Very warm nights in March 2019

Photo of dead public lawn

Our Nature Strip

While there were no very high or low temperatures, weekly mean temperatures were high. Warm spells through the second and fourth week-ends were about four degrees high.
There were nine rain days (twice the usual number for March), but none had more than 5 mm until the 30th. A rain front early that morning brought 39 mm.

Weather log for March 2019

Comparing March months

This month was very warm. It was like March in 2018 and 2016, but the nights were warmer. Both the mean minimum temperature (17.9°) and the monthly mean temperature (24.9°) were record high values for March in the 21st century.
It was not a dry month: values of all the moisture indicators were near normal. The (estimated) rainfall of 54.9 mm is very close to the long-term average of 53.4 mm. However, March rainfall at Manilla is strongly skewed, having many values just below the average and just a few values up to 240 mm above it. The median March rainfall is much lower: only 39 mm. This month’s total of 54.9 mm is at the 60th percentile: it is higher than 60% of all historic March rainfall values.

The last 7 March months

Drought

The on-going drought is reported in three posts, with three different kinds of graph:

  • a line graph shows rainfall status in the last two months, with duration on the x-axis and severity on the y-axis;
  • a contour graph shows 25 months sequentially on the x-axis, duration on the y-axis and severity by tints;
  • a duration graph shows how shortages began and ended in the last 20 years, with time on the x-axis and duration on the y-axis.

 


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, 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.

Warm, Dry February 2019

Photo of bushfire smoke at 40 km.

Bushfire at Warrabah

The month began warm, with weekly temperature three degrees above normal, but it ended slightly cool. Day and night temperatures remained near normal. The highest maximum was just under 40°.
The morning of the 13th had very dry air, with a dew point of only 1.7°. (Serious bushfires were burning that day.)
There were only 2 rain days (usually 7). Neither recorded as much as 7 mm.

Graphical log for Feb 2019

Comparing February months

After the extreme heat of January, February was only 1° warmer than normal, by day and by night.
Two indicators of moisture, cloudiness and daily temperature range, were normal. However, the mean early morning dew point, 9.2°, showed the lowest February humidity this century.
The monthly rainfall of 10.6 mm was at the 9th percentile, far below the average (67 mm). This was the 12th driest February, but it had more rain than either February 2017 (6th driest) or February 2015 (ninth driest).
I have reported the on-going drought in another post.

The last 7 February months


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, 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.

One- and two-year droughts recur in January 2019

Drought contour plot to Jan 2019

This contour plot shows the progress of the extreme drought at Manilla up to January 2019. Colours show rainfall shortages as percentiles. Dates plot along the top, and durations down the side.

One month rainfall totals (on the top row)

By January 2019, there had been six months without serious monthly rainfall shortages. The months of serious rainfall shortage (light brown) were earlier, in May, June and July 2018. The only other month with such low rainfall was September 2017.

Droughts lasting less than one year (rows 2, 3, 4, 5, 6, 9)

As the effects of low monthly rainfall added up, extreme droughts appeared (dark brown). That is, rainfall totals below the 1st percentile. (They are the lowest rainfall totals, that have occurred in less than 1% of the historical record.)
By June 2018, the 2-month and 3-month totals were already extreme shortages. Similarly, by July, the 3-month, 4-month, and 5-month totals were extreme shortages. By September 2018, extreme shortages extended as far as the 9-month total. That total, adding up the nine months from January to September 2018, included only one month (February) that had rainfall above normal.
In these durations of less than one year, extreme droughts were rare after September 2018. Because the last six months had no serious monthly shortages, the final month (January) includes no serious shortages for durations from 2 months up to 6 months.

Droughts of 1 year to 2 year duration (rows 12, 15, 18, 24)

By August 2018, an extreme 15-month drought appeared. That 15-month total then included not only the dry months of winter 2018, but also the dry month of September 2017. By September 2018, the 15-month total became the driest on record (400 mm). By October all four droughts in this group (12-, 15-, 18-, and 24-month droughts) were extreme. This became true again in January 2019. By that date, some of the dry months of 2017 were no longer included, but dry months in the current summer replaced them in the total.


Related graphs

A similar contour plot with data to October 2018 is here.

A line graph of the rainfall status for January 2019 reveals that extreme shortages also exist now at the much longer durations of six years and seven years that are not included in this contour plot.


Notes

The following notes include:

Classes of rainfall shortage

Rainfall rate versus percentile rank

Limitations of this analysis

Note: Classes of rainfall shortage

Continue reading

January 2019 very hot

Sun sets through gum tree

Eucalypt Silhouette

Weekly temperatures were high all month, peaking at 6.4° above normal on the 17th and never less than 3.4° above normal. Seven days had peak temperature over 40° (fewer than the nine in February 2017). Only one day was cooler than normal, while no nights were.
There were four rain days, with 18 mm recorded on the 21st.

Graphical log for January 2019

Comparing January months

January 2019 was very hot: more than two degrees hotter than any recent month. Mean temperatures were far above the normal January temperatures for this station (means for the decade from March 1999):

Mean Maximum: 38.4°, above normal by 4.6°.
Mean average: 30.8°, above normal by 4.8°.
Mean minimum: 23.2°, above normal by 5.2°.

Manilla was not the only hot place. Australia-wide, this was the warmest January on record.

Apart from high air temperatures, Manilla’s climate was near normal. Even the subsoil temperature was normal. So were the cloudiness, dew point and daily temperature range.
The rainfall of 25.0 mm was at the 15th percentile, far below the average (87 mm). I will report the on-going drought in another post.

