Senwes Scenario December 2016 / January 2017 | Page 44

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COME R AI N OR S H I N E

How is the season
progressing?

THYS GROBBELAAR
SENIOR GRAIN ANALYST,
SENWES GRAINLINK

RAINFALL DURING THE SEASON
Most weather forecasting services
forecasted a later than normal
2016/17 season. July, which is
the first month of the 2016/17
summer season, received above
average rain, which contributed
to the building up of sub-soil
moisture in the case of cultivated
fields. Almost no rain was received
during August and September this
year. Rainfall for October is indicated in the adjacent map. The
north-western and south-western
parts of the traditional Senwes
area received significantly less rain
than the long-term average rainfall. The Steynsrus and Arlington
areas received good rain for
October and winter wheat derived
a lot of benefit from this. The
average rainfall for October was
45.5 mm compared to the longterm average rainfall of 53.7 mm.
The cumulative rainfall for the
period 1 July to 31 October 2016
is indicated in the map below.
The largest part of the central
area of the traditional Senwes
area received more rain this season than the long-term average.
However, the north-western and
south-western parts of the area
were not so lucky. The Steynsrus
and Arlington areas have received
fairly good rain to date.
INDICATORS FOR THE
2016/2017 SEASON
Before looking at the climatolog-

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ACTUAL RAINFALL FOR 1 - 31 OCTOBER 2016

CUMULATIVE RAINFALL FOR THE PERIOD 1 JULY 2016 TO 31 OCTOBER 2016

ical indicators, we should look
at the impact of the El Niño, La
Niña and neutral episodes on the
South African maize crop. The
total maize crop produced by
commercial producers is indicated in graph 1. It is evident that
the two largest maize crops were
produced during neutral-type
seasons. The third largest crop was

DEC 2016/JAN 2017 • SENWES Scenario

produced during an El Niño-type
season. Various factors play a role
in the realisation of the size of the
crop, such as rainfall distribution,
temperatures, evaporation and
carry-over moisture. However,
it is a fact that various El Niñotype seasons have resulted in very
small crops. The 1983/84 season,
which was a La Niña-type season,