Changing shortages
January rainfall of 46.8 mm further reduced short-term shortages, bringing the 9-month total (212 mm) out of the “extreme shortage” class. Most longer-duration totals remained in that class, however.
Fewer record low rainfalls
By December 2019, there had been 10 new record low rainfalls. Records were set not only for 12-months duration, but for every one of the 9 chosen durations from 24-months to 96-months. In January 2020 there were only 5 new records, although there were 4 2nd-lowest values that also plotted on the 0.1th percentile line. The 5 new records were:
36-months duration: 1098 mm;
48-months duration: 11775 mm;
60-months duration: 2384 mm;
84-months duration: 3419 mm;
96-months duration: 4132 mm.
How to read the graph
This graph shows all the present rainfall shortages at Manilla, short term and long term, as percentile values. The latest values, as at the end of January 2020, are shown by a thick black line with large circles. Those from one month earlier are shown by a thinner line with small diamonds. [The method is described in “Further Explanation” below.]
Further Explanation
The following notes explain aspects of this work under these listed headings:
Data analysis
Cumulative rainfall totals
Percentile values
Severity of rainfall shortages
Limitations of this analysis
Monthly rainfalls form a single population
Observations are not retrospective
The rain gauge failed