Japan The Japanese snow season 2020-2021 Weather

[Sandy]

After a long and wet rainy season (June/July, 6 weeks instead of 3, record low sunny hours for Tokyo, and most rain in July in 20 years), it was followed by summer heat, the hottest August on record (daily av max 34.1C in Tokyo), with very little rain. (it suddenly switched from cloud and rain, to heat and dry on 1st August). Hamamatsu in Shizuoka prefecture, recorded the equal highest temperature ever recorded in Japan (41.1C, along with the regular summer humidity), and 40 degrees in Niigata prefecture, which is unheard of on that side of the mountains. You have to remember, this is a country that gets snow down to sea level in winter in Tokyo.

The heat has continued into September, maybe 2 weeks longer than normal, but it changed a little about a week ago, and by this coming Sunday, we will finally hit the slippery slope back towards winter in central Japan.
How do we know? Forecasts show that Sunday will be the first sub 20C degrees nights in Tokyo since May, with maximum temperatures forecast to be consistently below 30C degrees. This is what I call "late summer".

So here it is..... Post away, and here's hoping that some of you can make your way here to Japan after COVID, while the powder is still here.
I will make sure that I give regular reports on the consistency and depth of the powder, first hand!!!!

 

[hotsaki]

Thanks Sandy.Looking forward to sweltering in the Darwin wet season and reading of the deep pow that you will be enjoying.Pass the razor blade please.

 

[Sbooker]

I’m keeping hold of the dream to be able to travel internationally in the Easter school holidays. Anywhere in Japan have reliable conditions early April? Would have to be high and north facing I’d think.

 

[Sandy]

I’m keeping hold of the dream to be able to travel internationally in the Easter school holidays. Anywhere in Japan have reliable conditions early April? Would have to be high and north facing I’d think.

Hokkaido. They still get some powder then.

And also in some years, you get occasional powder in central Japan.... Some of the bigger resorts are normally open until the first week of May.

 

[Sandy]

Mt Fuji had its first snow for this season on Monday (21st September)

 

[ojisan]

Mt Fuji had its first snow for this season on Monday (21st September)

how does the timing compare to previous years?

 

[Asama]

how does the timing compare to previous years?

Surprisingly tricky question, as the JMA (met office) hasn't officially called it yet because it doesn't meet their criteria for announcing first snow. The snow needs to be visible by eye from a specific weather observatory to become official, so if the snow melts before the clouds break (as I guess is the case here) it doesn't really get recorded.

Having said that, I think it is relatively early this year. Wouldn't read much into it though as it's been a warm (maybe very warm?) September so far.

 

[Sandy]

how does the timing compare to previous years?

Surprisingly tricky question, as the JMA (met office) hasn't officially called it yet because it doesn't meet their criteria for announcing first snow. The snow needs to be visible by eye from a specific weather observatory to become official, so if the snow melts before the clouds break (as I guess is the case here) it doesn't really get recorded.

Having said that, I think it is relatively early this year. Wouldn't read much into it though as it's been a warm (maybe very warm?) September so far.

Clouds have broken.

FUJIYOSHIDA, Yamanashi — Mt. Fuji was seen lightly dusted with snow at the top for the first time this season, the Fujiyoshida city government in Yamanashi Prefecture announced Monday. The snowfall came about a month earlier than last year.

Since 2006, the city located at the base of the mountain independently confirms the snowfall on Mt. Fuji and issues a declaration separately from one released by the Kofu Local Meteorological Office.

Rain is believed to have turned into snow at the mountaintop due to cooler temperatures over the holiday weekend, according to the local government.​

 

[Asama]

Clouds have broken.

FUJIYOSHIDA, Yamanashi — Mt. Fuji was seen lightly dusted with snow at the top for the first time this season, the Fujiyoshida city government in Yamanashi Prefecture announced Monday. The snowfall came about a month earlier than last year.

Since 2006, the city located at the base of the mountain independently confirms the snowfall on Mt. Fuji and issues a declaration separately from one released by the Kofu Local Meteorological Office.

Rain is believed to have turned into snow at the mountaintop due to cooler temperatures over the holiday weekend, according to the local government.​

I think I read it was the 2nd earliest in the 16 years these records have been kept, but wasn't sure what "these records" were. Now I know

 

[Sandy]

I don't know where to post Autumn Weather related thingy, is it here?

It seems forecasting accurate typhoon routes a few day ahead is still a bit difficult even in 2020. A few days ago, weather forecasters were saying "A typhoon is coming and it's likely to hit Tokyo - Ibaraki (It's where we own a hobby farm)", so we were a bit scared but actually, it's not hitting here. This is the forecast we saw a few days ago.

