Dry September 2019

Striped Honeyeater at the Window

Weekly average temperatures increased slightly, as is usual in September. Unusual day temperatures came early in the month. The first 30-degree day was 18 days early, on the 5th. The next day was the hottest of the month, at 31.9°. During the next 3 days the daily maximum temperature fell by 16.9° to 15.0°, the coldest day of the month. Later, temperatures stayed closer to normal. There were 4 frosts, the usual number.
At the Manilla Museum, 1.2 mm of rain was recorded on the 23rd.

Comparing September months

The last three September months have all been dry, with low dew points, wide daily temperature ranges and not much cloud. They have not been nearly as hot as September of 2013, however.
The rainfall total of 1.2 mm is the 3rd lowest September reading, after 0 mm in 1980 and 1 mm in 1925. By way of contrast, the second graph also includes the deluge of 122.4 mm in September 2016, the 4th wettest on record.

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 August 2019

Summer record hot-dry (as smoothed)

3-year climate trends to August 2019

August raw anomaly data (orange)

Temperatures

Daily maximum temperature anomaly (all x-axes): near the maximum for smoothed values.
Daily minimum temperature anomaly (lower left): near normal.
Subsoil temperature anomaly (lower right): very high.

Moistures (moist is at the bottom)

Rainfall anomaly (upper left): very low.
Cloudiness anomaly (upper right): normal.
Dew point anomaly (middle left): low, like the other recent values.
Daily temperature range anomaly (middle right): very high.

 Latest fully smoothed data (red), summer 2018-19

Temperatures

Daily maximum temperature anomaly peaked at a record +1.79° in January.
Daily minimum temperature anomaly held the record vaue of +2.16° through January and February.
Subsoil rose rapidly from normal.

Moistures (moist is at the bottom)

Rainfall smoothed anomaly peaked negative in January at the record value of minus 31.75 mm per month.
Cloudiness was normal.
Dew point was low.
Daily temperature range was normal.


Notes:

January data points are marked by squares.

Smoothing Continue reading

New drought records in August 2019

Rainfall status July-August 2019

Graph of Rainfall Shortages

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 August, 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.]

Record low rainfall values

August rainfall of only 5.6 mm at Manilla has brought more drought records. The rainfall totals for 18-, 24-, 36-, 72-, and 84-months are new record lows.
The record-low 36-month total is remarkable. Only the great droughts of 1947, 1914, and 1967 had rainfall nearly so low for so long, but the current 36-month total (1283 mm) is more than 50 mm lower than in those great droughts. Given that Manilla’s mean  annual rainfall is 652 mm, 1283 mm represents less than two years of rainfall in three years.

Severe and extreme rainfall shortages

For plotted durations longer than four months, only the very longest (30 years) is not a severe or extreme rainfall shortage. For durations beyond 84 months (including 30 years) every total is lower than has been seen since 1954, 65 years ago.


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

Dry August 2019

Blossoms on a street tree

August Blossoms

Weekly average temperatures steadily increased as is usual in August. Day and night temperatures also were not far from normal. The warmest day reached 27.1° and the coldest night -1.4°. There were 15 frosts, the usual number.
Rain was recorded at the Manilla Museum on the 1st (1.0 mm) and the 12th (4.6 mm).

Weather log august 2019

Comparing August months

This dry month was very like August 2013, with the August months between being mainly rather cooler and wetter.
The mean maximum temperature (20.9°) was above normal by 1.4°, and the mean minimum temperature (3.3°) was near normal. The resulting temperature range (17.6°) was high, agreeing with the rather low cloudiness (26%) and dew point (-1.0°).
The rainfall total of 5.6 mm is at the 8th percentile for August.

Climate for August 2019

Drought

I have reported 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.  No 9 am readings were recorded from August 2018 to 19 July 2019. 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.

July 2019 had the warmest days

Ruby Saltbush Enchylaena tomentosa

Drought-proof Ruby Saltbush

Only the middle week of July was not warmer than normal. Nearly all days and nights were above average for this coldest time of the year, but none was exceptional. No night minimum was as warm as ten degrees. There were 15 frosts (normally 17), but, as happened in July 2009 and 2010, there were no severe frosts reading below minus two degrees in the screen.
Rain was recorded on the 8th and 9th, estimated as 5.0 mm and 5.5 mm.

Weather log July 2019

Comparing July months

The last three July months saw maximum, mean, and minimum temperatures steadily rising, with the temperature range (17 deg) staying high. That was not true earlier in the decade: from 2008 to 2012 temperatures were steady and the daily temperature range (14 deg) was low, with cool days and warm nights. It was the case again in July 2015 and 2016, as shown here.
Indicators of moisture were again low, but not as low as in July 2018, with its record low dewpoint and cloudiness. The (estimated) rainfall total of 10.5 mm is at the 14th percentile for July.

Climate at July 2019

Drought

I have reported 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.  Since no 9 am readings have been recorded since August 2018, I have substituted my non-standard gauge readings for all days.
All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

3-year trends to July 2019

Record dry and warm (as smoothed)

3-year climate trends to July 2019

July raw anomaly data (orange)

Temperatures

Daily maximum temperature anomaly (all x-axes): above the maximum for smoothed values.
Daily minimum temperature anomaly (lower left): just above the upper limit of normal values.
Subsoil temperature anomaly (lower right): very high.

Moistures (moist is at the bottom)

Rainfall anomaly (upper left): very low.
Cloudiness anomaly (upper right): normal.
Dew point anomaly (middle left): low, like the other recent values.
Daily temperature range anomaly (middle right): very high.

 Latest fully smoothed data (red), January 2019

Temperatures

Daily maximum temperature was a new record positive value of +1.79 deg, beating +1.62 deg set in March and December 2018.
Daily minimum temperature set a new record of +2.18 deg, beating +1.98 deg set the previous month.
Subsoil was normal due to phase lag.

Moistures (moist is at the bottom)

Rainfall smoothed anomaly was a new 136-year record value of minus 31.75 mm per month, breaking the record of minus 30.8 mm set the previous month.
Cloudiness was normal.
Dew point was low.
Daily temperature range was normal.


Notes:

January data points are marked by squares.

Smoothing Continue reading

Drought worse in July.

At Manilla, most rainfall totals just got lower.
Rainfall status June and July 2019

Graph of Rainfall Shortages

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 July, 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.]

Results for July

Rainfall totals for months to July 2019 are the lowest ever registered here for six of the twenty-five chosen rainfall durations: 15-, 18-, 24-, 30-, 72- and 84-months.
Only three of the chosen durations do not have serious rainfall shortages below the 10th percentile: 1-month, 3-months and 360-months. Even those three values are far below normal, at the 12th, 14th, and 14th percentiles.

Weatherzone forum closed

I posted a provisional version of this graph to catch the final deadline for posting to the weatherzone forum. My first post was nearly 16 years ago.
That forum is now closed to postings and will close completely in November. It closed due to lack of public interest in climate and weather in Australia.


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