Japan's southwestern prefecture of Okinawa is bracing for rough sea conditions, as a typhoon currently east of the Philippines travels north.

The Meteorological Agency says Typhoon Saola is moving north and will gradually change direction westward.

The powerful storm will bring high waves to the Sakishima Islands in Okinawa Prefecture. Weather authorities warn people in the area of possible rough sea conditions on Wednesday and Thursday, depending on the storm's trajectory.

Another storm could move close to Okinawa Prefecture. Tropical Storm Haikui is currently off the eastern coast of the Philippines and moving west.

Meteorological Agency officials say Haikui will travel northwest while picking up strength and could close in on the Okinawa region as early as Thursday.

Atmospheric conditions stretching from western to northern Japan are expected to remain unstable on Tuesday, due to an influx of humid air and forecast high temperatures during the day. There is a chance of torrential downpours, accompanied by thunder, in some places.

The Meteorological Agency is warning of landslides, flooding in low-lying areas, swollen rivers, lightning strikes, strong gusts and hail.