Japan weather agency warns of violent gusts, sudden heavy rain in east and west
In short
The Japan Meteorological Agency said on Oct 18 that the atmosphere over eastern and western Japan would be very unstable through Oct 20, and urged caution against lightning, tornadoes and other violent gusts, and sudden heavy rain. A front is forecast to stall near the region. Niigata Prefecture was also forecast heavy rain from the evening of Oct 19.
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The Japan Meteorological Agency called on Oct 18 for caution through Oct 20 in eastern and western Japan against lightning, violent gusts such as tornadoes, and sudden heavy rain. The warning was in its general weather information (lightning and gusts) No. 1, issued at 5:00 pm on Oct 18. [ 1 , 2 , 3 , 4 ]
The agency said a low-pressure system with a front would move from the Sea of Japan to the Sea of Okhotsk, and the front would move south and stall near eastern and western Japan through Oct 20. Warm, moist air flowing toward the front would make the atmosphere very unstable. Nikkei, citing the agency, reported on Oct 19 that the low in the Sea of Okhotsk was moving to the east of Hokkaido and the Kuril Islands, and that a maximum wind speed of 20.3 metres per second had been observed in Erimo, Hokkaido, that day. [ 1 , 2 , 3 , 4 , 24 ]
The agency said that if signs of a developed cumulonimbus cloud approaching appear, people should move into a building. Nippon TV reported that in Tokushima Prefecture the atmosphere would be very unstable from dawn on Oct 19 to the morning of Oct 20, and ran headlines urging caution in Ehime and Kochi until the evening of Oct 20. [ 1 , 2 , 3 , 4 , 5 , 19 , 23 ]
The agency issued further information at 5:00 on Oct 19 and its No. 4 at 5:00 on Oct 20. NHK reported on the morning of Oct 19 that rain clouds were developing in Hokkaido. On Oct 20 it said the atmosphere was very unstable mainly in eastern and western Japan and that rain clouds were developing in the Hokuriku region, with the agency urging vigilance against flooding of low-lying land and river rises, and caution against lightning, tornadoes and other violent gusts, and hail. [ 8 , 9 , 26 , 27 ]
For Niigata Prefecture, TBS reported that the Niigata Local Meteorological Observatory called for caution and vigilance against flooding and river rises, with heavy rain with thunder expected to continue until before noon on Oct 20 and a possible warning-level rain. TBS and Nippon TV gave a forecast of 80 mm of rain, though they differed on its spread: TBS said 80 mm in 24 hours in places across the prefecture, and Nippon TV said 80 mm across the whole prefecture by the evening of Oct 20. [ 13 , 21 , 22 ]
Yahoo! News Japan said on Oct 18 that heavy rain was possible mainly in Hokuriku until about Wednesday, and that very strong Typhoon No. 30 was expected to approach Okinawa's Sakishima Islands from about Thursday to Friday. NHK's Oct 20 headline asked readers to check the latest typhoon information. [ 7 , 26 ]
Why it matters
The agency told people to move indoors if signs of developed cumulonimbus clouds appear. Outlets also reported flooding and river-rise warnings for Niigata and heavy-rain risk in the Hokuriku region.
Key facts
- The Japan Meteorological Agency called on Oct 18 for caution through Oct 20 against lightning, tornadoes and other violent gusts, and sudden heavy rain in eastern and western Japan. [ 1 , 2 , 3 , 4 ]
- A low-pressure system with a front was forecast to move from the Sea of Japan to the Sea of Okhotsk, with the front moving south and stalling near eastern and western Japan through Oct 20. [ 1 , 2 , 3 , 4 ]
- Warm, moist air flowing toward the front is the reason the agency gave for the very unstable atmosphere. [ 1 , 2 , 3 , 4 ]
- The agency said that if signs of a developed cumulonimbus cloud approaching appear, people should move into a building. [ 1 , 2 , 3 , 4 ]
- Niigata Local Meteorological Observatory urged caution and vigilance against flooding of low-lying land and river rises from the evening of Oct 19 to before noon on Oct 20. [ 13 , 22 ]
- The agency issued its lightning and gusts information No. 4 at 5:00 on Oct 20. [ 27 ]
Confirmed by several sources
- The Japan Meteorological Agency warned that the atmosphere over eastern and western Japan would be very unstable through Oct 20, with lightning, tornadoes and other violent gusts, and sudden heavy rain. [ 1 , 2 , 3 , 4 , 8 , 24 ]
- The instability was attributed to a front stalling near eastern and western Japan, with warm, moist air flowing toward it. [ 1 , 2 , 3 , 4 , 24 ]
- Niigata Prefecture was forecast heavy rain with thunder from the evening or late night of Oct 19 to before noon on Oct 20, with 80 mm in 24 hours forecast. [ 13 , 21 , 22 ]
Still unclear
- Whether tornadoes, violent gusts or hail actually occurred. The documents report forecasts and warnings, not confirmed damage.
- Whether the Niigata rain would reach warning level. Outlets said only that a warning-level rain was possible.
- How the 80 mm rain forecast for Niigata is spread. One outlet said 80 mm in 24 hours was forecast in places across the prefecture; another said 80 mm was forecast across the whole prefecture by the evening of Oct 20.
What local media are saying
Timeline, local time
- On Oct 18, the agency issued general weather information (lightning and gusts) No. 1. [ 1 ]
- On Oct 19, the agency issued further information on lightning and gusts. [ 9 ]
- On Oct 20, the agency issued information No. 4 saying the atmosphere would be very unstable in eastern and western Japan that day. [ 27 ]