Characteristics of a Hailstorm over the Andean La Paz Valley

New insights on the atmospheric characteristics preceding hailstorm and flash flood episodes over a valley located within the Andes-Amazon interface are added through numerical investigations of the iconic 2002's event over La Paz city in Bolivia.

Conducting a series of high resolution numerical experiments (including terrain modification and artificial surface heat transfer) with the WRF-ARW model, the dynamic and thermodynamic contributions to this event are highlighted. The results suggest a mix between surface heating and orographic forcing in the lower levels and air convergence in middle levels as main actors of a strong convective instability; and the valley's shape importance for moisture transport from the Amazon basin. This study sheds light on the complex interaction between moisture transport, heat transfer and orographic effects and its influence on the formation of hailstorms over the La Paz valley.