NOAA GFS model
The "American model". Free, global, four runs a day out to 16 days, the most widely redistributed forecast on Earth. Also known as American model, Global Forecast System.
NOAA / National Centers for Environmental Prediction
~13 km (blended with HRRR 3 km over the US)
4 per day (00, 06, 12, 18 UTC) · up to 16 days
Where GFS is strong
Frequent updates, long range, US convective detail when blended with HRRR.
Where to be careful
More run-to-run swings than ECMWF in the medium range; can over-deepen distant lows.
How to read the GFS forecast on MeteoStack
On every city page, GFS is one row of the stack: each cell is one hour, coloured by rain, temperature, wind or cloud. Compare its row against the consensus line at the top. If GFS is far from the others, treat its outlier signal with caution, or as an early warning if it is a model that is strong in that situation (see above).