WMOD00590

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

Table 1.1 Mesoscale convective type definitions

Type Isolated r.1esosynopt i c
Property cells Clusters Lines events
Visible satellite imaoe
J
Max cloud diameter (km) 1-50 10-80 10-150 100- > 200
Length of line (km) 50- > 1,000
Organization of clouds Random Nonlinear Linear Wi des pread
Cb groups cloud broken to
of > 2 Cb or grouping overcast
> 3 Cb clouds
Sh ape: ratio of minor
to major axis of
cloud or group > 0.7 > 0.7 0.7< < 0,7
Radar echo structure
Maximum echo diameter
of 20 dBZ contour
(km) 0-35 5-55 10-175 25- > 180
Maximum echo duration
(mi n ) 5-100 30-300 30-400 60-400
Organization of echoes Random Nonlinear Linear cells Widespread
widely groups or group of general
scattered of > 2 > 3 cells echo or
celTs series of
embedded
cores

Note that all of the clouds in this study are considerably smaller than

those of severe local storms studies in mid-latitudes. Squall lines
studied by Byers and Braham (1949) averaged 302 km in length and were

67 km wide as observed by radar. Mesoscale convective complexes (MCC)
studied by Maddox (1981) had. large regions of cloud with temperatures
less than -320C covering at least 100 000 km2 (-660 km diameter),

nearly three times larger than the largest systems studied here.

T .
Iropl-

cal squall lines studied by Zipser (1969, 1977) and Houze (1977) tend to

have active updraft/downdraft regions 10 to 30 km wide with an anvil
precipitating region 100 km behind the squall front which may be 100 to

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