And this morning's forecast (the same typhoon)

 

[Asama]

Well, the long range JMA winter predictions are out.

The magic 8-ball says:
Temps average for most of Japan and average-to-warm for Hokkaido.
Snow average for Honshu, maybe under average for Hokkaido (sure Hokkaido can manage...)

In massively abridged summary they seem to be banking on la nina counteracting the global warming effect to give a more-or-less average winter.

Will leave here for posterity so we can see how they did in 6 months time.
To be fair, last year they called "warm" and they weren't wrong.

 

[Ramenman]

Basically, I don't count on any long term weather forecasts at all, but I often hear Japanese media say "La Nina can cause abnormally heavy snow".

La Nina sometimes brings heavy snow to a bit unusual places too. 0cm snow depth, then a crazy snowfall hits and it can make a house look like the image below within a day.

 

[Sandy]

Basically, I don't count on any long term weather forecasts at all, but I often hear Japanese media say "La Nina can cause abnormally heavy snow".

La Nina sometimes brings heavy snow to a bit unusual places too. 0cm snow depth, then a crazy snowfall hits and it can make a house look like the image below within a day.

There's a small correlation between La Nina & snowfall in some parts of Japan.
I've researched this, and here is some data(1994/95 to 2015/16):
Snowfall:
Myoko Kogen:
Average 1487cm
La Nina: 1756cm
El Nino: 1308cm
Neutral: 1332cm

Yuzawa:
Average 1369cm
La Nina: 1560cm
El Nino: 1121cm
Neutral: 1320cm

The worst La Nina years in that period came in around 1450cm.
The best La Nina was 1876cm for Yuzawa, and 2324cm for Myoko Kogen.

Strong El Nino is the worst. (but weak El Nino can still bring good snow ~ 1800cm was the best)

 

[Asama]

I think the La Nina/snow correlation tends to be brought up more with reference to the Pacific side. As far as I know there's no clear causal link, except generally colder weather increasing the chance of a Pacific low being able to cause heavy snow. Could be wrong on this.

I think @Ramenman 's first diagram is about the position of the jet stream - not directly related to la nina. But that position is a good place for it, I think. Warm air gets stuck to the south and cold air gets stuck to the north of the jet stream, so if it meanders north of Honshu that's trouble...

 

[Ramenman]

I think the La Nina/snow correlation tends to be brought up more with reference to the Pacific side. As far as I know there's no clear causal link, except generally colder weather increasing the chance of a Pacific low being able to cause heavy snow. Could be wrong on this.

I think @Ramenman 's first diagram is about the position of the jet stream - not directly related to la nina. But that position is a good place for it, I think. Warm air gets stuck to the south and cold air gets stuck to the north of the jet stream, so if it meanders north of Honshu that's trouble...

The image is from this website. I know Asama-san can read Japanese, so if you are interested in, read it
https://weathernews.jp/s/topics/201802/160125/

 

[Sandy]

I think the La Nina/snow correlation tends to be brought up more with reference to the Pacific side. As far as I know there's no clear causal link, except generally colder weather increasing the chance of a Pacific low being able to cause heavy snow. Could be wrong on this.

I think @Ramenman 's first diagram is about the position of the jet stream - not directly related to la nina. But that position is a good place for it, I think. Warm air gets stuck to the south and cold air gets stuck to the north of the jet stream, so if it meanders north of Honshu that's trouble...

El Nino / La Nina is associated with the Southern Oscillation Index. It essentially indicates abnormal Sea Surface Temperatures(SST) and currents, which are Pacific wide. They affect floods and droughts in Australia, North & South America and weather in east & SE Asia.
Typical La Nina producing drought in S. America and high SSTs in Sea of Japan, and wetter conditions in Australia:

It conducive to more evaporation off the Sea of Japan when the Lake/Sea Effect happens, leading to more snow.

Typical Strong El Nino producing floods in S. America, and low SSTs in Sea of Japan when the Lake/Sea effect happens, leading to less evaporation and less snow:

As for jetstreams, they are fast moving stream of air at 8000-11,000m(high level), affecting the severity and position of low pressure systems.
However, this is NOT the mechanism that produces most of the snow in Japan (particularly central Japan).
The cloud is low level cloud created by the Lake/Sea Effect, not higher level cloud. The requirement is for very high pressure across southern Siberia & Mongolia, which with clockwise rotation produces a long fetch prevailing northerly/NNW wind across the Sea of Japan.

