- During the summer months, the Bolivian High will block the polar troughs to no farther north than 30S/35S.
- Surface fronts then stall across southern Brasil (Rio Grande do Sul)-Paraguay-Bolivia.
- The trailing/quasistationary front will undulate back and forth.
- This makes it a favorable area for MCC/MCS.
MCC/MCS are to be discussed under separate cover. However, it is worthwhile to mention at this time that as the surface front moves under the southern fringes of the Subtropical Ridge, Paraguay-Northwestern Argentina-Eastern Bolivia-Mato Grosso do Sul are in high risk for an MCC to develop.