A few upper-air perturbations and surface moisture will keep conditions rather favorable for precipitation over the northeastern parts until the weekend. Thundershowers will however be less intense and somewhat less organised for the most part, compared to the storms moving over the summer rainfall region earlier this week. The period should not be characterised as excessively wet due to sunny periods and nature of rainfall events. More importantly, there is still no indication of a widespread frost event over the interior for the next week according to current forecasts.
The following is a summary of weather conditions during the next few days:
• General:
o The northern half of the maize-production region should continue to receive above-normal rainfall.
o The central to southwestern parts of the country are expected to remain dry for the most part while the southwestern winter rainfall region may receive some rain towards early next week.
o On average, temperatures will be near normal towards the east and along the coast, but above normal over the central to western interior.
o Partly cloudy and warm conditions will dominate the northeastern half of the country with thundershowers expected on most days through the week and weekend.
o Friday/Saturday (17th/18th) could see fairly extensive cloud cover over the northeastern parts resulting in relatively low maximum temperatures and fairly widespread thundershowers on the Highveld and surrounding areas in the northeast.
o Thundershowers over the northeastern to northern parts should clear by Monday (20th).
o A cold front will bring cooler conditions the southwestern parts from Sunday (19th) into early next week.
o There is no indication of a significant penetration of cold air over the country during this period, with no indication of widespread frost.
• Rainfall:
o Isolated showers/thundershowers are possible over KZN, Mpumalanga and Limpopo on Wednesday and Thursday (15th/16th).
o Thundershowers will spread westwards and become scattered, to include also North West, Gauteng and the Northern Free State on Friday (17th) and Saturday (18th). These days will also be somewhat cooler with extensive cloud cover over these areas.
o Thundershowers may contract northeastwards again by Sunday (19th).
o It should clear by early next week over the northeastern parts with little to no rain according to current forecasts over that region.
o By early next week, a new band of isolated thundershowers will develop over the central to western interior.
• Temperatures:
o Most of the interior will experience mild to warm conditions, with somewhat lower maximum temperatures over the northern to northeastern parts on Friday and Saturday due to extensive cloud cover.
o It will become hot to very hot over the western interior as well as the southern parts (mostly Karoo) - but including the south-eastern parts of the Eastern Cape on Saturday (18th) and Sunday (19th). Sunday (19th) will be especially hot and windy over the southern parts (berg-wind conditions).
o It will become cooler over the winter rainfall region by Sunday (19th), spreading into the southwestern interior by Monday (20th) and Tuesday (21st).
o Maximum temperatures over the western maize production areas will be in the order of 19 - 26°C - lowest temperatures expected on Friday (17th) and Saturday (18th). Minimum temperatures will be in the order of 10 - 14°C.
o Maximum temperatures over the eastern maize-production region will range between 19 and 24°C while minimums will be in the order of 8 - 11°C.
Overview of expected conditions over South Africa during the next few days
No less than four upper-air perturbations will move over the northeastern parts of the country during the next few days until Sunday, supporting thundershowers over most of the northeast. The upper air will become more stable towards Monday, with little to no rain expected early next week, except for a redevelopment of thundershowers over the western to central interior by mid-week. The area of thundershowers will move progressively westwards during the period, but it is not expected to extend to the southern parts of the country. A cold front is expected I the southwest by late Sunday (19th). While cooling will take place over the southwestern parts, current forecasts don't indicate extreme cold nor significant inland penetration (mostly limited to southwestern interior).
Conditions in main agricultural production regions (8 - 14 April)
Maize production region:
Thundershowers are possible over the eastern parts on Wednesday (15th) ad Thursday (16th), spreading westwards to cover the entire area and becoming more widespread while associated with extensive cloud cover by Friday (17th) and Saturday (18th). By Monday it should have cleared over the entire region, with partly cloudy and mild to warm conditions dominating. Maximum temperatures over the western maize production areas will be in the order of 19 - 26°C - lowest temperatures expected on Friday (17th) and Saturday (18th). Minimum temperatures will be in the order of 10 - 14°C. Maximum temperatures over the eastern maize-production region will range between 19 and 24°C while minimums will be in the order of 8 - 11°C. There is currently no indication of widespread frost over any part of the region.
Cape Wine Lands and Ruens:
The first few days will be mild with light winds. It will become hot with northerly to northwesterly winds on Saturday (18th) especially over the interior (pre-frontal conditions). A frontal system will move into the area by Sunday (19th), bringing colder windier conditions with showers especially over the southwestern parts by late Sunday (19th) and Monday (20th). It will remain cool on Tuesday (21st).
Possible extreme conditions - relevant to agriculture
According to current model projections (GFS model) of weather conditions during the coming week, the following may be deduced:
• Hot (and at times) windy conditions are possible over the western interior on Saturday (18th) and Sunday (19th). Where vegetation is dry, these conditions may enhance the probability for the development and spread of wild fires.
• It will be very hot and windy over the Karoo and into the southeastern parts of the Eastern Cape on Sunday (19th). Where vegetation is dry, these conditions may enhance the probability for the development and spread of wild fires.
• It will be cool to cold (and windy) over the southwestern interior from Sunday (19th). The cold and windy conditions may adversely affect small stock in the region.
• In isolated instances, thundershowers over the northeastern parts may become severe, especially by Friday (17th) and Saturday (18th). However, conditions will not be as supportive for development of large or widespread hail as seen earlier in the current week.