This picks up evaporated moisture from the sea, due to temperature differential. This cloud is low level, so a lot of orographic lift occurs when it hits the Japan Alps, causing huge snowfall.
Here is lake/sea effect cloud

The position of the jetstream is important, because it needs to be well south of Japan, so it doesn't create low pressure troughs like it did last season when the jetstream was right over the top of Japan in January. i.e. Better not to have ANY pressure troughs during the winter (which is completely opposite to just about anywhere else in the world). Pacific & Sea of Japan lows are disruptive to good snow in Japan.
Typical Jetstream positions winter summer:

See here:
https://www.ski.com.au/xf/threads/snow-forecasting-tutorial-for-japan.63512/

 

[Asama]

Thanks @Sandy
As far as I can tell you give the best explanation of this anywhere on the internet.

Pacific & Sea of Japan lows are disruptive to good snow in Japan.

Yes, if you're a skier on the SoJ side of the mountains... where I am it's the Pacific lows that bring the biggest snowfalls so ideally one or two of those will pass through each month to keep the snowpack maintained. We get lake effect snow too but rarely in the quantities needed to build up a resilient base layer.
Of course this has nothing to do with skiing, and everything to do with my desire for Christmas card scenery.

Got the kotatsu out today. Looking forward to temps dropping properly next week once the rain clears off.

 

[Sandy]

Thanks @Sandy
As far as I can tell you give the best explanation of this anywhere on the internet.


Yes, if you're a skier on the SoJ side of the mountains... where I am it's the Pacific lows that bring the biggest snowfalls so ideally one or two of those will pass through each month to keep the snowpack maintained. We get lake effect snow too but rarely in the quantities needed to build up a resilient base layer.
Of course this has nothing to do with skiing, and everything to do with my desire for Christmas card scenery.

Got the kotatsu out today. Looking forward to temps dropping properly next week once the rain clears off.

Ok, so you must be somewhere around Karuizawa? I was thinking maybe around Minakami initially, where they get more lake/sea effect snow, but Karuizawa/Asama are far from the coast.... You'd get snow on the days we get snow in Yokohama!!

 

[Ramenman]

It might be a bit off-topic, but I don't know where to post this, so I'll post this here. I heard some people say global warming have made Japan less snowy, but it's not actually correct. Having seen some data on JMA's website, latest 20 years (= 2000 - 2020) doesn't look less snowy compared to 1980 - 1999. For example, this is Hakuba's yearly snowfall. JMA started recording snowfall in Hakuba (at 703m asl) in 1981. As you can see, 6 out of 10 snowiest seasons of the last 40 years are in the last 20 years (between 2000 and 2020).

Hinoemata (Fukushma Pref, 973m asl). Started recoding snowfall in 1983 and 5 out of 10 snowiest season are between 2000 and 2020.

Yuda (Iwate Pref, near Geto Kogen, only at 250m asl). Started recording snowfall in 1980, and 5 out of 10 snowiest seasons are between 2000 and 2020.

1950 might have had more snowfall, but at least, 2000 - 2020 has had almost as much as snow compared to 1980 - 1999.

 

[Asama]

Ok, so you must be somewhere around Karuizawa? I was thinking maybe around Minakami initially, where they get more lake/sea effect snow, but Karuizawa/Asama are far from the coast.... You'd get snow on the days we get snow in Yokohama!!

Yes, Tsumagoi - halfway between Karuizawa and Kusatsu, and a climate kind of halfway between the two as well.
When Tokyo gets a few cm, we can get buried. I guess we also get the dregs of the lake effect when Shiga kogen is catching it.

 

[Ramenman]

Asahidake this morning

 

[Sandy]

Beautiful day today in Yokohama, (26 degrees, 45% humidity), sunny and the air was very clear after the humid, hazy summer sun of the last couple of months.
Snow on Fuji this morning, looks like about 800m down from the top.

 

[Asama]

Beautiful day today in Yokohama, (26 degrees, 45% humidity), sunny and the air was very clear after the humid, hazy summer sun of the last couple of months.
Snow on Fuji this morning, looks like about 800m down from the top.

Here too, high of 16 degrees and down to 7 degrees last night. Chilly in the shade but lovely in the sunshine. Good to feel the season really pushing forward now.

Looks like we will enjoy similar weather for the rest of this week too, which is a bonus.

