Japan to launch new weather system to better predict heavy rains

Tokyo >> The Japan Meteorological Agency plans to launch a new weather forecast system by 2030 in response to the frequent occurrence of heavy rain and other natural disasters. The system will predict certain rain systems that produce heavy downpours half a day in advance, as well as heat and cold waves and other weather events.

The agency aims to predict rainfall during typhoons across a three-day period, with plans to begin such forecasts three years from now, sources said. Data will be analyzed by a supercomputer to make predictions.

The agency hopes to warn residents of sudden changes in weather to provide adequate evacuation time.

According to the agency, line-shaped rain systems — in which a band of cumulonimbus clouds produces heavy rains — have caused enormous damage in recent years. In addition to last month’s heavy rains in western Japan, the phenomenon was responsible for downpours that battered northern Kyushu in 2017 and the Kanto and Tohoku regions in 2015.

However, line-shaped rain systems have been impossible to predict, as they occur suddenly when warm air flows in.

In June, the agency introduced a new supercomputer that will enable detailed analysis of such data as amounts of water vapor, amounts of rainfall and wind strength.

The data will be obtained from weather satellites and the Automated Meteorological Data Acquisition System.

In addition to the improved data analysis, the agency will develop a new analysis program and begin using observational data from private companies, among other measures.

As evacuation would be difficult if a line-shaped rain system occurs at night, the agency aims to forecast heavy rainfall 12 hours in advance. Color-coded risk levels of landslides and floods will also be announced on the agency website.

In addition, the agency will release weekly forecasts of heat and cold waves for the coming month, and begin issuing “severe storm alerts” that predict thunder and gusty weather.

Initially, the agency will aim to predict total rainfall per three-mile area over three-day periods within three years.

The forecasts will help predict water levels of rivers that can be affected by heavy rainfall. The agency aims to implement the new weather forecast system by 2030.

“We have a much better ability to analyze past events and current weather conditions, and to forecast future weather. We want to provide new information as early as possible,” an agency official said.