SA Weather Service

12 Jun 2018 07:30 -


3 months ago

MEDIA RELEASE: Wet and cold weather expected over the Western Cape Province, 14 to 15 June 2018. A ...

MEDIA RELEASE: Wet and cold weather expected over the Western Cape Province, 14 to 15 June 2018.

A strong cold front with an associated steep upper trough is expected over the Western Cape and Namakwa District of the Northern Cape on 14 June 2018 into 15 June 2018. The public and small stock farmers in the mentioned areas are advised of the following weather alerts:

Gale force north-westerly winds (65-70 km/h) are expected between Cape Columbine and Cape Agulhas on Thursday, moderating overnight.

Strong to gale force, gusty north-westerly winds (50-70 km/h) are expected over the Western Cape and Namakwa District interior on Thursday into Friday.

Heavy rain leading to flooding is expected over the City of Cape Town, Cape Winelands, western parts of the Overberg and West Coast District on Thursday and extending into Friday.

As the cold front makes its way to the south-eastern parts of the country on Friday, strong to near-gale force westerly to south-westerly winds (50-6 km/h) can be expected along the Eastern Cape coast with wave heights between 5 to 7 m.

Temperatures over the high lying areas of the Western and Eastern Cape as well as the southern parts of the Northern Cape are expected to drop significantly, with certain areas reaching very cold conditions. By Saturday, the cold front would have exited the country and the cold, dry air will spread to the interior of the country, resulting in cold daytime conditions over the Free State, North West Province, Gauteng as well as Mpumalanga.

Significant rainfall amounts can be expected from Thursday morning, where spells of heavy downpours are likely from late morning into the afternoon. Accumulated rainfall amounts of 10-25 mm can be expected, but 30-50 mm over the mountains (Figure 1). Further intermittent rain and showers are expected to continue over the western half of the Western and Northern Cape Provinces on Friday, with a further 10-20 mm likely over the western mountains.

Impacts:

Large accumulations of water will result in flooding of roads as well as formal and informal settlements. This may result in damage to property and lead to a disruption in services to communities. Due to the vastness of the areas and District Municipalities covered, this may put short-term strain on emergency personnel. Heavy downpours during Thursday could result in flash flooding, possibly affecting transport routes and low-lying infrastructure. Mudslides and rockfalls are also possible. As it is exam time, students in rural communities should be advised when making their way to and from school.

Gale force winds are expected along the coastal regions from Thursday morning into Friday. Areas likely to be most affected will extend from Cape Columbine to Cape Agulhas, averaging 25 to 35 kt (45 to 65km/h) (Figure 2). These winds will persist throughout Thursday, spreading along the south coast (remaining offshore) but moderating in the west overnight.

Strong and gusty surface winds are also expected in places over the interior of the Western and Northern Cape as well as southern Free State throughout Thursday into Friday. Figure 2 indicates strong to gale force winds over the interior of the Northern and Western Cape during the late morning of Thursday, averaging between 25 and 40 kt (45-75km/h), with gusts expected to reach 45 to 50 kt (75-93km/h). These strong winds are expected to be sustained into the evening, moderating slightly overnight, but still persisting over the Central Karoo into Friday. Farmers of small stock are advised that the combination of cold, wet and windy weather may prove fatal to stock, unless animals are taken to shelter, well ahead of the onset of the extreme winter weather.

Impacts:

Strong to Gale force and gusty crosswinds along the (Western Cape) N1 highway may result in this major route as well as corresponding rail transport being adversely affected. Hazardous driving conditions may result in road accidents along this route. Moreover, high-sided vehicles are at risk of being toppled by intense wind gusts along the route.

Gale force, gusty winds may result in localised damage to informal as well as formal structures and infrastructure. Travel routes may also be affected due to fallen trees and wind-blown debris.

Cold temperatures are expected for the western parts of the Northern and Western Cape on Thursday. Further cooling is expected on Friday over the entire Western and Northern Cape Provinces, where very cold conditions (approximately 10°C and lower) may be expected over the southern interior of the Namakwa District and northern parts of the Cape Winelands.

Very rough sea conditions can be expected along the west coast between Cape Columbine and Cape Agulhas, where wave heights are likely to reach 4-6 m in the afternoon of 14 June 2018, coinciding with the spring high tide period (high tide at 15:54 on Thursday 14 June 2018, 1.81 m). Coastal damage may occur along the south-west coastal regions. Small vessels should ideally remain in port during this period.

The South African Weather Service advises the public to take heed of the following precautionary measures associated with the above-mentioned weather advisory:

Strong, gusty interior winds over the interior increase the risk of runaway fires, therefore the public are advised not to start any fires or leave fires unattended under these conditions.

When encountering flooding: If possible stay indoors and off the roads, avoid crossing rivers and swollen streams where water is above your ankles. If trapped in a flooding situation whilst in a vehicle, rather abandon it and climb to higher ground. In buildings, move valuables to a safe place above the expected flood level. Switch off electricity at the supply point to the building.

In rural areas protect/relocate animals to a safe place on higher ground. Abandon your home immediately if evacuation is recommended by duly authorized officials, before access is cut off by flood water.

NEVER drive on a road covered or obscured by water. You do not know how deep it is or if the road has been washed away. If the vehicle stalls, leave it immediately and seek higher ground. Be especially cautious at night when it is difficult to identify flood hazards. Listen to the radio or TV for warnings and obey the instructions from Disaster Management officials.

The South African Weather Service will continue to monitor any further developments relating to this weather system and will issue subsequent updates as required. Furthermore, the public are urged to regularly follow weather forecasts on television and radio.

Updated information can also be found at www.weathersa.co.za as well as via the SA Weather Service Twitter account SAWeatherServic