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WEATHER PATTERNS

As El Niño looms, SA’s southwest may be in for a dry autumn/winter; northeast in for a wet one

As El Niño looms, SA’s southwest may be in for a dry autumn/winter; northeast in for a wet one
(Image: climate.gov)

South Africa is in the twilight of a protracted La Niña weather pattern that is expected to shift to ‘neutral’ conditions over April and May, with an El Niño – which heralds drought in the region – expected to form in early summer. This winter may be unseasonably dry in the southwest and unseasonably wet in the northeast as El Niño looms.

The latest monthly Seasonal Climate Watch issued last week by the South African Weather Service, which makes tentative five-month predictions, is chilling. The current one extends to August, with an outlook for wider potential trends beyond that.

“The multimodel rainfall forecast indicates above-normal rainfall for the northeast of the country and below-normal rainfall for the southwest during all predicted seasons. As most of the rainfall during winter is expected in the far southwest, the below-normal rainfall conditions in those areas are expected to have a significant impact,” it says. 

So, Cape Town, which just a few years ago faced the grim prospect of “Day Zero”, with no water coming from the taps, is expected to have less rainfall than normal during its rainy season. Meanwhile, the northeast of the country, where a canopy of blue skies normally define the months of autumn and winter, is expected to be wetter than usual. 

The impact of this will probably, indeed, be “significant” if the forecast holds true, and the possibility of a transition to El Niño in the summer could have an even greater impact. 

“The El Niño-Southern Oscillation (ENSO) is currently in a La Niña state, and forecasts indicate that it will likely return to a neutral state by autumn (Mar-Apr-May). However, ENSO’s impact is limited for the coming seasons until the next summer season which may be impacted by an El Niño state if early predictions are correct. Caution is advised, however, as changes in the ENSO prediction may change during winter and only monitoring is advised at this stage,” the weather service said. 

Nothing is set in stone but La Niña is basically finished – and South Africa’s forecasts largely dovetail with others such as that issued 10 April by the US National Oceanic and Atmospheric Administration – and El Niño looks to replace it later this year.

In layman’s terms, La Niña brings cooler surface temperatures to the eastern Pacific Ocean, and the upshot for southern Africa is often wetter-than-usual weather, in other regions drought. El Niño is triggered when those same surface waters heat up with the opposite effect. 

The last El Niño scorched South Africa with a record drought. This fading La Niña event set in more than three years ago, a duration that has only occurred twice before since 1950 and which may be linked to human-induced climate change. 

Read more in Daily Maverick: Wondering why it’s raining so much? A rare La Niña gripping SA the likely answer

South Africa has had a succession of good summer grain crops, notably for the staple maize, as La Niña has drenched much of the grain belt the past three seasons. So the return of El Niño would not be good news for the agricultural sector against the backdrop of the power crisis and its impact on things such as irrigation. Inflation and food price pressures are expected to ebb as 2023 advances, but a drought in the next summer season could trigger a fresh cost-of-living crisis ahead of the 2024 elections. 

And water-intensive sectors such as citrus and sugar could also wither in El Niño’s wake. South Africa, the world’s second-largest citrus exporter, posted record exports of the crop in 2022. 

Meanwhile, this winter’s weather looks like it will bring mixed blessings across the country.

“The expected above-normal rainfall may improve dam levels and benefit other water reservoirs in the northeast of the country. On the other hand, water reservoirs are likely to be significantly impacted in the southwest of the country due to the expected below-normal rainfall conditions coupled with above-normal minimum and maximum temperatures,” the weather service said. 

Water-logging in the northeast could also adversely affect the maize harvest, while the Western Cape’s winter wheat-planting season could be left high and dry. 

In an economy that is expected to barely grow this year against the backdrop of persistently high inflation, the weather warnings point to a potentially bitter harvest down the road. DM/BM

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  • Pedro Monteiro says:

    The ENSO is an extremely important driver of interannual weather variability in Southern Africa but the winter rainfall pattern in the Cape is a bit more complex. It also depends on the wave patterns of the mid latitude jetstream which influences the northerly reach of the cold front storms. The additional confounding factors here include the prediction of what is called the SAM index as well as the recovery of the Ozone hole in the Southern Hemisphere Stratosphere which influence the average latitude if the mid latitude jetstream. Cape Town is having an early start to the cool and rain winter most likely because of these factors. We understand far less about these dynamics than about the ENSO and most importantly how the ENSO the SAM and the recovering Ozone hole influence eachother.

    • Pedro Monteiro says:

      Acronyms for comment: ENSO El Nino Southern Oscillation – the El Nino – La Nina cycles. SAM – Southern Annular Mode a statistical property of the atmospheric system over the Southern Ocean that can be correlated to the north south movement of storm tracks.

    • Ed Rybicki says:

      Thanks, Pedro! 😁

  • Geoff Young says:

    It’s my fond hope that Lindiwe Mazibuko is successful in leading the formation of a new political movement to challenge any ANC/EFF coalition and offer a better alternative than the DA in its current form. A movement that discards socialist or Marxist ideologies that are irrelevant to SA’s problems and focuses on growth-oriented economic policies, invests heavily in law enforcement, education & healthcare and strips away the vast, unnecessary regulation & bureaucracy that suffocates investment & real growth. A sorely-needed democratic ideology that has nothing to do with race or culture and everything to do with real, practical economic liberation. In other words, the exact opposite of the nationalisation (aka theft) espoused by the “in name only” EFF and hopelessly corrupt ANC. Is this a dream or can it happen?

  • Larsen Bjorn says:

    Looking back at this from mid July – the winter in the Western Cape is most certainly wet this far. Is that a last remnant of the cycle change ?

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