The local dust storm occurred in the period between the two global dust storms. The area in which the local dust storm occurred slopes upward towards Arsia Mons. Infrared Thermal Mapper instrument data have shown that because of local differences in surface thermal properties, large temperature contrasts occur in this region. Downslope winds caused by these temperature gradients may be strong enough to create such clouds. The image is about 1600 km across.
North is to the top of the image.