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Author: Weatherman

The Week’s Weather up to Friday 08 December. Five-day outlook to Wednesday 13 December 2017

Map: 08 December 2017. Southern Hemisphere barometric pressure on the surface. Distribution of high pressure cells along the high pressure belt. Vertical depth of the atmosphere from 1000 mB to 500 mB surface. Source: COLA/George Mason University, The core of the South Atlantic high pressure cell has not budged. For the past four weeks it has been stuck in the same locality roughly one thousand kilometres west of Cape Town. Early in this week, its leading edge sent out a protrusion rounding the continent just south of Cape Agulhas but remaining offshore. Very little local impact was felt...

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The Week’s Weather up to Friday 01 December. Five-day outlook to Wednesday 06 December 2017

Synoptic Map: Early Friday morning, 01 December, as published by the South African Weather Service. Source: A comparison of the synoptic map earlier in the week with Friday morning’s map shows a weakening of the cores of both the South Atlantic and the southern Indian high pressure cells. At the same time, it is very obvious that the highs are fairly static and that over the course of a week, only minor movement has taken place. By the end of this week, the cores of the two highs were, give or take a hundred or so kilometres, still...

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The Week’s Weather up to Friday 24 November. Five-day outlook to Wednesday 29 November 2017

Map: Smoothed temperature anomalies for the 8-day period from Friday 24 November to Saturday 02 December 2017. Normal temperature is based on observations from 1901 to 2000. Source: US National Centre for Environmental Prediction, The temperature anomaly map is an aggregate of expected daily conditions measured against historical values. As such it is not indicative of the temperature at any given time on any given day, but it shows the departure from the average if all the readings were to be smoothed over the 8-day period. It has to be read in conjunction with the surface pressure map...

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The Week’s Weather up to Friday 17 November. Five-day outlook to Wednesday 22 November 2017

Map: Animated progressive map of southern Africa surface pressure and wind flow on Friday 17 November 2017. Source:,-2.548,52.734,3 An understanding of the South Atlantic high pressure cell is essential to understand what transpired weatherwise this week. As is evident from the coloured synoptic map, the South Atlantic high is a formidable weather phenomenon, arguably the single biggest driver of Namibia’s weather. The local impact of all other elements are defined by the relative strength and the physical locality of this high. The areas marked in yellow are the outer perimeter of the highs. Barometric pressure at this isobar...

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The Week’s Weather up to Friday 10 November. Five-day outlook to Wednesday 15 November 2017

Synoptic Map of southern Africa at 06:00 CAT on Friday 10 November 2017 Source: South African Weather Service. Link: The early Friday morning synoptic map of the SA Weather Service shows a rather unconventional picture. The leading bulge of the South Atlantic high sits directly south of the continent on its way to become the southern Indian high. Its core, however, is displaced much further south than usual, straddling the 45°S latitude. This is very far south for any high pressure cell’s core and then to remain at a strength of 1024 mB is also extraordinary. It is...

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The Week’s Weather up to Friday 03 November. Five-day outlook to Wednesday 08 November 2017

Satellite Image: Infrared photograph of southern Africa at 08:00 central African time on Thursday 02 November 2017, taken when the satellite is directly above the Greenwich meridian. The satellite receptor is designed to capture wavelengths in the 9.8 µm to 11.8 µm range. These are translated to a representation of surface temperature, clouds, wind fields and atmospheric instability. Source: EUMETSAT The early Thursday morning Eumetsat Infrared image of southern Africa provides a beautiful summary of what transpired earlier in the week, and what materialised on Thursday and Friday. At the beginning of the week there was still weak...

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The Week’s Weather up to Friday 27 October. Five-day outlook to Wednesday 01 November 2017

Map: Rainfall forecast from Friday 27 October to Saturday 04 November 2017 Source: COLA/George Mason University   This week saw the first significant showers in the north. Widespread rains were observed from Sunday to Wednesday in Ohangwena, Oshikoto and Kavango East regions. Cloud built-up started during the weekend and by Sunday afternoon the first showers appeared in a wide belt from Omuthiya eastward to the Kavango East border. The rainfall was so substantial that puddles formed extensively over large areas although none of these kept the water for more than a few hours after the actual showers. However,...

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The Week’s Weather up to Friday 20 October. Five-day outlook to Wednesday 25 October 2017

Graph. Southern Oscillation Index maintained by the Australian Bureau of Meteorology. The graph tracks the relative difference in surface barometric pressure between Tahiti in the Pacific and Darwin in North-east Australia. The two places are about 1000 km apart. The daily relative values are compared to the readings of a month earlier to derive at a moving daily index value. Values greater than +8 are deemed to indicate La Nina conditions while values less than -8 indicate El Nino conditions. (Published by There is a very strong, empirical correlation between the Aussie’s Southern Oscillation Index and rainfall conditions...

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