A weak wave of low pressure will move from eastern Canada to south of Japan Monday morning, before rapidly intensifying as it lifts northward along the east coast of Japan Monday night and Tuesday.
Rain will overspread southern Japan on Monday with soaking downpours expected in Kyushu, Shikoku and southern Honshu. The heaviest rain will spread northeast across Honshu during the afternoon, reaching Tokyo before days end. Tokyo will continue to experience rain into Monday night before tapering off to showers by Tuesday.
Farther north, the storm will start as rain across northern Honshu, however as colder air wraps southward on the back side of the storm, the rain will mix with and in some areas change to snow on Tuesday.
Northern Honshu and Hokkaido will bear the brunt of this storm Monday night into Tuesday as the chilly rain changes to snow and strong winds result in low visibility.
As the cold air drills southward, heavy rain and snow showers are expected along the west coast of Honshu. During any snow showers, the strong winds will result in visibility quickly deteriorating and creating dangerous travel conditions.
While Hokkaido will deal with rain changing to a heavy wet snow, the brunt of the snow will be directed farther west across Primorsky Krai, Russia. This region will experience all snow, which will fall heavily at times through Tuesday. Snowfall totals of 30-60 cm (12-24 inches) are expected, while strong winds will create low visibility and drifting snow.
Across Japan, snowfall will be generally 2-8 cm (1-3 inches) across the lower terrain of western and northern Honshu with 8-15 cm (3-6 inches) falling in the higher elevations.
Snowfall of up to 30 cm (12 inches) is possible in the hardest hit areas of Hokkaido, while snowfall amounts closer to 15 cm (6 inches) will be more common.
While rain and snow will result in travel disruption across the region, strong winds will also wreak havoc on travel, especially by air. Wind gusts over 80 kph (50 mph) are possible in coastal locations and over the higher elevations from the Korean Peninsula through Japan. Elsewhere wind gusts over 65 kph (40 mph) can still occur from Monday into Wednesday.