GFSCurrently selected. GFS is the global weather forecast model of the US weather service run at an internal resolution of 28 km. It offers a plethora of parameters for the next 15 days. Updated 4 times a day up to 384 hours ahead. The runs for the 0, 6, 12 and 18Z runs are usually coming in from 3:30, 9:30, 15:30 and 21:30 UTC, respectively.