Japan Meteorological Agency forecasts heavy rain with thunder along the Pacific Ocean side of Tohoku and Kanto.
From Mainichi Shinbun (4/22/2011), quoting the Agency:
In Tohoku and Kanto, heavy rain with thunder from April 23 noon till early hours of April 24.
24-hour cumulative rainfall forecast up to April 23, 6:00PM is 150 millimeters (5.90 inches) for Kanto-Koshinetsu, and 80 millimeters (3.15 inches) for Tohoku, and the numbers are set to increase further on April 24.
5-meter high waves expected on the Pacific Ocean side of Northern Japan due to strong wind.