Over the past decade, observational studies have advanced the understanding of mesoscale precipitating cloud systems in diverse ways.

Doppler radar observations over tropical oceans and over midlatitude continents have expanded on the paradigm of a mesoscale convective system as consisting of an advancing convective line and a trailing stratiform region. A variety of precipitation patterns and circulation structures have been identified. They are consistent with the convective-stratiform paradigm but exhibit more complex structures. The circulations in mature systems are seen increasingly as a mesoscale circulation distinct from convective-scale dynamics. The mesoscale circulations draw on a lower troposphere inflow layers that extend above the boundary layer, and the mid-level inflow is often controlled by the large-scale environmental relative flow. In midlatitudes the midlevel flow forms long-lived meso-vortices.

Satellite data and surface radar networks are showing the ensemble behavior of mesoscale convective systems. Intermediate scale wave motions are reflected in the motion and repetitive formation of mesoscale systems. Such behavior is possibly associated with inertio-gravity waves both over the western Pacific and over the continental U.S., and with gravity waves in the monsoon onset over the Bay of Bengal and off the west coast of South America.

Orographically enhanced rainfall accounts for a large proportion of global rainfall in both midlatitudes and the tropics, especially where mountain ranges face a persistent seasonal onshore moist flow. Several studies have identified upstream and synoptic conditions favorable for orographic enhancement. One of the longstanding mysteries of orographic precipitation enhancement has been how the rainout on the windward slope occurs so quickly and efficiently. Recent field projects over the European Alps and western U.S. have used polarimetric inference of particle type in conjunction with Doppler velocity data to illuminate the mechanisms by which the precipitation particles grow and fallout. These mechanisms involve cooperation of low-altitude coalescence, riming and aggregation on the microphysical side and embedded convection and mechanical turbulence on the dynamical side.