Weather forecasters use multiple numerical weather models to predict tornado potential. Understanding GFS, NAM, HRRR, and other models helps interpret severe weather forecasts. Here's how the science works.
GFS (Global Forecast System) - US model, 6-hour cycles
ECMWF (European Model) - considered best for medium-range
GEM (Canadian Model) - similar to GFS
Long-range forecasting (5-7 days out)
Global coverage
NAM (North American Mesoscale)
Higher resolution than GFS
Better for severe weather
3-hour cycles
24-48 hour forecast horizon
HRRR (High-Resolution Rapid Refresh)
1-hour cycles
Very high resolution
Excellent for tornado forecasting
Short-range severe weather
Multiple model runs
Probabilistic forecasting
Confidence intervals
Better uncertainty estimation
Modern forecasting standard
Compare multiple models
Look at ensemble spread
Consider recent verification
Update forecasts as new data comes in
Combine with observations
Cannot predict individual tornadoes
Storm-scale detail limited
Uncertainty in exact location
Rapid onset events difficult
Continued improvement
→ Simulate a tornado on our map