Understanding Weather – not predicting – 19 April 2013

What happened?
This last week saw an unexpected switch from the generally dry weather patterns which prevailed these past months. Although high pressure cells remained very much in evidence, the heart of these anticyclonic cores moved rather more to our east, than their previously predominant situation to the west of Namibia. The immediate upshot was that when a promising weather pattern presented itself, the ability to tap a moist air source to our north was given a better chance of success.
That this switch coincided with the new moon also attracted comment. The moon’s ability to pull both water and air cannot be denied but the compendium of other influences show that its effect on tides is more pronounced than its effect on weather, especially so late in summer.
But the new moon did coincide with the arrival of a broad system stretching all the way from the Western Cape to the South of Namibia, and producing showers of limited intensity of less than 10mm at best.
The synoptics patterns of the passing anticyclones and vortex cores, proceeded at will. Their ability to provoke activity further north, at least over central and southern Namibia, has brought an ability for showers to return to the countryside. But the expectations, based on April’s historical records, were still left wanting.