Cumulus Report: 29 November 2019 South Africa


Star InactiveStar InactiveStar InactiveStar InactiveStar Inactive
 

The next few days will be dry and warm to hot over most parts apart from some thundershowers over the central to south eastern parts and Eastern Highveld.
The thundershowers over the central parts will only result in light falls but will probably be associated with gusty winds/dust storms. By early next week, current forecasts indicate scattered to widespread thundershowers over large parts of the summer rainfall region, when atmospheric circulation patterns are expected to become more favourable following the current hot, anticyclonic conditions.

The following is a summary of weather conditions during the next few days:

• General:

o For much of the period, including the weekend, it will be warm to hot and dry for the most part.
o Scattered to widespread thundershowers are possible from Monday (2nd) into next week over the summer rainfall region according to current forecasts.
o Normal to above-normal rainfall is expected over the eastern parts during the next few days, even though most of the rain will only occur early next week.
o Below-normal rainfall is expected over the western and southern parts of the country.
o The southern parts of the country will on average remain cooler than normal while temperatures over the northern parts will be near normal to above normal on average. This pattern is consistent with conditions during the past few weeks.
o Fresh to strong southeasterlies are expected over the southwestern parts from Monday (2nd).

• Rainfall:

o Isolated thundershowers are possible over the central to south eastern until the weekend. Over the interior, these will be associated with strong and gusty winds, while only light falls are expected.
o Isolated thundershowers are also possible over the eastern Highveld until Friday (29th). o Widespread thundershowers are possible from Monday (2nd) over most of the summer rainfall region according to current forecasts. Some of these may have a tendency to become severe.
o Light showers are possible over the winter rainfall region and Garden Route on Friday (29th) and Saturday (30th) as well as Monday (2nd)

• Temperatures:

o Warm, dry and windy conditions may occur over the interior of the Northern Cape and southwestern parts of the Free State and surrounding areas during most of the period.
o Hot, dry and windy conditions will also dominate the interiors of the Western and Eastern Cape until Friday (29th).
o Hot and humid conditions are also expected over northern KZN until Saturday (30th).
o Very hot conditions are expected over the Limpopo River Valley and Lowveld of Mpumalanga and Limpopo until Tuesday (3rd).
o It will become cooler with south westerly winds over the southwestern to southern parts of the country (minimum temperatures my decrease into the single digits in high-lying areas) by the weekend, with cooler conditions remaining in place until next week over these areas.
o High temperatures over the northern to eastern areas during the current week will be replaced by normal to below normal temperatures from early next week.

Overview of expected conditions over South Africa during the next few days

Conditions in main agricultural production regions (27 November - 3 December)

Maize production region:

Warm to hot conditions with little to no rain will dominate until the weekend. Isolated thundershowers will occur during this period over mainly the southern parts (and in the east until Friday (30th)), probably only producing light falls but possibly associated with dust storms. Widespread thundershowers are possible from Monday (2nd) when temperatures will be lower.

Maximum temperatures over the western maize production region will range between 30 and 35 °C (lower temperatures towards next week) while minimums will be in the order of 21 - 24°C. Maximum temperatures over the eastern maize-production region will range between 27 and 33°C (cooler conditions by next week when maximum temperatures could fall into the high teens by mid-week according to current forecasts) while minimums will be in the order of 14 - 20°C. Cape Wine Lands and Ruens: Following hot conditions initially (Thursday 27th), cooler conditions will set in and remain in place into next week. Strong south easterlies are possible in the southwest from Monday (2nd) onwards. Light showers are possible on Friday (29th) and Monday (2nd).

Possible extreme conditions - relevant to agriculture

The South African Weather Service issues warnings for any severe weather that may develop, based on much more information (and in near-real time) than the output of one single weather model (GFS atmospheric model - Centre for OceanLand-Atmosphere Studies (COLA) and Institute of Global Environment and Society (IGES) - http://Wxmaps.org) considered here in the beginning of a week-long (starting 27 November) period. It is therefore advised to keep track of warnings that may be issued by the SAWS (www.weathersa.co.za) as the week progresses.

According to current model projections (GFS model) of weather conditions during the coming week, the following may be deduced:
• Thundershowers over the central interior until the weekend may be associated with dust storms.
• Hot and humid conditions are expected over the Lowveld of Mpumalanga and Limpopo and the Limpopo River Valley until Tuesday (3rd).
• Hot, dry and windy conditions over the interior of the Northern Cape and southwestern parts of the Free State (and surrounding areas) on most days may be conducive to the development and spread of wild fires where vegetation is dry.
• Very hot and windy conditions over the interiors of the Western and Eastern Cape Provinces until Friday (29th) may be conducive to the development and spread of wild fires where vegetation is dry.
• Strong south easterlies are possible along the southwestern coastal areas from Monday (2nd) onwards.
• Thundershowers over the central to eastern parts by next week may have a tendency to become severe.