CO ME R A IN O R SHIN E
Graph 1. Western production area: El Niño/La NIña episodes: adeviation from
5-year running average yield.
classified as El Niño, La Niña and
neutral seasons. The graph above
reflects the crop performance for
all the seasons. The El Niño-type
seasons resulted in very poor crop
performance on five occasions.
The neutral type of seasons realised
reasonably good yields, with the
exception of the 2013/14 season. The tropical cyclones in the
Mozambique Channel had an extremely negative impact during the
said season. La Niña-type seasons
mostly resulted in average to above
average yields.
However, there was one exception, when a La Niña-type season
resulted in below average yields. It
was during the 1982/83 season,
when a tropical cyclone moved
across the eastern parts of the interior. Floods were experienced over
parts of Mpumalanga and KwaZulu-Natal and the worst possible
drought in the western interior.
Moisture was drawn from the
western parts of the interior and
carried to the core of the tropical
cyclone. This resulted in a severe
drought in the western parts of the
interior.
Improved crop production
practices, production systems and
improved crop cultivars created
a buffer against the effect of the
drought to some extent this season
and a reasonable crop materialised
in certain instances.
SUMMARY AND CONCLUSION
After the past two, and in certain
instances three below-average seasons, everyone is looking forward
to a more normal season during
which water sources can be replenished, grazing can recover and
during which at least average crop
yields can realise. Historically
most La Niña seasons realised at
least an average yield in the case of
summer crops. We hope and pray
that it will be the case.
•••
The SOI (Southern Oscilation
Index), which is an index
calculated by making use
of the atmospheric pressure
difference between Darwin in
Northern Australia and Tahiti
in the Pacific Ocean, usually
gives a good indication of
future sea temperature chan
ges in the Nino 3-4 area in
the Pacfic Ocean.
The SOI is currently in
an ascending phase. It makes
us hopeful about the further
development of the La Niña.
The deviation of the sea
temperature from the longterm average in the NINO
3.4 area is almost neutral,
while it was a lot warmer
during January 2016. This
was at the time of the very
strong El Niño. It is expected
that the sea temperature will
cool down further.
The sea temperature in the
NINO 3.4 area is significantly
lower than during January
2016. The NINO 3.4 area
is outlined in black in the
map below. The Southern
Oscilation Index and the deviation of the sea temperature
support the prediction that
the coming season may be a
La Niña-type season.
PROSPECTS FOR THE 2016/2017
SEASON
The prediction of the expected La
Niña by the Australian Government's Bureau of Meteorology
now has a so-called watch-status.
It is predicted that the chances of a
full La Niña developing are good.
SENWES Scenario • AUG/SEP 2016
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