This forecast is based on measurements of critical solar wind parameters.
The measurements are done by a satellite at 1.5 million kilometers from Earth. From that point the solar wind needs between 40 and 75 minutes to arrive at Earth, depending on it's actual speed. (250-900km/sec)
- Density (# solar wind particles)
- Direction of the IMF (Bz)
- Strenght of the IMF (Bt)
- Solar wind speed