The Washington PostDemocracy Dies in Darkness

Extreme ocean-effect snow buries parts of Japan beneath seven feet, with more coming

The nation was sandwiched in between record-breaking weather systems.

The American GFS model simulates heavy snow targeting Japan during the next week. (WeatherBell)
Placeholder while article actions load

Barely two weeks after a prolific ocean-effect snowstorm dropped seven feet of snow and stranded thousands of motorists, the new year in Japan kicked off with another severe snowstorm. Up to another 85 inches fell through Saturday amid strong winds and record cold temperatures.

Up to seven feet of snow slams Japan, stranding 1,000 motorists

Photos emerged on social media of a landscape plastered in white as heavy snow covered the mountains of Japan. One shot captured a roughly five-foot block of snow balanced precariously on a phone booth, while another showed what appeared as a white blanket presumably cloaking trees, structures and vehicles.

The mind-boggling snowfall is linked to a pair of record-breaking weather systems that induced a prolonged period of westerly to northwesterly winds, the ideal wind fetch needed to yield the factory-like production and dumping of heavy snow.

Mountainous areas of Japan are bracing for yet another dump of heavy snow over the next five days.

The second extreme snowfall in two weeks’ time

Japanese news agency NHK reported that Okura Village in Yamagata Prefecture, a mountain community a little more than 200 miles north of Tokyo, had received 85 inches of snow by late Friday. The seven feet of snow matched what came down the week of Dec. 18 just to the south in the community of Fujiwara.

That snowstorm stranded more than a thousand motorists on the Kan-Etsu Expressway for more than 24 hours, with drivers forced to melt snow for drinking water during the overnight debacle.

While snowfall around New Year’s Day wasn’t quite as disastrous, it did pile up to staggering totals. Some locales hit hard included Uonuma City, 50 miles south of Niigata, as well as Yokote City in northern Japan. Those places saw 62 and 60 inches respectively by Friday morning.

Extreme accumulations snarl travel

NHK reported that at least 140 domestic flights were canceled leading up to the storm, with bullet train service suspended on the Yamagata line. That line navigates snow-prone regions near and west of the Ou Mountains in the Tohoku region of Honshu.

Additional 24-hour snowfall of up to 30 inches was forecast Saturday in Niigata Prefecture, with slightly lesser amounts closer to the coast in northwest Japan. Snowfall rates exceeded three inches per hour at times.

A perfect recipe for ocean-effect snow

The higher elevations of Japan, particularly along the Japanese Alps and Echigo Mountains, are among the snowiest regions of the world. Japan is situated in a perfect zone for ocean-effect snowfall, with frigid northwesterly winds blowing across the lukewarm waters of the Sea of Japan. That adds moisture to the air, which is then forced up the mountains and deposited in the form of heavy accumulating snowfall.

That sea-to-atmosphere temperature contrast is bolstered even more by the Kuroshio Current, akin to the Gulf Stream; a branch of it called the Tsushima Current is responsible for warming the Sea of Japan. It can routinely remain in the 50s to near 60 degrees at this time of year.

Meanwhile, a morning low of minus-27 degrees was set in Horokanai in Hokkaido on New Year’s Eve, while neighboring Shumarinai and both fell to minus-25. Each reading snagged a record low for the month of December.

The wintry weather wasn’t relegated to only northern Japan; southern Japan set a number of 24-hour December snowfall records, with 31 inches in Kaminagata.

How Japan was sandwiched between two record-breaking weather systems

The impressive bout of snowfall is tied to a pair of extreme weather systems that flanked the Japanese archipelago both to the west and east last week. An exceptionally cold air mass associated with Arctic high pressure parked over Mongolia, while a historically strong low-pressure system brought stormy weather and dangerous conditions to mariners in the northern Pacific.

A frigid air mass in Mongolia may have just crushed a world record for surface air pressure

The high-pressure system may have set a world record with the highest air pressure ever reliably recorded; a station in Tsetsen-Uul, Mongolia recorded a sea-level equivalent air pressure of 32.31 inches last Tuesday morning. Typical sea level air pressure averages closer to 30.00 inches. The extreme high-pressure “ridge” was accompanied by temperatures near minus-50.

Meanwhile, low pressure to the east near the Aleutian Chain became the “deepest” nontropical low pressure system ever observed in the North Pacific, with an air pressure of 27.20 inches. It stirred up 110 mph wind gusts over the open ocean and set a new state air pressure record in Alaska.

Bomb cyclone in northern Pacific Ocean breaks all-time records

Because air flows from high pressure to low pressure, the steep pressure gradient, or change with distance, spurred strong westerly winds that proved instrumental to ocean-effect snow production in the Sea of Japan.

In the meantime, record high and low-pressure systems aren’t anticipated in the upcoming week, but more snow is on the way as cold winds once again roar over the Sea of Japan.

Another 40 to 60 inches is likely for some in central and northern Japan in the next five days as a strong area of low pressure develops over the Sea of Japan Tuesday into Wednesday.

The Japanese Meteorological Agency has hoisted advisories for snow, thunderstorms and avalanches.