Category Archives: Rain

precipitation in the form of droplets

Cold outbreak – Snow, Cold, Rain and Wind – SE Australia 8 to 11 June 2021

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During August 2019, a significant cold outbreak occurred over Southern Australia that brought low level snow falls to the Blue Mountains including Katoomba and Leura as well as elevated areas of the Central Tablelands. My wife and I documented this event and for the first time ever, I saw snowfall at Leura, Katoomba, Blackheath and Mt Victoria.

The three photos attached are taken from this event. Roads were closed due to icy conditions and snow fell to low levels relatively close to Sydney.

There was also a similar event during the winter of 2020 and now another similar event has just occurred. During the period 8 to 11 June 2021, low level snow fell again across the Blue Mountains, the Central Tablelands and even elevated areas of the Northern Tablelands. In addition, the Snowy Mountains saw heavy snow falls to coincide with the start of the ski season.

The snow images seen in the above photos were again replicated at Leura, Katoomba, Blackheath and Mt Victoria. Generally, snow fell above 850 metres in elevation, roads were closed and icy conditions prevailed.

However this event was remarkable in that Sydney (Observatory Hill) saw its coldest day in decades in which the maximum temperature reached 10.3C following a minimum of just 6.7C (10/6/2021). However what is more remarkable is that this temperature occurred under northern winds. Frigid air was circulating around an intense low pressure cell so that the northerly winds had in fact originated from the south.

It reached a maximum of just 8.9C at Horsley Park and 9.5C at Parramatta.

It is suggested in the media that this could have been the coldest day in 37 years while other media reports suggests that it has not been this cold since 1899.

Some old weather records for Sydney have been reviewed and it is determined that the recent cold day is not the coldest ever recorded for the city as there have been colder days. However, cold days where the maximum temperature fails to reach 10C are rare. Sydney has grown over the years and there are records for Sydney Observatory Hill going back to 1859 and hence the coldest winter days have been:-

Maximum 7.7C on the 19 July 1868.

Maximum 9.1C on the 9 August 1872.

Maximum 9.7C on the 13 June 1899.

Maximum 9.5C on the 8 September 1869.

There is suggestion of a very rare cold day on the 28 June 1836 as reported in the Sydney Morning Herald and around 6 am, the temperature was around 38F (Roughly 3.3C) and it began to snow in the morning with the snow lasting a few hours. It is claimed that the maximum temperature reached 50F (Roughly 9C later that day). This cold day occurred 23 years before weather records began. This event is controversial as there are questions as to whether it was soft hail or actual snow and what instruments were being used to record the temperatures. Either way, the 28 June 1836 was a cold day but whether it was actual snow or soft hail will probably never be known.

The cold day Sydney just experienced was not the coldest on record, but it is rare to see such low temperatures given Sydney’s location and its climate.

There is an account of the 1836 event attached to this post and the fact that snow is suggested in the forecast or weather conditions being experienced for Sydney does make it significant.

The coldest maximum temperature that can be found for Richmond is 9.5C on the 13/7/2011. It reached 8.3C on Thursday which would make it a new maximum low for this weather station and colder than the 11.5C recorded as the maximum day temperature for the 27 June 2007. Records only go back to 1994 at this weather station.

Other low maximum day temperatures for Thursday include:-

Sydney region

Parramatta 9.5C.

Horsley Park 8.9C.

Penrith 8.3C.

Regional and Rural New South Wales (Including)

Albury Airport - 9.8C.

Armidale 5.6C (At Armidale, it reached 7.6C on the 9/6/21 and 9.7C on the 11/6/21).

Cooma 3.2C with a minimum of 0.0C.

Glenn Innes 5.1C.

Goulburn 6.9C with a minimum of -1.7C.

Orange -0.3C to a maximum of 3C.

Oberon -2C to 5.2C.

Rainfall

The same system also brought some significant rain to certain areas. While Sydney received light to moderate falls some of the rainfall that occurred elsewhere was remarkable given location.

Victoria

An area to the south of the Great Dividing Range but east of Melbourne received some heavy rainfall which resulted in flooding. Flooding was observed around Taralgon as well. Some of the heaviest falls for the 24 hours to the 10 June 2021 include:-

Thompson Yarra Divide - 241 mm.

Licola - 170 mm.

Noojee - 154 mm.

Reeves Knob - 144 mm.

The hilly areas of outer Melbourne’s east received between 50 and 100 mm. In addition to the rain, power was lost and trees were brought down due to wind and a clean up is currently underway.

New South Wales

Perisha Valley - 62 mm (Mostly as snow).

Thredbo - 50 mm (Mostly as snow).

A rain event across parts of the Central West of New South Wales saw good totals of up to 42 mm falling including 42 mm at Dubbo, 40 mm at Barina, 38 mm at Neura and 36 mm at Coonabarabran.

