Guest Contributor | Mar 20, 2018 | 0
Current weather pattern similar to late 2012
Following the prolonged dry and hot weather conditions experienced throughout the country, the Economist got a chance earlier this week to get an in-depth analysis from Namibia’s own weatherman, John Olszewski.
On whether another drought is looming, Olszewski said, “the current weather pattern has been building these past few days, plus/minus from Christmas time.
The Pacific Ocean sees a stumbling El Nino with sea surface temperatures (for start) wobbling above and below the warm anomaly benchmark, so much so that computer models are hesitant with regard to future or possible development into an actual event.”
Olszewski told the Economist that these current conditions are reminiscent and similar to a pattern that evolved in late December 2012. Explaining the weather patterns he said, “however, we do have a proximate presence of moist air in considerable depth from extreme eastern Angola eastward embracing the Zambezi catchment area away and across Mozambique.
It does not need too much of departure from the current synopsis to tap and advect a good layer of this moist air mass into, at least, the eastern third of Namibia, as we saw a few times during the past set of weeks.”
“The southern hemisphere mean sea level patterns (MSLP charts) show across the Atlantic a reversal of the previous scenario with an anticyclonic core between St Helena and Tristan da Cunha: this is text book sub-Tropical High Pressure at home, while across both the Indian and Pacific Oceans these anticyclonic cores are closer to the 40oS latitude.”
He said this is a climate change response to Global Warming and expansion of the Torrid Zone so pushing the sub-Tropical High Pressure zone that much further south.
Olszewski noted that the December pattern, locally at least, seemed to respond to the evolving global situation.
“The north-to-south division put the east of Namibia within a fairly responsive airmass with good showers being noted.
There were also similar incursions into the Cuvelai Delta and Okavango catchment area, perhaps more Isolated (30% ranges) than Scattered (60% ranges), matching the “Variability” designation of an Arid Climate.”
Historically this is part-and-parcel of our record, he explained.
Olszewski said the heat can also be evidence of Global Warming, pointing out that descending air contributes to the heat by the release of energy and issuing a reminder that it is mid-summer and high temperatures are to be expected.
Meanwhile, in terms of the country’s rainy season, he pointed out that it runs from November to April, a six-month period during which even the wettest corner, the Okavango catchment area, rarely exceeds 60 recorded rainfall days which may be as low as 40 days during a dry year.