EVOLUTION AND STRUCTURE OF THE 6-7 MAY 1985 MESOSCALE CONVECTIVE SYSTEM AND ASSOCIATED VORTEX

The storm began when a short squall line developed in an area of preexisting thunderstorm activity. Thunderstorm updrafts along the squall line lifted warm, moist air with its southerly momentum to the upper troposphere. A broad region of convective outflow and a mesoβ-scale updraft region with a mean vertical velocity in excess of -15 × 10-3mb s-1 were created. A stratiform rain area with an embedded mesovortex formed behind the squall line. The vortex resided beneath the deepest upper-level outflow. The mesovortex altered the wind field and consequently became the principal organizational feature within the MCS. A descending current from the storm's rear that, depending on location, extended from 1 km to the upper troposphere was intensified and focused by the vortex. The descending rear inflow had a peak vertical velocity of 10 × 10-3mb s-1 and concentrated into a jet that passed to the south of the vortex. -from Author