Japanese Snow Season Outlook 2017-18

Hello. It’s the Snowy Hibbo, back for another season of Japanese snow forecasting. If you haven’t read one of my outlooks before, I basically talk about long range snow opportunities for the Japanese and European Alps, as well as the Western North American mountains. Last season, I focused on model outlooks, primarily the EC Monthly model. This season I will include that, along with climate driver outlooks, and seeing how they will affect snowfall in the long range.

Today’s blog will include a full seasonal forecast for the Japanese Alps. So let’s get started.


ENSO or the El Niño-Southern Oscillation, is a major global climate driver. But it doesn’t mean too much for Japan, at least for the way ENSO is going.

This is the EUROSIP Niño plume from last month. EUROSIP is made up of Met France, ECMWF and the UKMO models. For this chart, forecasts from CFS and JMA models are added in too.

Most other indicators show that we are going into a weak La Nina. Bare in mind that the EUROSIP chart was from last month, where La Niña was forecast to be much stronger, than it is now. Here is another ENSO plume from the POAMA model, made by the BoM (Aus).

So the overall current forecast for ENSO is a borderline-weak La Niña. What does this mean for Japan? Not too much, the correlations are pretty weak. However, there is somewhat higher probability of a better than average snowfall season for Japan, with a La Niña. But this doesn’t mean too much, given that the La Niña is weak and the correlation is pretty weak.


The Siberian High is an important, yet relatively unknown driver for snowfall in the Japanese Alps. A strong, stable Siberian High provides very cold air down towards Japan, except if the High is too far west. This cold air from the Siberian High creates the lake effect, that provides the massive snowfalls in the Japanese Alps.

The Siberian High is affected by a number of things, including snow cover in the region and the AO. A negative AO causes a stronger Siberian High. The Siberian High is also affected by the snow cover in Siberia during October and November. This year’s snow over is above average. An above average Siberian snow cover creates an early, potentially more stable Siberian High. It also correlates with a negative AO.

Arctic OscillationAs mentioned before, the AO or Arctic Oscillation affects the Siberian High. But it also affects the general polar jetstream and how systems move through the mid latitude regions of the Northern Hemisphere. A negative AO creates a favourable Siberian High, and a strong East Asian Winter Monsoon. A strong East Asian Winter Monsoon is linked to more snowfall for the Japanese Alps. So a negative AO correlates to more snowfall in the Japanese Alps.

Factors that create a negative AO, include strong blocking in polar regions, above average snow cover in Siberia in Autumn, Low Sea Ice in the Barents-Karas Sea in Autumn and a -QBO. These factors have largely been satisfied. We currently have strong blocking forecast for the next week or so in the Arctic. We have a above average Siberian snow cover, as mentioned before, and below average sea ice in the Barents-Karas Sea. We also have a -QBO. So there is a good chance we will have a generally negative Arctic Oscillation winter, particularly during January and February. This is good for Japanese Alps snowfall.

For fun, here is the CFS forecast for the Arctic Oscillation over much of winter.

CFS shows a generally negative Arctic Oscillation December and January, which is consistent with my assessment above.

Model Outlooks

Now we will take a look at the individual models.

CFS shows ridging (high) over Japan over the winter period.

EC (considered the best seasonal model of the bunch) shows a ridging pattern throughout winter. This is just the January EC 500mb anom forecast, but the other months also have ridging over Japan.

CanSIPS will be our last model to review (the Japanese model is outdated and needs to hurry up and update!). It shows ridging again over Japan.

So the models seem to have a consensus on ridging over Japan for winter. This means less potentially snow bearing lows can get through (however much of Japan’s snowfall is caused by lake or sea effect snow). Looking at the climate drivers, it looks like a good winter for Japan, with a -AO pattern and a weak La Niña. I will go for a somewhat above average season for Honshu and Hokkaido. Many might think differently, but regardless this season should be interesting!

Thanks so much for reading.

Seasonal outlooks tend to have bias and errors, due to the fact that these forecasts are so far out. So don’t use these outlooks to make important decisions. These outlooks is meant to be interesting information, that can help to see what the season might be like.

This took a lot of work, so I appreciate your support. Starting in December, my long range outlooks for Japan will start! They will be produced every 2-3 weeks, looking out into the range of 10-30 days out. This season, I will explore climate Drivers as well, including the PNA, MJO and others. Stay tuned.

Thanks again for reading, follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above.

Stay Cool

Snowy Hibbo

4 thoughts on “Japanese Snow Season Outlook 2017-18

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