Following this past weekends heavy snowfall across Northern and Central Japan a high pressure system set up Monday ushering in clear skies and calmer conditions for most of the country.
This is not expected to last long though as a new storm is set to roll over the country through Tuesday in to Wednesday. This one will also bring some rough weather but the dynamics are a little bit different.
First there is a low pressure area moving in from the south west along the pacific coastline of Japan, this means warmer air at first and also rainfall in the Tokyo area.
It will start for those in the city Tuesday Evening and last through Wednesday morning. For both evening and morning commutes its best to be ready for the rain.
The heaviest rainfall will be in Shikoku as southerly moist air comes on shore off the pacific, up to 120mm of total precipitation is expected here through Wednesday morning.
After the low tracks north it will trigger some strong north westerly winds out of Siberia yet again and thus turning on the sea effect snow machine for Japan. Scattered snow showers are to be expected in Nagano and Niigata through the weekend with areas further north like Western Hokkaido basically seeing persistent snowfall all week.
Heaviest snowfall for central Japan will be across the mountains of Hokoriku where up to 20cm is possible through Wednesday. This is not taking in how much will fall in the mountains though in the second half of the week from the sea effect snow setup.
On a separate fun fact, the additional snow across Japan will add to a already above average season, this image I used on NHKWORLD Monday shows the snow this year compared to the average in Sapporo, at this point is has been the snowiest December for the city in 15 years and more is even on the say.