A mesohigh (sometimes called a "bubble high")[1] is a mesoscale high-pressure area that forms beneath thunderstorms.
[2] In the early stages of research on the subject, the mesohigh was often referred to as a "thunderstorm high".
[3] A mesohigh forms underneath the downdraft in a squall line and is associated with the cold pool of a thunderstorm.
It is largely formed by hydrostatic phenomenon, specifically the evaporation of falling precipitation.
[4] As precipitation, primarily rain, falls in the downdraft, it evaporates in the unsaturated air, leading to cooling in the downdraft due to an absorption of latent heat.