Extremely Arid October 2013

October’s climate was even more desert-like than this September or October last year. Afternoon humidity (normally 30%) was only 13.1%, which is the lowest value in ANY month in the last eight years. The early morning dew point of 0.5° was the lowest October value this century, and 7.8° below normal, a record anomaly value for any month. This very dry air often came with strong winds. Most of north-west NSW was affected.

The daily weather logWeather log October 2013.

The second of two warm spells brought weekly temperatures three degrees above normal. Each warm spell ended with a night above 20°. Three mornings from the 25th were exceptionally dry, having dew points of minus 7.2°, minus 8.0°, and minus 7.6°. (The record: minus 9.3° on 17/5/11.)
There were three rain days: the 2nd with 13.8 mm, and the 18th and 30th with 0.6 mm each.

Comparing October monthsClimate October 2013.

October’s days were not quite as warm as in 2007. Dryness was marked by low rainfall, little cloud, and wide daily temperature range, but most remarkably by the record low dew point and relative humidity.
At 21.0°, the subsoil was warmer than in any other October month. It was 1.6° above normal.
The total rainfall of 15.0 mm was in only the 12th percentile, far below the average of 58 mm. The three and four month rainfall totals (41 mm; 71 mm) are now severe shortages, in the 3rd and 4th percentiles.


Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Temperatures, including subsoil at 750 mm, and other data are from 3 Monash Street, Manilla.

3-year trends to September 2013

Parametric plots of smoothed climate variables at Manilla
“Desert-like climate”Trend to September 2013.

Raw values of climate anomalies for September 2013 all show extreme aridity: they are in the top right corner of the graphs.
The latest fully-smoothed data point, March 2013, continues a trend towards normalcy and away from the mild drought seen in spring 2012.

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.

Desert-like September 2013

September was an exceptionally arid month: like the Sahara Desert!

The daily weather logWeather log September 2013

Most days were warmer than normal, with the first 30-degree day of spring coming two weeks early, on Sunday the 8th. Weekly average temperatures showed two warm spells three degrees above normal. Half the mornings had completely blue skies. The air was extremely dry: the dew point early on the 12th was 6.3 degrees below zero, and all the afternoons of the final week had relative humidity below 10%.
Briefly, from the 16th to the 18th, the weather was cooler and more humid, with 19.4 mm of rain.

Comparing September monthsClimate September 2013.

Nearly all the monthly weather values were exceptional. As noted on the graph, they were record September values (from 1999): highest maximum and mean temperatures, widest daily temperature range, lowest dew point and fewest cloudy mornings. (The September daily minimum temperature had been higher: 9.7° in 2002, and 8.2° in 2010.)
The total rainfall of 19.4 mm is half the average of 41.2 mm. It is in the 28th percentile. The two and three month totals are now serious shortages, in the 6th percentile. The 24 month total (1508 mm) and 36 month total (2231 mm) are still very high.


Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Temperatures, including subsoil at 750 mm, and other data are from 3 Monash Street, Manilla.

Winter 2013 Warm

Weather log winter 2013

This winter, June was very cloudy and wet, July was very warm, and August was warm and dry. This pattern was common across northern NSW.
There were only 29 frosts, well below the winter average of 44, and fewer than in winter 2010 (32).
All winter average temperatures were above normal: daily max (18.9°), up by 0.8°; daily mean (11.6°), up by 1.2°; daily min (4.3°), up by 1.6°. In each case, winter of 2009 had been slightly warmer. As in last winter, the subsoil temperature was very high: 17.0°, which is 2.7 °above normal for winter in the decade from 1999. In that same decade, only 34% of winter mornings were cloudy; this winter’s value of 43% has become normal since.
The winter rainfall total of 134 mm is just above the average (125 mm) and in the 62nd percentile.Climate Winter 2013

Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Temperatures, including subsoil at 750 mm, and other data are from 3 Monash Street, Manilla.

3-year trends to August 2013

Parametric plots of smoothed climate variables at Manilla
“Still warm and dry”Trends to August 2013.

The raw value of maximum temp anomaly for August was lower than for July. Other variables were typical of “drought”, except for minimum temp, which was normal.

The fully-smoothed data point for February 2013 completes a summer season that moved away from drought. By February, smoothed values of anomalies for rainfall, temperature range, and minimum temperature had returned to normal, but dew point was still very low, and cloudiness and subsoil temperature were high.

El Niño – Southern Oscillation (ENSO)

The first points on these graphs (September 2010) just catch the La Niña event of spring 2010, which was followed by another La Niña event in spring 2011. At Manilla, both events produced extremely low daily maximum temperature. The 2010 event produced extremes of cloudiness, humidity (high dew point), narrow daily temperature range, and low subsoil temperature. The 2011 event produced quite different results: extremely high rainfall and extremely cold nights.

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.