To protect yourself from tornadoes

Tornados are generated by cumulonimbuses and cumulonimbuses, with spirals in the atmosphere reaching the ground. When a tornado occurs, it can cause serious damage, such as the roof of the house being peeled off or a large tree falling down, but it is difficult to predict when and where it will occur.
If you feel an unusual weather such as a black cloud approaching, or if you get information such as tornado caution information, take action to protect yourself by referring to the following.

When the following phenomena occur, a developed cumulonimbus that generates a tornado may be approaching.

・Black clouds approach and the surrounding area suddenly darkens.

・You can hear thunder and you can see thunder.

・The cold wind blows out.

・A large amount of rain and a "hyo" begin to fall.

From the Japan Meteorological Agency website

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

• Preliminary weather information (half to one day before the occurrence of the tornado)
  If a weather phenomenon that leads to a disaster is expected due to the development of low pressure, etc., call attention by clearly stating "strong gusts such as tornadoes".
• Lightning warning (a few hours before the occurrence of a tornado)
  If damage is expected due to severe phenomena (lightning, hail, sudden heavy rain, gusts, etc.) associated with cumulonimbuses, a lightning warning will be issued. At this time, if severe gusts such as tornadoes are expected to occur, we will call attention to the additional items in the warning text.
• Tornado caution information (0 to 1 hour before the occurrence of the tornado)
  Tornado caution information will be announced when it is determined that the weather conditions are likely to cause severe gusts such as tornadoes. This information informs you that the weather is very likely to cause tornadoes.

○○Prefectural Tornado Warning Information No. 1

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

○○In the prefecture, there is a risk of a tornado.

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

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

Example of tornado caution information

• Tornado Accuracy Nowcast (always including regulars)
  Areas with severe gusts such as tornadoes are represented by a distribution map (10km lattice), the movement up to one hour later is predicted, and the latest information is provided every 10 minutes, including normal times.
  Link　Japan Meteorological Agency Nowcast (outside site)

When tornado caution information is released, first pay attention to the state of the sky, and if you detect signs of a cumulonimbus approaching, take the following actions as much as possible.

• Evacuate to a nearby sturdy building.
• Without such a building, keep yourself small and protect your head in the shade that can protect yourself from scattered objects.
• Keep away from telephone poles and thick trees, as they may collapse.
• Do not evacuate to storerooms, garages, or prefabs (temporary buildings).

• Close the shutters, windows and curtains and move away from the window.
• In a house with two stories or more, 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.
• Protect your head by keeping yourself small, such as under a sturdy desk or table.

• Check "Tornado Announcement Accuracy Nowcast".
• Collect and confirm information on TV and radio.

Column Fujita (F) Scale
The Fujita (F) scale may be used as an expression of the strength of intense gusts such as tornadoes. This is a measure for estimating wind speeds such as tornadoes and downbursts (invented by Dr. Tetsuya Fujita of the University of Chicago). It represents six levels of strength from the strongest F5 to F0.
To date, no tornadoes with F4 or higher have been observed in Japan.

(From the Japan Meteorological Agency website)

• Japan Meteorological Agency booklet "Utilization of weather information on intense gusts such as tornadoes" (outside site)
• Cabinet Office / Japan Meteorological Agency Brochure "Protect yourself from tornadoes!" （PDF：2,596KB）