 

[Ramenman]

Some amount of JMA's weather stations are showing between 0 and 5 degree this morning. JMA's weather station at 820m near our lodge in Fukushima is 3.8 degree (The name of the weather station is 桧原=Hibara). The mountain ridge is 2,000m. So, if there was precipitation on the mountain, it could be snow, not rain early this morning.
https://www.jma.go.jp/en/amedas_h/today-36106.html?areaCode=000&groupCode=25

 

[Asama]

Nobeyama in Nagano dipped below freezing last night - first place to record sub-zero this autumn. Interesting that Honshu got there before Hokkaido, I wonder how common that is.
Obviously we don't know what the temperatures are in places w/o weather stations, so daresay the mountains of Hokkaido are still colder...

 

[Sandy]

Nobeyama in Nagano dipped below freezing last night - first place to record sub-zero this autumn. Interesting that Honshu got there before Hokkaido, I wonder how common that is.
Obviously we don't know what the temperatures are in places w/o weather stations, so daresay the mountains of Hokkaido are still colder...

I suppose it depends mainly on the elevation at this time of the year. Plus how low the humidity is, and clear the skies.
Nobeyama is 1350m. Yatsugatake (volcano group) is only a few km to the west, so I guess it's possible that on clear nights, there's a lot of cold air flowing off the mountain, down from 2800m.

It's also interesting that quite often, the coldest weather station in Japan is at Sugadaira, in Nagano prefecture, at 1250m. I've looked at the topography, and it's in a plateau surrounded by mountains, with only one pass heading down off the plateau... on a clear night air drains through the pass, and then drags very cold air off the surrounding mountains... I've often seen it getting down to -23 or -24 degrees.

 

[Ramenman]

Nobeyama in Nagano dipped below freezing last night - first place to record sub-zero this autumn. Interesting that Honshu got there before Hokkaido, I wonder how common that is.
Obviously we don't know what the temperatures are in places w/o weather stations, so daresay the mountains of Hokkaido are still colder...

Nobeyama is your rival village, I mean, they are also very famous for summer-time-cabbages

Near Nobeyama, there is 北斗市 (Hokuto city), Yamanashi prefecture. The village is popular in recent years. Good summer heat escape, close to Tokyo and cheaper than Karuizawa. It's very dry (longest sunshine hours in Japan), but not all people love skiing, so it's not a problem for Hokuto city. There is a ski resort there too. It's very cold, but the snow there is artificial snow like Chinese ski resorts. High altitude inland basins tend to be super cold in early morning of sunny days.

 

[Asama]

It's also interesting that quite often, the coldest weather station in Japan is at Sugadaira, in Nagano prefecture, at 1250m. I've looked at the topography, and it's in a plateau surrounded by mountains, with only one pass heading down off the plateau... on a clear night air drains through the pass, and then drags very cold air off the surrounding mountains... I've often seen it getting down to -23 or -24 degrees.

Sugadaira can be a bit weird - as you say generally very cold, but sometimes I've noticed (in winter) it can have a much higher temperature than the surrounding plains. Guess some sort of temperature inversion, but I don't understand the mechanics of that at all.
I pass through there if I'm heading towards Nagano (city). I like the vibe - interesting combination of sports and farming.

 

[Sandy]

Lows of 13 & highs of 18 degrees forecast for Tokyo later in the week!!!!
More snow for Mt Fuji, I'd say!

 

[Ramenman]

A typhoon is coming this weekend and local farmers are worried and local surfers are excited now.

 

[Sandy]

And here it is:

Since the typhoon looks like skirting to the south of the Pacific coast, the winds will be more to the NE and north on the western flank, keeping temperatures low. An overnight low of 12 degrees is forecast for Tokyo on Saturday morning, which is more consistent with this time in November.
Normally a path further to the north would drag warm air from the south, on the eastern flank of the typhoon. This also explains why temperatures will be a lot warmer in Kyushu.

 

[Ramenman]

Local media were reporting this morning "As an early October day, yesterday was the coldest in the last 41 years for Tokyo". The daily high temperature was low yesterday, but didn't know it was that rare.

 

[Sandy]

Local media were reporting this morning "As an early October day, yesterday was the coldest in the last 41 years for Tokyo". The daily high temperature was low yesterday, but didn't know it was that rare.

Yes, I knew this was very unusual.... It only got to 15.4 degrees yesterday in Tokyo (and 15.5 here in Yokohama)
There's been continuous rain in Yokohama since Wednesday afternoon up to midnight last night, with 92.5mm, and a further 35mm from midnight to 9am, including 20.5mm in the last 3 hours.

