Happy New Year to all, have been on holidays, sorry for the lack of posts. But I am back to decipher the long range snowfall forecast for Japan. Looking like a pretty nice season so far, with plenty of powder to play with. But what’s happening next? I will try and answer that, with a look at the drivers and models….
EPS Control shows a low crossing Honshu on the 19th, and directing NW winds into Honshu and Hokkaido, bringing moderate-heavy snowfall to the former and light-moderate snowfall to the latter, until at least the 22nd(except on the 19th, when Hokkaido gets heavy snowfall). GFS dismisses this forecast though, with light snow showers across the period in weird spots across Honshu.
EC Monthly forecasts a deep low, bringing rain to Honshu on the 24th and early 25th, before a period of NW winds, that bring heavy snow to Honshu from around 25th midday onwards. This sea effect snow brings light-moderate snowfall to Hokkaido and heavy snow for Honshu, until late on the 29th. CFS shows a NW wind fetch, bringing moderate-heavy snowfall to Honshu and Hokkaido, from late on the 25th to the 8th of Feb! That’s a long period for sustained NW winds, and that would be a massive dump of snow.
30 Jan-1 Feb
EC Monthly shows a trough impacting Honshu late on the 30th and early on the 31st. This brings rain down low and snow up high. Once the trough has moved out by 31st afternoon, the snow level will fall and the NW winds will come. Then heavy snow falls until late on the 1st of Feb in Honshu, only lighter snowfalls in Hokkaido. CFS continues to show NW winds, bringing moderate snow to Honshu and Hokkaido.
EC Monthly shows another low crossing on the 2nd of Feb, bringing NW winds and heavy snow for Honshu and Hokkaido later that day. The snow continues until late on the 3rd. CFS shows NW winds during this period, that deliver moderate-heavy snow for Honshu and Hokkaido.
5th Feb and beyond
EC Monthly hints at a warm low coming up along Honshu, and bringing rain to the resorts on the 5th Feb. CFS shows NW winds and moderate snowfall for Honshu and Hokkaido, until the 8th of Feb.
Climate DriversMost Monthly models or sub-seasonal models, show the MJO to enter Phase 7 during Early February, which is the best MJO Phase for more snowfall in Japan. Amplitude may be quite strong, but I expect the MJO signal to weaken during this phase, based on La Niña influence. EC Monthly(below) shows a weak MJO for Late Jan, going against what I think, but I predict it will change to a stronger MJO outlook soon enough.
The GWO is currently in Phase 1, and is expected to move into Phase 2&3 in the next week or so. A potential change to a Phase 4 GWO is forecast later in the month. The most favourable phases for Japan look to be Phases 6,7,8.
EPS(below) currently forecasts the Arctic Oscillation to be negative for the next two weeks (favourable for Japanese snowfall). GFS shows a positive AO in the second week in the latest run.
The Stratosphere continues to favour a +AO pattern, with a cold and stable polar vortex…
Overall, the Stratosphere isn’t favourable, but you still have Niña forcing that helps a bit. The AO forecast is a bit all over the shop, and the MJO looks good. The next phase of the Japanese Snow Season, could be good or it could be great. That may hinge on where the MJO signal goes, and how that affects the global jetstream.
Thanks so much for reading. I hoped you enjoyed reading it.
Disclaimer: There is low skill asssociated with using long range model forecasts to find snow systems. All systems you see here will change, as the date gets closer and may not eventuate all together. I don’t give much accuracy to these forecasts, but you can give these a bit of your time and your dreams might come true 😉 I find the chase of these long range snow systems awesome, so come and join me! The climate driver forecasts tend to have a bit more skill than the model forecasts, but certainly don’t put all your money on them. However, climate drivers are an awesome tool to explain the weather around us.
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