WMOD00590

• Title: Analysis and Classification of Mesoscale Cloud and Precipitation Systems
• Date: 8/1/1983
• Weather Modification - Doc Type: Report

layers which tend to focus the effect of lifting on the release of
convective instability. Meso-p convergence may be produced by
several mechanisms such as: dry line~ jet streak~ low-level jet~
local differential heating and meso-a frontal systems. Wind shear
plays a role in unloading precipitation in updrafts, establishing
regions of strong upper-level divergence which maintains mesoscale
updraft regions~ and transferring horizontal momentum to the convec-
tive cells which control their movement and evolution of updraft/
downdraft couplets.

4. Mesosynoptic convective systems form in an environment with
synoptic-scale forcing having sufficient instability and moisture
to generate convective clouds and precipitation. These systems
result from frontal systems~ cyclonic systems~ easterly waves and
upslope flow which produce widespread lifting. Mesoscale convective
triggers hypothesized in 1.2.2 and 1.2.3 above may be superimposed on
the synoptic lifting pattern to produce meso-o areas of more intense
convective precipitation along squall lines or in embedded showers
and thunderstorms. In these cases mesoscale lifting produces areas
of more intense convective activity within regions of widespread
synoptic-scale stratiform precipitation.

Table 1.1 provides a quantitative definition of scale and organiza-
tion of cells for each type of event based upon satellite image struc-
ture and radar echo characteristics. The satellite provides a unique
overview of cloud structure which clearly defines the cloud organiza-
tion~ the extent of clouds and cloud type. Radar provides a more quan-
titative analf'iS of detailed echo :ize and individual echo properties.