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To protect yourself from tornadoes
Last update date December 8, 2023
Tornadoes are generated by cumulonimbuses and cumulonimbus clouds, and swirls in the atmosphere reach the ground. If a tornado occurs, it can cause serious damage, such as the roof of a house being peeled off or a large tree falling, but it is a weather phenomenon that is difficult to predict when and where.
If you feel an unusual weather, such as a black cloud approaching, or if you get information such as tornado caution information, please take action to protect yourself by referring to the following.
A sign of a tornado
When the following phenomena occur, a developed cumulonimbus that can cause a tornado may be approaching.
・The black clouds approach and the surrounding area suddenly becomes dark.
・You can hear thunderstorms and see thunderlights.
・A chilly wind blows out.
・Great rain and "hail" begin to fall.
From the Japan Meteorological Agency website
Weather information about severe gusts such as tornadoes
The following information will be announced by the Japan Meteorological Agency in the event of a severe gust such as a tornado may occur.
- Notice weather information (half day to 1 day before the tornado occurrence)
If weather phenomena that lead to a disaster are expected due to the development of low pressure, etc., call attention should be given by specifying "severe gusts such as tornadoes" and call attention. - Lightning Warning (Several hours before tornado occurrence)
If damage is expected due to severe phenomena (such as lightning strikes, hail, sudden heavy rain, gusts, etc.) associated with cumulonimbus clouds, a lightning warning will be issued. At this time, if a severe gust such as a tornado is expected to occur, the warning will be given by stating "Tornado" in the text of warning. - Tornado Warning Information (0 to 1 hour before the tornado occurrence)
When it is determined that the weather conditions are likely to cause severe gusts such as tornadoes are likely to occur, tornado caution information will be announced. This information informs you that the weather is right now in a tornado is likely to occur.
○○Prefectural Tornado Warning Information No. 1
Heisei × × June 21, 15:26 △△ Local Meteorological Observatory Announcement
○○In the prefecture, there is a risk of tornadoes.
Tornadoes occur with cumulonimbus clouds. If there are signs of cumulonimbus approaching, such as sudden changes 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 occurrence accuracy nowcast (always including regular times)
Areas with a strong gusts such as tornadoes are represented by a distribution map (10km lattice), predicting movement up to one hour later, and the latest information is provided every 10 minutes, including normal times.
Link Japan Meteorological Agency Nowcast (outside site)
Actions to be taken when issuing tornado caution information
When tornado caution information is announced, first pay attention to the sky condition, and if you detect signs of a cumulonimbus approaching, take the following actions as much as possible.
When you are outdoors,...
- Evacuate to a nearby sturdy building.
- Without such a building, protect your head by entering a shade that can protect yourself from flying objects and make yourself smaller.
- Keep away from telephone poles and thick trees, as they may collapse.
- Do not evacuate to a storeroom, garage, or prefabricated buildings.
When you are indoors ...
- Close the shutters, windows and curtains, and move away from the window.
- In a house with two or more floors, move to a room without windows on the first floor.
- Move to a windowless room 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.
Others
- Confirm "Tornado Announcement Accuracy Nowcast".
- Collect and confirm information on TV, radio, etc.
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, downbursts, etc. (developed by Dr. Tetsuya Fujita of the University of Chicago). It expresses six levels of strength from the strongest F5 to F0.
In Japan, no tornadoes with F4 or higher have been observed so far.
| F scale | Wind velocity | Situation |
|---|---|---|
| F0 | 17～32m/s (Average of about 15 seconds) | A weak structure, such as a TV antenna, falls down. The twigs may break, and a tree with a shallow root may tilted. A non-residential house may be broken. |
| F1 | 33～49m/s (Average of about 10 seconds) | The roof tiles fly and the glass window breaks. The damage to the greenhouse was severe. Trees with weak roots fall, and strong trees break trunks. When a running car receives a horizontal wind, it is blown away from the road. |
| F2 | 50～69m/s (Average of about 7 seconds) | The roof of the house is peeled off, and the weak non-residential houses collapse. A big tree falls down or twisted. A car may be blown away from the road and the train may derail. |
| F3 | 70～92m/s (Average of about 5 seconds) | The wall is pushed down and the house collapses. Non-residential houses fall apart and scatter, and can be crushed even in steel frame construction. The train capsizes, and the cars are pulled up and fly. Even large trees in the forest can be broken or fall, and pulled out. |
| F4 | 93～116m/s (Average of about 4 seconds) | Houses fall apart and scatter around, and weak non-residential houses are blown away without trace. It's also made of steel frames. Trains are blown away, and cars fly tens of meters in the air. An object that is more than one ton is falling, and there is no danger. |
| F5 | 117～142m/s (Average of about 3 seconds) | The dwellings are blown away without a trace, and the skin of Tachiki is peeled off. Cars, trains, etc. are pulled up and fly, and fly to a ridiculous place. A few tons of objects fall out of nowhere. |
(From the Japan Meteorological Agency website)
Link
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For inquiries to this page
General Affairs Bureau Crisis Management Planning Division
Phone: 045-671-4096
Phone: 045-671-4096
Fax: 045-641-1677
Email address: so-bousaikikaku@city.yokohama.jp
Page ID: 794-221-514
