GFS vs GEM
NOAA GFS (American model) and Canadian GEM (Canadian model) are independent forecasts built by different weather services. GFS: Frequent updates, long range, US convective detail when blended with HRRR. GEM: Winter storms and cold-air outbreaks in North America; HRDPS short-range detail. Neither is right every time: the useful signal is whether they agree. Compare them live below for any city.
| NOAA GFS | Canadian GEM | |
|---|---|---|
| Run by | NOAA / National Centers for Environmental Prediction | Environment and Climate Change Canada |
| Origin | United States | Canada |
| Resolution | ~13 km (blended with HRRR 3 km over the US) | ~15 km global; 2.5 km HRDPS over Canada |
| Model runs | 4 per day (00, 06, 12, 18 UTC) | 2 per day global |
| Forecast range | up to 16 days | up to 10 days |
| Type | Physics-based NWP | Physics-based NWP |
| Also called | American model, Global Forecast System | Canadian model, CMC, GDPS, HRDPS |
| Strengths | Frequent updates, long range, US convective detail when blended with HRRR. | Winter storms and cold-air outbreaks in North America; HRDPS short-range detail. |
| Weaknesses | More run-to-run swings than ECMWF in the medium range; can over-deepen distant lows. | Has a known tendency to over-forecast precipitation in some setups. |
Key differences
- GFS resolution: ~13 km (blended with HRRR 3 km over the US); GEM: ~15 km global; 2.5 km HRDPS over Canada.
- GFS range: about 16 days; GEM: about 10 days.
- GFS updates: 4 per day (00, 06, 12, 18 UTC); GEM: 2 per day global.
- GFS weak spots: More run-to-run swings than ECMWF in the medium range; can over-deepen distant lows. GEM weak spots: Has a known tendency to over-forecast precipitation in some setups.
Questions
Is GFS or GEM more accurate?
NOAA GFS (American model) and Canadian GEM (Canadian model) are independent forecasts built by different weather services. GFS: Frequent updates, long range, US convective detail when blended with HRRR. GEM: Winter storms and cold-air outbreaks in North America; HRDPS short-range detail. Neither is right every time: the useful signal is whether they agree. Compare them live below for any city.
Which is the European model and which is the American model?
The "European model" is ECMWF (IFS, and its AI sibling AIFS). The "American model" is NOAA's GFS. The German model is ICON, the Canadian model GEM, the UK model UKMO and the French models ARPEGE/AROME.
Where can I see GFS and GEM side by side?
On every MeteoStack city page: the stack shows GFS, GEM and up to ten other models hour by hour, with their median consensus, spread and rain odds. It is free and works for any place on Earth.
More comparisons
ECMWF vs GFS · ECMWF vs ICON · GFS vs ICON · ECMWF vs AIFS · ECMWF vs UKMO · GFS vs GEM · ECMWF vs GEM · ICON vs ARPEGE · GFS vs AIFS · UKMO vs GFS · ECMWF vs JMA · ICON vs UKMO · ECMWF vs ARPEGE · GFS vs JMA