There will be longer periods with sunny and mild to warm conditions than what was experienced last week and rainfall totals will be lower for the most part.
Relatively wet conditions will occur especially on Wednesday and Thursday (10th/11th) and possibly again by the latter part of the weekend into early next week. With favorable upper-air conditions, rainfall should be wide spread. Hail can occur in some areas, but will once again remain small in the vast majority of cases. Temperatures are expected to remain in the near-normal to above-normal range, with no indication of frost yet.
The expectation of more rain over the interior follows a week of widespread rainfall, including both the western and eastern maize-production areas. Most of the western maize-production region received in excess of 50 mm of rain since the start of April. Sunny and warm periods during the next few days will probably have a positive rather than negative effect across the production areas, given late planting and the need for heat units.
The following is a summary of weather conditions during the next few days:
• General:
o On average, the north eastern and central parts of the country will again receive above-normal rainfall.
o Both the western and eastern maize-production areas are expected to receive normal to above-normal rainfall.
o The western to south western parts of the country, including the winter rainfall area, will receive below normal rainfall.
o Temperatures over the interior will on average remain in the normal to slightly above-normal range.
o There is no indication of early frost given the expected weather conditions during the next few days.
o Thundershowers will occur frequently over the summer rainfall region.
o Showers and thundershowers will remain in place for the most part over the central to eastern areas, focusing somewhat more in the northeast.
o It will be sunny and mild to warm over most areas on Tuesday (9th) and again from Friday (12th) into the weekend.
o Cloudy, wet and cool conditions are possible over the central to eastern parts of the country, including the maize-production areas on Thursday (11th)
o The winter rainfall region and the southern parts of the country will become wet, windy and cold on Saturday (13th) until Sunday (14th) as a cold front moves over the area.
o The south eastern to eastern coastal region and adjacent interior will be drier than during the last few weeks, but cloudy, wet and windy conditions will occur over these areas from Sunday (14th) and remain in place by Monday (15th).
o Fresh to strong south easterlies will occur over the south western parts on Tuesday (9 th) and again from Sunday (14th).
• Rainfall:
o Scattered thundershowers will occur from Tuesday (9th) until Friday over most of the interior, focusing on North West, the Free State, Mpumalanga, Gauteng and the interior of KZN.
o There may be cloudy and rainy periods in and around North West on Wednesday (10th) and Thursday (11th).
o Little to no rain is indicated for the summer rainfall region, according to current forecast, for Saturday and most of Sunday.
o Some thundershowers over the eastern parts of the Northern Cape, western Free State and western North West may become severe on Wednesday (10th). Some of these thundershowers may also produce significant daily rainfall totals.
o Cold, windy conditions with showers are expected over the southern parts and the winter rainfall region on Saturday (western areas) and Sunday (more towards the east).
o Widespread thundershowers are again possible, according to current forecasts, from late Sunday and Monday over the central to north eastern and eastern interior. o It will be cloudy with rain and showers along the south eastern to eastern coast and adjacent interior on Sunday (14th) and Monday (15th).
• Temperatures:
o Maximum temperatures over the western maize-production region will range between 19 and 27 °C while minimums will be in the order of 12 - 18°C.
o Maximum temperatures over the eastern maize-production region will range between 20 and 28°C while minimums will be in the order of 10 - 14°C.
o It will be warm to hot over the Lowveld on Tuesday (9th) and Sunday (14th).
o It will be hot over the Karoo and as far east as the coast of the Eastern Cape on Thursday (11th) and Friday (12th) due to berg-wind conditions.
o Temperatures will fall by about 10°C over the southern parts of the country where it will be cold and windy from Saturday (13th) evening.
Overview of expected conditions over South Africa during the next few days
Two upper-air troughs will move across the country and keep conditions favorable for a continuation of relatively wet conditions over the interior for the most part. The two systems will result in wet conditions over the interior especially on Wednesday (10th) to Thursday (11th) and possibly again from Sunday (14th) into early next week. Given low temperatures in the upper-atmosphere and dynamic nature of rain-producing systems, small hail could accompany several thundershowers during the period. In the vast majority of cases, these should remain small and have little impact. A cold front ahead of the ridging high by Sunday may result in wet and windy conditions over the winter rainfall region from late Saturday and continuing Sunday (14th).
The Atlantic Ocean Anticyclone will ridge strongly to the south of the country on two occasions, supporting the strengthening of the upper-air lows/troughs over the interior and also resulting in strong south easterlies over the south western parts on Tuesday (9th) and Sunday/Monday (14th/15th). Conditions in main agricultural production regions (9 - 15 April)
Maize production region: The region will continue to receive normal above-normal rainfall during the next few days. It will remain mild to warm. Abundant cloud cover may occur on Wednesday (10th) and Thursday (11th) as well as possibly early next week. While thundershowers are possible on most days, these may become most wide spread on Wednesday and Thursday (10th, 11th) over especially the North West. Maximum temperatures over the western maize production region will range between 19 and 27 °C while minimums will be in the order of 12 - 18°C. The cloudy conditions with showers or thundershowers on Tuesday and Wednesday (10th and 11th) will be responsible for relatively low maximum temperatures during these days. Minimum temperatures will remain in the normal range and no frost is expected according to current forecasts.
The eastern parts of the maize-production region can also expect thundershowers on most days, mostly of isolated to scattered nature. The main focus of the rain on Wednesday (10th) and Thursday (11th) will be somewhat further west. There are early indications that widespread rain may occur early next week. Cloud cover is expected to be fairly extensive on Thursday and Friday (11th/12th), with partly cloudy to sunny conditions for most of the remainder of the period. Maximum temperatures over the eastern maize-production region will range between 20 and 28°C while minimums will be in the order of 10 - 14°C.
Cape Wine Lands and Ruens: This region will be mild to cool for the most part. It will be mild to warm over the entire region with little to no rain until Saturday. A cold front will result in windy and cool to cold conditions with showers, mainly towards the south, from Saturday afternoon. The rainy conditions should clear during Sunday, with cooler conditions remaining in place until early next week when fresh to strong south easterlies are possible in the southwest.
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 - Center 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 9 April) 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 and CCAM atmospheric models) of weather conditions during the coming week, the following may be deduced:
• Some thundershowers over the interior may have the tendency to become severe, producing strong gusts and hail: o Eastern parts of the Northern Cape, western Free State and western North West (Wednesday (10th)).
• Hail may occur in association with some thundershowers over the interior in general, but these will remain small and have little impact in the vast majority of cases.
• Small stock farmers should take note that it will be cool to cold, wet and windy from late Saturday (13th), continuing Sunday (14th).
• Strong south easterlies are possible over the south western parts by early next week. These may be conducive to the development and spread of wild fires where vegetation is dry.
