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Board » General Discussion » Weather updates

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Posted by
Eddie C. Dost


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Registered at
2008-08-23 11:40:29
2008-09-19 18:16:16 - Re: Weather updates
I have two points:

1. About "manipulating" forecasts: This is a don't do. I was talking about using one forecast of a group of 20 trend forecasts. These are calculated from slightly disturbed start conditions using the same weather model as for the normal forecast. These forecasts are not "manipulated" but use stochastical "jitter" on the input data, i.e. the analysis data. Because in real weather the analysis data is never correct and far too sparse on oceans and other areas, met institutes use stochastics on the input data. With this you can get figures about stable or unstable weather situations. My suggestion was using 1 of 20 of these forecasts for calculation on the server and showing the normal forecast in the client. There will be a small but noticable difference in weather as seen in the wind vectors and as experienced on the own ship.

The server would pick a number between 1 and 20 for every update and use that weather for the next 12 hours. So there will be some stability in the weather, but with an offset the sailor has to figure out from data seen at his own ship and data seen in the forecast.

The forecast could be straight grib data without interpolation, so users may use ugrib or the client to interpret the forecast.

2. About increased forecast intervals: I have the feeling that the underlying GFS weather model oscilates slightly between the 0, 6, 12, and 18 UTC runs. If you watch a low moving NE on the atlantic for example, the motion will be contiguous from 0 UTC forecast of day 1, 2, and such. But the motion will be somewhat back and forth when looking at the 0, 12 of day 1 then 0, 12 of day 2 and so on. You should evaluate the data you receive for such effects carefully.
_/)_/)_/)
The sea is lovely, dark, and deep, But I have promises to keep, And miles to sail before I sleep, And miles to sail before I sleep.
Posted by
jakob


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364
Registered at
2007-09-04 10:05:30
2008-09-19 20:54:47 - Re: Weather updates
1) I see your point, agree and will add the idea to the list. However, to be realistic and honest we have more urgent development to take care of at this time.

2) Was that a "yes use 4 forecasts a day" or "no, stick to 2"?

3) You seem to have forecast knowledge. Are you a meteorologist?
...one of the guys behind the game...
Posted by
rudy.w


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Registered at
2008-09-02 08:12:48
2008-09-19 21:09:00 - Re: Weather updates
2) Was: I don't really know whether it's good or bad, just have a flaky feeling.

I am a mathematician and software engineer and got into working with weather data through sailing. Topic is interesting and demanding, so I started learning about backgrounds.
Posted by
Eddie C. Dost


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Registered at
2008-08-23 11:40:29
2008-09-19 21:14:51 - Re: Weather updates
That last post by rudy_w was really by me. My browser seems to have two cookies stored to log in...
_/)_/)_/)
The sea is lovely, dark, and deep, But I have promises to keep, And miles to sail before I sleep, And miles to sail before I sleep.
Posted by
Xinanhook


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Registered at
2008-02-18 23:01:07
2008-09-23 17:38:23 - Re: Weather updates
Hi sailors!

I'm not a professional on forecast stuff, so before read all your comments, I thought that a 4 forecasts update could help to do a smothly transition between forecasts and keep the game more realistic.

After read all what you explain, really I dont't know... :P

But I think that we IRL sailings, we can get the every six hours forecast updates, and follow or change our strategy from what we analyze on them and what we get on the boat.
So I'm still thinking that a 4 forecasts updates could help to do a smoth transitions and not only transitions about the weather also about our tactics changes.

And I'm not agree on manipulate the forecast, do that I think distorting completly the reality.

I hope someday can understand properly what are you talking about... :)

Nice winds! ;)


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