A strong cold front has passed through southern Australia which is now progressing into north eastern New South Wales.
Ahead of this change, a warm to hot air mass surged southwards which resulted in temperatures reaching into the low to mid 30S however the air behind the change is relatively cool to cold.
This is a significant change due to the temperature changes that are occurring ahead and behind the change. For example, it reached 32.6C in Blacktown on Saturday but it has struggled to reach 20C on Sunday (Maximum being 20.2C).
Similar conditions are being felt across New South Wales ahead and behind the change.
A feature of this change is the large slow moving north west to south east cloud mass and rain band that marks the change. A closer look at this reveals a band of cloud that marks the presence of thunderstorms / embedded thunderstorms that is occurring at the leading edge of the rain band.
The change reached Western Sydney including Blacktown after 4 am Sunday morning. Some thunder was audible on the leading edge of the rain band between 4 am and 5 am with heavy showers. More general rain followed thereafter before easing into lighter showers.
Some rainfall figures include:-
Victoria (For the 24 hours to 9 am 14/3/2021)
42 mm at Mt Baw Baw.
40 mm at Mt Donna Buang.
20 to 29 mm across parts of the outer eastern suburbs of Melbourne in areas close to the Dandenong ranges.
New South Wales (For the 24 hours to 9 am 14/3/2021)
53 mm at Orange.
48 mm at Putty.
47 mm at Kulnurra (Jeavons).
46 mm at Wyee.
37 mm at Nowra.
30 mm at West Pennant Hills.
(For the 6 hours between 9 am and 3 pm)
The impacts are more noticeable as the system moves towards and into north east New South Wales. Rainfall figures for the 6 hours include:-
72 mm at Tangary Mountain.
60 mm at Elderslie.
49 mm at Tocal.
40 to 44 mm around Maitland.
The satellite photo from Himwari clearly shows the cloud mass that features this change with cumulonimbus clouds visible on its leading edge. The radar image of Sydney early Sunday morning shows the structure of the change with heavier rain evident on its leading edge with the change encroaching onto the Hunter Valley by 8 am.
The photo attached is showing one of the heavier showers that occurred Sunday morning at Blacktown.
The period between the 8 and 12 of March 2021 has been active and rain / showers and storms have been a feature across large areas of eastern New South Wales. Storms have impacted Sydney on at least 2 days during this period being Monday afternoon with the area between Penrith and Blacktown being impacted the most and Friday afternoon with southern Sydney being impacted.
Rain and storms have featured across wide areas and some of the more significant events include:-
8 March 2021
Penrith to Blacktown Storm event - While the storm was embedded within existing cloud, this storm that traversed the Penrith to Blacktown region produced the occasional cloud to ground lightning including two cloud to ground strikes that occurred well ahead of the main storm core.
This storm produced peak wind gusts of 78 km/h at Penrith and a peak rainfall intensity of 13.4 mm between 4.25 pm and 4.30 pm (An intensity that exceeded 2 mm per minute). This storm impacted Blacktown and produced strong to gale force winds (Downbursts) and short but sharp heavy bursts of rain. Erskine Park recorded 23 mm followed by Penrith where 18.2 mm. The area around Blacktown had between 12 and 16 mm of rain.
The photos attached to this post are taken as the storm was approaching from the west.
This storm went into rapid decline as it passed over the Parramatta area.
Taree - A significant thunderstorm impacted the town which resulted heavy rainfall of up to 45 mm to 5.35 pm. At 5.01 pm, the rain gauge had registered 7.2 mm. However, by 5.10 pm, the rain gauge had recorded 29.2 mm. This is a fall of 22 mm in 9 minutes or just over 2 mm per minute.
The local weather station recorded peak wind gusts of 78 km/h during the peak of the storm.
11 March 2021
Cowra - The town was impacted by a significant event which resulted in 48 mm falling with 29.2 mm falling in 1 hour between 3.30 pm and 4.30 pm.
Goulburn (Gundowringa) (NW of Goulburn) - A rain / storm event saw a fall of 64 mm at this location.
Wingen - For the 24 hours to 9 am, 62 mm of rain fell.
Oberon - For the 24 hours to 9 am, 58 mm of rain fell.
Orange - For the 24 hours to 9 am, 52 mm of rain fell.
