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●Data Update Cycle
The cycle time for update is 5 minutes.
To view the latest data, click the key "Refresh"on the tool bar.
The update may halt temporalily due to radar maintenance or other inspection.
●Legends
The expression of the rainfall intensity in legend is indicated on ground-based situation.
On the one hand, rain precipitation indicated by radar differs from the actual rainfall on the ground, because it shows the rainfall intensity in the air before raindrops fall on the ground.
For reference, the image of rainfall display shown in the legend is shown below.
Hourly Precipitation
(mm)
Forecast Terms Image that people receive Influence on people Indoor
(in the case of wooden house)
Outdoor When riding a car
10 or more -
less than 20
Slightly Heavy rain Amid
driving rain
(The rain
sounds like “Zah Zah”)
The feet get wet by rain splashing from the ground Being unable to hear one’s voice well due to rain There are puddles on the whole ground  
20 or more -
less than 30
Heavy rain Dousing rain Getting wet even with an umbrella Taking approximately half of sleeping people notice the rain Visibility is poor even with a faster wiper
30 or more -
less than 50
Intense rain Rain as if a bucket of water is being emptied Roads become like a river When driving at high speed, a water film is formed between the wheel and the road surface and the brake does not work. (hydroplaning phenomenon)
50 or more -
less than 80
Very intense rain Rain in torrents (constant rain with rasping sound like “Goh Goh”) Umbrella is useless at all Splashing makes the surroundings whitish and poor visibility Driving a car is dangerous
80 or more - Torrential rain Feeling of pressure that makes feel stuffy. Feeling of fear.

Source: Created with reference to Japan Meteorological Agency website (Prepared in August 2000, partially amended in January 2002, in March 2017 and in September 2017)

(Note 1)
When there is a possibility of a disaster due to heavy rain, Heavy Rain Advisory or Flood advisory is announced, when a serious disaster is likely to occur, Heavy Rain Warning or Flood Warning is announced, and if there is a significant risk of a serious disaster, Heavy Rain Emergency Warning.
(Note 2)
When short-term heavy rain that occurs only once every few years is observed and analyzed, information of record-breaking heavy rain in short-time is announced. When this information is announced, it means that there is heavy rain in your inhabited area that can lead to landslides, inundation, and flooding of small-and-medium-sized rivers. Information standards vary by region.
JR Lines displays JR Lines in the map. companiesLine displays other companies’ line, subway is not included.
stationMark means the place of each station.
●Weather Warnings and Advisories
Japan Meteorological Agency issues weather information for disaster prevention, such as weather warnings and advisory, early advisory information (Probability of warnings) and weather condition information, to prevent and reduce disasters caused by heavy rain and storms.
In order that this information support the activities of relevant organizations of disaster prevention and the determination of safety activities of residents, weather information and early advisory information (Probability of warnings) are announced several days before a severe phenomenon that could lead to a disaster is expected. And then announcement of Advisory, Warnings, and Emergency Warning are made by stages according to risk levels.
Regarding the contents of these information and the timing of announcements, opinions are always exchanged among disaster prevention organizations such as municipalities, prefectures, national organizations, media organizations for support effective disaster prevention activities.
(From Japan Meteorological Agency website)

Japan Meteorological Agency has issued 6 types of Emergency Warning, 7 types of Warning, and 16 types of Advisory as follows, depending on the target phenomenon and disaster content.
Please refer to Japan Meteorological Agency website for details.
Emergency
Warning
Heavy rain、Storm、Snow-storm、Heavy snow、High waves、Storm surge
Warning Heavy rain、Flood、Storm、Snow-storm、Heavy snow、High waves、Storm surge
Advisory Heavy rain、Flood、Gale、Gale and snow、Heavy snow、High waves、Storm surge、Thunderstorm、Snow melting、Dense fog、 Dry air、Avalanche、Low temperature、Frost、Ice accretion、Snow accretion

About emergency warnings/warnings/advisories, refer to JMA-Website

The standard of warnings/advisories for Tokyo Metropolitan Area , only japanese

Examples of municipal and resident responses to weather Warnings/Advisories

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●Contact Us
  • Please send your commments to:.
    Consultation and Service Desk
    Public Relations and Service Section, General Affairs Division
    Bureau of Sewerage, Tokyo Metropolitan of Government
  • 163-8001 Nishi Shinjuku 2-8-1,Shinjuku-ku,Tokyo
  • Telephone:03-5320-6511(Direct)
  • Fax:03-5388-1700(Direct)
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