What does this graph represent?

The Kp index is one of the most common indices used to indicate the severity of the global magnetic disturbances in near-Earth space. This graph uses real time data to produce a 1 hour and a 4 hour advance prediction of activity. The latest predictions are located to the right of the white center line in the graph. Actual observed Estimated Kp data is located to the left of the white center line. The red line going across the middle represents the G1 Geomagnetic Storm threshold. The bottom portion labelled "Lead Time" represents the amount of time in minutes it will take for the the solar wind to propagate from the ACE satellite to the Earth.

Example of a Geomagnetic Storm prediction by Wing Kp

More information on the K and Kp Index

Please visit the following website for a full explanation of what the K-Index represents and how the Estimated Kp-Index is attained. http://www.swpc.noaa.gov/info/Kindex.html