Wherever we are in the world we need to have a good reliable forecast. Most countries will produce a local short range marine forecast which is good for day trips but we also need to know the bigger picture.
With so many yachts down island we will have a look at forecasting for the Caribbean. There are a number of web sites giving local forecasts as well as broadcasts on the radio and posted in Marina offices. http://www.caribwx.com is a general site for the Caribbean and http://www.srh.noaa.gov/sju/Forecast/index.php covers Puerto Rico and the USVI.
However it is good practice to know what is going on over a larger area and for the next few days.
The first place I always start is with NOAA, http://weather.noaa.gov/fax/gulf.shtml, for synoptic and forecast charts. This is the big picture and will indicate where the Azores (Bermuda) high is, along with any troughs, fronts, or tropical waves. As well as synoptic charts there are forecast charts for 24, 48, and 72 hours, along with wind and wave charts. So now we have a good idea with regards what to expect with the weather, but still on a fairly large scale. The high sea forecasts are also available on the same web site which helps to clarify the situation particularly if your reading of the synoptic charts is a little rusty.
We have become used to seeing satellite pictures and these are available from a host of servers but will all be from the same US satellites. The vast majority of pictures will be from the geostationary satellite GOES East which covers the Caribbean. The better resolution polar orbiting satellites are not so readily available although for a moderate coast a receiver can be carried on board to receive pictures direct from the satellite. This is very useful for high latitude and remote sailing but an unnecessary luxury for the Caribbean.
http://www.goes.noaa.gov/ is the place to begin with links to pictures for the Caribbean and around the world. With practice, matching satellite pictures with synoptic charts will add a great deal of understanding to the weather and helps to build a 3-D picture. The satellite pictures will also help to get an idea of squall frequency.
No look at the weather would be complete without a visit to the National Hurricane Centre http://www.nhc.noaa.gov/index.shtml and although we are out of the hurricane season, it is always worth a quick look to be sure. Additionally there is a link to the Tropical Weather Discussion and Outlook. Whilst this can be a bit heavy going, it contains a considerable amount of information and is useful for predicting the likelihood of squalls. In addition to the above we can add a Grib file for wind speed and direction. I use UGrib, however the majority of Grib files available, are all from the GFS model so whilst there are a number of suppliers of the files, most will give the same information. The grib files give an indication what the wind strengths will be away from land and away from any squalls.
One of the most often asked question on board, is what is the weather going to do? There is a lot of information on the web and now most boats have access to it, it is not difficult to get into a daily routine keeping one step ahead of the weather over the short term, and for the length of the cruise.