Author: Weatherman

Visual: Early Friday morning surface synoptic map of the southern African sub-continent Source: South African Weather Service, www.weathersa.co.za/observations/synoptic-charts What Happened Rainfall totals exceeding 100 mm for April are very rare for Namibia but with the wet spell of last week and the weekend, this is where most of the regions north of Hardap now stand. It is noteworthy that the local precipitation was matched by similar occurrences in Angola and Zambia with both the Kavango and Zambezi rivers rising by about four metres in a matter of days. As of Tuesday, the impact of the South Atlantic high could...

Visual: Change in soil moisture outlook for the next 8 days as of Friday 13 April Source: GrADS/Cola, George Mason University, National Centers for Environmental Prediction www.wxmaps.org/outlooks.php What Happened Following the anomalous synoptic pattern of last week, this week the weather returned to a more typical Namibian stance with the only exception being the continuing late rains. During the week the South Atlantic high pressure cell followed its customary route around Cape Agulhas on its journey to the east. By Friday, it has morphed into the southern Indian high with its core situated about 1500 km south of Madagascar....

Visual: 30-Day Moving Southern Oscillation Index Source: Australian Bureau of Meteorology http://poama.bom.gov.au/climate/enso/ What Happened The Southern Oscillation Index maintained by the Australian Bureau of Meteorology broke through the 10 index point level last week, this week moving further up to Friday’s 12.3 value. This is for the so-called 30-day moving average which expresses an intensification (positive) or weakening (negative) of the difference in surface pressure between Darwin in Australia and Tahiti, some 1000 km to the east in the western Equatorial Pacific. This difference is then compared to the values of a month ago to determine the movement and...

Visual: Extract from the full-disk infrared image from the Eumetsat satellite over the South Atlantic and southern Africa, disseminated by the US National Oceanic and Atmospheric Administration. Image compiled on Wednesday 28 March at 06:00. Source: http://www.goes.noaa.gov/f_meteo.html What Happened This week’s widespread rain over most of Namibia demonstrates just how critical the position of the South Atlantic high pressure cell is to local weather. For the first time in many months, the high’s core lay almost equidistant to Africa and South America, implying that it was more than 3500 km away from Africa. Usually, and for the past five...

First Visual: Digitally enhanced satellite image of convection over southern Africa on Thursday 22 March 2018. Image is based on refraction, i.e.temperature differences at 18:00 CAT. Source: Eumetsat at oiswww.eumetsat.org/IPPS/html/MSG/RGB/CONVECTION/ Second Visual: Eumetsat infrared satellite image of southern Africa on Thursday 22 March 2018 taken over the Greenwich meridian at 14:00 CAT. Source: oiswww.eumetsat.org/IPPS/html/MSG/IMAGERY/IR108/COLOR/SOUTHERNAFRICA/ What Happened With another cold front passing the southern Cape, conditions south of the Orange River this week displayed a distinctly wintery pattern. This was confirmed by the first widespread but light rain over large areas of the Western Cape and the southern Cape region....

Visual 1: Synoptic map, surface conditions, southern Africa, Friday 16 March at 06:00. Source: South African Weather Service, http://www.weathersa.co.za/observations/synoptic-charts Visual 2: Satellite image of southern Africa, Friday16 March at 16:00 Source: South African Weather Services on Twitter What Happened Tropical storm Eliakim that is now hugging the north-eastern section of Madagascar again has a major impact on local weather despite being so far removed from Namibia. As its predecessor of ten days ago, it is draining moisture from central Africa and offshore East Africa but at the same time it is putting it back in the alto levels from...

Visual: Outlook for Wednesday 14 March for surface pressure and the vertical depth of the atmosphere from sea level to 500 mB. Source: GrAds/Cola – George Mason University, http://www.wxmaps.org/fcst.php What Happened A strong zonal airflow from the east encountered the outer rim of the South Atlantic high pressure cell more or less over the Namibian escarpment. Where the warmer system from the north ran over the higher pressure on the surface, a broad convergence zone was the result. The convergence zone reached from southern Angola into the Namibian interior. On its western flank it covered the northern Namib and...