Wind

There were instances of wind damage and trees being felled especially across snow affected areas and across southern Victoria. However, the strongest wind gusts occurred at Mt William (The Grampians) where a single gust of 115 km/h occurred. Further, the lighthouse at Wilsons Promontory recorded one wind gust of 111 km/h at 2.30 am on the 10/6/2021 and the Puckapunyal West (Defense) weather station recorded a single gust to 111 km/h at 3 am on the same day.

At Mt Buller, peak winds gusts reached between 104 to 107 km/h for the 10/6/2021.

As such, this was a dynamic weather system that has created a wind range of weather that has disrupted large swathes of South East Australia. During Friday, conditions moderated dramatically allowing for a clean up to occur including a gradual warming of daytime temperatures.

Significant cold snap with low level snow NSW and Vic – 8 to 11 June 2021

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Weather models currently identify a significant cold outbreak for South East Australia during the period of 8 to 11 June 2021. Models show a cold front and later the development of a cut off low over South East Australia although the final exact position of the low is still difficult to determine at this stage.

On Tuesday, a cold front will cross the southern states that should bring a rain band across the inland. The cold air mass following the change is cold enough to allow snow to low levels. Forecasts are being made for snow as low as 600 to 700 metres within southern areas.

This system is expected to develop further as a cut off low that will allow cold air to move further north and with it, showers, small hail, sleet, low level snow falls and even gale force winds.

Snow is expected to fall across the higher areas of North East Victoria and Southern New South Wales. Further to this, the MET Eye models are suggesting that snow falls will occur around the Central Tablelands of New South Wales including Oberon and Orange by Wednesday and into Thursday. Models even suggest that snow will fall over higher elevations of the northern tablelands including towns such as Guyra, Glenn Innes, Walcha and Armidale.

While the ski resorts should receive significant falls, places like Oberon, Orange and possibly Lithgow in the Central Tablelands should receive some snowfall at times. Snow is even expected to fall close to Canberra but unlikely at this stage to fall within the Canberra City area. However, snow may still occur on Mt Ainslie and Black Mountain.

Models show a significant rain event from this with a rain band crossing the inland regions with at least 10 to 20 mm of rain to occur. However, over the longer run, higher rainfall totals are likely over the hilly regions of eastern Victoria grading to snow at higher elevations with as much as 100 mm falling.

For Sydney, a rain event is forecast from the event on Wednesday.

The primary concern for this event would be the cold and gale force winds, snow at higher elevations and issues of black ice on roads and threats to livestock such as sheep and cattle.

The models attached to the post shows the system that is expected to develop over coming days including snow forecasts, maximum temperatures and rainfall. However, as models develop further, there will be variations to final forecasts being made.

North Indian Ocean – Tropical Cyclone Tauktae – 15 to 18 May 2021

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A look at the Worlds tropical cyclone tracks will reveal that the majority of all tropical storms form within certain ocean areas including the north west Pacific Ocean, an area of the west coast of Central America and Mexico, the tropical Atlantic Ocean north of the Equator including the Gulf of Mexico, the Western Pacific Ocean including areas within Australian waters and the tropical Indian Ocean within the southern hemisphere between Australia and Africa.

There is also another area where such storms can occur but are much less likely being the North Indian Ocean situated between India and the Arabian Peninsula. Occasionally a storm will form within this area and track towards the North West India / Southern coast of Pakistan but instances of such occurrence are relatively rare.

During the period 15 to the 18 May 2021 a significant tropical storm has formed within an area where tropical cyclones are generally rare. This storm was named Tropical Cyclone Tauktae which formed off the west coast of India then tracked northwards towards the north west coast of India and even threatened the south east coast of Pakistan. Landfall occurred between Porbandar and Mahuva (Gujarat State - India).

At peak intensity, this storm reached Category 4 on the Saffir Simpson Scale with peak wind gusts at the core of at least 115 knots (Approximately 213 km/h). This storm was supported by ocean waters within the range of 30 to 31C and atmospheric conditions were certainly favourable for supporting such a strong storm. Strong convection and thunderstorm cells were visible on satellite images especially to the south of the eye which supported the storm. This storm weakened just before commencing landfall over Gujarat State.

This storm has brought heavy rain especially around Saurashtra and numerous west coast localities were warned for heavy rain as the storm tracked northwards. Media reports suggests a significant impact onto the north west Indian coast with at least 26 fatalities mainly within coastal locations, flooding, heavy rain and intense wind gusts. It is believed that upwards of 200,000 residents were evacuated prior to the storm making landfall.

The images attached to this post are taken from Worldview and CIMSS. Information was also sought from the India Meteorological Department 17/5/2021 prior to the storm making landfall.

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