Ex-cyclone #Dineo still wields destructive SA risk over next 48hrs

2017-02-16 13:01 - Louzel Lombard Steyn
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Cape Town - Just because the tropical storm Dineo has been downgraded from cyclone status on Thursday, 16 February, does not mean the adverse weather cannot be destructive. 

UPDATE: #Dineo hits SA: Stormy weekend ahead

This is according to the South African Weather Service and climatology change experts alike, who have indicated that the storm still has huge risks associated with heavy rain and flooding. 

The South African Weather Service says, "The system will still pose a great risk for the next 36 to 48 hours."

Climate change expert and Professor at Wits University Bob Scholes also confirmed, "The cyclone vs storm classification relates to wind speed, but not to rainfall. A lot of the destructive power relates to very high rainfall - 200 mm in 24 hours - which delivers flood."

On Thursday morning satellite images showed that ex-Cyclone Dineo had moved progressively inland, and is now classified as a tropical depression. 

An infra-red satellite image of ex-Dineo (now overland) in southern Mozambique, as at 08:15 SA local time on 16 February.
Source: South African Weather Service / Eumetsat 2017

Areas still in danger

According to the SA Weather Service, satellite-derived estimates of overnight rainfall indicate at least 100 to 200mm of rain occurred overnight in Mozambique along the coast and adjacent interior, between Inharrime in the south and Vilanculos in the north - with the same levels forecast for parts of South Africa.

Risk of heavy showers and thunderstorms over the lowveld and escarpment regions of Mpumalanga and Limpopo remain for Thursday, especially towards evening and overnight, with estimated at 100 to 200mm can be expected over the eastern half of Limpopo province. These conditions will continue into Friday, 17 February, says the weather service. 

In the latter half of Friday, patches of heavy rain may also occur over the western parts of Limpopo province as well as northern Botswana, as the remnants of the low track progressively further westwards over the African subcontinent. 

By Saturday, patches of heavy rain occurrence could even persist over the northern parts of Namibia and Botswana respectively.

The risk of flooding will be particularly severe along the banks of the lower Limpopo river and Olifants river systems, as they flow through southern Mozambique, towards the floodplain region adjoining Xai-Xai in the south of Mozambique, the SA Weather Service warns. 

SEE: UPDATE: #Dineo downgraded, but heavy rains still expected to hit SA

As the major risk associated with the storm will now be flooding, the following safety tips need to be adhered to during flooding: 

Do not try and cross flooded rivers or lakes. 
About 66 % of flood deaths occur in vehicles, and most happen when drivers make a single, fatal mistake trying to navigate through flood waters. Even 4x4 vehicles are not safe under these conditions.
Do not drink floodwater since it may be polluted.
Stay away from collapsed power lines and cables after a flood as live electricity could still pass through them.
Turn off the electricity during a flood, because water is a good conductor of electricity and could cause electrocution.
Store away clean drinking water and food.
Listen to weather reports and instructions of local disaster managers. If necessary, evacuate the area. 

ALSO SEE: #Dineo is storming towards SA: Here's what SA motorists should do

Why was Dineo downgraded?

According to Scholes, the reason for the tropical storm's weakening is simple. "Any time a cyclone wanders over land it slows down and eventually dissipates because it is cut off from its energy and water source, which is a warm ocean.

While Dineo as a cyclone is unprecedented it is unusual says Scholes, highlighting that the southern African region can brace for seeing more extreme weather patterns in future. 

"An increase in storm severity is consistent with a warming ocean," he tells Traveller24. "The equatorial Indian ocean is one of the big 'pools' of warm water, which evaporates and spawns these storm systems. 

SEE: Weird weather: SA's most extreme weather events of 2016

"The Africa mainland is shielded from most cyclones by Madagascar, but the warm water is also spilling out down the Mozambique channel, also raising the possibility that the tropical storm belt will extend further south than before, affecting the east coast of South Africa as far south as East London."  

He says there is no question as to whether climate change is one of the major role players in this regard. There only questions are how the storms will manifest, and exactly where

"There are two unknowns," he says. Firstly, "whether this increase will manifest mostly in frequency, or mostly in increases in severity and secondly, whether the susceptible area will expand poleward (as in further south)."

What to read next on Traveller24

#CycloneDineo's effects on SA: What you need to know

Naming a Storm: How Tropical Cyclone #Dineo got its name

UPDATE: #Dineo downgraded, but heavy rains still expected to hit SA