Cumulus Report: 31 January 2020- South Africa

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The next few days will be warm and relatively dry over most parts. Isolated thundershowers are possible over the central interior and Highveld on most days, but the high temperatures and the isolated nature of rainfall events will result in some drying during the period.

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

• General:

o Rainfall will be below normal for this time of the year, especially over the northern to north eastern parts of the country.
o The winter rainfall region is expected to be mostly dry.

o It will be warmer than normal on average, especially over the western interior.

o It will generally be windy for this time of the year over the central to southern parts.
o Strong south easterlies are possible over the southwestern parts in the beginning of the period.

• Rainfall:

o Isolated to scattered thundershowers will occur over the Eastern Highveld and westward into North West and northern Free State on Thursday (30th) and Friday (31st).
o Scattered thundershowers will occur over the Eastern Cape, especially towards the eastern parts, during the weekend and early next week.
o Isolated thundershowers will occur over the central to western interior, including the Northern Cape interior and Karoo from Saturday (1st) onwards. Thunderstorms may be accompanied by strong and gusty winds leading to dust storms in some places.

• Temperatures:

o It will be very hot over the interior of the Northern Cape, especially towards the north western parts of the province.
o Very hot conditions will spread into the Karoo and southern half of the Eastern Cape by Friday (31st) and early next week.
o Hot conditions will develop over the western parts of the country and along the West Coast by early next week

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

Local circulation patterns will be somewhat unfavourable for widespread rain as upper-air anticyclonic circulation will keep the large tropical cloud masses to the north of our region. Thundershowers should be isolated in nature for the most part while temperatures will for the most part be above normal.

Conditions in main agricultural production regions (30 January - 5 February)

Maize production region:

Scattered thundershowers will occur over the central to eastern parts on Thursday (30th) and Friday (31st). From the weekend until Tuesday (4th) thundershowers will focus more strongly over the western parts, albeit isolated in nature. Isolated thundershowers may spread over the entire area during next week. Maximum temperatures over the western maize-production region will range between 28 and 34 °C. Minimums will be in the order of 14 - 18°C. Maximum temperatures over the eastern maize-production region will range between 27 and 32°C while minimums will be in the order of 10 - 15°C.

Cape Wine Lands and Ruens:

It will be mostly warm and sunny to partly cloudy. Isolated thundershowers associated with the system over the interior may occur over the eastern mountainous areas during the weekend and early next week. Strong south easterlies are possible over the southwestern parts initially.

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:
• Thundershowers over the western to central interior during the weekend and next week may result in strong and gusty winds - causing dust storms in some areas especially further west.
• It will be very hot over the Northern Cape most of the time.
• Hot and windy conditions at times over the Northern Cape may be conducive to the development and spread of wild fires where dry vegetation is present.
• It will be very hot over the Karoo and further east over the Eastern Cape on Friday and again early next week.
• Thundershowers spreading into the eastern parts of the Western Cape may have a tendency to result in strong winds and hail in some places.