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'Guerrilla downpour' alert system could predict flash flooding hours in advance

Observation data for cumulonimbus clouds using the new radars provides a three-dimensional view of clouds rising upward as they develop, as seen in this image provided by Toshiba Infrastructure Systems and Solutions Corp.

TOKYO -- Flood warnings could be provided hours in advance with a new torrential rain alert system now undergoing demonstration experiments.

The system, developed by a team including Japan's National Institute of Information and Communications Technology (NICT), will use data from new powerful radars to provide warnings of so-called "guerrilla downpours" in the form of email alerts. Some 2,000 human monitors will then send back information on actual rainfall to increase the accuracy of predictions.

Team members say that if the system goes into operation, it will be possible to predict changes in river water levels, and release flooding predictions six hours in advance.

In November last year, the team set up new weather radars in the city of Saitama near Tokyo that can monitor areas in an 80-kilometer radius. Up until now, it had only been possible to monitor the lower part of clouds at an altitude of some 2 kilometers, but the new radars can capture clouds at altitudes of 16 to 18 kilometers. The time to take observations will also be vastly decreased, from 5 minutes to around 30 seconds. If rainfall is set to reach a certain level in 30 minutes, monitors will receive emails informing them of the expected amount of rain.

(Japanese original by Yuka Saito, Science & Environment News Department)

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