65% of the South African tornadoes are classified as F0 or
F1 (light damage), while more than 90% are classified as
F0, F1 or F2 (considerable damage) or less. The tornado which
occurred at Harrismith on 15 November 1998 was classified
as F2 and the Mount Ayliff tornado which occurred in the
Eastern Cape on 18 January 1999 was classified as F4.
Tornadoes can occur basically anywhere where a thunderstorm
is possible. From an analysis of the occurrence of South
African tornadoes it became clear that most of them have
been observed
in Gauteng, the Free State, KwaZulu-Natal (along a line
from Pietermaritzburg to Ladysmith) and the northern region
of the
former Transkei. There seems to be a preference to mountainous
areas.
The seasonal distribution of South African tornadoes is
given in Figure 1. Most of the events occur in mid-summer
from November
to January. It is also worth mentioning that most tornado
events (for which the time of the day were available)
occurred in
the late afternoon or early evening, typically between
16:00 and 19:00.
Figure 1
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