A frontal system will move into the southwestern half of the country from Sunday into next week, bringing colder conditions with it - but current indications are that it will not be sufficiently intense to result in widespread frost.
While the frontal system is expected to bring some rain to the winter rainfall region as well as the Garden Route, it is not expected to result in widespread significant falls over the area. There is also an indication of somewhat wetter conditions along the eastern coastal areas and into the Lowveld by early next week - apart from this the interior is expected to remain largely dry.
The following is a summary of weather conditions during the next few days:
• General:
o The maize production region will remain dry for the most part.
o On average rainfall over the interior will be absent.
o Some rain is expected over the winter wheat production region of the Cape during the weekend when a cold front will move into the region.
o Temperatures will on average be above normal for this time of the year.
o Rainfall will be below normal except for the eastern seaboard.
o No widespread frost is expected during the next few days according to current forecasts.
o Moderate to strong Southeasterlies will occur over the southwestern Cape from Sunday into next week.
• Rainfall:
o Isolated showers or thundershowers are still possible over the far eastern parts on Wednesday (29th), with somewhat more significant rain along the coasts of KZN and the Eastern Cape.
o The interior is expected to remain dry for the rest of the period according to current forecasts.
o Showers will occur over the southern parts of the winter rainfall region on Sunday (3rd) or late Saturday, spreading eastwards along the Garden Route.
o The rainy conditions along the coast will spread northwards towards the KZN seaboard by Monday (4th).
o Showers will move further north, into the Lowveld by Tuesday (5th).
• Temperatures:
o Temperatures will on average increase until the weekend over the interior.
o It will be warm to hot along the West Coast until Friday (1st).
o Hot bergwind conditions will develop over the western to southern interior on Saturday (2nd), especially the Karoo and onto the southeastern coastal areas, ahead of the frontal system.
o It will cool down significantly over the southern interior to become cool and windy on Sunday (3rd) and Monday (4th).
o Most of the interior, especially the southern half, will see a drop of 3 - 5°C in maximum and minimum temperatures early next week according to current forecasts, as a frontal system move in from the southwest.
o Maximum temperatures over the western maize production areas will be in the order of 21 - 26°C (somewhat cooler initially, warming). Minimum temperatures will be in the order of 8 - 14°C, also warming though the period.
o Maximum temperatures over the eastern maize-production region will range between 17 and 23°C, on an increasing trend through most of the period. Minimums will be in the order of 6 - 8°C - with lowest temperatures early on in the period.
Overview of expected conditions over South Africa during the next few days
Upper-air anticyclonic conditions will dominate during the next few days, resulting in dry conditions over the interior. A frontal system will influence the southwestern to southern parts from Sunday (3rd), with the associated ridging anti-cyclone possibly resulting in some rain over the far eastern parts (southern to eastern seaboard, Lowveld and escarpment). At this stage there isn't an indication of upper-air support for significant rain over the interior.
Conditions in main agricultural production regions (22 - 28 April)
Maize production region:
Except for some residual showers and cloud on Wednesday (29th), it will be sunny and mild to warm with light winds for the most part. Maximum temperatures over the western maize production areas will be in the order of 21 - 26°C (somewhat cooler initially, warming). Minimum temperatures will be in the order of 8 - 14°C, also warming though the period. Maximum temperatures over the eastern maize-production region will range between 17 and 23°C, on an increasing trend through most of the period. Minimums will be in the order of 6 - 8°C - with lowest temperatures early on.
Cape Wine Lands and Ruens:
It will be mild over the area but warm along the West Coast until Friday. By Saturday it will become windy ahead of a frontal system that may move into the area by Saturday evening, affecting mostly the southern parts (including the Garden Route) in terms of rainfall. It will clear by late Sunday (3rd), but is expected to remain cool with southerly to southeasterly winds.
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, windy conditions over the western to southern parts until Friday (1st) may be favorable for the development and spread of wild fires where vegetation is dry.
• Hot, bergwind conditions will develop over the Karoo and southeastern coastal areas on Saturday (2nd) and will be conducive to the development and spread of wild fires where vegetation is dry.
• Cold, windy conditions from Sunday (3rd) over the southern parts (Karoo) may adversely affect small stock in the region.
• Strong south easterlies may occur at times over the southwestern coastal areas by Sunday (3rd) into early next week. Where vegetation is dry, this may enhance the possibility for the development and spread of wild fires.
