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

2019 Climate by months

Monthly temp and rain 2019

The climate at Manilla, NSW,was extremely hot and dry in nearly all the months of 2019.

Mean temperature

In a normal year (See note below: “Manilla temperature Normals”), Manilla’s mean temperature has a cycle close to a sine-wave , being highest in January (25.9 deg) and lowest in July (9.5 deg). In 2019, the shape differed only in June being cooler than July.
Remarkably, every month of 2019 was warmer than normal. June, August and September were warmer by less than 1 deg, but December was 3 deg warmer, and January 5 deg warmer.

Monthly rainfall

Normally, Manilla’s monthly rainfall pattern (see note below) has two modes, with a main peak in January and a second peak in June. In 2019 there was no such pattern. Rainfall in most months was about 40 mm below normal, and was even lower in January, February and December. Only March and May had rainfall somewhat above normal.


Notes

Manilla Temperature Normals

The town of Manilla, NSW, had no recognised record of temperatures. When I had collected data for more than a decade, I felt the need to set up “normals” to compare actual values with those that are usual.

[Earlier, I quoted various official definitions of climatic normals in this post.
A climate normal is commonly taken as an average over three decades. To serve my purpose, I judged that a decade of data would be sufficiently stable.]

I based my normals on temperatures observed through the decade beginning 1 March 1999. I found mean values for the (366) days of the year, then made a more regular curve by using first, second and third harmonics.

Manilla temp normals

The graph shows mean maximum, mean average and mean minimum curves, as well as the resulting curve of daily temperature range. Numerical values that were posted earlier are repeated here:

Manilla’s dates of expected highest and lowest air temperatures during the year are marked on every “Weather” graph that is included in a monthly weather report in this blog. Each graph has curved dashed lines showing the “Normal” temperatures (Maximum, Mean, and Minimum) for each day of the year. The highest and lowest values in the annual cycle are marked on these curves. This list gives the dates of peaks and troughs and their seasonal lags in days after the solstice.
Highest daily maximum temperature (34.04°): January 20-21 (lag 31 days);
Highest daily mean temperature (26.19°): January 25 (lag 35 days);
Highest daily minimum temperature (18.44°): January 31 – February 1 (lag 42 days);
Lowest daily maximum temperature (16.91°): July 8 (lag 17 days);
Lowest daily mean temperature (9.35°): July 10 (lag 19 days);
Lowest daily minimum temperature (1.78°): July 13 (lag 22 days).

Apart from the peaks and troughs, one can see that the curves show a steeper rise in early spring. The rise is more marked and earlier for the maximum curve. This results in a wider daily temperature range at that time.

Manilla’s monthly rainfall pattern

As my normals for the rainfall of calendar months, I have adopted the mean values recorded in the 125 years 1884 to 2008 at Manilla Post Office, Station 055031. Values are shown in this table:

Manilla monthly rain normals.

Model of seasonal rainfall, ManillaIn the post of 20 June 2013, “A Seasonal Rainfall Model for Manilla, NSW”, I showed that the observed seasonal pattern fits very well to a model of two Gaussian curves of almost equal width but unequal height. The higher (summer) curve peaks at 84 mm/month near 27 December, while the lower (winter) curve peaks at 42 mm/month near 27 June. The peaks lag just 6 days after the solstices, and do not show the long and unequal seasonal lags that are seen in temperature data (above).

[There are discrepancies of less than 1 mm in monthly rainfall normal values between the table above and those cited in 2013. As the normal period, I replaced 1883 to 2007 with the more secure period 1884 to 2008.]

December 2019: very hot and dry

Sun in smoke

Red Sun 17 Dec

After the first week, each week in December was very hot, reading up to 5.9° above normal. Both days and nights were hot, but only one record was set: 42.2° on the 21st was the hottest December day. That was well below the record hot day of 44.9° set on 11/2/17.
Twenty mornings were cloudless which was twice the usual number. Smoke from mainly coastal bushfires reduced visibility to 15 km or less from the 8th to the 25th. Early in the month, rain fell on three days, the highest reading being 12.4 mm on the first day.

December 2019 weather

Comparing December months

This month broke 21st century records for December mean monthly temperatures. The mean minimum of 18.7° just beat 18.6° of December 2009, the mean average of 27.6° easily beat 26.1° last year, while the mean maximum of 36.5° was far above last year’s 33.9°.
On balance, indicators of moisture make this the driest December of the century. Rainfall, at 19.6 mm, was lower than any but December 2006 (18.8 mm), and the dew point was equal lowest with 2013. This month had by far the fewest cloudy mornings (10%) and the widest daily temperature range (17.8°).

