A Banner Season in Japan

There's so much bad news on the weather front in the US due to the wildfire catastrophe in SoCal, that I thought I would talk about something more uplifting: The remarkable snow season that they are having in Japan.  

I like to say that if Utah has the Greatest Snow on Earth, but Japan has the Greatest Snow Climate on Earth.  Really, there is nothing like Japan's "Gosetsu Chitai" or heavy snow region near the Sea of Japan.  It is the snowiest, densely populated region on Earth with Sapporo the snowiest city in the world with a population of more than 1 million and Sukayu Onsen in the Hakkoda Mountains in northern Honshu the snowiest inhabited place on Earth.  The numbers below are based on 1981-2010 climate normals.

There are three things that make Japan's Gosetsu Chitai so special for snow.  First, it lies downstream of Eurasia, the world's biggest continent, which results in frequent and prolonged cold-air outbreaks over the Sea of Japan during the East Asian Winter Monsoon.  Second, the Sea of Japan is an enormous body of water, 12 times bigger than Lake Superior, the largest of the North American Great Lakes.  The Tsushima Current that flows through the Korea Strait also ensures a steady supply of warm water along the Japanese coast during the winter.  Third, the sea-effect precipitation systems that form over the Sea of Japan (basically the equivalent of lake-effect snow) run into the formidable topography of Honshu and Hokkaido Islands.  

Utahn's are rightfully proud of the snowfall in Little Cottonwood Canyon, but it is worth comparing the numbers from the Town of Alta to Sukayu Onsen.  Not only is the seasonal snowfall more plentiful at Sukayu Onsen, but after a slow start in October and November, it also comes much faster, especially during the peak of the East Asian Winter Monsoon from December to February.  Basically, climatology is a 3-month pig wallow with an average of more than 140" in each of those months, peaking at 180" in January, more than double the Town of Alta.  

This year the snow in has come fast and furious, with skiasia.com reporting remarkable snow depths last month.  Current snow depths in central Honshu include 169 cm/67" at Shirakawa (478 m/1568 ft elevation), 150 cm/59" at Tsunan (452 m/1483 ft), 163 cm/64" at Oisawa (440 m/1444 ft), and 188 cm/74" at Hijiori (330 m/1083 ft).  All of these sites are south of 38.6ºN and at relatively low elevation.

Source: JMA

Given that the Japanese Meteorological Agency (JMA) does not have any high elevation observing sites in central Honshu, I took a look at the snow report for Hakuba Cortina Ski Resort in the northern Hakuba Valley near the Sea of Japan (location on map below).  It is reporting at current snow depth of 340 cm/134 inches.  Event that is probably an observation from below 1400 m/4593 ft as the resort is on the lower slopes of the Hida Mountains.  

Source: Google Maps

A look at the map above for central Honshu illustrates the remarkable transition in snow climate across Japan.  At low elevations near the coast, snow depths are < 35 cm/14".  These areas are actually quite wet during the East Asian Winter Monsoon, but they experience more precipitation in the form of rain.  Going inland and up in elevation and you get into much deeper snowpacks, even at the lower (< 1600 ft) observing sites operated by JMA.  Go across the mountains to the east side of Honshu and there is no snowpack at lower elevations.  

In northern Honshu and southwest Hokkaido, Sukayu Onsen (890 m/2920 ft) is at 380 cm/150", which is down from their peak at over 400 cm.  Kutchan (176 m/577 ft), which is near the base of the Niseko United Resorts, is at 147 cm/58".  

Source: JMA

Media reports suggested that Kutchan was at record snow depths at times in December.  I suspect that's not the case currently, but cannot confirm this.  Regardless, it is an impressive start to the Japanese snow season.