Fourth article in a series that discusses the technical aspects of rainfall
“Daily rainfall” is an approach which gains no attention from the aspects of literature.
How to apply the mass of figures on record for just one station into a format from which detail can be extracted may seem to be too obvious to require a detailed set of steps.
In other words, the individual finds square one and proceeds.

At the Weather Office, Mrs. Ronel le Grange had built a spreadsheet to cover monthly detail providing for both monthly and individual season totals to be instantly available following the completion of the relevant entry. With the assistance of Dr. Richard Moorsom, then chief research officer at NEPRU, the existing detail was electronically copied and transferred to his own data base. This seemed to provide an adequate square one.
First, though, the certain indicators needed a presentation. Taljaard and Steyn had in the previously-noted Technical Paper identified the peak months of the season which they named the Core Months. These certainly identified a bulk of the individual season's expectations (some 70 per cent in fact) but there remained useful months requiring an identity. The link of these months gave birth to the title of “Associated Months”. Together these Core and their Associated months (A&C) contributed 95 per cent of the expectations: fair enough. The A&C and Core months provide the focus from which the entire display is, and would be, based.
A third tier does exist: the September, October and May range. These with a less than 5 per cent overall contribution have been named “Possible” months.
Even to the most distant observer, the considerable range of variability to the rainfall scene has several dimensions: the extent of the season is just one more.
The name El Nino was readily apparent, so those years were listed with A&C months together and then just the Core Months. Later on, as their events years came to hand, Benguela El Nino and La Nina were placed in the adjacent, following El Nino, columns. The full range of years was then given the A&C and Core month columns listing. Then followed Wet and Dry Years based on ranges of percentages, appropriate to our rainfall ranges, of the mean.
The Lotus123 programme does not count spaces and, with our rainfall patterns in mind, each season, each month, will all experience enough dot days to take good value from this burden of the unrecorded.