Coen Welsh | Nov 14, 2017 | 0
The curtain raiser is lovely but wait for the main event
The country’s most popular social event, the Windhoek Show, starts this Friday. The widespread rains that occurred over large parts of a drought-stricken country are a welcome prelude to the show since a very large section is for the agricultural sector.
Early rains are typically associated with showtime, not because the show exerts some magic influence on the environment but simply because it is the turn of the season creating weather conditions that allow the first, but shallow, intrusion of moist air from the north.
This week’s rain could not have come at a better time despite our superstition about too much early rain. The real small rain season must only follow about a month later at the end of October, beginning of November. It must also be brief, bringing nothing more than a promise of the actual rains that must start towards the end of December. Between the small rain and the start of the main rain season must be a six-week lull, blistering hot by day, and almost bearable by night. That is a typical rainfall pattern and those are the conditions we are used to.
However, the weather has not stuck to the rules for the past ten years and we have had more than our fair share of weather anomalies and extreme weather events. From 2001 to 2011 we have had floods for seven out of the ten years. Then came the drought this year, the first we have had since 1998.
It is an open question whether we shall see a repeat performance of early rain across much of the country, but at least, this week brought a brief respite to a parched land. Yet, from an agricultural perspective we need to be realistic that the drought has not been broken by a long shot. The deficit in precipitation is still measured in the hundreds of millimetres and it will take much more water than this small amount of rain to restore grazing.
When I speak to farmers who are all hoping for some early rains I constantly remind them that we are now only at the beginning of the harshest part of the year. September, October and November are notorious for being very hot and relatively dry. So, if one thinks the farmers are in a difficult position now, wait until mid-November to appreciate the full impact of the survival months.
Even in a normal year, finding sufficient grazing during this time, is often not easy. Consider what the condition of grazing is like now for perhaps 80% of the country, following nine months of drought.
I have yet to meet the farmer who does not bargain on the resumption of a normal rain season from December onwards, and while I must admit atmospheric conditions have improved somewhat, I must also point out that this is only marginal. The Australian counterpart of our Meteorological Service maintains a so-called Southern Oscillation index which tracks, on a daily basis, the monthly variance in air pressure between Tahiti and Darwin. While some researchers describe this index as “noisy” referring to the wild up and down swings it is known for, this is a result of its methodology and not a lack of credibility. I have found over several years that there is a marked correlation between the current value of the index and current local weather conditions. This index has only recently moved into positive territory, but again it must be stressed, it is marginal.
Another group of scientists at the National Oceanic and Atmospheric Administration in the United States maintain an index which they call the Multivariate ENSO (El Nino Southern Oscillation) index. This index moves much slower than the Aussie ENSO index but it has been pointed out to me recently that this is a good leading indicator of future local weather conditions, about six months from now. This index is exactly the opposite of the Aussie index, meaning negative values indicate La Nina conditions while positive values indicate El Nino. This index has now moved further negative three months in a row, but again, also only marginally. Thus, if one has to make some sort of rainfall prediction, it is safe to say that two indices with somewhat different methodologies are both indicating a positive rain season, or at least not a negative one.
Already I have heard several people saying (hoping) that December will herald a new wet year. That may be so, nobody really knows. Predicting the weather is just as dangerous as predicting financial markets. But any hopes for a very wet year, at this stage, are not supported by the available evidence.
A second dry or below average rainfall season will certainly spell true disaster for us but we have to be realistic and admit Namibia did not become an arid zone yesterday. Aridity and drought are the norm, and I would advise anybody who lives off the land, to first wait for the grass, before buying the next batch of tollies.