Japan on the long term 17th Dec

Hey, welcome back to another Japan on the long term, where I focus on the longer range model forecast, and the climate drivers that control the models. Just a handy hint when looking long term: the models follow the drivers, not the other way around. So take that into consideration, when watching models. Anyway, let’s get into it….

27-31 Dec

GFS shows a NNW wind fetch developing on the 27th, dumping snow across Honshu. The associated low brings heavy snow to Hokkaido too. The system gradually weakens over the 30th and 31st. EPS Control agrees with GFS, showing a NNW fetch for Honshu and Hokkaido in this period.

1-4 Jan

EC Monthly shows a low crossing Honshu on New Years Day, bringing moderate-heavy snowfall to Honshu after the main system has passed until the 3rd. The NNW winds favour Hokkaido as they move east on the 3rd and 4th, bringing moderate snowfall there. CFS shows a NNW fetch from the 1st through to the 3rd for Honshu, bringing moderate snowfall. It continues to the 5th for Hokkaido, with moderate snowfall on CFS for there too.

5-10 Jan

EC Monthly shows a prolonged period of good snow potential for Honshu. On the 5th, into the 6th, a big system crosses Japan, bringing potentially wet precipitation to all of Japan, but soon turns colder with NNW winds settling in later on the 6th. This brings moderate-heavy snowfall from the 6th through to the 9th for Honshu and Western Hokkaido(Niseko area), before the snowfall contracts to Northern Honshu, and fully weakens by the 10th. CFS shows a low crossing Honshu on the 6th and 7th, bringing a northerly wind for Honshu and Hokkaido from the 7th to the 12th, bringing moderate snowfall to both of those islands.

11-14 Jan

EC Monthly shows a lot of potential for a low to suddenly strengthen in the Sea of Japan on the 11th, and travel over Hokkaido, bringing lots of snowfall there. This brings a NNW fetch to develop over Honshu and Hokkaido by the 12th, and brings heavy snowfall to Honshu. The snowfall weakens gradually over the 13th and early 14th. CFS shows a weak low being formed over the 12th and 13th, before crossing Japan, to form a northerly fetch for Honshu and Hokkaido on the 14th, with the latter getting the most snowfall.

15-16 Jan

There’s not a lot to say about this… except that it is ugly. EC Monthly shows a low bringing heat and rainfall to Central Honshu on the 15th, not a good look. CFS on the other hand shows continued northerlies from the 14th, continuing to the 17th.

Climate Drivers

MJO is currently in between Phases 6 & 7. Phase 7 MJO, particularly in a La Niña (which we are in), is correlated with more snowfall and more cold for Japan. GEFS shows the MJO basically to sit around in Phase 7 for at least the next two weeks, which will favour Japan in a week’s time. So the Christmas-New Years period and Early January is favoured for more snowfall, as per MJO. EPS(below) shows the MJO to go a little faster and weaken in the New Year, but it still favours Japan for more snowfall during the Christmas-New Years period.

GEFS shows weakening of zonal winds in the next two weeks, before restrengthening again. This creates a weaker vortex, that may cause a -AO setup to begin. However, the period of a weak vortex may continue longer than expected, with a warming of the vortex expected(below) to peak on the 29th Dec on EPS, before cooling back down before 2018.

This may weaken the vortex further, and continue a -AO setup. CFS(below) also believes this, and shows a change to a -AO by Christmas, correlated with more snowfall for Japan.

So the setup looks to change favourably for Japan around Christmas, with a -AO forecast, a weakening polar vortex, and a Phase 7 MJO. The signs look very good for Japan.

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.

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

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