and hands. If outdoors, stay clear of trees due to the threat of their being blown over or struck by lightning.

If you are in an automobile and a tornado threatens, get out and go to the lowest level of a sturdy building. If you cannot reach a building, lie in a ditch or depression and protect your head.

If you are in a school and a tornado warning is issued, your teacher will direct you to the school's tornado shelter. Kneel on the floor facing the wall with your hands covering your neck and head. Auditoriums and gymnasiums should be avoided. In malls or large buildings, go to the middle of the hall on the lowest level away from windows.

Lightning is a very dangerous component of all thunderstorms. Most lightning deaths and injuries occur when people are caught outdoors, either in or near a thunderstorm.

It does not have to be raining in order to be in danger from lightning. A good rule of thumb is that if you can hear thunder then you should seek shelter. Lightning can occur up to 10 miles away from rain. Lightning is most likely to strike individuals in open areas like golf courses, lakes, ball fields, and farm fields; also, tall trees have a higher probability of being struck.

The best course of action to protect yourself from lightning is to go indoors well before a thunderstorm strikes. If there are no buildings available, get into an automobile with a metal roof. If you do not touch metal, any lightning strike will then be directed into the ground.

If trapped outdoors, seek shelter in a low area. If in a forest, stay away from the tallest trees and seek shelter in a clump of lower trees or brush.

While indoors during an electrical storm stay away from windows, and do not use hard-wired telephones.


Tornadoes are the most violent storms on Earth. In an average year, 800 tornadoes are reported nationwide resulting in 70 deaths and over 1,500 injuries. The most violent tornadoes are capable of tremendous destruction with wind speeds in excess of 200 mph.

Maine averages about 2 tornadoes a year, with most occurring from May through July. Tornadoes are most likely to occur between 3:00 p.m. and 9:00 p.m., but they have been known to occur at any hour of the day or night.

The average tornado moves from southwest to northeast, but tornadoes have been known to move in any direction. The average forward speed is 30 mph but may vary from nearly stationary to 70 mph.

Most tornadoes are of the weak variety. They account for less than 5 percent of tornado deaths; they last from 1 to 10 minutes on average; and their winds are less than 110 mph. About 30 percent of all tornadoes are of the strong variety. They account for more than 25 percent of tornado deaths, last up to 20 minutes or longer, and have wind speeds between 110 to 205 mph. Less than one percent of all tornadoes are considered violent. These account for 70 percent of all tornado deaths. They can last for over an hour and have wind speeds in excess of 205 mph.

Sometimes tornadoes appear plainly visible as a rotating column or funnel that extends to the ground. At other times the tornado may be obscured by rain; the only clue to its presence may be a loud roaring sound like a freight train.

Did you know?

  • Every state in the U.S. has had a tornado.
  • Low pressure associated with the tornado does not cause buildings or homes to "explode." The damage is caused by violent winds and debris slamming into the buildings.
  • Windows should not be opened in a tornado. Even in the most tightly sealed home or building, the pressure will equalize. Leave the windows alone. The most important action is to seek safe shelter.
  • Most people are killed or suffer injuries because of flying debris.

What should you do in case of a tornado? The National Weather Service urges you to do the following:

Before the storm:

  • Now is the time to plan for tornado emergencies. A little planning, now, may save your life. Develop a plan for your family for home, work, school, and the outdoors.
  • Have frequent drills. Know what to do!
  • Know the county in which you live, and keep a map close by to follow storm movement from weather bulletins.
  • Own a NOAA All Hazards Weather Radio with a warning alarm and battery back-up.
  • Listen to radio and TV for weather information.

If a warning is issued or a tornado approaches:

  • When at home, stay away from windows, doors, or outside walls. Go to a basement or interior part of the house on the lowest floor. Put as many walls as possible between you and the outside. Cover your head with something sturdy for protection.
  • If caught outside, lie flat in a nearby ditch or depression and shield your head with your arms.
  • If in a car or truck, do not try to outrun a tornado. Leave your vehicle and take cover in a sturdy building. If no building is available, leave your vehicle for a ditch or low ground, lie flat, and cover your head.
  • Mobile homes offer little protection. If threatening weather is approaching, seek sturdier shelter. If no substantial shelter is nearby, lie flat in a ditch or depression and protect your head.
  • When in a public building, move to a designated shelter area. These are usually identified in schools, hospitals and other public buildings; otherwise, go to a small interior room or hallway on the lowest possible floor.

Remember, a tornado watch means conditions are favorable for tornado formation. You should continue your daily routine; keep an eye on the sky; keep abreast of current weather information for your area; postpone outdoor activities away from sturdy shelter; and be prepared to take quick action if necessary.

