Weather
Weather -
Seasonal Climate Watch
November 2015 to March 2016
Advisory
Most models are showing the strengthening
of an El-Niño episode towards the summer
season with the expectation to continue
throughout the autumn season. The
forecasting system is confidently showing
that going towards the mid- and late-summer
season, the likelihood of the continuation of
dry conditions over most parts of the country
is high. However, conditions over the Indian
Ocean adjacent to South Africa may promote
chances of rainfall activities for the northeastern South Africa including some part
of KwaZulu-Natal for late spring and early
summer season. The likelihood of extreme
warmer temperatures over most of South
Africa is predicted to be high throughout
the summer season. Other international
forecasting systems also similarly indicate a
tendency of drier and warmer conditions for
South Africa..
Recommendation
There is some evidence that the likelihood
of the country experiencing consistently
dry and hot conditions toward the summer
season remains high. The condition over
the north-eastern part of the country for
the start of the summer season may not be
strong enough to change the status quo.
This persisting dry condition may promote
a regional or localized drought depending
on the state of the existing water stress.
It is highly recommended that medium
and shorter range weather forecasts be
monitored for the development of conditions
that may alter or strengthen the expectation
of the current forecast.
Rainfall
Minimum and Maximum Temperatures
The forecasting system indicates significant
probabilities of above-normal rainfall for parts
of north-eastern South Africa at the start of
summer and below-normal for parts of the
southern parts of South Africa for the same
period. High probabilities of below-normal
rainfall for the mid- and late- summer season is
predicted by the forecasting system countrywide
(Figure1).
The forecasting system indicates generally above-normal temperatures across the country through
early summer towards mid-summer, with an exception of below-normal minimum temperatures
for the southern parts of South Africa (Figure 2).
For improved confidence in a probabilistic prediction use is made of skill scores most notably
the Relative Operating Characteristic (ROC) which indicates the ability of the forecasting system
to distinguish events from non-events. As noted earlier, areas of ROC scores above 0.5 may be
considered as areas of added confidence for the prediction (Figure A2).
For improved confidence in a probabilistic
prediction use is made of skill scores most
notably the Relative Operating Characteristic
(ROC) which indicates the relative performance
of the prediction system. Areas of ROC scores
above 0.5 may be considered as areas of
added confidence for the prediction (Figure A1)
Figure 2: Probabilistic minimum (left panel) and maximum (right panel) temperature forecasts for the three overlapping
seasons valid for the period of November 2015 to March 2016.
Figure 1: Rainfall forecasts for the three overlapping seasons
valid for the period of November 2015 to March 2016.
Information supplied by South African Weather Service. Enhanced Probabilities is considered to be more than
45% probability for a specific category.
If there are areas that do not show an indication of more than 45% probability, then the forecasts for that area
is considered to be uncertain.
For more information: email [email protected]
Weatherlines: 082 162 - *120*555*3 - 083 123 0500
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SABI | DECEMBER 2015/JANUARY 2016