Tag Archives: drought

3-year trends to August 2014

Posted in 3-year climate trends, Manilla NSW by

Parametric plots of smoothed climate variables at Manilla
“August 2014 back to normal”

Trends to August 2014

 August data (orange)

Most raw anomaly values for August have returned to near normal. The daily maximum temperature anomaly has finally fallen below normal and rainfall has risen above normal. The dew point anomaly remains well below normal, but its value is on the (green) trend line that has applied during the last three years.

Fully smoothed data (red)

Fully-smoothed data is now available for the summer season ending in February 2014. During the summer all variables except daily minimum temperature moved decisively away from drought. Rainfall increased rather slowly, but cloudiness increased very rapidly, and daily temperature range fell very rapidly.

The hot-arid climatic peak (drought) of spring 2013

Extreme anomaly values of climate variables came in the following order:

Highest minimum temperature (not high): July;
Highest subsoil temperature (extreme): July;
Widest temperature range (very wide): October;
Highest maximum temperature (extreme): October;
Least cloudiness (normal): October;
Lowest dew point (extreme): December;
Lowest rainfall (very low): December-January.

This is not the order that is typical in recent extreme episodes. The smoothed rainfall anomaly minimum of -22.3 mm (not nearly as low as the -27.1 mm of July 2002) came much later than the peak of daily maximum temperature. On the top left graph the trace curved anti-clockwise, which is unusual.

Note:

Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.
Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

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.

 

3-year trends to July 2014

Posted in 3-year climate trends, Manilla NSW by

Parametric plots of smoothed climate variables at Manilla
“July 2014 dry again”

Trends to July 2014

 July data (orange)

Most raw anomaly values for July have now moved back to be like the smoothed values during the summer drought. Very few of the partially-smoothed values during the last few months suggested a trend in this direction.

Fully smoothed data (red)

January 2014 is now the latest fully-smoothed data point. Through November, December and January all variables moved decisively away from drought, except for rainfall and daily minimum temperature. In those months, rainfall remained near a (drought) minimum. Daily minimum temperature (which has a cryptic relation to drought) increased, bringing very warm nights in autumn.

Note:

Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.
Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

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.

 

3-year trends to June 2014

Posted in 3-year climate trends, Manilla NSW by

Parametric plots of smoothed climate variables at Manilla
“Climate normal for now”

Trends to June 2014

 June data (orange)

Raw anomaly values for June 2014 have nothing in common with the droughty conditions at the end of 2013. Daily maximum temperature and rainfall (top left graph) are both normal. A return to a moist climate, like that in spring 2011, shows as cloudy skies (top right), high dew point (mid left), and narrow temperature range (mid right). Daily minimum temperature (lower left) has moved independently to a high value (that is, very warm nights). Only subsoil temperature (lower right) has jumped back to warm 2013 values, after a period of normalcy.

Fully smoothed data (red)

December 2013 is now the latest fully-smoothed data point. It seems to mark the point of lowest rainfall and dew point anomalies in recent months. In other variables (except daily minimum temperature) December continued a retreat from recent extreme (drought) values.

Note:
Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.
Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

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.

 

17 Years of “Droughts and Flooding Rains” at Manilla

Posted in 21st-century climate, Anomalies smoothed, Australian Climate, Climate Change, Manilla NSW by

Manilla 17-year smoothed rainfall anomaly record

Times when Dorothea Mackellar’s “droughts and flooding rains”* affected Manilla in the years from 1997 are shown by the wavy line on this graph. The climate swings in and out of times of high and low rainfall.

Peaks or troughs were often a year or two apart, but most of them were not very far from the normal rainfall value. Only two of the troughs were so far below normal that they were severe droughts: August 2002, and December 2013 (or maybe later). Milder droughts came in October 2006 and September 2009.
The rainfall in these 17 years was not below the long-term average, but slightly above it. As well as droughts there were two peaks of extremely high rainfall: in July 1998 (when the new Split-Rock reservoir suddenly filled) and in November 2011. These “deluges” had rainfall that was further from normal than the low rainfall in the droughts. Other rainfall peaks came in November 2005, October 2008, and October 2010.
In total, there were nine peaks and troughs with rainfall outside the normal range. Six of them came in the spring months of September, October or November.
Peaks and troughs in rainfall at Manilla quite often come near times of La Niña and El Niño. These are events in the record of Pacific Ocean temperatures called ENSO (El Niño – Southern Oscillation). The ENSO record for the last 17 years is shown in the second graph.

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Profile of an Extreme Drought

Posted in 21st-century climate, Climate events, Manilla NSW by

Rainfall vs Maximum temperature, 2002 droughtAt Manilla, NSW, there was a drought in 2002 that was extreme, but brief. There have been no other extreme droughts at Manilla in the 21st century. The current drought is not as bad (yet).
The first graph shows a profile of the 2002 drought. Low rainfall is at the top, and hot days are on the right. Droughts, with low rainfall and hot days, will be near the top right corner. Normal climate is marked by a rectangle (coloured aqua (aqua)) in the middle.
The climate in these months moved into drought and out of it. January 2001 (Start) had perfectly normal climate with no drought, and so did February 2003 (Finish). Rainfall first became lower than normal after January 2002, and reached a minimum 27 mm below normal in July 2002. Rainfall returned to the normal range by December 2002. Day-time temperature went above the normal range in May 2002, reached a peak 1.3 degrees above normal in September-October 2002, and fell back into the normal range in January 2003. For rainfall lower than normal, the drought lasted ten months: for days hotter than normal, it lasted eight months. In this drought, the time of lowest rainfall came two to three months earlier than the time of hottest days.

(There is more detailed analysis of  the 2002 drought in a post dated September 2004.)

Graphs showing the progress of the drought as rainfall shortages are in the post “The 2002 rainfall shortages at Manilla”.

The loop on the graph shows this drought as a simple event with a beginning, a middle, and an end. Droughts are not usually seen to be so simple. This graph is made using two “tricks”: anomalies and smoothing. You must judge whether you trust them to describe the drought as it happened.

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