February is normally the driest month within the winter rainfall areas of the Western Cape and it seems that the same can happen this year. The total monthly rainfall for February (slide1) indicated the typical dry west (mostly ≤10mm) while the eastern parts showed some rain (mostly 10 to 50mm). When viewing rainfall against the historical long term means (slide 2), then the southern to western coastal area including the southern parts of the Karoo region distinctly indicate below normal rainfall. Above normal rains appeared to be present in most districts but to a lesser extent. Slide 1 Slide 2 February 2018 Climate Summary A similar trend to the above description was found from data of 37 weather stations (slide 3) containing total monthly rainfall, mean monthly maximum (Tmax) and minimum temperatures (Tmin) for February 2018, including corresponding historical long term means (LTA). Rainfall for February on average was slightly below normal, i.e. overall mean of these weather stations averaged 11mm vs LTA 17mm vs 9mm in 2017. Half of the weather stations each recorded a total monthly rainfall ≤9mm (2017 2.5mm). The highest monthly rainfall was recorded at Merweville (55mm versus LTA 20mm), 4 weather stations recorded ≤1mm rain (mainly in the Swartland and Cape Winelands), while 9 weather stations ≥ LTA rainfall (mostly in the West Coast and Central Karoo).
Transcript
February is normally the driest month within the winter rainfall areas of the Western Cape and it seems that the same can happen this year. The total monthly rainfall for February (slide1) indicated the typical dry west (mostly ≤10mm) while the eastern parts showed some rain (mostly 10 to 50mm). When viewing rainfall against the historical long term means (slide 2), then the southern to western coastal area including the southern parts of the Karoo region distinctly indicate below normal rainfall. Above normal rains appeared to be present in most districts but to a lesser extent.
Slide 1 Slide 2
February 2018 Climate Summary
A similar trend to the above description was found from data of 37 weather stations (slide 3) containing total monthly rainfall, mean monthly maximum (Tmax) and minimum temperatures (Tmin) for February 2018, including corresponding historical long term means (LTA). Rainfall for February on average was slightly below normal, i.e. overall mean of these weather stations averaged 11mm vs LTA 17mm
vs 9mm in 2017. Half of the weather stations each recorded a total monthly rainfall ≤9mm (2017 2.5mm). The highest monthly rainfall was recorded at Merweville (55mm versus LTA 20mm), 4 weather stations recorded ≤1mm rain (mainly in the Swartland and Cape Winelands), while 9 weather stations ≥ LTA rainfall (mostly in the West Coast and Central Karoo).
As for temperatures (slide 3): February experienced a normal monthly Tmax (Celsius), resulting in an overall average of 31.1 (LTA 30.6) degrees, ranging from 24.9 (George) to 36.0 degrees (Citrusdal). Monthly Tmax anomaly at Oudtshoorn was 2.4 degrees.
Monthly mean early morning temperatures (Tmin) for February obtained from the weather stations resulted in a normal overall average of 15.4 degrees, with Tmin’s ranging between 13.2 (Murraysburg) to 19.5 degrees (Prince Albert).
Overall water level of provincial state dams on 26th February (slide 4) was 21% (last year 32%). The water content of dams in the southern coastal parts and some specific dams in the Karoo regions increased due to the better rainfall conditions.
Slide 3
Improvement in rainfall during January and February brought some relief in terms of veld growing conditions (slide 5) thereby decreasing large red areas (January map) into smaller areas (February map). Larger and more intense green areas, depicting more vigour in vegetative growth, remain to a great extent absent.
The Seasonal Forecast Worx (released March 2018) indicate that the Western Cape can experience below normal rainfall conditions during the first half of winter (slide 6 & 7).
