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Discussion in 'Weather' started by Nozawaman, Nov 26, 2013.
Yeah I do, but perhaps you guys use a different more reliable source.
Ok, here's the NEXT installment of the terrain map snow guide for central Japan. Strangely enough, I only seem to get time to do this when the Xmas holidays roll around!!!!
This shows the approx locations of the major resort areas of northern Nagano and Niigata.
Things to note:
- Myoko, Nozawa & Yuzawa seem to cop the biggest snow of those areas, along with Cortina, which is more exposed to the wind than the other Hakuba resorts.
- Some conventional wisdom says that the resorts closest to the sea get more snow. However, this is not the whole story. For example, Yuzawa is further from the sea but gets a lot of snow.
More to follow.....
Good wind directions for various resorts. I will explain more a bit later, but it has to do with blocking, and early orographic lift.:
More to follow....
The key for Nozawa & Yuzawa is the ridge line I've indicated. I watched from the top of Nozawa, a bit of cloud pushing in from the north, hitting the ridge line, and seeing great blobs of cloud form right as you watch. This thicker cloud then pushes across Nozawa and further inland to Yuzawa. Since the ridge line is curved, almost like a focus on Nozawa, Nozawa can get big snow from a number of directions. Yuzawa's directions are a bit more specific.
Yasuzuka to the north of Nozawa, at 126m often gets a lot of snow when the winds are lighter and the cloud is unable to push over the mountains from the coastal plain. It's a good indicator for wind direction and snow amount to hit Nozawa & Yuzawa when the wind picks up later on.
Shiga Kogen has limited wind directions, with NW crossing a gap. NNW is best as the cloud thickens on the ridge and skirt to the west of Nozawa.
Thanks for taking the time to post all this info Sandy.
Looking forward to seeing a bit more detail around Myoko & Madarao.
Probably worth mentioning that if you get any south in the wind beware of skiing loaded slopes lea to the w s/w. Snow from that direction tends to be heavy and wet and is prone to slab formation.
Sandy's explanations previous re the best wind direction for the good snow, might help some better understand the conditions which lead to a sketchy snowpack.
On thing about the GFS is that they seem to have two different running models: 00z & 12z, and the 06z & 18z
So if you look at the next 6 hours, you might see an upgrade or a down grade, but what you are seeing is the two different model runs.
So for example the 00z Nov 25 2016, for 00z Dec 09:
06z Nov 25 2016, for 18z Dec 09:
00z Nov 25 2016, for 12z Dec 09:
06z Nov 25 2016, for 06z Dec 10:
These are SUPPOSED to be sequential, 6 hour increments.
The 2nd & 4th have a deep low east of Hokkaido, while the 1st & 3rd don't.
So the 1st & 3rd are one model run, while the 2nd & 4th are a DIFFERENT run. THIS is why it looks like there are 6 hourly "upgrades: and "downgrades". Each run uses as the input, the output from the previous 12 hours. So you have two runs which are different.
When the two models converge (usually about 5 days out), you have a reasonably good forecast. You tend to find that when the two runs are VERY SIMILAR a long way out, then it's more likely to be right.
Is there any indication as to which is more likely to be better at predicting the most accurate forecast for Japan?
Like, is there a greater probability that the 00z/12z models are more reliable? Or does a certain run predict better if it is a certain 'type' of system?
TBH, I'm not sure.... but that will give me a project before the season starts proper!!!!
This apples to all the major models. These are the datasets used to make the forecasts
0Z and 18Z use the most data sources, so are usually the most accurate.
(from the 2016/17 Japan thread)
There's been a few questions about the lake/sea effect. e.g. "Winds are from the north, why is there no lake effect?" or "Isobars are close, why no lake effect?", or "there's a lot of lake effect cloud, why isn't it snowing?" etc.
Here is more explanation for central Japan.
1. Optimal. Strong NNW wind. Long fetch from Siberia. Better inland penetration, as it's more perpendicular to the coast. Low temperatures with maximum temperature differential from air to sea.
2. Very good. Similar but more to the NW, less inland penetration, but still good enough.
3. When we get low pressure, there's a good place for it to be, that generates moderate lake effect (not very strong because the air doesn't circulate from Siberia). But can generate #2 when it moves off to the NE.
4. Too far to the NNE. The air is not super cold because it's not traveling over land. Although it SEEMS good, it will NOT generate much lake effect.
5. Too far from the west. Lake effect happens, but the winds rake the coast and don't penetrate far inland. This was a big problem in 2015/16 season. Works better for resorts close to the coast in central Japan, and northern Honshu.
6. Winds are too slow and variable to generate much lake effect cloud. You can usually tell on the maps, where the isobars curve a lot.
7. Too much loop off low pressure. This generates a northerly, but the air is not very cold, because it loops from the east
8 Low pressure in the middle of the Sea of Japan brings warm air from the south.
Generalisation of Hokkaido wind impacts.
@Sandy - Can we get this thread stickied and possibly update the links to the images?
Hmmm..... clearly they have changed their usage rules....
Now stickied again.
@Sandy seems as if your charts have disappeared from the first page. Is there any chance of resurrecting them?
Just try to educate myself to Kindergarten level
Please be patient..... Photobucket has suddenly & quietly changed their terms of usage regarding 3rd party photo hosting from $0 per year to $399!!! Before I change to another 3rd party photo hosting site, they may relent, because of a heap of user backlash.
Sorry @Sandy i didn't see @Crispy013 post.
$399 is crazy talk. Hope this changes.
Ok thank you for the link
Sea affect snow.
1. A low pressure tough right in the middle of the Sea of Japan.
This type of double headed low, is generally the worst scenario for Hokkaido.
Warm air is dragged into central Japan, but not from as far south, whereas it's long warm stream for Hokkaido.
As the northern low approaches Hokkaido, cloud and warm air combine. OTOH, the cold air arrives in central Honshu earlier, while Hokkaido is still getting rain. A double headed low extends the northerly fetch more than with a single low, so it comes more from the north than the west, kicking in the lake/sea effect earlier for central Honshu.
Hokkaido continues to get the injection of warm air on the eastern flank of the two lows.
There were some questions about "Siberian Highs". @Tonester
These are the average pressures for January. You can see how the prevailing wind across Japan is a northerly, with the high rotating clockwise.
2C and very cloudy + north-facing
-10C and very sunny + south-facing
which deteriorates snow condition on ski slopes more?