Climate for January months


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, 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.

2018 hottest and driest

In the nineteen years 2000 to 2018, this last year was the hottest and the driest.

Climate logs 19 years

Climate records kept at 3 Monash Street, Manilla from April 1999 yield these eight graphs of climate variables. The graphs on the left (red) show heat and those on the right (blue) show moisture.
These graphs show the figures for calendar years. They do not show hot summers or cold winters. In particular, each summer spans two calendar years.
In general, the temperatures in this 19-year record rose, with a pause between 2004 and 2012. Moisture peaked about 2010.

Day Temperatures

Daily max temp, 19 years

Day temperatures are shown by the mean maximum temperature in the thermometer screen. The year 2018, at 27.13°, had the hottest days by far. Four other years with hot days were widely spread: 2002, 2009, 2014, and 2017. The coldest days were in 2008 (24.57°) and 2010 (24.60°), followed by 2001 and 2011.

Average Temperatures

Daily Mean Temp, 19 years.

This graph shows warmth in general, as is done in the study of global warming. For each day, the daily maximum and daily minimum temperatures are averaged. Then these values are averaged for each year. The year 2018 was the warmest (19.11°), but 2017 was only fourth, beaten by 2014 and 2009. The coolest year in this century was 2008 (17.19°), followed by 2001, 2011, and 2012.

Night temperatures

Daily min temp, 19 years

Night temperatures are shown by the mean minimum temperature in the thermometer screen. The year 2018 , at 11.09°, had only the fourth warmest nights. The warmest were in 2014, at 11.34°, followed by 2010 and 2009. Years with nights cooler than 10° on average were 2012, 2008, 2006 and 2001.

Subsoil temperatures

Continue reading

December 2018 dry and hot

Tropidoderus stick insect

Stick Insect

Weekly temperatures, which began normal, then remained high all month, peaking
around four degrees above normal on the 18th and again on the 29th. Only a few days or nights were cooler than normal.
There were six rain days, grouped around the 16th, which had 25 mm. Earlier and later times had sunny skies and low dew points.

Graphical log of weather December 2018

Comparing December months

Remarkably, the three mean temperatures this month are practically the same as those of both December 2017 and December 2016. They are higher, but by no more than 0.2°, near the limit that can be read on my thermometers. The mean daily maximum of 33.9° and the mean daily mean of 26.1° are the hottest for December in this record from 1999. (The mean daily minimum of 18.3° was exceeded by 18.6° in December 2009.)
This was one of the most sunny December months. The percentage of cloudy mornings (19.4%) was the same as in December 2006, but higher than in 2002 or 2005 (both 16.1%).
The rainfall of 34.5 mm is at the 22nd percentile, far below the average (74 mm). Lower rainfall totals occurred in December of 2001 (34 mm) and 2006 (19 mm). I have reported the on-going drought in another post.

Climate in December months


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, 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 December 2018

December hot and dry

3-year trends to December 2018

December raw anomaly data (orange)

In December 2018, the top two graphs show that rainfall was low and skies sunny.
The daily maximum temperature (x-axes, all graphs) and daily minimum temperature (lower left graph) were extremely high, but the subsoil was cool. Dew point and daily temperature range were near normal.

 Fully smoothed data (red)

Climate anomaly data when smoothed in this way do not show changes from month to month, but only those cycles that last for a year or more. The smoothed data identify the month when a peak occurs in a cycle .

By June 2018, the last date for which data can be fully smoothed (as described below), some variables had already peaked in their contribution to the current extreme drought.

The anomaly of daily maximum temperature (x-axis, all graphs) had peaked in March 2018. Two months later, in May 2018, the rainfall anomaly peaked (negative) to a 21st-century record low value of minus 28.3 mm. (In the 2002 drought daily maximum temperature had not peaked until after the peak of minimum rainfall.)
By June, cloudiness was decreasing towards a minimum (perhaps in August 2018) without becoming much less cloudy than normal. Dew point anomaly was still decreasing, and seemed likely to reach a record low value about August.
The anomaly of daily temperature range had been at a (high) level characteristic of drought since the previous winter (2017). It had changed little, and peaked in May 2018 without getting near the record high value of July 2002.
The anomaly of daily minimum temperature has a cryptic relation to drought. In this case, the value peaked sharply in February 2018 before falling rapidly. It may have reached a minimum about August 2018.
The anomaly of subsoil temperature was high in June 2018, and seemed likely to peak about July, lagging four months behind the daily maximum temperature anomaly.


Notes:

January data points are marked by squares.

Smoothing

Smoothing uses Gaussian functions.
For fully smoothed data the function has a Standard Deviation of 2.5 months, it spans 13 monthly data points, and has a half-width of 6 months, which suppresses cycles shorter than 12 months. For partly smoothed data, the span of the function is reduced to 11 months, 9 months and so on.

Fully smoothed data points are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange.

Limiting values

Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

Normal values

Normal values are based on averages for the decade from March 1999.* They appear on these graphs as a turquoise (turquoise) circle at the origin (0,0). A range of anomalies called “normal” is shown by a dashed rectangle in aqua (aqua). For values in degrees, the assigned normal range is +/-0.7°; for cloudiness, +/-7%; for monthly rainfall, +/-14 mm.

 * Normal values for rainfall are based on averages for the 125 years beginning 1883.