Archive | January, 2020

Where has the snow gone this Winter in Japan?

The amount of snow coming down in Japan this winter has been rough. Snow fall has been at record lows and many ski resorts have been suffering . For example in Sapporo the first non-white Christmas on record was seen in 2019. So I wanted to get to the bottom of this, here is a quick article explaining what is going on right now. I say quick because I know I could get a lot more detailed but I wanted to keep it simple and to the point as to why this winter has failed overall for Japan.

My first thought on this terrible winter in Japan may be the ENSO phase. In 2015 to 2016 it was extremely strong. One of the strongest on record so it was easy to blame the poor winter that year on that. But this year it is neutral so I took that off the table. Follow this link for a look at the current ENSO Phase >>> https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml#current

Instead it seems the problem in Japan is more broad; meaning the overall temperature this year has been high on average. In fact in 2019 Japan had it’s warmest average temperatures in the country on record. It’s not just Japan though, Moscow had its warmest December temperatures on record in 2019 and this overall temperature trend has extended east well in to Siberia where cold air masses control the general weather pattern for East Asia; if you mess with that you mess with the overall pattern. This summer and Autumn in South East Siberia this year wild fires burnt huge swaths of the area, this along with the warm temperatures have been linked to an increase in the AO index pushing it to a positive phase.

https://advances.sciencemag.org/content/6/2/eaax3308

What is the Arctic Oscillation? Simply put it indicates that the Jet Stream is not meandering very much. Which is problematic for Japans weather. If you don’t have deep jet streams to fuel deep lows then you don’t get the big sea effect snow makers in to the mountains of Japan. Instead what we have been seeing are more weaker southern coast lows, this bring rainfall over Tokyo and snow in the higher peaks but nothing on PAR with a good cold surge, the type of setups that make the snow in Japan famous.
In all my years working in Japan and researching Japanese weather I’ll be honest I’m a bit baffled by this, typically by February the pattern changes as cold air finally sets in over Siberia. This year this pattern change has not yet developed.
WHAT CAN CHANGE THIS PATTERN?
A few things, a mild summer in Siberia for starters will be a big player. But on a more immediate time scale a large low off of Japan can snap the long range jet stream in to place. Think of whipping a rope and watching the waves bow out from it. Even if this did take place it would mean one or two big storms across Japan to wrap up the season. Enough to make people happy but the overall pattern would need to change and big shift to a Negative Phase of the AO. Which at this time numerical model ensembles including the GFS and ECMWF outputs indicate the phase will not only stay positive but get even stronger through the Month of February shown below. This means overall the rest of the winter may be shot.

Most important for next year would be less wild fires in Siberia and hopefully temperatures being all around cooler than this year. With the general trend on the up and up thanks to our changing climate one can only hope.