Stalling -- When a storm stops its forward motion, making the forecast hard to predict.

Trough -- Low pressure, convection, rain.

Vertical Stacking -- Tropical systems need low pressure at the earth's surface, and high pressure in the upper levels. Such conditions keep a storm properly ventilated. If not, it will remain weak.

Water Vapor Imagery -- Functions as a type of X-ray view on our maps. It indicates where dry air is.

Wind Shear -- Winds that change with height that can tear a tropical system apart.