December 2019 climate

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 December 2019

December dry and very hot

3-year trends of climate anomalies

December raw anomaly data (orange)

Temperatures

Daily maximum temperature anomaly (all x-axes) extremely high: now five degrees above 21st century normal and three degrees above the record for smoothed values.
Daily minimum temperature anomaly (lower left): very high, just above the record smoothed value.
Subsoil temperature anomaly (lower right): still near normal.

Moistures (moist is at the bottom)

Rainfall anomaly (upper left): extremely low.
Cloudiness anomaly (upper right): extremely low.
Dew point anomaly (middle left): still rather low.
Daily temperature range anomaly (middle right): very high.

 Fully smoothed data values (red) 

Smoothed anomaly values now include June of 2019. From the rather static values of the spring, nearly all smoothed values for June began to move in the direction towards drought that seems to have prevailed since then.
There were two exceptions. Daily minimum temperature anomaly continued to fall very rapidly. Subsoil temperature anomaly approached a peak value.

Detail of rainfall vs. max temp

Rainfall and temperature anomaly trendsThe relation of smoothed rainfall anomaly to smoothed daily maximum temperature anomaly (top left graph) is important, but the graph is hard to read. I have drawn a part at a larger scale here.
The value for September 2017 is the first to show the current drought by falling on the hot-dry side of the normal range (aqua). Values became successively warmer and drier until March 2018 (max temp) and May 2018 (min rain). Values (especially temperature) then cycled away from drought until August-September 2018, and back to record-breaking drought in January 2019.
After January 2019, there was a retreat from drought until May 2019, when anomaly values were like those of 17 months earlier, in January 2018 (red square).
June 2019 began a renewed cycle towards drought, seemingly confirmed by later data.


Notes:

January data points are marked by squares.

Smoothing Continue reading

“Novel graphs for rainfall shortages”

I display my drought poster

Garry’s drought poster

Drought poster for conference

Grasslands Conference Poster Display

A conference paper about drought graphs

This blog “Climate by Surly” has analyses of the current drought at Manilla, mainly in the form of graphs. I was invited to present these findings as a “Poster Paper” at a conference of the Grassland Society of NSW at Gunnedah in July 2019. The poster itself is shown in the photo and the reduced image above.

The paper

The paper is published in two parts: the colour poster shown above, and four pages of text and figures. Both have the title “Novel graphs show extreme rainfall shortages”.
The point of my paper was that these novel graphs bring out features of the current drought at Manilla in a way that could be applied at other times and places.
Because the paper is brief, I have referred the reader to further information in posts in this blog. The construction of each of the three kinds of graph is fully explained in the posts that I linked:
/2019/03/31/march-rain-leaves-drought-extreme/
/2019/04/09/rainfall-shortage-sequence-03-2019/
/2019/04/15/rainfall-shortage-history-manilla/
/2019/04/16/rainfall-shortage-jan-2000-mar-2019/

The complete reference to the paper is:
Speight JG (2019) Novel graphs show extreme rainfall shortages. In
‘Proceedings of the 31st Conference of the Grassland Society of NSW Inc.’ (Eds SR Murphy, SP Boschma, and M Simpson). pp. 36-39. (Grassland Society of NSW Inc., Orange).

The text can be accessed here as a pdf:

Click to access 6-2019-grassland-conf-proc-speight-pp35-39-web-ver.pdf

The paper will become accessible on the website of the Grassland Society of NSW.

The Poster on display

Thanks to the generosity and interest of the proprieters, the original of the poster can be seen at Molly May’s Coffee Shop in the main street of Manilla.

Rainfalls: 8 in the 0.1th percentile

Rainfall status October November 2019

Normal rainfall in November

Rainfall in November 2019 (40.2 mm) was near normal. That reduced shortages at durations from 2-months to 5-months. Otherwise it had little effect: fifteen of twenty longer durations remained extreme shortages.

Values plotted in the 0.1th percentile

For simplicity, the bottom line is labelled with the 0.1th percentile value, and percentile values below 0.1% are plotted on the line. As there are 1600 months of record, both the 2nd-driest month (percentile value 0.063%) and the driest month, (percentile value 0.000%, by convention), which would plot below the line, are plotted on it.
Driest records have again been broken at durations of 12-months (270 mm), 24-months (611 mm), 30-months (834 mm), 72-months (2927 mm), and 96-months (4205 mm). The 96-month record had stood at 4405 mm since November 1919.
A value that equals an earlier record occurs at 84-months (3555 mm).
Values that are 2nd-driest occur at 36-months (1129 mm) and at 240-months (11816 mm). The 240-month (20-year) total is now only 50 mm more than the lowest-ever value of 11766 mm set in February 1931.

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 October 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.]


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