Rain waves expected to bring heavy downpour
14 January 2022 | Weather
ELLANIE SMIT
WINDHOEK
Although rainfall performance during the first part of the rainy season has been poor, things are looking up, with rain waves expected to bring heavy downpour into the country until next week.
Due to poor rainfall received for the past three months, the first part of the season ended with a large deficit of rainfall over most parts of the country.
A report by the Namibian Meteorological Services on December rainfall performance said this resulted in depressed agriculture preparations.
Last month was very dry over western parts of the country, it said, while rainfall was confined to the east of Namibia.
“The remainder of the country mostly received below average rainfall for December, while pockets of areas over the eastern and north central regions received above average rainfall with adjacent areas that received normal rainfall.”
Rain waves coming
Very heavy rain, with several rain waves extending to Namibia in the second half of this week until next week, are expected.
This is according to the LandWater Facebook page, which contains comprehensive and researched information on the latest weather trends.
“At least two waves are coming, with possibly a third and then we may see serious trouble,” it said.
LandWater added that for the time being, the north-west of Namibia remains challenged, but the rain waves will soon push feelers their way as well.
“The waves’ impact remains somewhat uncertain... with the bulk of Namibia that also needs to open properly first.”
It further explained that a tropical temperate trough, a strong diagnostic rain channel between Namibia and South Africa, will form a “more classical route along which tropical moisture will flow" to open the channel. This usually produces widespread heavy rain.
"We are clearly in a season that has the potential to move and/or challenge historical boundaries, with broad and general rainfall that will also move to Namibia. It will support the greater southern Africa favourably," LandWater said.
Misconception
According to the page, La Niña usually promotes a more favourable rainy season, but this ‘favourableness’ is still subject to other climatic factors that limit or broaden it, and does not guarantee good rain cover everywhere.
"It is a misconception that is still flourishing that La Niña ensures good rain everywhere, even in a larger environment of rain favourableness."
The sluggishness in Namibia's rainy season this year can probably be explained by the upper air, LandWater said.
"When the upper air's rain energy moves more strongly to South Africa, it creates a significantly more challenging rainy environment over Namibia, with the 'bankrupt' westerly wind that often dominates powerfully. It all happens within good sense and reason due to the placement of the surface air pressure systems.”
However, this dominance is currently waning, according to LandWater.
"It is therefore no coincidence that southern Africa is now opening up so ‘violently’ during the follow-up moderate-to-stronger La Niña. The upper air now offers 'more space', while ground level 'pushes back stronger'."
It also referred to sea temperatures along Namibia that have been colder than average for some time.
"When the water in the Atlantic Ocean is too cold - or hot - it undermines or supports rain. This picture has changed over the past three weeks and it is currently warmer than average,” it said.
Meanwhile, the Namibian Meteorological Services is forecasting widespread thundershowers in the Ohangwena, Oshikoto, Kavango and Zambezi regions.
[email protected]
WINDHOEK
Although rainfall performance during the first part of the rainy season has been poor, things are looking up, with rain waves expected to bring heavy downpour into the country until next week.
Due to poor rainfall received for the past three months, the first part of the season ended with a large deficit of rainfall over most parts of the country.
A report by the Namibian Meteorological Services on December rainfall performance said this resulted in depressed agriculture preparations.
Last month was very dry over western parts of the country, it said, while rainfall was confined to the east of Namibia.
“The remainder of the country mostly received below average rainfall for December, while pockets of areas over the eastern and north central regions received above average rainfall with adjacent areas that received normal rainfall.”
Rain waves coming
Very heavy rain, with several rain waves extending to Namibia in the second half of this week until next week, are expected.
This is according to the LandWater Facebook page, which contains comprehensive and researched information on the latest weather trends.
“At least two waves are coming, with possibly a third and then we may see serious trouble,” it said.
LandWater added that for the time being, the north-west of Namibia remains challenged, but the rain waves will soon push feelers their way as well.
“The waves’ impact remains somewhat uncertain... with the bulk of Namibia that also needs to open properly first.”
It further explained that a tropical temperate trough, a strong diagnostic rain channel between Namibia and South Africa, will form a “more classical route along which tropical moisture will flow" to open the channel. This usually produces widespread heavy rain.
"We are clearly in a season that has the potential to move and/or challenge historical boundaries, with broad and general rainfall that will also move to Namibia. It will support the greater southern Africa favourably," LandWater said.
Misconception
According to the page, La Niña usually promotes a more favourable rainy season, but this ‘favourableness’ is still subject to other climatic factors that limit or broaden it, and does not guarantee good rain cover everywhere.
"It is a misconception that is still flourishing that La Niña ensures good rain everywhere, even in a larger environment of rain favourableness."
The sluggishness in Namibia's rainy season this year can probably be explained by the upper air, LandWater said.
"When the upper air's rain energy moves more strongly to South Africa, it creates a significantly more challenging rainy environment over Namibia, with the 'bankrupt' westerly wind that often dominates powerfully. It all happens within good sense and reason due to the placement of the surface air pressure systems.”
However, this dominance is currently waning, according to LandWater.
"It is therefore no coincidence that southern Africa is now opening up so ‘violently’ during the follow-up moderate-to-stronger La Niña. The upper air now offers 'more space', while ground level 'pushes back stronger'."
It also referred to sea temperatures along Namibia that have been colder than average for some time.
"When the water in the Atlantic Ocean is too cold - or hot - it undermines or supports rain. This picture has changed over the past three weeks and it is currently warmer than average,” it said.
Meanwhile, the Namibian Meteorological Services is forecasting widespread thundershowers in the Ohangwena, Oshikoto, Kavango and Zambezi regions.
[email protected]
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