Final comments on the 2010 / 2011 La Nina for NSW including March 2011

This is the final statement for this topic from me and provides some final conclusions to the La Nina summer of 2010/2011.

For the month of March, the wettest areas were the far west, southern Central West of the state, Riverina, South Coast, Illawarra and north east Sydney. Rainfalls were up to 200 mm above average on parts of the South Coast. The driest areas of the state were the North Coast and Northern Inland. A couple of pockets on the North Coast and the Hunter Valley had rainfalls that were 50 to 100 mm below average. In Western Sydney, rainfall returned but rainfall was average or just below average for the month.  

For the 6 month period 1/10/10 to 31/3/11, South West New South Wales has done very well with rainfall right across the summer. However La Nina has left Western Sydney, Newcastle and Hunter Valley with rainfalls that are below average. Rainfalls of 100 to 200 mm below average has occurred. In most areas, La Nina delivered strong rainfalls or at least average rainfalls except in the areas mentioned. There was rain in March across Western Sydney or Sydney in general but deficits remain. South West Western Australia was also a little dry but the deficits are greatest around Sydney and Newcastle region.

Looking at the March to October Rainfall Anomaly, there is no drought anywhere in New South Wales following summer rainfall. However La Nina has not been as good as expected for Western Sydney, Newcastle area and parts of the Hunter Valley. It was drier than expected in the areas mentioned. Amazingly and unexpected, an area of the Lower Hunter around or near Singleton started to experience a serious rainfall deficiency. This is more pronounced in the January to March period. An area near Tamworth and a small area near the New South Wales / Queensland state border also started to experience a 3 month rainfall deficiency till 31/3/2011.

Further to the above, there was was 75 mm of rain last month at the Collins Street Weather Station site at Seven Hills. The records have been recovered to provide a better outcome for Blacktown and to complete the records.

The plots described above have been produced on the Land and Water site Bureau of Meteorology on 10/4/2011. However I will upload these as soon as I fix the problem with my computer with respect to uploading plots.

Harley Pearman

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