Tag Archives: Hunter Valley

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

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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

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

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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…

Storm Events and Reports

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Some of the storm events that have been photographed over this below average season have been documented below with some information in regards to hail size intercepted.

March 15 20090315jd021 Storm Events and Reports

Severe storms affected the Hunter Valley region but most storms of more significant severity producing large hail were near the Karuah to Bulahdelah region. Hailstones to 3cm were widespread along this path perhaps larger in the main core as these hailstones were falling predoinantly ahead of the main core in the anvil region.

23rd February 20090223jd08 Storm Events and Reports

A severe storm on Monday 23rd February exhibited classic supercell structure with very definite hailstones! The structure did not last for long before it went into a slow decline. Nevertheless althoguh Sydney area did not have any storms predicted storms did develop further west. Twice the storm tried to organise before basically sending up an impressive explosive updraft and organising rapidly.

 21st February 2009

Several storms were reported with storms rapidly developing near funnel cloud in the form of a dimple almost overhead whilst near Wallerawang - Lithgow regionLithgow initially and also east of Mudgee a little later. There were likely two supercells out of this region. The Lithgow cell had an interesting base – this nice image of a base circulation and dimple of a funnel almost overhead. This coincided with a wind change in the near storm environmental boundary.

This storm eventually moved towards but narrowly bypassed Singleton with very large hailstones. Another severe storm passed in the hinterland west of Muswellbrook – both this and the Singleton storm were likely supercells producing very large hailstones.

February 10 2009

Hailstorms Lithgow to near Lake Macquarie. The storm that approached Lake Macquarie was a fast moving storm and dumped hailstones to a diameter measured at 4cm. hailstone from hailstorm at Dora Creek from February 10 2009It most likely was an elevated supercell and was interesting to watch as it altered its local environment suddenly clearing the low cloud as it raced across.

Another sharp right moving storm approached Lithgow from near Mudgee and produced hail damage in Lithgow where The Dent Shed helped repair vehicles over the following weeks.