Category Archives: 21st-century climate

May 2020: as in March, no new drought records

Posted in Australian Climate, Climate events, Manilla NSW, Rainfall from 1883 by

Rainfall shortages at Manilla NSW

Changing shortages

Nine extreme rainfall shortages persisted at Manilla in May, one fewer than in April. No serious shortages occurred at 9-months or less. However, the 12-month total (440 mm) once again became a serious shortage (9th percentile).
The two rainfall totals nearest to record values for dryness were those that made new records most recently. The 42-month total of 1485 mm (2nd driest) had reached the record value of 1468 mm in April, while the 96-month total of 4141 mm (4th driest) had reached the record value of 4104 mm in February.

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 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

Data analysis

Continue reading →

April 2020: once again a new drought record

Posted in Australian Climate, Climate events, Manilla NSW, Rainfall from 1883 by

Changing shortages

Many extreme rainfall shortages persisted at Manilla in April. That is despite no serious shortages at 12-months or less. Extreme shortages, below the first percentile, occurred at 24-, 30-, 36-, 42-, 48-, 60-, 72-, 84-, 96-, and 240-month durations. Once again, the 42-month rainfall total broke the record for dryness with 1468 mm, surpassing the record of 1477 mm set in December.
The 96-month total of 4116 mm was also very close to the record low total of 4104 mm mm set in February.

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 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

Data analysis

Continue reading →

March 2020: no new drought records

Posted in Australian Climate, Climate events, Manilla NSW, Rainfall from 1883 by

Changing shortages

Despite high rainfall (165 mm) in February and normal rainfall (53 mm) in March, many severe and extreme shortages persisted. Only at durations shorter than one year were rainfall totals near normal. As in February, the 12-month total remained at 432 mm: a serious shortage.

Three near-record low rainfalls

Although no records were broken this month, three rainfall totals were the third-driest ever: those for 42-months (1508 mm), 84-months (3495 mm) and 96-months (4142 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 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

Data analysis

Continue reading →

2019-20 summer hot and moist

Posted in Manilla NSW, Season Weather, Weather extremes by
Sef-sown senna plants

Pepper-leaf Senna

Through December and January, this summer had a series of heat waves perhaps worse than those of the previous two summers, and rainfall and humidity were low. Similar droughty weather elsewhere brought catastrophic bushfires.
On the 3rd of February the weather changed dramatically. Heat waves were replaced by spells of cool or normal temperature, with high humidity, overcast days, and rain. Up to that date, cool spells had not occurred since November 2018, 15 months earlier. During those 15 months, regardless of the season, the weekly mean temperature often rose several degrees above normal, but never fell below normal.
Coincidentally, there were 14 rain days in both the hot-dry part of the season (65 days) and in the cool-wet part (26 days).

Weather log summer 2019-20

Seasonal average or total figures for this summer mean little because of the climatic break from 3 February.
Mean temperatures (max, mean, min) were close to the records set in the summers of 2017 and 2019, which they would have exceeded if February had not become cooler. Subsoil temperature remained normal.
In summer 2018-19, two of the moisture measures (daily temperature range and cloudiness) had been near normal, while rainfall and dew point had been low. Now, in 2019-20, rainfall and dew point were higher, making all four moisture measures normal.
The summer rainfall total of 232 mm is at the 55th percentile, very close to the average (227 mm).

Manilla summer climate

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. I have used it since 20 July, when the Museum gauge began recording again.  Unfortunately, the gauge failed during this season (25/02/2020 ). Pending repair, I am using my own gauge. My estimates of early morning dew point have become anomalously low. From 1 August 2019, I use values taken from Tamworth Airport graphs at the time of minimum temperature.
All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

February 2020: one drought record left

Posted in Australian Climate, Climate events, Manilla NSW, Rainfall from 1883 by

Rainfall status Manilla Jan-Feb 2020

Changing shortages

Very high February rainfall of 165.4 mm further reduced nearly all rainfall shortages, especially short-term ones. The 12-month rainfall total (432 mm) now just qualifies as a “serious shortage” below the 10th percentile.
Despite the general improvement, 10 of the longer-term totals are still extreme shortages, below the 1st percentile. However, only one breaks a record.

One record low rainfall

Only one rainfall total was a new record low value: the 96-month (8-year) total of 4104 mm. This record, having stood at 4405 mm since November 1919, was broken successively in November and December 2019 and January and February 2020.

Record-breaking low rainfall totals from 2018

Until 2018, no new records for low rainfall had been set since 1971. Most records had stood since the droughts of the 1940’s, more than 70 years ago.
In September 2018, a new record was set for the 15-month total (400 mm).
Since then (to include February 2020), new records have been set for 12-, 15-, 18-, 24-, 30-, 36-, 42-, 48-, 60-, 72-, 84-, and 96-months. That is, at 12 of the 25 selected durations. Some records have been broken repeatedly; five times in the case of the 15-month duration.
To judge by records broken, this drought is by far the worst at Manilla since readings began (1883).

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 February 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

Data analysis

Continue reading →