Slide 39 of 45
This upper-level cyclone normally develops (or an existing one intensifies) 12 to 24 hours after a strong cold front penetrates deep into South America. Figure 2-40 shows the development sequence. Developing convection ahead of the cold front increases latent heat release and strengthens the Bolivian High. An upper-level ridge develops southeast from the Bolivian High, primarily from advection of warm air ahead of the cold front. This creates an upper-level wave pattern that ultimately leads to a cut-off low.