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 December 2019, 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.]
The following notes explain aspects of this work under these listed headings:
Cumulative rainfall totals
Severity of rainfall shortages
Limitations of this analysis
Monthly rainfalls form a single population
Observations are not retrospective
The rain gauge failed
Weekly average temperatures were 7 deg high early in the month, normal in the third week, then 6 deg high at the end. In these hot weeks, ten days went over 40 deg.
The night of the 11th, at 28.1 deg, was extremely warm. It was the 2nd warmest on record, after 28.2 on 14/01/17.
Although the wettest day had only 22.8 mm of rain, there were 11 rain days. Other signs of moisture included 11 days with half cloud cover or more, and 9 mornings with dew points over 20 deg.
Comparing January months
Mean temperatures this month are the 2nd highest for January, being lower than last year. Subsoil temperature is normal.
All moisture indicators are higher. The early morning dew point, at 16.8 deg, is remarkably high, exceeded only in January 2006.
The rainfall total of 46.8 mm is at the 28th percentile for January, well below the average of 87 mm.
I will report separately on the on-going drought that continues to break low-rainfall records at durations of 15-months and longer.
Data. A Bureau of Meteorology automatic rain gauge operates in the museum yard. From 17 March 2017, 9 am daily readings are published as Manilla Museum, Station 55312. These reports use that rainfall data when it is available. Recording resumed on 20 July 2019.
My estimates of early morning dew point have drifted anomalously low. From August 2019, I use data from the Tamworth Airport published graphs.
All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.
January much more humid
January raw anomaly data (orange)
Daily maximum temperature anomaly (all x-axes) high, but not now extreme: now only three degrees above 21st century normal.
Daily minimum temperature anomaly (lower left): extremely high, twice as high as the record smoothed value
Subsoil temperature anomaly (lower right): still near normal.
Moistures (moist is at the bottom)
Rainfall anomaly (upper left): no longer extremely low.
Cloudiness anomaly (upper right): back to normal.
Dew point anomaly (middle left): suddenly rather high (humid).
Daily temperature range anomaly (middle right): suddenly narrow, due to cloud.
Fully smoothed data values (red)
Smoothed anomaly values now include July of 2019. From the rather static values of the autumn, nearly all smoothed values for June began to move in the direction towards drought that seems to have persisted through spring.
There were two exceptions. Daily minimum temperature anomaly continued to fall. Subsoil temperature anomaly reached a peak value in June.
January data points are marked by squares.
Smoothing Continue reading