WMOD00590

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

stor~ Project rawinsondes by Newton and ~ewton (1959) prior to the
passage of a squall line showed the effect of lifting on temperature
and dewpoint profiles in a sheared environment. The e;fec: which was
similar to that predicted by the MESOCU model using vertical motion
profiles derived from objective analyses clearly showed adiabatic
cooling and vertical moisture transport in conditions of moderately
sheared thunderstorms,

Initial studies to determine the basic thermodynamic character-
istics af HIPLEX soundings (Matthews~ 1981a)~ and their response to
mesoscale triggering in the form of lifting (Matthews and Silverman~
1980)~ were performed on HIPLEX rawinsonde data fro~ 1975 to 1977.
Large variations in the effect of lifting on model analyses of
convective cloud growth were found in sensitivity studies using a
sample of 232 rawinsondes observed from Texas to Montana during the
summers of 1975 to 1977. The numerical model analyses were strati-
fied by satellite observations of convective cloud mesoscale organi-
zation and type of clouds. Results showed that mesoscale lifting was
required to initiate convective cloud growth in most cases and that
its intensity largely controlled the simulated intensity of convec-
tive cloud development. Analyses of satellite imagery in these cases
indicate that the scale of mesoscale convective triggering mechanisms
is below the synoptic observations and requires stations separated by
80 to 100 km or less. This density of observations requires an
analysis method which is able to consistently detect the smaller-
scale~ shorter wavelength features which develop regions of more
intense vertical ~otion.

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