Weather officials say cold air masses over Japan are expected to bring unstable atmospheric conditions to wide areas of the country through Tuesday, with possible localized thunderstorms.

The Meteorological Agency says unstable atmospheric conditions have caused rain clouds to develop in some places.

During the one-hour period to 5 p.m. on Monday, 33 millimeters of rain was observed in the town of Nan-bu in Tottori Prefecture.

Atmospheric conditions are expected to remain unstable from the Tohoku region to western Japan through Tuesday.

Weather officials warn of possible localized downpours of more than 50 millimeters per hour.

Over the 24-hour period through Tuesday evening, up to 100 millimeters of rain is forecast for the regions of Kanto-Koshin, Tokai, Hokuriku, and Niigata Prefecture. Up to 80 millimeters is expected for the Tohoku, Kinki and Chugoku regions.

The officials are advising caution against possible mudslides, floods in low-lying areas, swollen rivers, lightning strikes, gusty winds and hailstorms.