Weather Briefing at 12/10/2020
As we proceed towards the core of austral summer, the weather outlook over southern Africa (SAF) becomes all the more interesting. On today's satellite image, there is a distinct cloud band extending from NW SAF into the SW Indian Ocean (Fig. 1). This cloud band is indicative of Tropical Temperate Trough (TTT) events (Macron et al., 2014; Quangraine et al., 2019) that transfer momentum and energy from the low-latitude regions towards the extratropics. In general, TTTs form as a result of the interaction between a tropical disturbance (eg. the Angola Low) with an upper-level westerly flow (Lyons, 1991) (Fig. 2). The intensity of TTTs has been found to be linked with the strength of the Angola Low pressure system (James et al., 2020).
Figure 1: Infra+ imagery with pseudo-colours for cloud top temperatures <-33oC, indicative of deep convection at 12/10/2020.
Figure 2: Wind speed at 250hPa (shaded) and surface pressure contours at 12/10/2020.
*All maps are taken from Windy