The ability to tap this and advect
deep levels to displace the intense dry upper pattern does not appear from the current charts and their outlooks for our part of the hemisphere.
Wind-flow patterns, both recorded and predicted, describe motion aloft from directions unlikely to advect
moisture in any quantity.
The ability to advect
a broad band of this moisture was restricted by an equally persistent upper air anticyclonic core extending from our mid sub-continent westward across the Atlantic to South America, holding sway from some 16000 to 27000 feet and its core between 25 and 30oS.
this polar air further north and the result is the cold blast we experienced.
Any prospect of late Spring showers depends on the persistent heat-low generating an upward convective extension to tap the adjacent moister air mass gathering above much of Zambia, linking with the equally adjacent Congo air mass then to advect
this combination into our Kavango area or further west.
The lower pressure to the north and the west of this system brought rain to Zimbabwe and northern Botswana but the push was not strong enough to advect
more moist air over Namibia.
Their southerly ridges reach deep into the polar region from where they quickly advect
very cold air northward across southern Africa.
During Tuesday, a ridge pushed east along the southern coast, with limited southward extension, but with the ability to advect
a band of colder air northward and then circulate it into much of our airspace.
The effect of the changing climate is an increase in rainfall across a more limited time-frame, yet the ability to advect
sufficient moist air at the appropriate levels has not been lost.
The colder override could easily advect
from the coast, undercutting the warm, moist air mass but overriding a valley.