Watch for oncoming sandstorms by checking the horizon for what appears to be a moving along the surface of the terrain.

The correct answer is - dark clouds.

Explanation:

Sandstorms are the storm of dust that form in arid and semiarid areas. The sand storms can be predicted by various models developed by scientists. It takes place as strong winds lift the grain of the sand with it.

The oncoming storm looks like dark clouds on the horizon that move along the surface of the terrain or ground. The dark clouds are an indicator as they appear on the horizon before a sandstorm comes.

answerformal;