Africa Wearther

Categorized | General

With thunderstorms expected in the SW Cape today, what lies ahead weatherwise for the next 10 days?

Cut-off low to the SW of Cape Town late on Thursday - blue indicates that the atmosphere is unstable.

Cut-off low to the SW of Cape Town late on Thursday - blue indicates that the atmosphere is unstable.

Scattered showers and thunderstorms are expected to pass through the SW Cape and Cape Town from later this afternoon and into this evening (Tuesday).

This is unusual weather for this part of South Africa and is more difficult to accurately forecast for due to thunderstorms being very hit and miss in nature.

US weather model - 24 hour forecast rainfall to 8am on Friday and air pressure.

US weather model - 24 hour forecast rainfall to 8am on Friday and air pressure.

The difficulty of forecasting this event is compounded further as temperatures are so warm and may cause the rain to evaporate before it reaches the ground – this is known as virga and the computer models struggle to accurately forecast this phenomenon.

European weather model - 24 hour forecast rainfall to 8am on Friday and air pressure.

European weather model - 24 hour forecast rainfall to 8am on Friday and air pressure.

Therefore the weather for this evening is likely to be more thunder than rain, with a 60% chance of to 1-5mm of rain.

Tomorrow (Wednesday) is expected to be partly cloudy and dry, it will also be much cooler than yesterday and today with temperatures expected to reach the mid to low 20Cs.

UK weather model - 24 hour forecast rainfall to 8am on Friday and air pressure.

UK weather model - 24 hour forecast rainfall to 8am on Friday and air pressure.

On Thursday and into Friday morning, a cut-off low in the upper atmosphere and surface low are likely to develop to the SW of Cape Town. There is quite a lot of uncertainty with regards to this weather feature -  2 of the 3 major weather models have significant rain for the SW Cape whereas the other model is indicating that the low will slip to the south with only 1-2mm of rain expected.

Although there is uncertainty there is still a 70% chance of rain and perhaps thunderstorms. If this occurs there is likely to be widespread falls of rain of 10-30mm over Cape Town and the catchment areas for the dams.

Over the weekend the South Atlantic high pressure system will make an unwelcome return and will lead to fresh to strong SE winds between Saturday and around Thursday next week. The high pressure system will cause any frontal systems to slip well to the south of the country and with windy and warm conditions expected, evaporation levels from the dams will be high.

From Thursday or Friday next week the high pressure system should start to weaken and this may allow cold fronts and some welcome rain to affect the SW Cape.

 

 

 

 

 

AfricaWeather will continue to keep you posted on this weather event via our Twitter Feed and Facebook page.

AfricaWeather, Smarter Weather Insights.

 

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