Weather

Understanding Weather – not predicting – 18 January 2013

Summary

What happened?Weather condition across the region were rather static for most of the week.A well-developed and active equatorial low pressure core present above south-eastern Angola and western Zambia marked the southern limit of the Inter-Tropical Con…

What happened?
Weather condition across the region were rather static for most of the week.
A well-developed and active equatorial low pressure core present above south-eastern Angola and western Zambia marked the southern limit of the Inter-Tropical Convergence Zone causing widespread rains across several hundred kilometres in the belt south of the Angola border.
It is the anticipated pattern of such low pressure cores to drift westward, being given a gentle nudge by the adjacent, equally persistent, Trade Wind flow and the rotation of the planet itself. Unusually, this equatorial core remains stationary. The associated rainfall belt remains within the convergent airmass and resultant falls are considerable.
This situation can be likened to our experience in 2011.
The seemingly complementary pattern is the cohesive upper air anticyclonic core holding sway between the middle layers and higher upper levels on the edge of the jet-stream that twists and turns from west to east above the surface core of the sub-Tropical high pressure belt.