Abstract:
Cut-off low (COL) weather systems that are associated
with rainfall over the Eastern Cape are considered in
this study. COLs are objectively identified and tracked over a
31-year period. Daily rainfall data of 22 evenly distributed
stations over the Eastern Cape are utilized. Only COLs with a
minimum spatial distribution, defined as more than a third of
the rainfall stations that need to report rainfall on at least 1 day
of a COL event, are considered for analysis of rainfall attributes.
These attributes include the occurrence of COL rain
days of different magnitudes, the distribution of the depth and
temperature of the COL centres for the rain days of different
magnitudes, the associated spatial distribution of rainfall as
well as the associated atmospheric circulation. The frequency
of COLs over the Eastern Cape has a winter maximum and a
summer minimum. COL rain days of small, mediumand large
magnitudes occur most frequently during the winter, while
small- and medium-magnitude COL rain days experience
peaks in autumn and spring, respectively. The low-level flow,
and in particular the position of the low/trough, seems to be
the determinant factor in the occurrence, magnitude and spatial
extent of COL-induced rainfall.
