The Japanese Meteorological Agency has declared a 50% likelihood that La Niña conditions will develop throughout autumn or winter.

The Japanese Meteorological Agency is, once again, predicting that La Niña is a chance (50%) of emerging before the season’s end. If this were to happen, Japan would likely experience one of its coldest, snowiest winters in recent years.

La Niña is a phenomenon that occurs when surface temperatures across the Eastern Central Pacific Ocean drop 3-5°C below average. This drop in temperature, if sustained, is significant enough to disrupt weather patterns worldwide. However, the effects of La Niña are notoriously difficult to predict.

In many parts of the world, La Niña is bad news (e.g. the 2010/11 Queensland floods). Not so for skiers in Japan. When La Niña occurs, temperatures across Japan plummet, leading to increased snowfall and a longer ski season.

The phenomenon last appeared in 2011/12, during which ski resorts across Japan were hit with record levels of snowfall. On the main island, Myoko Kogen – one of Nagano’s more popular resorts – recorded more than 23 m of snow, almost double its seasonal average of 13 m. Prior to this, the resort hadn’t seen snowfall in the +20 m range since 2005/06 – also attributable to La Niña.

Hirafu Village in Niseko, at just 250 m elevation, saw more than 15 m of snowfall throughout the 2011/12 season. Measurements taken by 360niseko show that it snowed almost daily, with only 27 snowless days across a 147-day period – at ground level!

It’s worth noting that similar predictions were made of last season, and, of course, failed to eventuate. Temperatures in the Pacific dipped to 0.8°C below average across a 3-month period – not enough to have any significant impact on the Japanese winter. As a result, Japan’s ski season failed to bring about the record snowfalls that were initially forecast.