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Legends
Discriptions in the table below refer to the situation on the ground as generalized image for each rainfall intensity.
It should be noted that radar meaures the intensity high above the ground, which is not necessarily consistent with the intensity low on the ground.
Expression in legends Human impression Effect for humans Situation of indoors
(wooden house)
Situation of outdoors Effect for a driver Possibility of disaster
Drizzle       Ground gets wet    
Weak          
Moderate       Puddles sparsely    
Slightly Strong Sound audible Splash wets footwear Conversation disturbed Puddles all around   Need to be cautious when it continues
Strong Feel force or strength of rain Umbrella works insufficiently Clamorous sound of raindrops disturbs sleep, e.g. awakes more than half of sleepers. Poor vision with fast wiper Overflow from roadside gutters, wastewater drains or small streams
Occurrence of small-scale mudslide
Rather Fierce Feel like buckets of water poured over Puddles make a road like a river Risk for hydroplaning (Occurrence of water film between wheel and ground) Mudslides or even landslides are prone.
Preparation for evacuation is necessary in dangerous zone.
Overflow from discharge pipelines in cities.
Fierce
Bitter Fierce
Severe Torrential Umbrella is useless White landscape and poor vision Driving is dangerous Rainwater runs into underground cells or shopping mall
Sprouts from manholes
Brings other disasters
Extreme Severe Feel fright with choking pressure Large-scale disaster is possible.
Highest alert is needed.

Data quoted from Japan Meteorological Agency (Data as of August, 2000, revised in July,2002).

[ Notes ]
The table assumes the continuation of one-hour for each rainfall intensity.

  1. The degree of disater varies with conditions of initial intensity or topological feature.
  2. The descriptions are based on recent cases.. Alteration should be done for deviation from actual situation.


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 heavy rain emergency warnings/warnings/advisories to call attention or precaution expecting damage possible.
The 1 hour rainfall amount, the 3 hours rainfall amount, the 48 hours rainfall amount and the tanked rain amount in soil are used to judge them.
All types of information written below will be shown in this site when announced by JMA.
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

The standard for Tokyo Metropolitan Area is shown below.

[Standard for weather emergency warnings/warnings/advisories for Tokyo] Revised on March 30, 2015
JMA issues heavy rain emergency warning, alerting people to the significant likelihood of catastrophes.
Reference : JMA“Criteria for Issuance of Emergency Warnings
Area Municipality Heavy rain advisories

JMA issues heavy rain advisories, expecting a possibility of damage. The standard is as follows.

Heavy rain warnings

JMA issues heavy rain warnings, expecting a possibility of grave damage. The standard is as follows.

1 hour
rain amount
[mm]
3 hours
rain amount
[mm]
Soil Tank
Index*
1 hour
rain amount
[mm]
3 hours
rain amount
[mm]
Soil Tank
Index*
23 Wards WestChiyoda 50 139100174
Chuo30 15470
Minato30
(Not-Flat Ground)
50
(Flat Ground)
12360
(Not-Flat Ground)
100
(Flat Ground)
154
Shinjuku 25 138 40 173
Bunkyo 25 134 40 168
Shinagawa 25 123 45 154
Meguro 25 12350154
Oota 25 12350154
Setagaya30 12060151
Shibuya 25 13350167
Nakano 25 139 40 174
Suginami30 13160164
Toshima 25 13850173
Kita 40 123 70 154
Itabashi30 124 45 155
Nerima30 13260165
23 Wards EastTaito30 13450168
Sumida 40 15460
Koto30
(Not-Flat Ground)
60
(Flat Ground)
15460
(Not-Flat Ground)
110
(Flat Ground)
Arakawa30 13450168
Adachi40 15460
Katsushika40 15460
Edogawa 40
(Flat Ground)
60
(Not-Flat Ground)
154 60
(Flat Ground)
110
(Not-Flat Ground)
Tama NorthTachikawa30 136 45 161
Musashino 25 14450
Mitaka30 13950164
Fuchu30 14470170
Akishima30 136 50 161
Cyofu 40 13970164
Koganei30 14150167
Kodaira 25 141 45 167
Higashimurayama 20 144 40 170
Kokubunji 25 14450170
Kunitachi30 15070177
Komae30 15060
Higashiyamato30 14450170
Kiyose 40 14160167
Higashikurume 20 141 45 167
Musashimurayama 40 11170131
Nishitokyo 20 141 40 167
Tama WestOume 50 12870151
Fussa 50 12070142
Hamura 50 13470158
Akiruno 50 12070142
Mizuho 50
(Flat Ground)
70
(Not-Flat Ground)
134 90
(Flat Ground)
120
(Not-Flat Ground)
158
Hinode 40 12370145
Hinohara 50 12470147
Okutama 50 12470147
Tama SouthHachiouji 40 10460131
Machida 40 10760134
Hino30 11250141
Tama30 11750147
Inagi30 11750147

*Soil Tank Index shows rain amount tanked in soil.

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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), 03-5321-1111(Key)(Ext. 51-061)
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