weather grib

[graham42]

an article in yachting world march 2007 refers to grib.us
its a good free weather grib reader that saves the cost of maxsea.

can anyone explain to me how downloading a local area>western approaches and biscay will save time and money with grib.us of 591KBs compared to D/L from globalmarine.net for the whole of the north atlantic in chrystler & diamler 200KBs.
true, with grib.us you get precipitation & isobars.
how big would true comparisons be.
they both source their weather from noaa and the gribs are interchangable.

it doh add up

 

[gfbalduc]

The default settings of Ugrib are for a 3-hourly set of data, at 0.5 degree interval, which lead to a pretty substantial file-size!

The ability to configure these parameters is useful to get the best compromise for your needs, for example a 3-hourly, detailed graph for a small area, or a 12- or 24-hourly, less detailed graph for an entire ocean.

On other services, like the one you mention, you get predefined files with no options available.

Agreed that, in the end, the source of the data is the same! /forums/images/graemlins/grin.gif

 

[HenryB]

You can also download predefined area Gribs from Raymarine which include wind, temperature, precipitation and pressure, and Saildocs.com will email you custom area Gribs.
And I almost forgot to mention, I sell an inexpensive viewer which will download them for you /forums/images/graemlins/smile.gif

 

[dod]

UGRIB allows more localised areas for smaller download data hence faster and less time on internet.
By the way this is only an 'laymans' opinion which I'm sure the experts will correct.

 

[jeremyshaw]

Saildocs is free, so I rather like that.
Also, they are starting to make Coamps available in limited areas, which (unlike the standard NOAA gribs) calculate the effects of land masses.

And, the latest thing is more detailed spot forecasts, which I think you can get globally. Not gribs, but the same kind of data in table form. This can include wind, waves, surface pressure and periodicity, with flexibility on frequency. Lovely. See below:

From: query-reply@saildocs.com
To: "Zingano"
Date: Jan 11 2007 - 1:11pm

Data extracted from file gfs070111-06z.grb dated 2007/01/11 10:43:26
Data extracted from file ww3-20070111-06z.grb dated 2007/01/11 11:00:16
request code: Spot:12.0N,068.0W|5,6|WIND,PRMSL,WAVES

Forecast for 12°00'N 068°00'W (see notes below)
Date Time WIND DIR PRESS WAVES
utc kts deg hPa mtrs
----------- ----- --- ------ -----
01-11 18:00 19.0 072 1014.6 2.0

01-12 00:00 20.6 076 1013.1 2.2
01-12 06:00 18.6 080 1013.4 2.4
01-12 12:00 21.3 085 1012.3 2.4
01-12 18:00 18.6 077 1011.6 2.3

01-13 00:00 17.6 070 1010.9 2.1
01-13 06:00 16.2 076 1012.7 1.9
01-13 12:00 13.3 074 1012.8 1.9
01-13 18:00 14.3 084 1010.8 1.8

01-14 00:00 18.0 066 1010.5 1.8
01-14 06:00 16.5 089 1010.0 1.8
01-14 12:00 14.8 090 1012.3 1.8
01-14 18:00 16.4 079 1011.1 1.8

01-15 00:00 18.7 071 1011.5 1.9
01-15 06:00 18.2 078 1010.6 2.0
01-15 12:00 17.7 078 1012.2 2.1
01-15 18:00 18.4 083 1010.9 2.1

01-16 00:00 19.3 073 1011.8 2.1
01-16 06:00 19.7 080 1011.3 2.1
01-16 12:00 17.9 088 1012.5 2.1

Refer to notice & warnings sent 2006/12/22 13:08:27, for another copy
send a (blank) email to: SpotWarning@saildocs.com

=====
Thanks for using Saildocs! (info@saildocs.com).

 

[graham42]

where are you downloading and what size/time are you talking of?

wifi in marina`s are very very slow. often only 6KBs.

 

[webcraft]

[ QUOTE ]
Saildocs is free, so I rather like that.
Also, they are starting to make Coamps available in limited areas, which (unlike the standard NOAA gribs) calculate the effects of land masses.


[/ QUOTE ] Does this include the Canaries? GRIB files are next to useless between the islands here due to the height of the mountains. Winds are frequently accelerated by up to 15 knots, the direction, speed and area of the acceleration zones varying with the wind direction.

- Nick

 

[dod]

AAAahhhhh! Marina wifies. My advice to you would be to download both and see what takes the longest or shortest time. Then you will know which is cheapest. All UGRIB is free to download but given your internet source may take some time. So if you already have software in place then you might be better off sticking with it.
Keep up to date with the forecasts on vhf. That is free and usually accurate enough. Don't worry just reef early.
Come on how technical do you want it to be.

 

[jeremyshaw]

Webcraft - not sure if COAMPS cover the Canaries, but even if they did I don't think they would deal with the kinds of winds you are talking about. Standard GRIBS ignore land masses completely. COAMPS try to factor in the impact of land mass on the wind data in the GRIB, but I doubt very much they will be any use (and this is my experience in the Caribbean) with truly localised conditions, or anabatics etc. But then little is I'd think apart from local knowledge and experience.

 

[jeremyshaw]

Re GRIB size Saildocs also allows you to size the grib and control granularity.

This request
request code: grib:13N,10N,069W,064W|1,1|24,48,72,96|WIND,PRMSL,
produces a 2k GRIB.

The lat/long stuff is obvious. 1,1 is 1 degree granularity. the next bunch is requesting data for 24, 48 hrs ahead etc. and the data requested is Wind and Surface Pressure. I think you can go down to half a degree granularity - or make it much bigger.

 

[stevehayles]

If your files are bigger with GRIB.US then the data you are downloading contains more parameters / timesteps and /or is at a higher resolution.

UGRIB gives you complete control over the resolution, the time interval etc. Compare apples with apples and you will see the filesizes will be pretty much identical