February 2020: one drought record left

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

February 2020: wet, humid, cool

Garden path suddenly overgrown.

Overgrown Path

High weekly temperature persisted only a few days into February. After that, the temperature was normal or below normal. Day temperatures varied, without reaching extremes. Although the warmest February night (27.6°) came on the 2nd, most nights were near normal (18.0°).
After the first days, the dew point was high, making for very humid mornings, which were also overcast.
There were fourteen rain days, over twice the usual number.
Two days had over 40 mm of rain, causing local erosion and flooding. For Manilla, these are not very wet days. [See note below: “Very Wet Days”.]

Weather log for Feb 2020.

Comparing February months

The mean monthly temperature, at 25.2°, is near normal, and cooler than the last four February months. More dramatic is the low mean daily maximum temperature (31.1°), which is fourth coolest for February in the new century.
All moisture indicators were extremely high. Compared to 21st century February values, they were:

Cloudy days percent (62%): highest.
Daily temperature range (11.9°): lowest.
Dew point (16.7°): 2nd highest.
Rainfall total (165.4 mm): 2nd highest.

The rainfall total of 165.4 mm is at the 92nd percentile for February, well above the average of 67 mm. The previous eight months all had rainfall below average.

Clime to Feb 2020.

Drought

I will report separately on the on-going drought that has again broken a low-rainfall record for a duration of 96-months.


NOTE.
Very Wet Days

I have a blog post that shows the 125 rain days at Manilla that exceeded 50 mm.
From time to time, there is a period of years without extreme daily rainfalls: when no day has more than 80 mm of rain. We are in the longest such period, beginning 21 years ago, on 7 September 1998. [That day was the 5th wettest, at 112 mm, which filled Split Rock Dam.] See the “Comments” section in the linked post.


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. Unfortunately, the gauge failed during this month (25/02/2020 ). Pending repair, I am using my own gauge.
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.

3-year trends to February 2020

February suddenly cool and wet

3-year climate trends to Feb 2020

February raw anomaly data (orange)

Temperatures

Daily maximum temperature anomaly (all x-axes) suddenly fell by 5° to -2°.
Daily minimum temperature anomaly (lower left): fell from extremely high to normal.
Subsoil temperature anomaly (lower right): still near normal.

Moistures (moist is at the bottom)

Rainfall anomaly (upper left) suddenly rose by 130 mm/month to plus 100 mm/month.
Cloudiness anomaly (upper right): rose from normal to +32%.
Dew point anomaly (middle left): remained rather high (humid).
Daily temperature range anomaly (middle right) reached -3°.

 Fully smoothed data values (red) 

Smoothed anomaly values now include the winter season (JJA) of 2019. From the rather static values of the autumn, nearly all smoothed values for winter moved steadily in the direction towards drought that seems to have prevailed through spring.
There were two exceptions. Daily minimum temperature anomaly steadily fell. Subsoil temperature anomaly fell from a peak value in June.


Notes:

January data points are marked by squares.

Smoothing Continue reading

January 2020: still 5 drought records

Rainfall status Dec-19, Jan-20

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

Data analysis

Continue reading

January 2020 more humid

Rain in the main street

It rained!

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.

Weather log January 2020

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.

January climae

Drought

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.

3-year trends to January 2020

January much more humid

3-year climate trends to Jan 2020

January raw anomaly data (orange)

Temperatures

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.


Notes:

January data points are marked by squares.

Smoothing Continue reading