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of the Eastern Cape received very
little rain over the past twelve
months. The largest part of the
South African summer rainfall
area received significantly more
than the long-term average season-
al rain. A strong La Niña-season
was predicted initially, but a weak
La Niña-system realised.
INDICATORS FOR THE
2017/2018 SEASON
The prospects for the coming
season are unknown as yet. A
strong El Niño-type season,
which is normally associated with
below-average rainfall and high
temperatures, has been predicted
since the beginning of April 2017.
It usually results in poor crop per-
formance and poor grazing. The
International Research Institute
for Climate and Society from
the Columbia University, whose
predictions are based on various
prediction methods, predicts
an ENSO-neutral phase for the
coming season. This prediction
addressed the fears of another
drought to some extent.
The Australian government’s
Bureau of Meteorology, which
does a lot of research on the El
Niño/La Niña phenomenon,
reflects an inactive status, as
indicated in the diagram below.
We will have to wait at least
four months to get clarity on the
season as far as the El Niño and
La Niña-status is concerned. A
neutral or inactive ENSO-type of
season usually results in good cli-
matic conditions over the summer
rainfall areas.
The SOI is calculated on the
basis of the atmospheric pressure
differences between Darwin in
Australia and Tahiti in the Pacific
Ocean and is one of the indi-
cators taken into account. The
index gives an indication as to
whether the sea temperature in
the NINO 3-4 area will increase
or decrease. It plays a huge role in
the development of an El Niño or
La Niña-cycle. The SOI has been
neutral for quite some time, but it
changed to negative over the past
month. However, time alone will
tell about the direction in which
the SOI will move.
The sea temperature is increa
sing in the NINO 3-4 area. We
will have to wait and see what
happens here as well. One should
have a much better idea by
September 2017. Most of the pre-
diction models indicate that the
sea temperature in the NINO 3-4
area will probably not increase.
The South African Weather
Bureau indicates in its latest
Seasonal Climate Watch that rain-
fall will be slightly above average
for the period August to October
207. The previous two predictions
indicated above-average rainfall,
which did not materialise. The
map below indicates the regions
where above-average rainfall is
expected. It is positive, however,
that more rain is indicated for the
dry Western Cape.
SUMMARY AND CONCLUSION
Concerns were addressed over the
past few weeks when the predic-
tions for another El Niño-cycle
changed to a more neutral cycle.
The previous two droughts emaci-
ated man and animal. We are hop-
ing that the coming season will be
a good one.
SENWES Scenario • AUG/SEP 2017
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