THE record-breaking rainy season that large parts of Namibia have been experiencing this year can be attributed to the strongest La Niña condition in the Pacific Ocean in at least 35 years.
This is indicated by the Meteorological Service of Namibia in its latest monthly report on the 2010-11 rainy season.For the greater part of the Namibia, the total quantity of rain received during the rainy season from October to the end of April has been unprecedented, with rainfall totals at most places having exceeded historical records, the Meteorological Service is reporting.Only the extreme north-east and south of Namibia bucked the trend, with below average rainfall recorded in these parts of the country.Places where the total rainfall measured during the 2010-11 season has set new records include the Windhoek Met Office, Ondangwa and Rehoboth.At most other weather stations throughout Namibia the seasonal totals are substantially higher than the normal average.The La Niña episode in the Pacific Ocean, during which the sea surface temperature across the eastern parts of the Pacific Ocean is lower than normal, has been in place since August and has by some measures been the strongest La Niña since at least the mid-1970s, according to the World Meteorological Organization.The La Niña event is associated with above-average seasonal rains in southern Africa.Rainfall records dating back some 95 years in the case of Ondangwa and Rehoboth, and close to 120 years in the case of Windhoek, have been rewritten during the 2010-11 season.At the Windhoek Met Office, a total of 1 027,4 mm of rain was recorded from October to the end of April, according to figures that the Meteorological Service released on Tuesday. This rainfall total is the highest to be measured at the Windhoek Met Office since the start of rainfall records at that site in 1893.The previous record was a seasonal total of 762,3 mm in 1933-34.On average, a total of 354,8 mm is measured at the Windhoek Met Office between October and April.A new record was also set at Ondangwa, where rainfall records stretch back to 1916.In the 2010-11 rainy season, 1 026,6 mm was recorded at Ondangwa, where in an average season a total of 448,5 mm can be expected.Ondangwa’s seasonal total this year is the highest since at least the 1916-17 rainy season, when that site’s previous record of 981,8 mm was recorded.At Rehoboth, too, a new record has been set. The 730,8 mm of rain recorded at Rehoboth this season is the most since at least 1916 as well, surpassing the previous seasonal record of 716,6 mm measured in 1993-34. In an average rainy season Rehoboth receives about 238,7 mm of rain.Other places where the seasonal total in 2010-11 has significantly exceeded average seasonal totals include Ruacana, with 960,4 mm (normal seasonal total 425,8 mm), Ombalantu (Outapi), with 732,3 mm (normal total 443,9 mm), Rundu with 757,4 mm (average seasonal total 565,6 mm), Okaukuejo at 675,7 mm (normal seasonal total 350,9 mm), Grootfontein with 956,3 mm (normal total 556,9 mm), Kalkfeld with 857,9 mm (normal total 345,7 mm), and Hochfeld with 708,7 mm (normal total 421,8 mm).South-east of Windhoek, Dordabis recorded a seasonal total of 605 mm, compared to 293,1 mm in an average rainy season, while a total of 530,1 mm was measured at Leonardville (235,7 mm in a normal season), 505,2 mm at Aranos (187,5 mm in an average season), 493,7 mm at Gibeon (normal seasonal total 147,6 mm), 253,7 mm at Keetmanshoop (seasonal average 152,4 mm), and 111,3 mm at Gobabeb in the Namib Desert (normal seasonal total 21 mm).However, the rainy season was below average at Katima Mulilo in the north-east, which received a total of 506,1 mm, compared to 653,6 mm in an average season, and in the south-east, where a total of 113,5 mm was recorded at Karasburg (127,6 mm in a normal season) and 92,8 mm was measured at Warmbad (96,1 mm in an average season).
