Tag Archives: drought

3-year trends to May 2014

Posted in 3-year climate trends, Manilla NSW by

Parametric plots of smoothed climate variables at Manilla
“Drought status not clear”

Trends to May 2014

May data (orange)

Raw data for May 2014 give mixed signals on whether the drought is fading. Daily maximum temperature is now on the high limit of the normal range and rainfall again well into the “drought” range. However, other variables do not agree: skies were very cloudy, and dew point and daily temperature range were back to normal.

Fully smoothed data (red)

The spring months (SON) of 2013 are now fully smoothed, with some variables showing a drought peak in that season.
Smoothed daily maximum temperature anomaly peaked in October, reaching a record high of +1.39°, beating +1.34° in November 2009 and +1.30° in September-October 2002. Through spring the smoothed rainfall anomaly decreased; it may have reached a minimum in January. Dew point also decreased, the smoothed anomaly reaching a new record low of -4.85° in November, and likely to reach a minimum in December.
Cloudiness reached a minimum in October, and daily minimum temperature and subsoil temperature anomalies had reached maximum values earlier, in July.

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 April 2014

Posted in 3-year climate trends, Manilla NSW by

Parametric plots of smoothed climate variables at Manilla
“Are we coming out of drought?”

Trends to April 2014

After a very cool moist March, raw values of climate anomalies for April 2014 are nearly all back near the (slightly smoothed) values for February. However, neither month was as hot or dry as December or January.
Fully-smoothed values for October 2013 show the deepening drought. That month set a new 21st century record for smoothed daily maximum temperature anomaly of +1.39°, beating the value of +1.35° set in November 2009. It also set a new low record for dew point anomaly of -4.53°, far more arid than the record set the previous month: -3.53°.
These curves show clearly that the climate (at this site) consistently became warmer and drier through the two years from spring 2011 to spring 2013, except for a brief time of reversal in the six warm-season months from October 2012 to March 2013.

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.

Predict weather from ENSO?

Posted in Australian Climate, Climate Change by

(Someone asked me to set down my thoughts about this.)

“Droughts and flooding rains” *

The climates of places in Australia cycle from hot, arid and dry, to cold, humid and wet every couple of years. (Dorothea Mackellar said she loved a sunburnt country “of droughts and flooding rains”. *) This is a kind of quasi-biennial oscillation (QBO).  For more about the QBO, see this post, and the links in it. The cycles get weaker and stronger, more droughty or more rainy, and sometimes take about one year, sometimes three or more.

The climate of the Pacific Ocean has similar cycles, called the Southern Oscillation, discovered by Gilbert Walker a century ago. The pressure difference between Darwin and Tahiti oscillates in a way that reflects other widespread changes in climate. This is now called the El Niño – Southern Oscillation (ENSO) and it is monitored by sea-surface temperature east of Nauru in the Pacific Ocean, called NINO3.4. Now that we have up-to-date data on NINO3.4, the public has been led to believe that the data can be used to forecast Australian weather. It really can’t.

Problem No.1: Weather varies from place to place.

Every district in Australia has different weather, so one size does not fit all. Wasyl Drosdowsky made a map defining the regions that have consistent relationships to ENSO and other indices, but nobody has taken up the idea. (I would if I was boss of the Bureau of Meteorology!) Drosdowsky’s regions are rather similar to the States, but Victoria and the southern half of South Australia form a single region.

Problem No.2: Forecast is too late.

The ENSO cycle does not predict a cycle in any part of Australia because it happens at about the same time, and it takes a month or more to collate the data. Weather prediction from ENSO is always late. Consequently, there is a business to predict ENSO some months ahead. These predictions are very unreliable. Then the predictions of ENSO values are used to predict Australian weather, with vague statements of which regions will be affected.

To make matters worse, my Manilla data from 1999 shows that my weather happens in advance of the ENSO changes. I compared the ENSO log from 1999 to 2011 with smoothed daily maximum temperature anomaly, (1 month ahead)  smoothed monthly rainfall anomaly, (2 months ahead) and smoothed early morning dew point anomaly(3 months ahead). If droughts and deluges happen before peaks and troughs of ENSO at other places in Australia, this makes prediction from ENSO even less likely to work.

[Note added 14/07/2015. Updated graphs comparing the ENSO log from 1999 to 2014 with smoothed daily maximum temperature anomaly and smoothed monthly rainfall anomaly at Manilla are in this post. Manilla’s climate has not related very well to ENSO since mid-2011.]

[Note added 10/10/2019. Updated data confirm that ENSO lagged Manilla rainfall by 2 months from 1999 to August 2011, then failed to relate to Manilla rainfall after September 2011.
See: “21-C Rain-ENSO-IPO: Line graphs” and “21-C Rain ENSO IPO: Scatterplot”.
According to Power et al.(1999), Australian rainfall usually fails to relate to ENSO when the IPO goes positive, as it did from 2014 to 2017 (and 2018?).]

* By arrangement with the Licensor, The Dorothea Mackellar Estate, c/- Curtis Brown (Aust) Pty Ltd.

Data are cheap; information is expensive!

Originally posted on 12/5/2013 to a thread “ENSO Discussion 2013” on a “weatherzone forum.

Extremely Arid October 2013

Posted in Manilla NSW, Monthly weather by

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 December 2012

Posted in 3-year climate trends, Manilla NSW by

Parametric plots of smoothed climate variables at Manilla

“Retreat from drought”Trends to December 2012.

In December, the anomaly of daily maximum temperature retreated from the November extreme of +3 degrees to +1.5 degrees. Dew Point and daily temperature range also retreated from drought values. Cloudiness remained normal and daily minimum temperature high. Subsoil temperature returned to the very high values of the winter months.
The variables maximum temperature, minimum temperature, and temperature range are now close to the smoothed values they had three years ago, in December 2009.

Fully-smoothed data (in red) for June 2012 have reached new records for low Dew Point anomaly (-2.61 degrees) and for high subsoil temperature anomaly (+1.99 degrees).

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.