1. Detect a Halo CME - Coronal Mass Ejections headed toward Earth look like a "Halo" when seen on the LASCO instrument. When detected, a disturbance may hit the Earth's space environment several days later.

A few days later

2. Examine the Solar Wind Conditions - The first direct indicator of a disturbed solar wind is from the ACE satellite, upstream of the Earth in the solar wind flow. Rapid changes in the z-component of the magnetic field, as well as in the velocity and density of the solar wind particles may cause a geomagnetic storm.

Immediately to Hours

3. A geomagnetic storm is detected by sensing increased magnetic fields at the Earth's surface and forming the Dst index. A high Dst indicates that the disturbed solar wind has impacted the Earth's space weather directly.

Immediately to Hours Later

4. During a geomagnetic storm, another current system is measured by the Kp index, indicating at what geographic latitudes the aurora may be seen.

Simultaneously with Kp

5. A second indicator of auroral activity comes from direct measurements of the particles raining down in the Earth's polar regions that carry the auroral currents.

The above timeline is useful for predicting the larger space weather disturbances; however, not all aurora are a direct result of CMEs. Any disturbance in the solar wind may cause a geomagnetic storm, and several auroral displays often occurr within a given storm, so it can be useful to check solar wind conditions, Dst, Kp, and auroral particles independently of CME activity. This is particularly true if you live in the higher latitudes (>50 degrees). People in lower latitudes may only see auroral displays during large Halo CME events that cause significant disturbances in solar wind conditions.