Welcome to our first long term forecast for Japan this season.
GFS is looking at moderate-heavy snowfall for Honshu and Western Hokkaido from the morning of Boxing Day, through to at least the 29th of Jan. EPS Control shows rain from a southern low on Christmas, and then moderate-heavy snowfall for the same areas on the 26th. These falls lighten to showers on the 27th and 28th.
Looking like a quick one over just one day on EC Monthly, wet first up for Central Honshu and moderate-heavy snow later from the NW. Snowfall for Northern Honshu and Southern Hokkaido as well throughout.
3rd to 5th January
Nice and cold starting on the afternoon of the 3rd, lasting moderate-heavy snowfall for Central & North Honshu and Western Hokkaido over the 4th and 5th, contracting north on the morning of the 6th, before ending. So 2-3 days of solid snowfall for Honshu, and some for Hokkaido as well.
Another low from the south, just far enough south to have some cold on the northern flank for some wet snowfall. But still marginal here on EC Monthly
A day of snowfall from the afternoon of the 8th to the morning of the 9th, with moderate-heavy snowfall for Honshu, with most of Hokkaido largely left out.
We are likely to see a weak Phase 6-7-8 MJO influence on the climatic pattern. This may bring a mild positive influence on Japanese snowfall.
The Arctic Oscillation is also looking desirable for Japanese snowfall…
Yes, I say Eastern US and Europe, but the same logic applies to Japanese snowfall, giving us good chances over the next few weeks. This period of negative AO could possibly end in the last week of December, leaving us with a far less favourable outlook in the New Year.
A key factor here is the distribution of momentum in the atmosphere, specifically from the East Asian Mountain Torque:
- 13th-19th Dec, +EAMT produces conditions conducive for Japanese snowfall.
- 20th-26th Dec, -EAMT produces conditions less conducive for Japanese snowfall.
- 27th-31st Dec, beyond perhaps, +EAMT comes back and helps re-calibrate Japanese snowfall prospects again.
It also looks like the Aleutian low will strengthen later in the month, and same for the Siberian High, both helpful for Japanese snowfall:
I can definitely see good snowfall prospects for the last days of the year, and the first week of January. We will have to wait and see beyond that. But looking good overall.
Thanks so much for reading.
Disclaimer: There is low skill asssociated with using long range model forecasts to find snow systems.
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