Weather forecasting is the science of predicting the future atmospheric conditions across the globe. It's not perfect but in the current state of the technology it's amazingly good.
The forecasts are calculated by supercomputers that are funded by governments most of the time. They run software that contains scientific knowledge developed over the last four decades. First they get the current atmospheric data as input and depending on the software and model they then output a computer simulations of the atmosphere which is the expected weather. Each software and model is a different way to solve the problem and have a different usage. There is long term forecast like GFS and short term one like NAM 3km. By comparing prediction models the meteorologists can determine chances of weather event to happen. They factor in knowledge of the area they cover and they try to recognize patterns. iGetwind was built to easily compare the most important models so you can learn the ability to better predict wind in your area.
So the models fits in 2 main categories, short term and long term. The long term models are global (covering the whole world) and short term model are regional. In the USA the most popular short term models are NAM 3km and HRRR 3km. The "3km" part refer to the area where one set of forecast data apply. So a model having a resolution of 27 km like GFS cover more space (the world), is less precise and is used to forecast long term trend. A model having a resolution of 3km is more precise and usually factor in terrain characteristic but it covers smaller area (North America). Most models data are freely distributed but the high resolution models data are more difficult to get as most country weather agency will sell these highly valuable data.
iGetwind is a wind/wave/tide forecast website. It covers any locations on planet earth with different forecast models. Try iGetwind.com