The reason for the cold air is the typhoon.... it's quite slow moving, and because it's skirting the Pacific coast, it's been dragging a NE breeze across the northern half of Honshu. There's also been no sun for 3 days.
Not only has the air been chilly, it's cooling the ground, so I suspect that even when the wind changes, it will end up maintaining cooler temperatures. (no more 26-27 degrees)

 

[Sandy]

Ok, so although not a strong typhoon, it's been wet in Tokyo/Yokohama.
I live about 300m from the weather station in Yokohama, and we've had 172.5mm in 4 days (Wed afternoon up to 10pm Sat night).

 

[Sandy]

JMA seasonal forecasts.... I think most people knows that I don't put much faith in these. The % : % : % figure doesn't make sense IMO. (e.g. 30:30:40. Could mean 60% probability of average to below average and 40% probability of above average.... or 70% chance of average or above average... etc)
However, it looks like a La Nina, and here's the JMA winter forecast, for the record:
December:

Winter season (Dec - Feb)

 

[Asama]

JMA seasonal forecasts.... I think most people knows that I don't put much faith in these. The % : % : % figure doesn't make sense IMO. (e.g. 30:30:40. Could mean 60% probability of average to below average and 40% probability of above average.... or 70% chance of average or above average... etc)
However, it looks like a La Nina, and here's the JMA winter forecast, for the record:
December:

Winter season (Dec - Feb)

Well we shall see... but nice to see that map a colour other than red for a change.

 

[Ramenman]

 

[Asama]

Things starting to happen up in Hokkaido!

 

[Jacksong]

This is the best summary of information I can find on the internet regarding up-to-date weather predictions/info in Japan. Thanks to everyone for sharing.

I bet all of those who will be in Japan this winter are starting to get very excited.

Which ski resorts are usually the first to open?

 

[Sandy]

This is the best summary of information I can find on the internet regarding up-to-date weather predictions/info in Japan. Thanks to everyone for sharing.

I bet all of those who will be in Japan this winter are starting to get very excited.

Which ski resorts are usually the first to open?

Some of those in Hokkaido are first to open, and in central Japan Kagura is usually the first place.

 

[ojisan]

Some of those in Hokkaido are first to open, and in central Japan Kagura is usually the first place.

what about Fujiyama snow Yeti resort?
Isn't that due to open in the next couple of weeks on the shaved ice they are able to mass produce?

 

[Ramenman]

Things starting to happen up in Hokkaido!

初冠雪 = the first snowcap was confirmed on Mt.Teine and Hakkoda mountains too yesterday. Both are ski resort mountains which are not that tall. They say that the first snowcap on Hakkoda is 21 days earlier than last year and 2 days earlier than average year, which is good to hear after the very worst season

 

[Sandy]

what about Fujiyama snow Yeti resort?
Isn't that due to open in the next couple of weeks on the shaved ice they are able to mass produce?

Well, technically, Is it a resort you'd want to visit?

 

[David-eTO]

初冠雪 = the first snowcap was confirmed on Mt.Teine and Hakkoda mountains too yesterday. Both are ski resort mountains which are not that tall. They say that the first snowcap on Hakkoda is 21 days earlier than last year and 2 days earlier than average year, which is good to hear after the very worst season

Not that good if you can't go .

 

[skichanger]

It snowed at Shiga Kogen over night.

 

[Asama]

It snowed at Shiga Kogen over night.

Yes, snow on the ground at Shibu-toge on the Gunma/Nagano border too... about 2100m asl I believe.
Cold 5C rain here. Brrr.

 

[Ramenman]

Yes, snow on the ground at Shibu-toge on the Gunma/Nagano border too... about 2100m asl I believe.
Cold 5C rain here. Brrr.

That's nice, and I think it's actually snowing on a lot of mountains in Honshu now. I mean, Central Honshu (such as Japanese alps) has tall enough mountains to snow this morning. JMA has a weather station in Fukushima at 1200m asl and it was 2.7C this morning. It's a small weather station and snowfall is not measured / recorded there, but it's actually raining in the village site at 850m asl now and it means it's likely to be snowing between 1500m asl and 2000m asl, where we are usually skiing in winter

 

[Sandy]

Only 12.2 degrees in Yokohama this morning and dropping, which is unusual for this time in October.

 

[Ramenman]

A mountain road in Fukushima Pref is tweeting "Be careful, It's snowing this morning" (降 = fall, 雪 = snow, 降雪 = snowfall)


This is the mountain road in summer and closed between November and late April. They are saying it's snowing there now.

 

[Kobe]

Great discussion, very informative. I am new to looking at mainland Japan (I live in Okinawa), does the potential for early snow from La Nina also generally affect southern regions like Kansai having an early winter? My wife and I are interested in seeing Kyoto region changing leaf colors before skiing, and I'm trying to decide if should try earlier than normal this year.