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to protect yourself from the tornado

Final update date March 18, 2019

A tornado occurs with cumulonimbus and cumulonimbus clouds, and spirals in the atmosphere reach the ground. If a tornado occurs, the roof of the house may be peeled off, or a large tree may fall, which may cause serious damage, but it is difficult to predict when and where it will occur.
When you feel something unusual, such as when a black cloud approaches, or when you get information such as tornado caution information, take action to protect yourself by referring to the following.


a sign of a tornado

When the following phenomena occur, developed cumulonimbus clouds that may cause tornadoes may be approaching.

・The black clouds are approaching, and the surrounding area suddenly becomes dark.

・You can hear thunder or thunder.

・A cold wind blows out.

・Large rain and hail are starting to fall.

Japan Meteorological Agency website

Weather information about severe gusts such as tornadoes

The following information will be announced by the Japan Meteorological Agency when severe gusts such as tornadoes may occur.

  • Precise weather information (half day to one day before tornado occurrence)
    If a weather phenomenon that leads to a disaster is expected due to the development of a low pressure, etc., call attention by specifying "a severe gust such as a tornado".
  • Thunder Warning (several hours before tornado occurrence)
    If severe phenomena associated with cumulonimbus clouds (thunderstorms, hail, sudden heavy rain, gusts, etc.) are expected to cause damage, a lightning warning will be issued. At this time, if severe gusts such as tornadoes are expected to occur, call attention by specifying "tornado" in additional items in warning's text to call attention.
  • Tornado warning information (from 0 to 1 hour before tornado occurrence)
    When it is determined that the weather conditions are likely to cause severe gusts such as tornadoes, tornado caution information will be announced. This information informs you that the weather conditions are very likely to cause tornadoes.

○○Prefectural Tornado Warning Information No.1

15:26 on June 21, Heisei x △△ Local Meteorological Observatory Announcement

○○There is a risk of a tornado occurring in the prefecture.

Tornadoes are caused by cumulonimbus clouds. If there are signs of cumulonimbus approaching, such as lightning or a sudden change in wind, move to a sturdy building to ensure safety.

This information is valid until 16:30 on the 21st.

Examples of Tornado Warning Information

Actions to be taken when issuing tornado warning information

When the tornado warning information is announced, first of all,SoraPay attention to the condition of (Sora) and take the following actions as much as possible if you notice signs of cumulonimbus approaching.

When you are outdoors ...

  • Evacuate to a nearby sturdy building.
  • If you don't have such a building, keep yourself in the shade that can protect yourself from the scattered objects and keep your head small.
  • Keep away from utility poles and thick trees as they may collapse.
  • Do not evacuate to a storeroom, garage, or prefabricated building.

When you are indoors ...

  • Close the shutters, windows and curtains and leave the window.
  • In a two-story or more house, move to a room without windows on the first floor.
  • Move to a room without windows as close as possible to the center of the house.
  • Keep yourself small and protect your head, such as under a sturdy desk or table.

In addition,

  • Check "Tornado Announcement Nowcast".
  • Collect and confirm information via television and radio.



Column Fujita (F) scale
Fujita (F) scale may be used as an expression of the strength of severe gusts such as tornadoes. This is a measure to estimate the wind speed of tornadoes and downbursts (invented by Dr. Tetsuya Fujita of Chicago University). Six levels of strength from the strongest F5 to F0 are expressed.
Until now, no tornadoes with F4 or more have been observed in Japan.

F-scalewind speedSituation
(Average of about 15 seconds)
A weak structure such as a TV antenna collapses. The twigs may break, and the shallow roots may tilt. The house may be broken.
(Average of about 10 seconds)
Roof tiles fly and glass windows break. The damage to the greenhouse is enormous. A tree with weak roots falls, and a strong tree breaks its trunk. When a running car is hit by a side wind, it is blown off the road.
(Average of about 7 seconds)
The roof of the house is peeled off, and the weak non-residential house collapses. The big trees fall and are twisted. A car may be blown off from the road and the train may be derailed.
(Average of about 5 seconds)
The wall is pushed down and the house collapses. Non-residential houses are scattered separately, and even steel frames are crushed. The train is overturned and the car is lifted up and skipped. Even large trees in the forest can be broken or collapsed or pulled out.
(Average of about 4 seconds)
Houses fall apart and scatter around, and weak non-residential houses are blown away without traces. It's also made of steel. Trains are blown away, and cars fly dozens of meters in the air. More than a ton of objects are falling and there is no danger.
(average for about 3 seconds)
The house is blown away without a trace, and the skin of the tree is peeled off. Cars and trains fly up and fly to ridiculous places. Several tons of objects come down from nowhere.

(From the Japan Meteorological Agency website)


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Inquiries to this page

General Affairs Bureau Crisis Management Department Disaster Prevention Planning Division

Telephone: 045-671-4096

Telephone: 045-671-4096

Fax: 045-641-16777

Email address: [email protected]

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