Understanding Weather – not predicting – 01 February 2013

What happened?
No rain of any significance so far and the outlook for much of the new calendar year is only bleak!
But we have had rain, early and quite evenly distributed for quite sometime, so? The value of rain in the ground has its limits: these have been tested to the full during these past weeks.
For some time, even looming before the New Year, the synoptic patterns have shown an unusual pattern in the upper air with the ability to thwart further influence and limit whatever moisture flowed in closer to the surface.
Across our skies and above the South Atlantic, from about 16000 feet altitude thence high in the upper layers a persistent high pressure core has, if anything, become more prominent during the past two months. This means a dry influence dominating whatever weather can develop lower down.
This upper-air high pressure cell is coupled with a low pressure core close to Antarctica around which the regular vortex sequence flowed, yet the core persists. Being the lowest core in the polar area, situated due south of the Cape, it appears these two cores create a restricted space through which surface level anticyclines must squeeze.