GRIB weather files and FREE GRIB viewer

[Bill NH]

Don't know if anyone else is using these, haven't seen them come up in posts, but thought it might be of interest to the group...

GRIB (GRidded BInary) weather files are small, compact weather data files that can be downloaded over even the slowest connections (like HAM/SSB or even satphones).  Of course you can get them in port via any wireless connection as well.  These files contain wind data, isobars and rain data and are used by many commercial mariners, offshore racers (like the real Vendee competitors) and even folks just out cruisin'.  They contain real-time data and computer model forecasts.  Some nav software packs can overlay GRIBs on charts, but even with the free GRIB viewer it's like WeatherFax on steroids...  HIGHLY RECOMMENDED!   ;D  Check them out if you sail with a laptop aboard.

More info on getting started at http://www.grib.us/.

[Tim]

A Big thanks Bill, I just recently started looking again for weather info (I lost a lot of links in a computer crash) and this one is definitely  worth looking into. And it's FREE !

[AdriftAtSea]

Grog to ya for that... :)

[Auspicious]

It's worth noting that available gribs are the product of computer models untouched by human hands. The algorithms are based on continuous equations and so smooth of discontinuities like fronts.

They are very useful, but sailors should be aware of their limitations. I currently peek at synoptic charts (weather fax) to locate highs, lows, and fronts and then use gribs for wind and wave speed and direction.

On the grib viewer that is bundled with Airmail (HF e-mail) it is really nice to be able to step forward and backward through accumulated forecasts. It helps substantially with doing your own routing when you are looking for a particular range of wind strength.

If someone would put Gulf Stream analysis in grib format s/he would be a real hero.

I can't think of a scenario where one can get gribs but not wefax. Conversely, all you need for wefax is an SSB receiver, a laptop, and an inexpensive sound card interface. Software like JVCOMM is free.

sail fast, dave
S/V Auspicious

[Bill NH]

It's worth noting that available gribs are the product of computer models untouched by human hands. The algorithms are based on continuous equations and so smooth of discontinuities like fronts.

They are very useful, but sailors should be aware of their limitations. I currently peek at synoptic charts (weather fax) to locate highs, lows, and fronts and then use gribs for wind and wave speed and direction.

On the grib viewer that is bundled with Airmail (HF e-mail) it is really nice to be able to step forward and backward through accumulated forecasts. It helps substantially with doing your own routing when you are looking for a particular range of wind strength.

Good point about the fronts.  Highs and Lows are pretty easy to determine from the wind data, but frontal discontinuities are important features not shown on GRIBs. 

The free GRIB viewer can compile an "animation" of sequential forecasts, but one must remember that they are forecast data and reliability decreases as the time from the current data increases.  I've generally avoided looking more than a couple days out - kinda like when you listen to a weather report...

[Auspicious]

I've generally avoided looking more than a couple days out - kinda like when you listen to a weather report...

I agree. Once thing I have found useful is to look at the 72 hour forecast from two days ago, the 48 hour forecast from yesterday, and the current 24 hour forecast. If the forecasts are significantly different I go back to the synoptic charts, particularly the 500mb charts, to try to figure out why. If the forecast has been stable I have more confidence in it.

Ultimately I'm not going to be able to run from bad weather that pops up -- the boat is just not fast enough. I can route myself to stay close to the 15 - 20 kt wind regime (if it's out there) I like the most.

I guess that's more relevant to long passages than to coastal hops.

sail fast, dave
S/V Auspicious

[Joe Pyrat]

Aye, grog to ye matey...