A tornado warning means a tornado has been sighted or is indicated by Doppler radar. When a warning is issued, move to safe shelter immediately.

Also remember that tornadoes occasionally develop in areas in which a severe thunderstorm watch or warning is in effect; so remain alert if your county is under a severe thunderstorm watch or warning.

Severe Thunderstorms

A severe thunderstorm watch means that conditions are favorable for the development of severe thunderstorms. It tells you when and where severe thunderstorms are most likely to occur. Severe thunderstorm watches are intended to heighten public awareness and should not be confused with warnings.

A severe thunderstorm warning means that severe weather is occurring or is about to occur. Warnings indicate imminent danger to the life and property of those in the path of the storm.

Severe thunderstorms produce damaging straight line winds, large hail, lightning, and, occasionally, tornadoes. What can you do to avoid the dangers of thunderstorms?

Before a thunderstorm occurs:

  • Know your county, as severe thunderstorm warnings are issued on a county basis.
  • Postpone outdoor activities if thunderstorms are imminent. This is the best way to avoid being caught in a dangerous situation.
  • If you must be outdoors, keep a NOAA All Hazards Weather Radio or AM/FM radio with you, and monitor the latest weather forecast.
  • Watch for towering clouds, darkening skies, lightning, and increasing winds. If you see one of these signs be prepared to take cover.

When a thunderstorm approaches:

  • Remember, if you can hear thunder, you are close enough to be struck by lightning.
  • Move to a sturdy building or car. Do not take shelter in small sheds, under a tree, or in a convertible automobile.
  • If lightning is occurring and sturdy shelter is not available, get inside a hard top automobile and keep the windows up.
  • Get out of boats and away from the water.
  • Avoid using phones or electrical appliances except when absolutely necessary.
  • Do not take a bath or shower.

If caught outdoors in a thunderstorm:

  • Find a low spot away from trees, fences, and poles.
  • If you are caught in the woods, take shelter under the shorter trees.
  • Get off of tractors and other metal farm equipment or small open vehicles such as motorcycles, bicycles, and golf carts. Stay away from wire fences, clotheslines, metal pipes, and rails.
  • If you are boating or swimming, get to land and find shelter immediately.

Lightning myths:

If it is not raining, there is no danger from lightning.
False: lightning often strikes outside of heavy rain and may occur as far as 10 miles from any rainfall.
The rubber soles on shoes or rubber tires on a car will protect you from being struck by lightning.
False: they provide no protection; however, the steel frame of a hard-topped vehicle does provide increased protection if the vehicle is struck.
People struck by lightning carry an electrical charge and should not be touched.
False: lightning victims carry no electrical charge and should be attended to immediately.
"Heat lightning" is produced because of very hot summer days.
False: what is referred to as "heat lightning" is really the distant flash of a thunderstorm too far away for thunder to be heard. Be alert, the storm could actually be moving toward you.
Flood / Flash Flood Terminology

Flooding has overtaken lightning nationally in weather related fatalities. Heavy rain can turn a usually tranquil stream into a life threatening torrent.

General river flooding occurs most often in the winter months, as heavy rain combines with snow melt; however, flash flooding can also occur in these months due to ice jams on rivers and streams.

Flash floods are most common in the warm season of the year when thunderstorms drop large amounts of rain in a short period of time. Hilly and mountainous terrains are especially prone to flash floods.

A flood watch is issued when flooding and/or flash flooding is possible but not imminent. Watches are can be issued up to 36 hours in advance of a flood/flash flood event.

A flash flood warning is issued when imminent flooding requires immediate action to protect lives and property. The flooding may arise from events such as short-term excessive rainfall, the sudden release of water held by an ice jam, or a dam failure. Your immediate action is required if you are in the path of the waters.

A flood warning is issued for actual flood situations not covered by the flash flood warning. The urgency for protection of life and property is lessened only by the longer term of the warning. Your action is still required; flooding is imminent.

All three can be issued for counties, parts of counties, river basins, rivers or specific points on rivers, depending on how widespread the flooding is expected to be. The two warnings can also cover general small stream or urban area flooding.

Often times flooding develops quickly, so it is important to know where you need to go to find safety. Sometimes only minutes or seconds are available to get out of harm's way in a flash flood situation.


Home - NWS Forecast Office - Caribou, Maine

National Weather Service
Caribou Weather Forecast Office
810 Main St
Caribou ME 04736
(207) 492-0170
Page last modified: April 23, 2007
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