Other significant falls include Ben Bullen 55 mm and Newbridge 53 mm.
Southern Sydney - At least two storm cells have impacted the coastal suburbs close to the airport and Cronulla which has seen rainfall totals top 45 mm at Little Bay and 42 mm at Marrickville Golf Club.
Sydney’s Observatory Hill recorded 20 mm of rain between 7.30 pm and 8.10 pm with a total of 25.6 mm falling.
Wallis Lakes (Pacific Palms) on the lower North Coast recorded 104 mm of rain.
The last photo attached to this post is showing one of the storm cells just after sunset looking east.
There have been other similar events across the Hunter Valley, North Coast, North West Slopes and Central Tablelands during this period. Generally only the far west and south west of New South Wales have missed out on this event.
A significant heatwave has gripped south east Australia over the past 4 to 5 days and is presently ending due to a cool change that is slowly crossing the southern part of the continent.
This event has been most noteworthy across the inland regions of Victoria and New South Wales although it has been strong enough to spill over into parts of Western Sydney although generally west of Parramatta.
As shown in the plots produced on the “Water and the Land”, for temperature, the worst affected regions haves been the south west part of New South Wales, Northern Victoria and South Australia.
There has also been a major bushfire emergency in the Adelaide Hills although a cooler change and at least 20 mm of rain has helped fire fighters to contain the blaze.
Maximum temperatures within the worst affected regions have included:-
Other significant temperatures during the event include
Yarrawonga - 40.8C on Saturday.
Ivanhoe - 40.7C on Saturday,
Wilcannia and Yanco - 42C on Monday.
Walpeup (NW Victoria) - 43.9C on Sunday.
Mildura (NW Victoria) - 40.4C on Saturday and 43.3C on Sunday.
Swan Hill (NW Victoria) - 41.8C on Sunday.
The most affected regions are those that have not received the benefit of the recent rainfall.
Sydney has generally missed the worst of the heat although some has spilled into the Sydney basin affecting mainly areas away from the coast being the inland suburbs of Blacktown, Penrith, Camden, Richmond and Campbelltown. Anywhere further east has been cooler due to the sea breezes.
Even with maximum temperatures forecast to reach between 36C and 41C across Sydney, it is coming ahead of a cooler change Tuesday night / Wednesday morning.
Maximum temperatures during this event have included (Penrith east to Sydney as an east to west cross section):
This gives some indication that the level of heat being experienced across the inland suburbs is not progressing east beyond Parramatta. However, it is noted that it has reached 30C at Sydney Observatory Hill on 4 days in a row and if the 36C is reached for the 26/1/2021, this would result in 5 consecutive days where it has reached 30C which is not common in summer.
A feature of this event for the Sydney basin were the development of an isolated thunderstorm on Friday afternoon (Over NE Sydney), Saturday afternoon that produced flooding at Marsden Park (Covered in a separate article) and another isolated stormcell on Sunday afternoon across the Blue Mountains as shown in the attached photo looking west. This storm did not make it into the Sydney basin but the anvil cloud cover and later additional cloud provided some relief Sunday afternoon from the heat although it made for a warm uncomfortable night.
The cool change across the south has brought welcome rain including 16.8 mm at Deniliquin and 12 mm at Mildura and useful totals of up to 29 mm over the Dandenong Ranges (East of Melbourne). The cool change will progress towards Sydney Tuesday and conclude this current weather event late Tuesday / early Wednesday for Sydney and much of New South Wales.
Addendum 26/1/2021 - On Tuesday maximum temperatures reached 37.1C in Sydney City (Observatory Hill) making it 5 days in a row where maximum temperatures have reached 30C. Other maximum temperatures include 41.6C at Sydney Airport, 41C at Sydney Olympic Park, 40.7C at Penrith, 39.8C at Richmond and 39.1C at Horsley Park.
Most areas of Sydney has topped 38C to 41C with minor variations and it is noted that maximum temperatures were reached between 2 pm and 3pm. Increasing cloud cover from the approaching cool change after 3 pm is resulting in a slow drop in maximum temperatures and as such the worst of the heat has now passed.
It also reached 39C at Coonamble and over 36C at Dubbo but the cool change is having a significant effect across New South Wales, lowering temperatures, producing some light rain / showers especially to the south and concluding this weather event.