More sea-effect snow in Japan's forecast

After a quick-moving storm brought snow to parts of Hokkaido and northern Honshu during the middle of last week, another storm took a swipe at the region at week's end before more sea-effect snow moved into the region.

Due to more mild air being pulled north by both the midweek and late-week storms, areas of rain showers were common across central Honshu, while rain mixed with snow in northern Honshu through the end of the week.

While rainfall totals only reached around 25-50 mm (1-2 inches) from western Tohoku to northern Kansai, additional water from snowmelt triggered by moderate temperatures can lead to flash flooding in low-lying and poor drainage locations. This will be especially true in areas where snow piles hinder drainage.

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The warmer air can also loosen deep packs of snow. This can increase the risk that snow or ice may slide off buildings.

However, this more mild air did not last long as the next surge of cold air followed quickly behind the storm. Along with this colder air, sea-effect snow showers will return to coastal areas, mainly across Kansai and Chubu.

By Tuesday, the coastal areas of Tohoku and Chubu could receive up to 30 cm (12 inches) of additional snowfall with even higher amounts likely where the heaviest bands set up.

In addition to persistent snow showers through Sunday and into Monday, temperatures expected to drop below freezing during the overnight hours can cause any snow that melted to refreeze. This can lead to dangerous traveling conditions, especially where water was standing because it couldn't drain.

With colder air in place over Japan during the beginning of the week, the next storm expected to move through the area can bring more widespread snow to the country.

The same areas that have been hard by sea-effect snow in recent weeks may receive another round of heavy snowfall from this storm on Monday and Tuesday.

Last weekend, the snow depth in the city of Toyama surpassed about 1 meter (3.3 feet) for the first time in 35 years, according to NHK, the Japanese Broadcasting Corporation.

The snow depth is a measurement of the snow on the ground through the winter season so far and is not a direct result of this storm system.

Even heavier snow fell farther to the north in Takada where an astounding snow depth of 249 cm (8.2 feet) was reported, according to the Japanese Meteorological Agency. The measurement was taken near sea level which makes the observation rather unusual. Typically, snow that deep is typically reserved for the nearby mountainous areas.

Fukui City is hit by heavy snow in Fukui Prefecture, a district along the Sea of Japan, in January 11, 2021. Lots of vehicles have been stuck in snow, and Japan Self Defense Force officials remove the snow from the street. (The Yomiuri Shimbun )

Snow depths in excess of about 3 meters (10 feet) are typically reported across some of the mountainous terrain of western Japan and have led to great ski conditions.

This unusual amount of snow in a short period of time left about 1,500 vehicles stranded on the Hokuriku Expressway in Fukui Perfection and lead to at least 10 fatalities.

Another round of sea-effect snow in December left another 1,000 vehicles stranded on a highway in Niigata.

"It is not terribly unusual to have sea-effect snow across those parts of Japan," AccuWeather Lead International Meteorologist Jason Nicholls stated.

He added that observations from December 2020 show that snowfall was above normal for the sea-effect areas in Japan.

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