Re: La ~ Nina and her effect on the Australian storm season / General weather

February conditions for New South Wales 2011

Weather conditions for the month varied considerably to what was suggested by POAMA. It appears that the POAMA plots for February did not accurately predict the conditions. Rainfall was expected to return closer to normal but instead heavy falls occurred in the southern Murray Darling Basin while much of NE NSW was dry. Further, a cooler than normal month occurred over the south west of the state while other parts of the state was warmer than normal.
 
Rainfall anomalies

An extremely wet month for parts of south west New South Wales contrasts with a dry February around Sydney and parts of the far north coast around the Tweed Valley. Significant rainfalls occurred over the southern Murray Darling Basin with the highest falls in order of 200 mm up to 400 mm above average for an area from Corowa east to Mt Kosciusko. West and south west New South Wales had above average rainfalls from 25 mm to more than 200 mm. The rest of the state was drier. Other than small pockets near Armidale and Barrington Tops, the rest of the state was rather dry. The driest areas occurred around Sydney, Gosford and the Tweed Valley where rainfalls were 100 mm to 200 mm below average.

Of note and not produced here, when looking at the rainfall plot 1 December 2010 to 28 February 2011, the area around Sydney / Newcastle / Wollongong and lower north coast has had the driest summer of any region in Australia.

Maximum temperatures for NSW

South west New South Wales experienced a cooler than normal month. Much rainfall occurred in that region and as a result of cloud cover and rain, maximum temperatures were 2C to 3C below average. Contrast to north east New South Wales, daytime temperatures were 1C to 3C above average for the month. The area around Sydney, Newcastle, Wollongong and the Hunter Valley had day time temperatures that were 2C to 3C above average. This co incides with a dry February.

Minimum temperatures for NSW

The plot shows that night time temperatures were for the whole of the state, average to above average. The warmest night time minimum temperatures occurred over the northern inland of New South wales where temperature anomalies were 2C to 3C above average.

Further to the above, I made a trip into southern New South Wales 19 to 22 February 2011 and the effects of the rain in that area was evident. Rivers such as the Murray was flowing swiftly. The Ovens River at Bright (Victoria) was at minor flood level following a heavy downpour. The Hume Reservoir was at 99.3% capacity and rarely seen at this level at this time of year. The Murray River at Albury was not at flood level but was unusually high. Further the region looked unusually green. I was at Albury when a new monthly rain record was set there (267 mm of rain in February being the highest ever). This is a big contrast to the recent drought years.

The plots referred to are provided below and have been generated from the Water and the Land site Bureau of Meteorology dated 12/3/2011.

Harley Pearman

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