From WindsportAtlanta.com: Wiki
As we've mentioned elsewhere, Atlanta area windsurfers tend to become students of the weather. Since we don't have any particular geography (e.g. ocean, desert) to drive wind on a regular or daily basis, we depend upon weather systems. Systems vary in occurrence and magnitude- a fancy way of saying: when it blows and how hard it blows isn't something you can anticipate or expect very far into the future.
If you go some place like Cape Hatteras for a week in season, you can generally anticipate getting anywhere from four to six days of wind. For windsurfers, Florida in the spring and San Francisco in the summer deliver wind almost on a daily basis due to persistent local patterns such as thermals.
We don't have that luxury. To plan our outings, we look to weather forecasts. To confirm the forecasts (forecasts can be wrong), we depend on certain indicators to tell us the likely or actual conditions on the water.
Forecasts, of course, helpful. Forecasts for within three days are fairly reliable. Forecasts further out than that should be considered, in our experience, suggestive. They tell you that things may develop but we've seen plenty of great forecasts five days out wither to hardly any wind at all.
Different Forecast Models
There isn't simply "a forecast". Weather forecasting is difficult and expensive. Typically it requires some of the most powerful computing systems available. There are two primary models in use: the Global Forecasting System (GFS) and the European Center for Medium-Range Weather Forecast (ECMWF). For a period of time, the European model tended to be better and in some cases significantly better because it had a higher resolution. These articles explains it well: Are Europeans Better Than Americans at Forecasting Storms? and What the European model ‘win’ over the American model in Joaquin means for weather forecasting
The NWS, however, is putting into place a more powerful modeling system that are now (2016) online: NOAA completes weather and climate supercomputer upgrades
The bottom line, however, is that no model gets it right all the time. From our experience, each tends to be good at certain things and you should never assume a forecast more than a few days out is written in stone.
Update: Here's a great video describing the different models in more detail and where they are generally strong or lacking. For us in 2020, the Euro and GFS still seem to be the best performing over time because our weather patterns have few of the very local features such as seabreezes that some of the private services try to capture.
We find graphical map forecast presentations such as windy.com to be more useful because you can often see the nuances of how the wind over an area and the chances that you are sitting on the edge of something rather than in the middle. They also can suggest when your odds will be better by visiting a nearby lake (say, Hartwell Lake or West Point Lake) will improve your chances of scoring a good session even if the drive is a bit further.
Unlike days of old when we had to ferret out National Weather Service (NWS) computer model output from deep in their servers, now, the information easily found from a menu on the standard 7-day forecast.
Note that summer forecasts, both model and regular text, may overstate the wind if thunderstorms are in the forecast. The gusts you see predicted are most likely to happen in a storm rather than the rest of the day.
These are popular
- Windy.com Great graphic forecast with both GFS and Euro models
- Windmapper.com Has been pretty dependable recently
- Windguru.cz Output of a number of models
- Windfinder.com from the folks behind iWindsurf. Not as strong in our area
Generally, these links are for the Lake Lanier area but you can find forecasts for your area easily. The first three seem to be the go-to private web sites currently.
The Guy/Gal on TV or Radio
Be careful of news meteorologists. First, they look at all the same data you do and come up with their own conclusions. Secondly, what they think is breezy may not be that breezy at all. You'll tend to get better advice from your fellow windsurfer and kiters on our forums.
A prediction of wind doesn't always mean that there's wind. It's best to confirm things before you go.
- Check our forums. Club members will often post conditions they find at local lakes on windy days.
Some of the best observations come from airports close by local lakes:
- Lake Lanier: Gilmer Memorial Airport. Gainesville (KGVL). It is elevated so the wind readings are fairly dependable and consistent with on the water readings. The principal exception is warm days in the spring when we have a Dome Effect.
- Allatoona Lake: McCollum Field, Marietta (KRYY). It also is elevated. Allatoona is smaller and has signficant wind shadows in certain wind directions. That should be considered in translating McCollum readings to the lake.
There are private wind meters, as well.
- Windfinder.com reports those readings for Lake Lanier.
- The Lake Lanier Sailing Club on Lanier gives fairly accurate readings on west winds but because of its location, can underestimate easterlies. As well, the bay in front of Van Pugh Park can have slightly stronger wind than the LLSC reports.
Generic Atlanta weather readings can be misleading. Often, Atlanta readings are given from the NWS office at Falcon Field in Peachtree City which is about 20 miles south of downtown Atlanta and 85 miles from Gainesville. Other readings come from the Atlanta Airport (63 miles to Lake Lanier) where is always seems to blow in the summer even when there is no wind anywhere else in the area.
Tropical weather (storms, hurricanes) sometimes bring wind after the come ashore close by. Many times, the wind field can be relatively small so forecasting whether you actually will have wind is difficult.
Wunderground.com has an excellent collection of tropical weather forecasts, reports, discussions, etc.