The Low That Might Just Ruin Christmas

Japan’s snow season has not got off to the best start this year, particularly on Honshu. Many resorts are still unable to open due to lack of snow and those that have are offering only limited skiing.

For the past week everyone’s been hoping the weather system moving over Japan from today into the weekend will finally get the season underway. But with forecast totals dropping daily there are more than a few people wondering if Santa is going to come through with the goods or not.

Here’s the current outlook:

Myoyo snow report

image: snow-forecast.com

Let’s have a look at what’s really going on:

All weather maps are taken from snow-forecast.com. Click through to their site for more details.

The chart below shows us the current situation. The pressure gradient between the big high over China and the low to the west of northern Honshu has set up a northerly airflow that is funneling cold air down across the Sea of Japan from Siberia. This looks like it should develop into the classic NW airstream that is responsible for Japan’s big, dry snowfalls. That’s what the models were picking up earlier this week and why such big snowfall figures were cast about for the next two days.

myoko snow report

This pattern will see the temperatures drop in Honshu over Christmas day as the cold air moves in. It was siting around zero in Akakura, Myoko at 6am this morning and there was some light rain around.

We’ll probably see a bit of more rain lower down early today as the temperature falls but we should have some snow by tonight. Then things go a little pair-shaped as the small low-pressure cell in the top left of the frame above establishes itself over the Sea of Japan and disrupts the northerly flow tonight. This pushes warmer air from the west in over the southern Japanese Alps and is responsible for the temperature spike forecast through Saturday in Honshu. Hokkaido is doing better out of this.

Screen Shot 2015-12-25 at 7.27.53 AM

By Saturday night the low has moved out into the North Pacific and we’ll see a cold northerly airflow again as the isobars bunch up. This will bring temperatures right down across Japan and should give us the best snowfall from this system.

Screen Shot 2015-12-25 at 7.28.08 AM

The high takes control as of Monday morning in Honshu. Hokkaido should still be cold and snowy under an established NW airflow, but resorts further south such as Hakuba and Myoko will be hanging their hopes on whatever snow we can squeeze out of this system through Sunday. On the upside, we’ll see low temperatures and light winds into next week – great weather to get out and enjoy whatever snow is on the ground.

Myoko Snow Report

So what does this all mean?

First, we’ll still get snow. Christmas won’t be ruined, but it might be a bit damp to start with and we’re probably not going to see enough snow through today to allow resorts to open properly. Boxing day will be warmer than we’d like, and the best snow from this system is likely to come through from tomorrow night through Sunday. The resorts in Honshu are right on the edge of this NW airflow so things could still go better than expected. If low stalls out to the east of Japan and the high over China is weaker than expected we could see the strong NW winds and a lot more snow than expected through Saturday night and Sunday.

Let’s hope it’ll be a happy new year for Japan!