Similar to the way terrestrial forecasters use models to help forecast weather here on Earth, space weather forecasters also use a number of models to help predict future trends and impacts. 

One such model is the Wang- Sheeley-Arge Enlil model which is explained and shown in the video below. Forecasters use this model to assist in predictions of whether a CME will impact Earth, timing, and the likely geomagnetic activity levels of response.

Note: The video above does NOT contains audio.